*>
THE JOU'RNAL
<$nritett
Microscopical Club,
EDITED BY EDWARD MILLES NELSON,
SECOND SERIES.
VOLUME V.
1894-1897.
MARINE
BIOLOGICAL
LABORATORY
LIBRARY
WOODS HOLE MA:s. W. H. 0 I.
[Published for the Club]
WILLIAMS AND NOKGATE,
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PRINTED Br
HAZELE, WATSON, &■ Y1NEY I,D.,
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THE JOURNAL
OF THE
tymlutt lp.er08£0pual €lnh.
The Fossil Diatomace^: Older than those of Virginia and California, which are Older Miocene.
By Prof. Arthur M. Edwards, M.D., Newark, N.J., U.S.
{Read December 21st, 1894.)
I have found Diatomaceaa older than the Lower Miocene, and I desire to place this on record, more especially as they are not developing forms, but identical with those growing at the preset time.
As some geologists have expressed a doubt of my finding Diatomaceae in the Newark-period sandstone of Arlington N.J., I will state how and when I did so, and trust that others will collect the clay in which they were found, and repeat the discovery. I should say that the Newark-period sandstone is so called by Prof. T. C. Russell, and includes the red sandstones that crop out in New Brunswick, at New Haven, Connecticut, and in which the celebrated tracks were found by the late Prof. Hitchcock, at Newark, N. J., and south into Virginia. It has also been called the Jura-Triassic sandstone, and is supposed to represent the upper part of the Keuper-Sandstein of Germany.
It is now nearly twenty years since I came to reside at Newark. I saw the sandstone and came to the conclusion it must have been formed in shallow pools of fresh water, because the plants found in it were those of the shores of fresh and not salt water ; the Mollusca, scarce, of course, were fresh-water forms also. I expected to find the remains of Diatomaceas if they existed; they had been found in the coal of England, in the Carboniferous coal by Castracane, and in the Tertiary by Ehrenberg and Bailey, but I sought in vain. The fact was I searched only in Newrark itself, in the sandstone alone, and not
Journ. Q. M. C, Series II., No. 36. 1
2 A. M. EDWARDS ON FOSSIL DIATOMACE^l.
the red shale that occurs in the sandstone elsewhere. Last summer I examined the shaley sandstone at Arlington, or between Arlington and Kearney, about two miles from Newark, on the opposite or eastern side of the Passaic river, where the clayey or shaley sandstone is intercalated in strata with the ordinary red sandstone. In this clayey shale I found the Diatomaceee occurring in spots of clay about one inch or less across. The material was cleaned by washing in weak aqua ammonia and subsequent boiling in acids. The species found are as follows : —
Achnanthes subsessilis, Blir. (Achnanthidium) coarctatum, A. B.
Amphora ovalis, Ktz.
Cocconeis placentula, Ehr.
Epithemia iurgida, Ehr.
Melosira v avians, Ag.
Nitzschia (Hantzschia) amphioxys, Sm.
Synedra ulna, Ehr.
Achnanthes (Achnanthidium) coarctation, A. B., is the same as Stauroneis constricta, Ehr., and should be called Achnanthes constricta, Ehr. It was found in Chile and Mexico by Ehrenberg, and published by him in the " Abh. Berl. Akad.," the reprint in 1843 being commonly known as the " America." I have seen it only in this preparation from the Newark sandstone. The above are all I have detected up to the present, but a con- sideration of how the shale originated warrants me in the conclusion that other forms will be discovered when this sand- stone is searched more thoroughly, and at other places than Arlington, N.J.
I have found every year, for the last four or five, in a run- ning brook which is fed by the trickling of water down the sandstone, coming from the glacial drift above it, the following diatoms : — Nitzschia spectabilis, Ehr., not N. spectabilis, W. S., and which includes N. linearis, W. S., N. multifasciata, Ktz., and Synedra spectabilis, Ehr. There is also present a sigmoid form, which looks like Nitzschia sigmoidea, Ehr. (= Navicula sigmoidea, Ehr., = Nitz. elongata, A. EL H., = Sigmatella Nitzschii, Ktz). I enumerate these to show they are not the same as those found in the Newark sandstone.
Now I wish to point out the way in which I think the sand- stone and shale were formed. There were shales and sandstones
A. M. EDWARDS ON FOSSIL DIATOMACE^I. .3
in the Carboniferous period, but I have not examined them as they do not occur here. They were probably deposited in comparatively quiet water of no great depth, and it was fresh water, as there are no marine fossils. The Newark sandstone was formed in damp meadows, not marshes, containing pools of water of no great extent or depth ; for the DiatomaceaB in it are not the same as now occur in wet, but merely moist meadows, such as those around Newark, and the same diatoms exist there now in the same circumstances. I think, too, the temperature was the same in the Newark period as in the meadows between Newark and Jersey City at the present time. Ferns grew in the meadows, but no trees, and animal life was scarce. This accounts for the occurrence of shaley sandstone on the top of the red and white sandstone.
Now I have carried the Diatomacese down to the Newark period, which is much lower than the Lower Miocene, the Tertiary, to which Virginia, Maryland, New Jersey, and Cali- fornia belong, if indeed they be as old. And I wish to show they are in the Lower Silurian also, the oldest rocks except the pre-Cambrian and Laurentian, in which M. Cayeux found Eacliolaria and Sir W. Dawson Foraminifera, viz., the Eozoon. In the Hudson River epoch of the Lower Silurian age I have found Diatomaceae, and they are of the same forms as occur at the present time. I believe, of course, in evolution, but why certain Mollusca, Foraminifera, and Diatomaceae have remained unchanged up to now I, of course, cannot tell.
They have been using for ballast and filling at Lyon's Farm, N.J., on the Lehigh Valley railroad, material brought from Jutland, N.J. It consists of shale mixed with slate. The shale is yellowish or reddish, and breaks down readily wrhen exposed to the air; the slate is blue-black in colour. The shale sometimes passes into a yellowish clay, and in it occa- sionally are spots of white clay. I have examined the latter, and was delighted to find some Diatoruacese in it. They are fresh-water forms corresponding with those growing in fresh water now, and the species enumerated below are identical with those now found in existing meadows which show no sign at all of evolution. It is well to remember then that as evolu- tion has not affected the Diatomaceas in all the millions of years since the Hudson River epoch shale was thrown down, we
4 A. M. EDWARDS ON FOSSIL DIATOMACE.E.
cannot expect it to affect them now. And we must look foi something into which they were developed if we believe in evolution at all. The diatoms here are in small quantity mixed with a high percentage of sand and clay, and in the white clay only ; at least I have not been able to find them in the yellow.
I detail the method used in searching for the diatoms, so that observers may see that care has been exercised. Filtered water was always used. The rock is broken in pieces and washed with filtered aqua ammonias; this is nearly all poured off, and finely powdered bichromate of potassium added in excess. After a time sulphuric and a small quantity of hydro- chloric acid is poured on and let stand for about a quarter of an hour. The whole is washed until colourless, treated with aqua ammonias, and again washed. A portion of the deposit is dried on a slide, and a freshly-prepared solution of gum Thus in wood spirit or alcohol added ; the slide is then warmed to drive off the spirit, the cover glass imposed and pressed down.
I do not see how foreign diatoms can be introduced in this process unless by the acids, spirit, etc., used, but the forms are always fresh-water ones, and the same solutions and acids have been used to clean and mount marine Diatomacea3, and no fresh- water forms have been detected amongst the latter. Moreover the valves are often seen involved in the clay. Species identi- fied are : —
Cy rubella cistula, Hemp. Navicula elliptica, Ktz.
Epithemia gihba, Ehr. „ viridis, Ktz.
„ turgida, Ehr. Nitzschia scalaris, Ehr.
Fragilaria striatula, Grev. Stauroneis plioenic enter on, Ehr.
Melosira cremdata, Ktz. Synedra ulna, Ehr.
Navicula dicephala, Ehr. Spicules of fresh-water sponge.
I have submitted this material to the examination of a well- known geologist, and he thinks the Diatomaceae may have been washed in by percolation. I do not see, however, that this can be the case, for the clay was hard and came from the interior of the specimen.
In conclusion I believe the loess was formed in the same way as this, i.e., on large meadows, and not by the wind, in spite of the opinion of Baron Von Richthofon to the contrary. The loess of Germany, China, and America belongs to the Iceberg period,
Second Note on a Method of Preserving Rotatoria.
By Charles F. Rousselet, F.R.M.S.
(Read January 18th, 1895.)
It is now just two years ago (" Quekett Journal," 1893, Vol. v., p. 205) that I read before you a paper on preserving Rotifers as permanent objects. Since then I have continued my investigations, and have now made such progress and im- provements in the method that a second communication on the subject becomes desirable.
The principle of the process, consisting of narcotizing, killing, fixing, and preserving in a watery fluid, not appreciably denser than water, as explained in my first note, remains the same, the improvements being chiefly made in the details of the process and the choice of the fluids.
The first defect which became apparent was a darkening of the specimens, due to the trace of osmic acid remaining in the dilute Flemming's fluid used for preserving ; this was soon remedied by omitting the osmic acid in the preservative fluid, and the animals then kept their complexion very much better.
The yellow colour, however, produced by the chromic acid in some animals displeased me very much, as it gave an unnatural appearance to the usually perfectly white, glassy transparent bodies of Rotifers. I made many experiments with a number of different substances to get rid of the chromic acid. The most promising fluid for preserving seemed to be a Jn per cent, solution of bichloride of mercury, but owing to its liability of forming crystals, which could not be wholly prevented by the addition of a little common salt, I had finally to abandon it, ex- cept in a few special cases.
At the beginning of last year I noticed in the German periodical "Biologisches Centralblatt" an article by Dr. Blumm, on Formalin,* which was said to fix and preserve vertebrate eyes and tissues without shrinkage and fairly transparent. I
* Formalin, or formol, is a watery (40 per cent.) solution of formaldehyde (CH20), a gaseous substance which is produced when methyl alcohol is subjected to oxidation. It is used as a disinfectant, and iustead of alcohol,
G C. tf. ROUSSELET ON PRESERVING ROTATORIA.
procured some of tin's substance, and soon perceived that it would be very useful for my purpose. Formalin by itself, I find, does not fix the Rotifers at all well, as I was led to expect from the above article ; it rather dissolves protoplasmic structures, such as cilia, more or less completely, but it preserves them re- markably well after they have first been fixed with Flemming's fluid or osmic acid, and crystals are never formed. It has the very valuable property of preserving the animals without the least shrinkage or turgescence, and as perfectly transparent as the fixing process leaves them. The thin and delicate loricaof some Rotifers, such as that of Euchlanis triquetra, which I had not been able to satisfactorily preserve in any other fluid tried, remains perfect in shape and transparency in formalin. The strength used is 2| per cent, in distilled water.
For fixing the Rotifers I have found that osmic acid alone fixes as well as Flemming's fluid ; when used strong it darkens the animals, but if a very weak solution of \ per cent, or less be used, and allowed to act for a very short time only, half a minute at most, the animals remain white and transparent, ex- cepting only the maturing ova, which become more or less darkened on account of the fat-like substance, lecithine, which they contain. Moreover, if the animals have become coloured a little by the osmic acid the colour can be removed by passing them for a few (1-3) minutes through peroxide of hydrogen.*
For narcotizing I found the following mixture to give better results than 2 per cent, cocain alone : —
2 per cent, solution of cocai'nf ... 3 parts Methylated spirit £ ... ... 1 ,,
Water 6 „
for preserving museum specimens, is non-poisonous, and very cheap. The solution obtainable in commerce being of thestrength of 40 per cent., dilute 2g volumes of this with 374 volumes of distilled water in order to get the required solution of 2\ percent.
* Peroxide of hydrogen is simply water containing an excess of oxygen, either in loose combination or only in solution, or more probably both'; the oxygen is readily given off and bleaches by oxidizing the reduced osmic acid to OsO4. This substance does not keep good very long, and it is best to obtain a small quantity at a, lime and renew it after four or six months.
f Hydrochlorate of cocain is a very expensive drug; it is best to procure only one gramme at a time, and dissolve it in 50 c.c. of water, which will give a 2 per cent, solution. As this solution does not keep well I add at once 12 c.c. of methylated spirit, then four parts of this mixture and six parts of water will make the above narcotizing fluid.
X I mean the methylated spirit prepared with wood naphtha, not that now generally sold, which is prepared with mineral naphtha, and becomes milky ■vhen mixed with water.
C. F. ROUSSELET ON PRESERVING ROTATORIA. /
It is used by adding first a few drops to the water in which the Rotifers have been placed, then more and more at inter- vals until the animals are sufficiently narcotized. The different species vary very much in the length of time they require for narcotization ; some patients require to be treated very slowly, others very rapidly, to be able to kill and fix them fnlly extended, and for this reason it is best to treat each species separately. The general rule I follow is to add little of the fluid at first, and then, if the animals continue to expand or swim about, more and more at intervals of a few minutes, until their movements begin to slacken. Most free swimming species, I find, can be killed when still swimming about slowly, but with some it is necessary to wait until the cilia have just ceased beating. A few examples mentioned below will give some more details. In order to ascertain the right moment for killing an animal I have not before prepared, I usually separate one or two individuals, and if these can be killed fully extended with a drop of osmic acid, then the others are also ready. Of course, it is very important to kill and fix the animals before they are quite dead, as swelling and other post-mortem changes begin at once after death.
My process, then, now consists of narcotizing the Rotifers with above cocain-spirit mixture, killing and fixing with £ per cent, osmic acid for half-a-minute or less, washing out immediately and thoroughly in water for a few minutes to half-an-hour, and finally preserving and mounting in 2| per cent, formalin, or, in some cases, in bichloride of mercury and salt solution.
Rotifers with shells having high ridges or mouldings, such as Uuchlanis triquetra, Mastigocerca bicristata, Metopedia tripicra and oxysternon, some species of Brachionus, etc., must not be left long in water, as the lorica often swells a little and the ridges and mouldings become more or less obliterated ; such species must be washed quickly in water and transferred at once to the formalin, which preserves the shell perfectly.
It is very necessary, in order to avoid greater trouble after- wards and make satisfactory mounts, to transfer the living Rotifers first of all into perfectly clean water, free from any particle of foreign matter, living or dead. I keep some clean filtered pond water, and pick out and transfer the Rotifers into clean cells as many times as may be necessary. Small particles
8 C. F. ROUSSELET ON PRESERVING ROTATORIA.
become readily attached to the cilia of Rotifers when dead, and it is then often very difficult to remove them ; for the same reason it is not advisable to mount small species in the same cell with larger ones.
Instead of micro-troughs, as recommended in my first paper, I now use small square blocks of glass, with a hollow ground in and polished, as much more convenient for all the necessary manipulations. These blocks can be placed under the lens of the dissecting microscope,* or the compound microscope, if necessary, and the animals can be watched more closely, which is indispensable with the smaller species. For the purpose of washing, etc., I transfer the Rotifers from one glass block to another by means of a small and very fine pipette, funnel- shaped at one end, the funnel covered with an india-rubber membrane. I have had such pipettes made of various sizes, and can recommend them as the best yet devised for picking up small animals of all kinds in water.
In killing it is merely necessary to introduce a drop of osmic acid on to the animals under water, and then almost immedi- ately transfer them to some fresh water in another block kept ready, and then again to two or three more lots of distilled water, so as to get rid of all traces of the acid, and finally in 2 J per cent, formalin.
The following notes will give an idea of the treatment some Rotifers require, and serve in some measure as a guide to the treatment of other species : —
Stephanoceros and Floscules. — Although I had been occa- sionally successful in preparing a few of these Rotifers, I have only quite lately found the means of killing them fully extended with some degree of certainty. I will describe the modus operandi with regard to Stephanoceros; the Floscules must be treated similarly, but are more difficult. Before beginning the operation, cut and trim a very small piece of the weed to which Stephanoceros is attached, ready for mounting, and place it in a cell of perfectly clean water; then transfer the animal to a hollow-ground glass slip, the hollow of sufficient size and depth, in three drops of water, to which one drop of the narcotizing fluid has been added. After five minutes the
* A dissecting microscope of some kind is necessary ; my tank micro- scope, provided with an aplanatic lens of G or 10 power, can readily be adapted as a dissecting microscope by screwing it to a suitable stand with arm rests.
C. F. ROUSSELET ON PRESERVING ROTATORIA.
9
animal will have recovered from the first shock, and you can add one more drop of the cocain- spirit mixture, and so on? one drop every three minutes, until five drops have been added ; wait then ten minutes longer, that is 25 to 30 minutes (not more) from the beginning of the process, and Stephanoceros will be ready to be killed with one good drop of J per cent, osmic acid, which is to be placed right on the animal, not run in at the side of the cell. The animal may contract into various shapes during the process, but at the end of the 25 minutes will generally be found fully extended. It is well to place your watch on the table and follow these directions some- what closely. After half-a-minute, wash out the osmic acid, which must be done very carefully, and mount on the same slip in bichloride of mercury and salt solution. It is not advisable to mount more than one Stephanoceros on a slide, or, at least, only one small piece of weed, to which, of course, several animals may be attached.
It must here be stated that the gelatinous cases of Stephano- ceros, the Floscules, and also of Melicerta tubicolaria seem to be about the only structures which are not well preserved by the formalin ; these cases seem to swell out in length, not in width, squeezing the animals in the central opening. I had some very well prepared Melicerta tubicolaria, the tubes of which have grown to nearly three times their original lengths, showing the heads of the uncontracted animals about the centre. Unless the gelatinous cases are first removed, it will be better to pre- serve and mount these Rotifers in dilute Flemming's fluid with- out osmic acid, or in bichloride of mercury and salt solution.*
Melicerta ringens is easier to prepare, but requires patience ; little of the narcotizing fluid must be added at first, and the creature watched until the cilia move very slowly, then is the time for killing with a drop of osmic acid.
Limnias presents no difficulty. After the first dose more and more cocain mixture can be added rather quickly, and the animals may be killed fully extended while the cilia are still in motion.
GonocMlus volvox must be narcotized very quickly. The first good dose of cocain-alcohol sends the colonies spinning round
* I recommend that this solution be made as follows, as least likely to produce crystals :— Equal parts of bichloride of mercury, ^ per cent. solution, and common salt, \ per cent, solution.
10 C. F. ROTJSSELET ON PRESERVING ROTATORIA.
at a great rate. This must be followed after one or two minutes by continuous further doses until the cilia cease to move and the colonies become motionless, which is accom- plished in five to ten minutes. They are then killed quickly with osmic acid, which must be allowed to act for half-a- minute, washing out in water rather quickly, otherwise the animals separate, although perfectly preserved. The gela- tinous substance in which these Rotifers are embedded also swells somewhat in formalin, and it is, therefore, advisable to preserve the colonies in the sublimate and salt solution, and mount them in that fluid.
Asplanchna priodonta can be narcotized very quickly. Five minutes after the first dose the animals receive continually fresh doses until they swim very slowly, and are killed whilst still moving, all fully extended, almost without exception, the whole process being finished in about ten minutes.
Asplanchnopus myrmeleo must remain about half-an-hour under the influence of the narcotic, until the cilia beat very feebly, and the animals are hardly able to move.
Not ops brachionus requires a good dose of coca'in- alcohol mixture to begin with, and after ten minutes more and more doses until they gradually fall to the bottom and are unable to swim ; but as long as the cilia beat with force they will con- tract, and they must, therefore, be closely watched and killed at the moment when the cilia have stopped moving in some of the animals.
Euchlanis. With coca'in alone I had no success at all with the various species of Euchlanis, but with the cocam-alcohol mixture I have been able to prepare all the species without difficulty. They must be narcotized very quickly by adding large doses, and killed whilst still swimming about, otherwise they gradually contract.
Brachionus pala is readily killed fully extended, either by narcotizing quickly or slowly.
Brachionus urceolaris, on the other hand, is quite spoiled by the slow process, and must be narcotized as quickly as possible with large doses of the narcotic until the animals become motionless, when they are quickly killed and fixed with a drop of osmic acid.
Synchwta tremula and similar illoricate free swimmers can be narcotized fairly quickly in 10 to 15 minutes, and killed whilst
C. F. ROUSSELET ON PRESERVING ROTATORIA. H
still swimming about at a reduced speed; with a few only it is necessary to wait until the cilia have ceased beating.
Notommatadce. Those members of this family which are possessed of a slightly stiffened skin can be preserved easily enough, but the very soft, larviform species present greater difficulties, as they wriggle about constantly from one shape into another when under the influence of the narcotic, and it requires patience to kill them well extended. By trying several times one succeeds in getting a few good ones, suffi- cient for a slide ; so I have Notommata aurita with both auricles fully extended. It must here be mentioned that the formalin causes the black or opaque brain sac, which is so characteristic of some species of Notommata, to clear up and disappear. This is a drawback for these particular Rotifers, and I recommend that these species be preserved in the bichloride of mercury and salt solution, which preserves these structures.
The Philodinadce also offer considerable difficulties on account of their very soft and contractile bodies. I think, however, these difficulties are not insurmountable, but have not yet had many opportunities, having been so much occupied with other species
I may remark in passing that infusoria can be preserved by the same method. All those infusoria which have not the power of contraction are readily prepared, without narcotizing, by killing and fixing with j °/0 osmic acid, washing out im- mediately in water, and preserving in 2| 7G formalin. The con- tractile infusoria will have to be narcotized in some way, but owing to the absence of a differentiated nervous system this may prove somewhat difficult ; I have not investigated how far this can be done with 2 D/0 coca'in and the cocai'n-spirit mixture, but both these fluids should be tried.
A few hints and wrinkles on mounting Rotifers when killed and prepared may prove useful.
Instead of cement cells I now use hollowed out glass slips, which can be obtained of all sizes from Jin. to fin. in diameter, and proportionately deep. These are always ready, and have the great advantage that the often very minute animals cannot go to the edge, where they cannot be properly seen in a cement cell. Some difficulty may be experienced at first in closing the cell with a cover glass without an air bubble. This will, how- ever, soon be overcome by proceeding as follows : — Place a drop of the 2\ per cent, formalin solution in the cell, just filling it
12 C. F. ROUSSELET ON PRESERVING ROTATORIA.
and transfer the prepared Rotifers with a pipette into the cell, then place another drop on the slip by the side of the cell, about half an inch to the left, lower your clean cover glass on to this last drop, which will present no difficulty, then with a needle push the cover glass slowly, and by little jerks, over the cell, stopping short for a moment if the Rotifers show a tendency to move to the edge of the cell. But before covering the cell examine it under the dissecting microscope, and remove every fibre and every particle of foreign matter, however small, with a mounted bristle. The superabundant fluid is then removed with blotting paper until none is left round the cover ; the cover must not, however, stick too fast, and you must be able to move it with a needle, otherwise the cement will be forced in at the sides by atmospheric pressure. When ready the cover glass is sealed down by tipping some Miller's caoutchouc cement* all round the edge with a fine sable brush. The cement must not be liquid, but thickened by exposure to the consistency of a very soft jelly. The edge of the cover-glass must be carefully looked over under the lens to see that the cement covers it everywhere, and that no air bubble has been left at the edge. Cover-glasses have frequently small cracks runninginward some little distance; these must be carefully covered with cement to their ends, otherwise the fluid will slowly evaporate through these cracks, and in time an air bubble will appear in the mount When the cement is dry, that is next day, the slide can be finished with a ring of asphalt, or any other ornamental cement.
In conclusion, I wish to say that my object in this method of preserving Rotifers is not to bring out any particular organs or structures, but to preserve the animal as a whole, white and transparent, and as life-like as possible, and suitable for identi- fication and study at any time. The process as now explained certainly does this for the great majority of species, and the delicate organs even, such as the very fine flagella attached to the vibratile tags in Asplanchna priodonta, are perfectly pre- served, and can be seen more distinctly than in the living animal. The red eyes and green food particles in the stomach
* Miller's caoutchouc cement is very good, and the best I know for scaling all kinds of fluid mounts, except, of course, alcohol. Its composition is kept a profound Becret by the inventor, but it probably consists of a mixture of shellac (buttonlac) dissolved in strong alcohol (or possibly Venetian tur- pentine) and caoutchouc dissolved in chloroform. The diluting fluid is a mixture of e<pial parts of chloroform and strong or absolute alcohol.
C. F. ROUSSELET ON PRESERVING ROTATORIA.
13
are also well preserved when weak osmic acid is used as the fixing agent, except perhaps when the eyes are only faint patches of red pigment, which then may disappear more or less in time. So far I have prepared and possess slides of 130 different species of Rotifers, including some of all the families, which is sufficient proof that this " unpreparabie " group, as Mr. Bolles Lee has styled the Rotifers, is now fairly conquered. It is my intention to prepare a similar series for the cabinet of our Club, to form in time a complete type collection, if possible, of all the known Rotatoria, and I trust the members will assist, in this task. This will prevent in future the confusion which exists with regard to a number of species which have been described three or four times under as many different names.* As a beginning, I have much pleasure in presenting to the Club 77 slides, which will form the nucleus of this collection; they contain 72 different species, of which the following is a list . —
Stephanoceros eich-
hornii. Melicerta ringens.
„ tubicolaria.
,, conifer a. Limnias annulatus.
„ myriophylli. Conochilus volvox. (Ecistes stygis. Asplanchna priodonta.
„ amphora. Asplanchnopus myrme
leo. Synchata tremula.
„ tavina.
„ stylata. Triarthra longiseta.
,, mystacina.
,, breviseta.
Hydat na senta. Phinops ritrea. Phinops (?) orbiculodis-
cus. Notops brachionus.
„ pygmceus. Triphylus lacustris. Notommata lacinulata.
Notommata aurita. „ tripus.
„ cyrtopus.
Cyrtonia tuba. Proales decipiens.
„ parasita, in volvox. Furcirfaria Longiseta. Diglena forcipata. Ploesoma lynceus.
„ Hudsoni. Anapus ovalis. Mastigocerca bicornis. ,, carinata.
,, bicrisiata.
Rattulus sejunctijpes. Coelopus porcellus.
„ brachiurus. Dinocharis tetractis. Stephanops longispi-
natus. Stephanops intermedins. Diaschiza semiaperta.
„ exigua.
Salpina brevispina.
„ marina. Euchlanis triquetra.
Euchlanis
„ parva.
„ deflexa.
,, pyriformis.
„ Lyra.
Cathypna ungulata. Monostyla cornuta. Distyla spinifera. Metopedia solidus.
„ acuminata.
„ lepadella. Pompholyx sulcata. Brachionus pala.
„ urceolaris.
Noteus quadricornis. Schizocerca diversicor-
nis. Anurcea aculeata. var.
valga. Anuraa cochlearis.
,, serrulata.
„ hypdasma. Notholca acuminata.
„ scapha. Pedalion mirum.
* Members who do not wish to mount the specimen themselves can assist in this work by sending me living examples of rare species of Eotifers when they happen to find them. The above list may be taken as an indi- cation of what is not required, but the following species are particularly wanted: — Apsilus lenliformis, Cephalosiphon limnias, Asplanchna Ebbes- bornii, Microcodon clavics, Pedet.es sallator, Ptercessa surda, Scaridium eudactylotum, Dinocharis Collinsii, Stephanops chlana and unisetatus, Erethmia tetrathrix, Notogonia Ehrenbergii, and many others.
14
THE PRESIDENT'S ADDRESS.
By Edward Milles Nelson, F.R.M.S.
{Delivered February 15th, 1895).
Gentlemen, — I cannot proceed with the work of this evening without alluding to the great honour you have done me in again electing me your President in spite of my numerous absences from this chair during the past year. I had the comfort of knowing that you were in better hands than my own through the kindness of Mr. Michael, and to you and him I now give my best thanks.
In brass and glass the past year has been a busy one ; it might, to use a cycling phrase, almost be called a record. The new inventions and improvements in brass work have been neither few nor unimportant, and although we have nothing further to discuss with regard to the glass portion of the subject, yet in the optical theory part we have had enough new matter put before us to occupy our minds for some time to come.
To proceed with the brass work from the point where we left off last year, we must go back to the latter part of 1893, when we find a microscope made by Leitz having a tripod (claw) foot and a horse-shoe stage. This instrument is in- teresting because of its divergence from the continental model, and of its convergence towards the English. The grooving of the substage focussing slide is peculiar, but as a special note on 1 hat point has already appeared in this Journal, we may pass on to Swift's four-legged microscope.
It is, however, difficult to follow the argument respecting this novelty, for past experience has shown that both the microscope and the telescope perform better the firmer their stands are. It has been repeatedly said, and no one has ever contradicted the statement, that the same optical lenses when used od B portable .-land will not perform so well as on a rigid stand. With the same objective, eye-piece, and condenser the delicate points which can just be caught when using a Powell's
THE PRESIDENT'S ADDRESS. 15
No. 1 will be invisible if the stand is changed for their portable. Leaving the portable instrument out of the question the image with a large massive stand is always superior to that obtained with a small and lighter stand, however well made it may be, the optical apparatus being the same in both cases. Now the objection to the claw foot is, first, insufficient spread, and secondly, the breadth of the back foot. The first fault makes the instrument easily capsizable sideways, and the second tends to make it rock on four points. The proper remedy for the first fault is to increase the base, and for the second is to make the stand a true tripod. My objection to the cutting and pivoting of the back leg is that it at once degrades the instrument to the level of a portable stand ; but if the instrument is put forward as a new portable microscope it will probably be admitted that it is about the best form that has yet been devised.
There is another innovation with regard to this stand, and the former pattern brought forward by Messrs. Swift and Son, which suggests an important question for the consideration of microscopists, viz. : is it an advantage to make the legs of the tripod or tetrapod hollow ? Lightness is of course gained, but then it is at the cost of a higher centre of gravity, and more- over how about rigidity ? If these stands are intended for portable microscopes only, the lighter the better, and on that account one is prepared to sacrifice something. If on the other hand they are intended for the highest possible work, solid legs would perhaps be better ; probably by filling up the tubes with lead the necessary weight and rigidity would be secured.
With regard to the next two instruments, you will know more about them than I, for they were exhibited here during my absence, so unfortunately I have not seen them ; they are dirties' instantaneous photomicrographic shutter, and Leitz's low-power projection camera.
We now come to a great, and what we may venture to think will prove a most useful invention, viz., Swift's friction geared mechanical stage.* It has since its first in-
* Frictional gearing was first applied to the microscope by F. H. Wenham, who says that " he found it answer perfectly well in lieu of the ordinary rack-and-pinion of the body and stage of microscopes .... it works very smoothly and lifts a weight of 161bs. without slipping." — "Quart. Journ. Micro. Science," Vol. vii., p. 201, two woodcuts (1859).
16 THE PRESIDENT'S ADDRESS.
traduction been improved by bringing the friction wheels nearer together, and also by fixing a milled head to each end of the pinion for the horizontal movement. This stage secures a maximum range of motion in each direction, and at the same time the whole apparatus can be removed, leaving the main stage perfectly plain. A copper ring is swedged on the wheels which impart the horizontal movement to the slide, and corundum powder is rubbed into it, which increases the grip on the lower edge of the slide. Next we have a series of microscopes, exhibited here by Messrs. Ross ; they do not materially differ from the ordinary Anglo- Continental pattern of students' microscopes except in the foot. The limb is fixed by a compass joint to a pillar which is attached to the periphery of a circular foot ; so far they are not unlike Salmon's microscope (1853) described by Dr. Beale. This pillar is, however, pivotted so that the foot may be turned backwards, which gives great steadiness to the instrument when in an inclined or horizontal position. This forms a simple, inexpensive and thoroughly practical foot, and it is strange that such an efficient design has not been oftener employed in the construction of students' microscopes. This idea was first suggested by Mr. A. McLaren.*
We next come to Baker's photomicrographic instrument. Here we have a microscope which cannot be used in any other but the horizontal position. The focussing racks of the body and substage are all ploughed in the bedplate, and the foot and arm are dispensed with. This seems to me the most solidly- e< instructed photomicrographic instrument yet made. This excellent design is due to Mr. E. Hartley Turner, of Man- chester. It is an instrument that will be much appreciated by those who do all their microscopical work on the photographic bench. Personally I work on different lines, the magnification, lens, adjustment, illumination, position, etc., of the object being all determined before it is placed on the photographic bench, so 1 naturally prefer to photograph with the same instrument by which those adjustments were made, and would find some inconvenience in changing to another instrument; but this is a mere raa1 fcer of detail.
The Last microscope is Watson's new model Van Heurck.
* "Journal It. M. 8.," 1884, p. J 11, Pig. 9.
THE PRESIDENT'S ADDRESS. 17
This in general resembles their older form, except that the distance between the optic axis and the limb has been increased, so that complete rotation is given to the stage. The foot is an equilateral tripod of 10-inch side, and its height is such that when the instrument is placed in a horizontal position the optic axis is ten inches from the table. The stage movements are similar to Powell's No. 1, and the instrument is thoroughly well made and sprung throughout. Leaving the microscopes, we pass on to apparatus, and we have Mr. R. Smith's rocker microtome. This is similar to the Cambridge rocker, but it is fitted with a movable knife-holder, which allows the edge of the blade to be placed at any desired angle to the cut. Another ingenious arrangement permits the instrument to assume a vertical position, so the cut can be made in a spirit trough. We have also from America clay wicks for microscope lamps, which are said to give a greater intensity of white light, and to be without smell. Finally there is my own camera, which has been already described here.
We must now notice the improvement in coloured screens, a very important branch of microscopy to which in the past it is to be feared that sufficient attention has not been given. The office of a screen in popular language is to improve the image with apochromatics, strengthen the resolution, and at the same time to soften the light when large illuminating cones are used. They are of special service with cheap lenses (z.e., semi-apo- chromats), because they remove the secondary spectrum, making the lens as efficient as an apochromat. So markedly is this the case that with equal apertures it is impossible to say whether the objective on the nose-piece is an expensive apochromat or a cheap semi-apochromat. In photomicrography not only are the preceding remarks applicable, but also colours difficult to photograph are rendered neutral. My reason for dwelling at length again this year on the subject of screens is not only because its importance is not so fully recognized as it should be, but also because some improvements have been effected during this past session. Mr. Lovibond, of Salisbury, who has been both a member of this Club and also a Fellow of the Royal Microscopical Society for twenty-nine years, has given this subject much attention. He sent me a flashed glass screen of peacock blue and a fluid screen of methylin blue,
Journ. Q. M. C, Series II., No. 36. 2
18 THE PRESIDENT'S ADDRESS.
and Mr. J. W. Gilford, who has also done excellent work in this direction,* sent me subsequently a very fine fluid screen of malachite green and picric acid. These were the screens you heard about last year. Since then Mr. Lovibond has sent me another sample of bluish green pot glass, which cuts the red out more thoroughly than the peacock blue glass. Mr. Gifford also has given me two more fluid screens, one a green and the other a violet. f The violet screen is too dark for visual purposes, and as yet I have not experimented with it photographically, but the green screen passes a large quantity of light. The results obtained with it are certainly up to, and probably superior to those with monochromatic light from my apparatus of the most approved pattern. There is one very important point with regard to the use of screens for visual purposes, viz., that if they are too dark they will obliterate fine detail, and it will be found better to pass a wider band, even should it contain some objectionable rays (i.e., not so monochromatic), than cut down the intensity of the light too much. In fact, there is a happy medium between the monochromatism of the screen and the light intensity; for example, Mr. Gifford's new green screen, which passes all the green and a great deal of blue, is a much better screen than that of Prof. Zettnow, which is more monochromatic.
Before entering on the subject of the evening, a few words must be said regarding a pamphlet published last year by Mr. Allan Dick, entitled, "Additional Notes on the Polarizing Microscope."! Most of us are acquainted with his former excellent pamphlet, and with the improvements he has made in petrological microscopes. This new work, however, deals largely with the manipulation and management of an ordinary microscope, quite apart from petrological work. It is to this portion of the book that we must, therefore, confine our atten- tion.
In the book is described a new method for measuring the aperture of a lens, which depends on the number of rings that can be counted in a biaxial crystal when viewed under a wide- angled axial cone of polarized light. The angles of the ring
* "Journal R. M. S.," 1894, p. 164, and PI. V., Pig. 4.
t An account of these will shortly appear in the " R. M. S. Journal/'
X Published by Messrs. Swift & Son, 81, Tottenham Court Road, W.
THE PRESIDENT'S ADDRESS. 19
distances are first measured by an apertometer, and when these have been tabulated, the crystal takes the place of an aper- tometer. The apparatus required, if one does not possess a petrological microscope, is a Nicol polarizer, of a size not less than that sufficient to fill the back lens of your condenser, (if that happens to be an Abbe it will be rather a costly item), an analyzer, a lens inside the tube of the microscope to convert the instrument into a telescope, and a properly cut crystal. Whether this extra apparatus is more costly than an ordinary apertometer I am unable to say, but it is claimed for the new method that it will measure the aplanatic aperture better than the Abbe apertomer. On page 14 a very pretty experiment is described by Mr. Dick, which visibly demonstrates in a most conclusive manner that a greater angle of light is grasped by an immersion than can possibly be by any dry objective.
Mr. Dick, it will be noticed, uses the sliders with his Abbe apertometer ; these in my hands have always given very rough and, in the case of large angles, erroneous results.
A preferable method of using the Abbe apertometer is to rotate the hemispherical disc until the light is extinguished, read off the angle of rotation on both sides of zero, take the sine of the mean reading and multiply it by the refractive index of the apertometer ; the result will be the N. A. of the lens. If in this manner you measure wide-angled condensers you will find curious effects. In some the flame image will dis- appear before the periphery of the back lens has been reached ; this shows that the front lens has not sufficient aperture to fill the back lens of the combination. In others the light, after extinction, will become visible again. In some the image of the flame will continue to be in focus during its passage over a large area of the back of the objective, in others it will begin to go out of focus almost as soon as it has left the centre of the back lens.
Mr. Allan Dick has fallen foul of that dreadful nightmare of diatom structure interpreters, viz., images in the areola?. Images in all kinds of areolations, whether of diatomic or other structures, follow the laws of those arising from minute per- forations. As this is an important and often misunderstood subject, you will pardon me if it is treated at some length.
Procure a small piece of tinfoil and a fine-pointed needle,
20 THE PRESIDENT'S ADDRESS.
place the tinfoil on a smooth piece of cork and make several fine punctures in the foil, then placing the foil in a compressor view it under a f objective. When the image of the edge of the flame is focussed by the substage condenser on the foil the only image that can be obtained will be that of the diaphragm at the back of the condenser. The image of this will be erect when the hole in the foil is beyond the focus of the objective, and inverted when within the focus of the objec- tive. A better plan, however, is to rack the condenser so that its focus shall be either within or without the plane of the foil, because it will then be possible by altering the focus of the objective to obtain an image of the edge of the flame itself. If an opaque object, such as the flat of a paper-knife, be moved up and down in front of and near the flame it will then at once be seen whether the image is erect or inverted by watching the direction in which the image of the flame is extinguished; thus, if the paper-knife be moved upwards, and the image of the flame is extinguished in a downward direction, the image is an inverted oue, and vice-versa. The results obtained by the above method are given in the following table : —
|
Condenser. |
Objective. |
Image. |
|
Beyond focus. |
Beyond focus. |
Inverted. |
|
Beyond focus. |
Within focus. |
Erect. |
|
Within focus. |
Beyond focus. |
Erect. |
|
Within focus. |
Within focus. |
Inverted. |
We see, therefore, that when the foci of both the condenser and the objective are either beyond or within the plane of the object the image will always be inverted, aud that when one is within and the other beyond it will always be erect.
Now, if we examine other structures, such as the eye of a fly or beetle, diatomic structures, dry or in balsam, the bubbles in the fluid cavities in quartz sections, or the fluid cavities them- selves, we shall always find that the images will follow the rules of those of minute perforations in an opaque substance as given in the above table. It is difficult, therefore, to see how the character of the image can decide the question as to whether the minute structure under consideration is acting as a positive or negative lens.
In the first paragraph of the appendix Mr. Allan Dick men- tions a difficulty which has probably puzzled not a few. He
THE PRESIDENT'S ADDRESS. 21
correctly remarks that " the hexagons are always turned 30° " to their positions in Fig. 63, in the last edition of " Carpenter on the Microscope," when the spectra at the back of the objective are represented as in Fig. 62.*
I think an explanation of the phenomenon will be found by the examination of any hexagonal structure, such as a honey- comb, fly's eye, or diatom ; by doing this we shall at once see that the three directions of the rows of hexagons are at right angles to the three directions of the sides of any particular hexagon. In the above-mentioned erroneous Abbe-Eichhorn figures the hexagons are turned, as Mr. Allan Dick has pointed out, 30° from their proper position. These figures are, as I have frequently remarked, incorrectly drawn. If you will examine Figs. 63 and 64 you will observe that the directions of the rows of hexagons are in an alignment with the angles of any particular hexagon ; they are therefore 30° out of position.
With regard to the spectra, it is well known that the spectra assume a direction at right angles to those of the lines causing the interference. Now it is the rows of hexagons which cause the interference, and not the edges of the hexagons them- selves. If, therefore, we draw three lines at right angles to the three directions of the edges of any particular hexagon, they will represent the three directions of the rows of hexagons ; and if we draw a line at right angles to each of these, they will re- present the proper position for the spectra. And also because the angle subtended by a side at the centre of a hexagon is 60°, and that angle and a half makes a right angle, the spectra will therefore lie in the same direction as the corners of the hexagon. The term used above, "rows of hexagons and not the edges of the hexagons themselves," requires explanation ; it much simplifies this question by regarding in the first instance the inter-spaces rather than the lines. Of course it is the intercostal material that diffracts the light, and in the case of diatoms such intercostal silex has been isolated by our well- known member Mr. T. F. Smith. This intercostal material forms a wavy line, composed of short pieces inclined 120° to each other, being the sides of contiguous hexagons. It is there- fore this It.ng and ccntinr.cus wavy line that deteimines the
* These figures, together with €4, are similar to tbcte in the "Journal E. M. S." for 1881, p. 353-4, Figs. 1C5, ICG, and 107.
22 the president's address.
position of the spectra, and not the detached short pieces which form the sides of the hexagons ; for every side of a hexagon is separated by twice its own length from the next side that is in a straight line with it. In order that a filament of this structure should break off and become separated, as in Mr. Smith's specimen, it is necessary that the silex forming the sides of the hexagons in the third direction should be weaker than that forming the other two.
We now pass on to the subject for the evening, and you will probably agree with me that the one selected for your kind con- sideration is the most important in the domain of microscopy that has appeared since 1875, when the Abbe diffraction theory of microscopic vision was first published in the "Monthly Microscopical Journal." I, of course, allude to the physical theory of microscopic vision written by my friend Mr. Lewis Wright in the " English Mechanic " * during the months of September, October, and November of last year.
The questions at issue are very large, for if Mr. Wright's conclusions are correct the table of the " Limit of Resolving Power" in the " R. M. S. Journal " is incorrect, because it is only valid for spurious images, and the true limit for micro- scopic vision becomes reduced, as we shall see later on. But, before proceeding, we must first consider the Abbe theory, both as it first appeared, and also in its present position. In the first instance we had a dioptric image for structure larger than the -5-5V0 °^ an incn> an^ after that a diffraction image. In accounting for other pictures recourse was had to a double theory, a dioptric one for one portion of the image and a diffrac- tion one for another part. In simple words we were told that a cataclysm took place in the physical phenomena of light at a point denoted by the Y5V0 °^ an incri- And we were further taught that it was impossible to know anything of minute structures unless certain impossible conditions were fulfilled, such as the grasping of the entire diffracted fan.
There was also the Eichhorn theory with its alleged predic- tion of structure. This has been entirely refuted both prac- tically and theoretically, and moreover it was shown to be quite at variance with the fundamental laws of the diffraction theory. The diffraction theory in its pristine condition was therefore both incorrect and illogical. As it now stands, however, with * " English Mechanic," Vol. lx. (1894), Nos. 1537-38-40-42-43-45-47.
THE PRESIDENT S ADDRESS.
23
those embellishments and errors removed, it is a consistent working theory, its limit of resolving power agrees very well with results practically obtained, and it also affords valuable information for checking the interpretation of periodic struc- tures.
Our next point is a digression, which I trust you will pardon, for we must investigate the theory of telescopic vision before we can proceed.
Mr. Wright has given a very clear explanation of the theory of telescopic vision in the " English Mechanic."* Very briefly stated it is this : Let A B W (Fig. 1) be a long isos- celes triangle with a narrow base A W. Let B represent the focus, and A W the diameter of a telescope objective.
Then, if light having travelled along A B arrives at B in a certain phase, it will also arrive there in the same phase when it has come via W B, because W B is equal to A B. Now let us take another point D, at one side of and close to B, and let us draw lines from D to A and W, then it is clear that the triangle ADW will not be isosceles, for one side must be longer than the other, and the greater the distance of D from B the greater will be this inequality of the sides A D, W D of the triangle ADW. Let the point D be placed at such a dis- tance from B that the difference in the lengths of the two sides A D and W D of the triangle ADW amounts to half a wave-length, it is then obvious that light arriving at D via A D will differ in phase from that coming via W D by half a wave-length. In other words, to use a familiar figure, at the point B the crests of the waves will meet the crests, and the hollows will meet the hollows, consequently there will be a reinforcement of wave action, but at the point D the crests will meet the hollows, and vice-versa, so that there the wave motion will be annihilated, * "English Mechanic," Vol. \x., No. 1540, p. 125.
24
THE PRESIDENTS ADDRESS.
i.e., there will be darkness. If the point D is moved a little further from B, so that A D is longer than W D by one whole wave-length (see dotted isosceles triangle ADC), there will be another reinforcement of light at that point, and so on.
Hitherto we have only been considering the effect of the wave-action of light at a small spot on either edge of an
objective ; we must now take into account its action over the whole area. Let us, in the first instance, suppose that the object-glass is square, and let us divide this square into equal rectangular spaces by drawing lines parallel to one of the sides of the square (Fig. 2) ; we can then easily see that the light passing through one rectangle will Fm. ^- oppose that passing through
another; thus, if we divide our square objective into eight rec- tangles, and name them consecutively EFGHIKLM, E will oppose I, F will oppose K, Gr — L, and H — M. The case being that of thedotted triangle AD C(Fig. 1), where the light passing at the E or A edge of the object-glass to the point D has one wave-length further to travel than that passing at the AC or W edge, therefore that passing at the centre of the square, viz., at the line between H and I to the point D, will have half a wave-length less to travel than that at E, and half a wave-length more than at M. Moreover, the rectangles being all equal to each other, the opposition of the rays will consequently be equal in effect. From this we learn that the image of a bright point, such as a star, at the focus of a telescope is made up of a bright disc in the centre of a dark ring, encircled by a bright ring, etc. Now, so long as the objective is square, it is easy to calculate the distance the dark point D is from B. When F is the focal length of the objective, A its aperture, and A. the wave-lenoth,
A F
then the distance between D and B, $ is equal to . This
A means that the least separable distance in the image at the fouus bears the same propori ion to the local-length, as the wave- length does to the diameter of the objective. But the ratio of
THE PRESIDENT'S ADDRESS. 25
the least separable distance in the image at the focus, to the focal-length, is the same as that of the least separable distance in the object itself to its distance from the telescope ; there- fore, the least separable distance in the object bears the same proportion to its distance from the telescope, as the wave- length does to the diameter of the object-glass.*
* As it is important that even our most junior members should thoroughly comprehend this exceedingly simple problem, which is a common rule-of-thre i sum, and which precisely resembles, and requires no more mathematical knowledge than, the well-known child's problem abouo the herring-and-a-half which cost three-halfpence, this note is appended. Cut out of a piece of paper two precisely etpaal triangles like A B W (Fig. 1), and placing one over the other, so that the lower is exactly covered by the upper, stick a pin through both their corners at A. Now take hold of the lower one at the point D and move it out at one side, as shown by the dotted triangle (Fig. 1). It will then be seen that as the point D is moved to one side, so the point C of the lower triangle will protrude beyond the point W of the upper one. A moment's thought will show that the displace- ment at D is proportional to the protrusion C W, and that this proportion is that of the length of the line A B or AD (the focus of the object-glass) to the length of the line A W (the diameter of the object-glass). For example, if the focal length A B is four times as great as the diameter A W, and if 1) is moved four-tenths of an inch from B, the point C of the lower piece will protrude one-tenth of an inch beyond W the upper. Stating this simple problem mathematically, let us call 5 the displacement of D from B, and \ the protrusion at W, let A C or A W, the aperture, be called A, and A B or A D the focal length, F. Then
3 : X :: F : A (i)
and every school-boy knows that to find S we must multiply X by F, and divide the product by A.
When the dotted line C D (Fig. 1) protrudes one wave-length beyond W, then the remainder, W I), must be shorter than A I) by that one wave- length, and we have seen in Fig* 2 that when the distance from the M side of the object-glass to D is one wave-length shorter than that from the E side, the light will be extinguished at the point D. The distance B D, therefore, represents the minimum visible, when the protrusion of C D beyond W is one wave-length. Now, as the wave-length, the focal length, and the diameter of the object-glass are all known, £, the minimum visible, can be determined.
Now one word with regard to the proportion between the size of the image at the focus, which we have just been considering, and the size of the object to which the telescope is supposed to be directed.
26 the president's address.
In order, however, to accurately represent the area of an objective we must inscribe a circle in our square (Fig. 2), and we shall see that the rectangles H and I in the centre of the circle very nearly represent the true area of that portion of the objec- tive, but at the opposite sides of the square the rectangles E and M are ever so much larger than the corresponding portions of the circular object-glass, therefore the effect of the light passing through that portion of the objective represented by E is insufficient to neutralize the portion passing through I. The
In Fig. 3 let O B be the object, and I M the image, A C the object glass, A being the point where the lines O M and B I intersect. Because B I and O M are straight lines the alternate angles O A B, I A M are equal, and the triangles O A B, I A M are similar, therefore O B bears the same proportion to B A that I M does to M A. But B A is the distance of the object from the telescope, and A M is the focal length ; therefore we have
object : distance : : image : focus. Let us call for brevity the object O, its distance D, the image (supposed to be a minimum visible) 8, and the focal length F, then
O d
D F.
Next let us transpose our previous proportion (i.) thus —
5 : F : : A : A, S \ that is — = — ... ... ... (ii)
F A,
8 O
but we have just seen that — = —
F D,
5 A O
therefore — = — = — (iii)
F AD. Now because the angles in question are very small (about 5") these ratios
0 express the angles themselves, therefore — becomes the anule the object
D subtends at the object-glass (1) being the distance between the object
x and the telescope), and — the angle one wave-length subtends at a distance
A equal to the diameter of the object-glass {i.e., A the aperture), therefore the statement above is correct which says that the smallest object that can be seen with a telescope is that which subtends an angle at the object-glass equal to that subtended by one wave- length at a distance equal to the diameter of the object- glass.
In Fig. 4, A C or A W is the diameter of the objective, and C W is one wave-length, then equation (ii) shows that the angle C A W (Fig. 4) is equal to the angle I A M (Fig. 3) for a minimum visible, but the angle I A M is equal to the angle O A B, therefore the angle () A B is equal to the angle C A W, provided that the image is a minimum visible, equa- tion (iii). Fig. 4
THE PRESr DENT'S ADDRESS. 27
distance from B to D must, therefore, be increased. The calcula- tion of the distance between D and B (Fig. L), when the object- glass is circular, is a much more laborious and complicated problem. It was first solved in 1834 by Sir Gr. Airy,* the late Astronomer Royal, who was the originator of this theory, of which the above is a mere outline. He found that with a circular objective, 8 the distance between D and B, was equal
1'2197 A. F
to r * It is not my intention to trouble you this evening
with any dry mathematical formulae, or repeat what I have
demonstrated elsewhere, but you may take it as correct that the
. ■ X F, . formula for a square aperture given above, viz., 6 = —r~ *s
practically the same, that it yields the same numerical values as Abbe's formula for microscopic vision, with which you are all well acquainted.
Unfortunately, however, the apertures of both telescope and
Fig. 5.
In Fig. 5 the three triangles are superimposed ; it is a simple and easily remembered picture which contains the whole germ of the theory. Let A C be the diameter of the object-glass, A I its focal length, and A O the distance of the object. Then when C W is one wave. length, I M is the size of the minimum visible image at the focus, and O B is the size of the object.
This result I have expressed in a simpler and more handy form in another place thus : — " One unit of Aperitive resolves one unit of Interval at a distance equal to the Reciprocal of the Ware-length." Example: — Let a wave-length be chosen between lines C and J), viz., ^o^eo iuch. Then
Aperture resolves Interval at Distance. 1 inch 1 inch 42,260 inches.
1J inch 1 inch 1 mile.
3 inches 1 inch 2 miles.
3 inches | inch 1 mile.
This table agrees with practical results obtained for terrestrial objects seen by reflected light with the best telescopes.
When a wave-length of ^fIto (between lines 1) and E) is taken for bright celestial objects the above rule agrees with Dawes' empirical formula for the separating power of astronomical telescopes, viz., 4"56", divided by the aperture of the object-glass in inches.
* "Cambridge Philosophical Society's Transactions," Vol. v. (1835).
28 the president's address.
microscope objectives are not square, but circular, and referring to the formula for circular telescope objectives we see that it is a trifle more than one-fifth larger than that for square apertures. It therefore comes to this, that so long as the telescope objec- tive is square, and the microscope objective is circular, the mathematical formulae for both are numerically identical, although the reasonings by which those formulas are obtained lie along""wholly different paths; but when we have circular objectives in both cases, the resolving power of a telescope, according to the physical theory, is about one-fifth less than that of a microscope, according to the diffraction theory. Now, we know that it is impossible that light should act in one way in a tube because it is called a telescope, and in another way when it is called a microscope, and it was this glaring discrepancy between the telescopic and microscopic theories which led me to publish in 1893 a pamphlet on " The Theory of Telescopic Vision." Thus it was my endeavour to bring the theory of telescopic vision into harmony with that of the microscope. This evening you have before you the converse problem in Mr. Wright's articles, bringing the microscopical theory into consonance with that of the telescope. There is one thing for certain, that sooner or later either the Airy or the Abbe theory will be abandoned, for both cannot possibly be correct.
You must now know that with regard to these articles in the 11 English Mechanic " 1 am in a somewhat better position than you, because, in reply to some notes, Mr. Wright most kindly wrote to me at great length explaining several of his points, and giving me fuller information concerning others. What follows next with regard to the resolving limit will therefore have more reference to his letter than to what has appeared in print.
Lord Rayleigh, whose work on the undulatory theory is so well known and appreciated by all, made careful experiments with a telescope,* and obtained a somewhat smaller limit for circular apertures, viz., one lying about half-way between those calculated by Airy for circular and square apertures.
* " The Resolving Power of Telescopes," bj Lord Rayleigh. " Pliilo gophical Magazine," August, 1880.
THE PRESIDENT'S ADDRESS. 29
We have therefore three limits, viz. : — *Square aperture (same as Abbe) .. .„ $=
Circular „ (Rayleigh experimental) 8 Circular „ (Airy calculated) ... 8
A
109 AF
A 1-2197 AF
A
It is stated that there are certain theoretical considerations which show that a star disc as seen in a telescope should be smaller than that calculated by Airy ; this reference, however, I have not been able to look up. Now it is quite reasonable to expect that a limit obtained practically with instrumental appliances should fall short of a calculated theoretical limit, but it is difficult to understand how it can exceed it. This is certainly a point upon which more explanation is required. The actual resolving power of the microscope, therefore, accord- ing to Mr. Wright's theory, for a full cone, adopting the middle formula above, viz., that derived by Lord Rayleigh from actual experiment with a telescope, and employing the same wave- lengths as those given in the tables in the " R. M. S. Journal " for white and monochromatic blue light, viz., for lines E and F, will be
88,450 multiplied by the N.A. for line E. and 95,880 „ „ „ F.
But, as before remarked, the line E is too high up the spectrum for visual purposes ; it will be better to take one somewhat similar to that selected for my table in the " R. M. S. Journal " for 1893, p. 17, then the limit will be
85,630 multiplied by the N.A.
As, however, a full cone in practice can seldom be used, and because with a 3/4 cone spectra are present in the outer annulus, the table which is given presently will still hold good.
To reduce this question to its simplest terms, the resolving power of a microscope objective of N.A. TO, with a full cone,
* My own experiments with telescopes on terrestrial objects, as well as those ofDawes on Double Stars, agree with this value,
30 THE PRESIDENT'S ADDRESS.
and with white light (line E, the same as used in R. M. S. tables), will be
96,410 according to Abbe theory.
88,450 „ Rayleigh experiment.
79,044 „ Airy theory.
Now the results from experiments both with full and 3/4 cones go largely to corroborate Mr. "Wright's conclusions. It is common knowledge that when a full cone is em- ployed the resolving power falls off, and it has been cus- tomary to account for this falling off in the resolving power by the outstanding spherical aberration in the objective. To test the accuracy of this current notion a critical image was set up, and matters arranged so that access could be obtained to the back lens of the objective without disturbing any of the adjust- ments. When a full cone of light was used the resolving power fell off, and when a 3/4 cone was employed it was as usual restored again; a stop was then placed at the back lens, cutting off the peripheral unilluminated annulus. We had, therefore, an objective of less aperture, but illuminated by a full cone. Under these circumstances one would have expected to see a critical image, but not so, and this is the crucial point. In order to obtain the maximum resolving power for that reduced aperture the illuminating cone had to be reduced until only three-quarters of the back lens was illu- minated. This is a most important fact, because it shows that spherical aberration is not playing the role commonly assigned to it, and the blotting out of structure has a deeper meaning. Reading this in the light of the new theory we see that when a full cone is used the image comes under the physical or Airy limit, but the moment we use a 3/4 cone we have diffraction spectra in the peripheral annulus. The picture therefore obeys the Abbe limit with its greater resolving power.
Probably spherical aberration is present as well, and pro- duces a certain amount of indistinctness of image which helps to obliterate the fine detail, but the above experiment proves that spherical aberration does not account for the whole pheno- menon as it was previously thought to do. With regard to the 3/4 cone illumination, it should be remembered that the areas of circles are in the proportion of the squares of their diameters ; therefore the area of the peripheral annulus where the spectra
THE PRESIDENT'S ADDRESS.
31
pass is only 12| per cent, less than the area of the central por- tion illuminated by the 3/4 cone. The numerical values are: — Darkened annulus ... ... ... 43' 75
Illuminated central portion ... 56 25
100
Because in practice we are bound to use a 3 4 cone we shall therefore have an image compounded of a true image in the central three-quarters of the whole aperture, according to Mr. Wright's theory, and an Abbe diffraction, or " true false " image, in the peripheral annulus, according to my nomenclature. The resolving limit will therefore, as stated above, agree with this table from the " R. M. S. Journal."
Table of Resolving Powers in Lines to an Inch with 3 [4 Gone of Direct Illumination.
|
White Light. Between lines D and E 46,666 waves per inch. |
Monochromatic Blue |
|
|
N.A. |
Light and Photo- graphy. Near line E 53,333 waves per inch. |
|
|
o-i |
7,000 |
8,000 |
|
0-2 |
14,000 |
16,000 |
|
0'3 |
21,000 |
24,000 |
|
0-4 |
28,000 |
32,000 |
|
0'5 |
35,000 |
40,000 |
|
0-6 |
42,000 |
48,000 |
|
07 |
49,000 |
56,000 |
|
0'8 |
56,000 |
64,000 |
|
0-9 |
63,000 |
|
|
10 |
70,000 |
The same as for |
|
11 |
77,000 |
white light. |
|
12 |
84,000 |
|
|
13 |
91,000 |
|
|
14 |
98,000 |
|
|
1*5 |
105,000 |
|
|
T6 |
112,000 |
The above table agrees remarkably well with results actually obtained with the best lenses, and to show that this is so the following table gives the actual resolutions made on diatoms in
32
THE PRESIDENT S ADDRESS.
balsam with a 3/4 cone from a Powell fluorite apochromatic condenser (1/4 of 0'95 N.A.) : —
Objective.
Apochromatic lin. ...
1. Achromatic 4/ 10 (1875)
2. Apochromatic 12
3. Semi-apochromatic 1 4 Achromatic 1/4 (1875) Semi-apochromatic 17
4. Achromatic 1/5 Apochromatic 1/4
5. Semi-apochromatic 1/12
6. Apochromatic 1/8
|
O.I. 28-9 |
1 NA. •32 |
|
20-0 |
•04 |
|
320 |
■66 |
|
18-6 |
•71 |
|
165 |
•79 |
|
115 |
•86 |
|
16-3 |
•88 |
|
23-2 |
•95 |
|
9-7 |
1-26 |
|
170 |
143 |
White Light. | Blue Light.
22,000
40,000 strong
46,000
53,500
53,000 barely
60,000
60,000
65,000
90,000 barely
94,000
25,000 49,000 53,500
60,000 barely 60,000 barely;: 65,000 65,000 barely
1. Would resolve probably 42,000 with white light (construction same as achromatic 1/4, viz., triple front and back, double middle).
2. A very fine lens.
3. A little more than 3/4 cone used ; this lens is a very strong resolver, and stands blue light even better than some apochromatics.
4. A fine example of an achromatic by Gundlach.
5. Will not resolve the Nitzsehia curvula, 90,000.
6. Resolves Amphipleura pellucida, 93,000-95,000. Less than 3/4 cone used.
To return to the diffraction theory, it has been recognized for some time past that there is more than one kind of image, and on a former occasion it was my endeavour to prove to yon that there were three distinct kinds of images, one being a " true " image, which went in and out of focus as a daisy under a 4in., the other two being " false " images, one of these a " true-false " image, whose character was similar as regards the arrangement of the elements of the periodic structure to that of the object itself, but under focal alteration it passed into another kind, called a "false-false" image, whose character entirely differed from that of the " true " image. Now Mr. Wright's position, if I have interpreted him correctly, is this, that his new " true " image comes under the laws of the Airy or physical theory, but the other two images, viz., the "true-false" and the "false- false," conform to those of the Abbe or diffraction theory. With regard to this last image, it is admitted by all genuine microscopical workers that it is not only of no use, but is abso- lutely a hindrance to the interpretation of microscopical struc-
THE PRESIDENT'S ADDRESS. 33
tures, and on this account it, as well as the small cone by which it is produced, ought to be got rid of as far as possible. Mr. Wright has assigned it to a class of physical phenomena known as Fresnel's interference bands. These images therefore will in the future be only regarded as interesting examples of experiments in physical optics. It is important to consider for a moment the " true-false " image and its influence on that obtained by the only correct method of microscopical illumina- tion, viz., a 3'4 cone. It is, as we have seen, one of the com- ponents of the resultant image, and it is formed by spectra passing through the peripheral annulus. The new theory shows that this image also partakes of the nature of Fresnel's interference bands, but because it is a " true-false " image it strengthens, by its superior resolution, Mr. Wright's new " true" image, and as we must put up with it, full cones being impracticable, it is consoling to know that it is a " true-false " image that we have to deal with, which will assist, and not injure, our new "true" image.
Putting the case in another way we see that it is the image formed by the central three-quarter portion of the whole objec- tive that definitely fixes the focus, and consequently we are unable to play upon focal adjustment for the formation by means of the Fresnel bands of various pictures, which, however beautiful they in themselves may be, yet have nothing what- ever to do with the structure under the microscope. Some will say that we have at last come back to Abbe's original theory, which he has since abandoned, viz., that the microscopical image is compounded of two superimposed images, one a dioptric image and the other a diffraction image beginning at 23V0 inch- To this we reply that, although in words it may be so, in meaning the case is far different. To mention two differences : Abbe's double image was the essence of the micros- copical image, but now the double image is an accident arising from the impossibility of using full cones. Again the resolu- tion in the centre conformed to the Abbe limit, whereas it now possesses less resolving power owing to its dependence on the Airy limit.
With regard to the action of the four kinds of illumination by means of axial cones, the following are from results obtained
Journ. Q. M. C, Series II., No. 36. 3
34 the president's address.
in practical work. The order given is from the strongest to the weakest resolver : —
Appearance at Bach of Objective.
1. Peripheral annnlus bright, 3/4 centre dark.
2. Peripheral annulus dark, 3 '4 centre bright.
3. The whole dark (dark ground).
4. The whole bright (full cone).
No. 1, which is made by placing an opaque central stop* at the back of the condenser, is the strongest resolver of all symmetrical systems of illumination. (This stop at the back of the condenser must on no account be confused with a stop at the back of the objective for the purpose of cutting out a narrow central dioptric beam). It is nearly, but not quite, so strong a resolver as the asymmetrical method by light in one azimuth by means of a slotted stop. The resolving power of No. 1 does not come under the new theory, because spectra are formed in the 3,4 central portion ; the theoretical limit is there- fore 96,410 times the N. A. of the objective, the wave-length being the same as that used in the R. M. S. tables (line E.). No 1 cannot, however, be recommended for practical work, because it is so liable to produce false images, and especially to double the structure. Any structure near the limit for a lens of half the aperture is likely to be doubled, e.g., an Angulatum, which can be resolved by an objective of N.A. "7, is likely to exhibit inter- costals when examined by a lens of N.A. 1*4, and illuminated in this manner. This method will require a condenser whose aperture must be fully equal to that of the objective.
No. 2. — This, which is known as 3/4 cone illumination, is the best for general purposes, and because of the presence of spectra it also does not come under the new theory. The theo- retical resolving limit for line E is 72,307 times the N.A. of the objective. The image, as we have seen above, is compounded of the new " true " image, and the " true false " image of the old diffraction theory. It may, therefore, be relied upon. The aperture of the condenser need only be 3/4 that of the objective.
* It would be far better if the meaning of the word "stop" in micro- scopical literature were coniined to the opaque central stops used at the back of the condenser for producing dark grounds, etc. The common stops, with central circular apertures, might be appropriately called "dia- phragms."
THE PRESIDENT'S ADDRESS. 35
No. 3. — Dark ground obtained by a condenser and a stop ; this is only available for the lower powers ; the apochromatic | or | of -65 N.A. may be said to exhaust this method of illumination. This case, in my opinion, comes wholly under the new theory, because all the aperture is uniformly utilized. To all intents and purposes an object such as a diatom may be said to be self-luminous ; under these conditions the action of a microscope most closely resembles that of a celestial telescope. The practical resolving limit is only a trifle below that of No. 2 ; theory, however, demands that it should be higher. Taking the same wave-length the resolution for No. 3 should, according to the new theory, be 79,044 times the N.A. of the objective, against 72,307 times the N.A. for case No. 2. Practice, how- ever, as we have seen, reverses the order, and gives No. 2 a slightly higher resolving power. The condenser must, of course, have far more aperture than the objective.
No. 4 comes entirely under the new theory, but resolution falls off considerably; there is also an indistinctness in the coarse structure. Theoretically the limit is the same as that of No. 3, viz., 79,044 times the N.A. of the objective. This mode of illumination is not practical. A condenser of larger aperture than that for No. 2 is required, because it must, of course, equal that of the objective.
It is interesting to notice that with No. 2, the 3/4 cone illumi- nation, if the object is placed at the edge of the image of the side of the flame, especially if the edge is somewhat undefined by the condenser being brought a trifle within or without its focus, the resolving power is increased. This well-known illuminating dodge becomes an important confirmation of the new theory, for Mr. Wright, with reference to the action of the illumination from a wide-angled cone, says, in Art. 23, that a " plenum " of rays "in the same phase" diverge from each point in the structure, so that the points become centres of wave propaga- tion, but along the edge of the cone diffraction phenomena arise. Does not, therefore, the above experiment fully confirm the statement in Art. 23, which should itself be read, as it is far better expressed than in my condensation.
In this connection it will be found that a curious effect is produced when examining fine-lined structures with the naked eye, if an obstacle is held somewhat nearer the eye and the lined
36 the president's address.
structures be viewed through the haze at the edges of the obstacle. For example, if the finger be held in front of the eye at a distance of about four inches, when the vision is normal, and if the eye be focussed on some object at a greater distance, a haze will be seen surrounding the out-of -focus finger. Now if a fine-lined object, nearly at the limit for resolution, be examined, the resolution will be found to be strengthened when it is viewed through the haze at the edge of the finger. A black-edged card might with advantage replace the finger. Some ridges, which counted 45 to the inch, on the black cover of a cloth-bound book were examined, and it was found that they became much more distinct when they were viewed through the haze at the edge of a card.
After this digression, let us see what Mr. Wright says about the Microscopic Image. In Art. 21 (6) he attacks the Eich- horn intercostals from a point of view different to that I have taken, and I heartily concur in all his conclusions. The next paragraph (c), with regard to the statement that the striae of A. Pellucida, which Mr. Sollit measured as 120,000-130,000 per inch, were ghosts, is not so clear for the following reasons : —
First. — At that time there was no objective with a resolving limit approaching such figures.
Secondly. — A false ghost must always be within the resolv- ing limit of the lens.
Thirdly. — A false ghost must always be an integral multiple of the true structure.
Therefore, assuming that Mr. Sollit had a coarse A. Pellucida of say 90,000 striae per inch, the coarsest false ghost he could have made must have had 180,000 lines per inch, and the next one 270,000, and so on. Now, as 180,000 lines per inch was beyond the limit of any lens then constructed, no one had ever seen a ghost of the true striae on A. Pellucida. In some dry mounts of this diatom, especially those burnt on cover, there are apparently coarse wrinklings of some outer membrane, which have nothing whatever to do with the striae in question ; these can easily be seen with any quarter-inch objective. It is more than probable that some running about 40,000 per inch were doubled and afterwards erroneously measured, for it is
THE PRESIDENT'S ADDRESS. 37
only in comparatively recent years that accurate measurements of the so-called striae on the diatomaceee have been made.*
The deductions which Mr. Wright has postulated in the next Art., No. 22, is a most important addition to microscopical literature. Speaking of the Fresnel interference bands, i.e., microscopical images formed by a small cone or beam, centric or excentric, he says " that these lines are in no sense images, but mere interference bands or fringes with no definite focus ; that whenever thus really produced they are a constant source of uncertainty and error, and to be got rid of as far as possible by the use of large aplanatic cones ; that when we use such cones we lose such fringes altogether and get a real focussed image, true to the object so far as the aperture and correction of the lens permit of its definition ; and that this image is a dioptric image."
Further on, he says " that the narrow cone and the diffrac- tion theory stand or fall together." This statement is per- fectly correct, provided that it is the diffraction theory as enunciated by Abbe and his exponents which is meant; and can this be wondered at, seeing the theory at its inception was not even a logically sound argument ?
With regard to Abbe's statement, quoted in this article, viz., " Strictly similar images cannot be expected, except with a central illumination with a narrow incident pencil, because this is the necessary condition for the possible admission of the whole of the diffracted light," let me put before you a simple experiment. Place a P. Angulatum under an objective of '65 N. A., and illuminate it by a narrow central incident pencil ; you will see neither structure nor spectra. Enlarge the in- cident cone until it fills three-quarters of the objective, and you will now see both spectra and the angulatum pattern. This proves that the wide cone is a better condition than the narrow incident pencil for the admission of diffracted light.
I am perfectly aware of the imperfections of this brief review on Mr. Wright's important articles, but it has been my endeavour to discuss them fairly ; neither have I consciously slurred over or omitted any difficulties or unexplained points for the purpose of making the case appear stronger than it really is. The sub-
* "M. M. J.," Vol. xv. (187G), p. 223.
38 the president's address.
ject is so large that it would take a longer time than is at ray disposal this evening to do it full justice, and I am also aware that although it is a momentous question in the interests of microscopy, it is, nevertheless — and from the nature of the case must be — dry as dust. An apology, therefore, is due to you for bringing it before you at an Annual Meeting, when it is naturally expected that the address should be of a lighter nature, but I felt that its importance was paramount, and therefore ven- turpd to trespass on your good nature.
In conclusion, let me briefly sum up. In the first place, it will be conceded by those who have studied his articles with- out prejudice that Mr. Wright has been the first to give a cor- rect theory of microscopic vision with large illuminating cones, and, secondly, that he has disproved the theory, generally accepted among microscopists for the past 20 years, with regard to spectral images, and has shown that they belong to a class of physical phenomena known as Fresnel's interference bands.
39
On a New Camera Lucida.
By Edward M. Nelson, F.R.M.S.
{Bead November 16^, 1894.)
The well-known neutral tint of Dr. Beale is such a simple and inexpensive form of camera that it seemed a pity that the only drawback to its coming into more general use, viz., that of transposing its erect image, should not be corrected. This drawback is a serious one, because a picture drawn by a Beale's camera only becomes similar to the original object when it is viewed as a transparency from the wrong side of the paper. For instance it is well known that some insects have one leg on one side of their bodies different to the corresponding leg on the other side, and it is necessarily important that such micro- scopic objects should be depicted correctly. Now all we have to do is to correct the transposition without altering the image in any other manner. Obviously this can be accomplished by adding a lateral reflection. If, therefore, we place over the eye-piece, at an angle of 45°, a small silvered mirror (a first surface mirror is unnecessary, a piece of ordinary silvered glass, such as is used in sextants, answers every purpose), so that when the microscope is placed in a horizontal position the image may be reflected at right angles to the body, either to the right or left hand of the microscope in a plane parallel to that of the table, and then if we intercept this horizontal beam by an ordinary Beale's neutral tint, an erect image, with its transposition corrected, will be reflected upwards to the eye, and seen on the table through the neutral tint in the usual way. In brief, the lateral reflection corrects the transposition, w^hile the vertical reflection forms the first surface of the neutral tint, the inversion of the image. The resultant image is, therefore, precisely similar to the object on the stage of the microscope. Anyone possessing a right-angled prism can produce the same effect by placing it anywhere between the objective and the eye-piece, and by placing an ordinary neutral tint on the eye- piece ; of course, the horizontal position of the right-angled body, when the microscope itself is in a horizontal position, must be maintained.
40
PROCEEDINGS.
October 5th, 1894- Conversational Meeting.
The following objects were exhibited : — Comatula rosacea, pinnae with ova ... Mr. G. E. Mainland, Aulacodiscus evcavatus ... ... ... Mr. H. Morland.
Euchlauis triquetra, $ ?, mounted ... Mr. C. Rousselet.
October 19th, 1894. — Ordinary Meeting.
E. M. Nelson, Esq., F.R.M.S., President, in the Chair.
The minutes of the preceding meeting were read and con- firmed.
The following gentlemen were balloted for and duly elected members of the Club :— Mr. R. W. Howard, Mr. F. Hughes. The following additions to the library were announced : — " Journal of the Royal Microscopical ) ^ , tl S ' t
Society" ... ' J 101 e y'
" Proceedings of the Manchester )
Microscopical Society " ... J
" The Botanical Gazette " ... ... In Exchange.
" Proceedings of the Belgian Micro- scopical Society " ... 1 ' Annals of Natural History " ... Purchased.
Series of reprints on " Infusoria " ... Monsieur Certes. The Secretary said it was well known to members that the specimens in the cabinet had for some long time been under- going revision, but as it was a very tedious and laborious task, owing to the large number to be gone over, and still very far from completed, the Committee had deemed it advisable to print a catalogue of the Williams collection, which was a fairly representative and carefully-selected one, as a beginning, and this was now ready and obtainable from the Curator, price sixpence a copy. He thought it would prove a useful guide to such of their junior members who might be putting together a
}
41
general collection of their own, as it was a classified catalogue, and not merely a list'of preparations.
Mr. Goodwin thought that some greater facilities might be afforded to the members of the Club for seeing what slides were in the cabinet. If some microscopes could be kept there as well as the slides it would enable them to do this without the trouble of bringing their instruments with them.
The President said there was a drawback to this idea on account of the high charges made for rental, and he really thought with regard to these preparations the best thing to be done was to select from the catalogue, and take the slides home and study them at leisure.
Mr. Yezey said that fresh regulations as to borrowing slides would be found printed inside the catalogue, which increased the facilities hitherto given, and were much more to the advan- tage of the members than those previously in force.
Mr. Watson exhibited a microscope which was similar in design to the Yan Heurck microscope, but contained several alterations and improvements. The stage could be rotated completely either by the hands or by rack work. The milled heads were fixed on one centre, and did not travel with the stage. The optical centre was lOin. high from the table when horizontally placed, and the spread of the feet also lOin., giving great stability. There was also a centring motion which could be clamped when required.
The President thought they were to be congratulated upon having so fine an instrument upon the table before them. It was beautifully made, and he was satisfied it was capable of doing the highest work required to be done. The complete rotation of the stage was an advantage, and it should be re- membered that none of the movements in the old microscope had been sacrificed in obtaining it.
Mr. Karop said he had received from Mr. Swift for exhibition a new mounting for an Abbe condenser, which was made to carry the usual iris diaphragm, but had a movement by which it could be made eccentric and rotated in that condition. He also exhibited a new pond weed grapnel which was made for conveniently carrying in the pocket.
The President thought the Abbe condenser was a very prettily contrived thing and thoroughly well made, but it was
42
designed for obtaining oblique light, and for making false images of diatom structure. The pond weed apparatus was just like a " centipede " used for grappling submarine cables.
Mr. Western thought it was a great improvement upon the ordinary drag hook, which was an extremely inconvenient thing to carry in the pocket and uncomfortable to sit upon.
Messrs. Ross and Co. sent also for exhibition a collection of their latest instruments, representing nearly every class of their work, from the small star microscope upwards.
The President said they were much indebted to Messrs. Ross for sending down these instruments. The chief novelty was the means for rotating the body on the round stand, by means of which very great stability wras secured when the body was inclined or placed in the horizontal position. The second novelty seemed to be in the substage, which was made some- what on the Reichert plan, turning out on one side in a manner which certainly had its advantages. He thought this arrange- ment of the foot would make it very good for photography, for though the base was circular it really rested on three points, and therefore it was steady.
Mr. Karop could not help thinking that the position of the iris diaphragm was a mistake, because it cut off the rays in the wrong place, viz., too near the apex of the cone.
Mr. Ingpen said with regard to the diaphragm not being used with the condenser, the old French plan was to have three apertures, and these were adopted and used in the old Zeiss instruments, but they were meant more to be used when the condenser was out of use. The origin of the plan was the old Varley dark chamber.
Mr. Western read a paper " On four Foreign Rotifers not previously recorded as found in Britain."
Mr. Bryce said he had an opportunity afforded him of seeing the form last mentioned by Mr. Western, and he came strongly to the conclusion that it was not Rotifer mento, i.e., if any reliance was to be placed upon Anderson's drawings. It was very like Rotifer vulgaris, and required very careful observa- tion to distinguish it.
The thanks of the meeting were voted to Mr. Western for his communication.
Mr. Karop said that as the matter on the agenda paper was
43
somewhat short, he should like to read an interesting letter he had received from Mr. T. H. Buffham earlier in the year, relating to the organisms found in the estuary of the Thames at a certain period, and which gave rise to the phenomenon known as "foul " or " May- water." The subject was brought forward at the May meeting of the R.M.S., by Mr. Shrubsole, of Sheerness-on-Sea, who gave an interesting account of this peculiar state of the water, and distributed samples. Knowing Mr. BufBkam's active concern with anything relating to marine algae, to which these organisms presumably were related, and thinking he might be able to throw some light upon it, I wrote to him, and he, after examining material provided by Mr. Shrubsole, sent me this letter (read). The chief forms found in the water were spheres, about the size of small volvox, or cylindroids of transparent, gelatinous stuff, and containing large numbers of greenish-yellow or brown crescentic bodies imbedded in it. The exact nature of these organisms appears to be, at present, quite undetermined. The matter was of economic as well as of scientific importance, because Mr. Shrubsole states that during their apparition the whole of the fish precipitately retire from the mouth of the river and so put an end for a time to one of the chief industries of the locality. It seemed reasonable to suppose that the reason for this emigration of the fish was either that the organism was poisonous or unfitted for food, or, from its abundance and slimy consistence, it would choke up the breathing apparatus of the fish if they remained. I understand the phenomenon is of yearly recurrence and it certainly deserves careful study.
Notices of meetings, etc, for the ensuing month were then given, and the proceedings terminated. The following objects were exhibited : —
Syringa, section of flower bud Mr. H. E. Freeman.
Floscularia campanulata, mounted ... Mr. C. Rousselet.
November 2nd, 1894. —Conversational Meeting.
The following objects were exhibited : — Floscularia cornuta ... ... ... Mr. M. Allen.
Rotifer a, various species .. . ... .. Mr. W. Burton.
Corethra jplu unicornis ... ... ... Mr. J. A. JJaniell.
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Stem section of a Brazilian Liana ... Mr. G. Dunning.
0scillaria,8v.? Mr. W. Goodwin.
Peueroplis pertusus ••• Mr. A. Jenkins.
Alcyonium palmatum Mr. G. Mainland .
Navicula tumescens Mr. H. Morland.
Corallistes BowerbanMa, Ceylon Mr. B. Priest.
Euchlanis lyra, mounted Mr. C. Rousselet.
Arrenurus buccinator ... ... ... Mr. C. D. Soar.
November 16th, 1894.— Ordinary Meeting.
E. M. Nelson, Esq., F.R.M.S., President, in the Chair.
The minutes of the preceding meeting were read and con- firmed.
The following gentlemen were balloted for and duly elected members of the Club :— Mr. Walter P. Shadbolt, Mr. Edwin Wooderson, Mr. W. B. Stokes.
The following additions to the library were announced : — 11 Nova Acta Car-Leopold Akademie Nat. Cur.," two vols. " Proceedings of the Literary and-\
Philosophical Society of Man- V From the Society. Chester" ... ... ... J
" Annals of Natural History" ... Purchased. "Photomicrography" Dr. VanHeurck.
"Synopsis of the Naviculoid")
_/. / „ -d . T \ Prof. Cleve.
Diatoms, Part I )
The thanks of the Club were voted to the donors.
Mr. Karop said the last on the list of additions to the library deserved something more than a mere formal acknow- ledgment. This was Prof. Cleve's Synopsis, the first instal- ment of a very important work. He had taken one genus, the Navicula?, which by the unnecessary and unscientific multipli- cation of species had grown to most unwieldy proportions, and endeavoured to reduce it to order. The literature was equally colossal and scattered, and, therefore, a revision necessarily involved very considerable labour and research, as well as special knowledge of the subject, and those who worked at diatoms would not be astonished to hear that it had occupied Prof. Cleve i\\v besi pari of eight years. The present part
45
contained four plates, and he was informed the second would not be long before it appeared.
A special vote of thanks to Prof. Cleve for his valuable donation was unanimously passed.
The President said he had also received from a friend — Mr. Marryat — two beautiful series of photomicrographs of Karyo- Kinesis in Lilium bulbiferum. These were all taken by cheap leuses with peacock-blue glass screen, the sections beiug stained with blue haematoxylin.
The President said that he wished to make a remark with regard to a note of his which was read on March 16th last. In that note, in which he had made no claim to originality, he had referred to common optical formulae, which could be found on the first page of elementary text-books on the subject ; but the alternative formula (vi.) was, so far as he knew, not given in any text-book, and, therefore, might have been considered original. Last night, however, while searchiag some back volumes of the "R.M.S. Journal " for a reference on a totally different subject, he came across the same formula in a paper by Mr. C. R. Cross in the " M.M. J.," 1870, Vol. iv., p. 149, and in the " Journal of the Franklin Institute " for June, 1870, p. 401. So that to Mr. Gross must the honour be accorded for first publishing this simple and very useful formula.
The President said he had lately come across an article exhibited in a tobacconist's shop as a pipe cover. It was an iris diaphragm, which might be used for cheap microscopes. He had brought it to the meeting for inspection.
The Secretary said that at their last meeting Mr. Swift exhibited a little portable pond drag which could be carried in the pocket. Since then Mr. Allen had suggested a further improvement by adding a cap to one end to which an eye was fixed, so that a piece of string could be attached.
The President exhibited and described a new device which he thought might prove of service in microscopical work. It was an addition to the principle of Beale's neutral tint reflector, which, though possessing great advantage over the Wollaston camera or the Soemmering mirror, had the disadvantage of exhibiting the picture laterally inverted. By means of a second lateral reflector this inversion was got rid of and the image appeared erect in both directions.
46
Mr. J. E. Ingpen thought this would prove a very useful addition to the large number of drawing contrivances which existed. He remembered that many years ago when the subject was before the Club a number of these were exhibited, and if he had known the sabject would be cropping up that evening he could have brought up a considerable number of examples.
Mr. Michael said it was difficult to estimate the importance of this contrivance, because a camera which did not distort and did not require the head to be held quite steady was what everybody who made drawings in that way was most anxious to possess, and if anything could be done to get rid of the fatal error of Dr. Beale's camera it would be a most valuable achievement.
The President said that Cook in 1865 tried a mirror for the purpose of casting the image down upon the paper, but with high powers there was insufficiency of light. With low powers, however, it worked very well.
Mr. Ingpen said that an interesting illustration of this method was found in the case of " Varley's Graphic Telescope," which was an instrument of about 6in. focus, with a mirror in front of the object glass. There was a large specially-constructed eye- piece, and then another mirror at an angle of 45 degrees coming half over the eye-piece. Varley wrote a book on drawing instru- ments, and was going to publish it in conjunction with Mr. Home, but they quarrelled over it and destroyed all the copies except a very few, one of which he was fortunate enough to obtain through his friend Mr. Ackland.
Mr. Karop thought anyone who could draw hardly required any apparatus at all beyond cross-lines in the eye-piece and some sectional paper. Possibly a camera might be useful for making an outline, but all detail must be put in subsequently, and it was to be borne in mind that the use of any special appliance did not obviate inaccurate drawing in the least, although it was often stated as a sort of guarantee.
The President said that a great deal of the correctness depended upon the person who made the drawing. He remem- bered once seeing Mi-. N. E. Green make a most perfect drawing from the microscope without once looking at the paper.
Mr. Michael thought there could be no doubt that drawing carefully upon square ruled paper gave more accurate results,
47
but a great deal of time was lost by tbis metbod, and a certain amount of rougb detail as well as tbe outline could be done witb the camera in a much shorter time. He thought, how- ever, that this was a matter upon which one man could not be taken as a rule for another. Many persons had a difficulty in seeing the paper and the object equally well at the same time, and a man who was a good draughtsman would naturally do better than one who was not, and there was also a good deal in the idiosyncrasy of the individual eye. Personally he might say that he preferred the method with ruled lines.
Mr. Rousselet said he had a home-made camera, which he found to answer very well. A small mirror of speculum metal reflected the image upon a cover-glass, through which the paper was seen. The image in this case was not reversed. The plan was Mr. Usher's invention.
The thanks of the meeting were voted to the President for his communication.
The President intimated that there was nothing further upon the agenda paper, but as he saw Prof. Chas. Stewart present he ventured to ask if he would favour them with a few remarks.
Prof. Stewart said that when he came into the room he had no expectation of being called upon to speak, but as the President had done so he would in response say a few words upon what was to be seen in one particular section of the Museum with which he was more especially connected, and he thought it possible that some persons present might be interested in the structural varieties of fish bones. In the case of fish which had frames of rigid structure, they found these to be composed of a substance which was different in many respects from such bone as they found it in mammals, although it was rather difficult not to regard it as bone. When examined under the microscope it was found to be wanting in the familiar so-called bone-corpuscles ; it had a somewhat fibrillated matrix, and in that matrix were rows of large spaces much larger than the ordinary haversian canals. These certainly were not blood-vessels, and they did not contain cells, but if they were hardened and sections were taken they were found to contain fine granular material, but in not one which he had examined had he ever succeeded in finding either a cell or a blood-vessel. The cod, haddock, and fish of that class all had this kind of bone. In other classes of fish a very different structure
48
was found. In the sword-fish the matrix was traversed by tubes which were no doubt Haversian canals containing blood-vessels, but around each canal were more or less defined lamellae, but no corpuscles. In another group, which included nearly all the flat fish, the structure differed again, and a typical example was furnished by the " tobacco pipe fish," the bone of which was found to contain numerous fine tubes like those of dentine branching out, and usually terminating in two branches. It was composed of lamellae, and had all the characters of a thoroughly dentine-like structure. Then in the salmonidae a further development was found, the matrix being occupied by small spaces, lacunae, each containing a single cell, but there were no canaliculi. In herrings, carps, and eels, etc., there were lacunae with well developed canaliculi. As far as he was aware, since the time of Kolliker, there had been very little done in this direction. Most people seemed to be content to make sections of the dry bone and to examine them, but there was no paper, so far as he could ascertain, which treated of the soft parts with which the hard parts were associated. If, there- fore, anyone having leisure to do it would undertake the inves- tigation, he would be adding important information to their present knowledge of the subject. Prof. Stewart illustrated his remarks throughout by drawings of the structures upon the black-board, by means of which their peculiarities were made readily apparent.
The President thought they were greatly indebted to Prof. Stewart for his admirable and interesting lecture, for which he had great pleasure in proposing a hearty vote of thanks. This having ben carried by acclamation,
Mr. E. T. Newton inquired if the dentine was found in all the bones of the pipe fish, or whether it was peculiar to those only which Prof. Stewart had described.
Prof. Stewart said it was stated that all the bones had that structure. Certainly this was the case with all those which he had himself examined, and he thought it would be a new observation if it was found that the other bones of the fish did not possess the same character.
Announcements of meetings, etc., for the ensuing month were then made, and the proceedings terminated with the usual conversazione. The following objects were exhibited : —
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Gallidina vorax, G. plena, C. ligula Atherix crassicmnis. Mouth organs Algie (various fresh-water species) Daphnia (sp. ?) Synchoeta tremula ... Asplanchnopus myrmeleo ...
Mr. D. Bryce. Mr. H. E. Freeman. Mr. W. Goodwin. Mr. G. Hind.
Mr. C. Rousselet.
December 7th, 1894.
Asplanchna priodonta Hydatina senta Vespa. Mouth organs ... Schizocerca diver sicomia ... Polyxenus lagurus...
Rock-section. Basalt dyke in lime- | stone, Carlingford ... ... )
Mr. J. M. Allen. Mr. W. Burton. Mr. W. Goodwin. Mr. C. Rousselet. Mr. C. D. Soar.
Mr. G. Smith.
December 21st, 1894. — Ordinary Meeting.
E. M. Nelson, Esq., F.R.M.S., President, in the Chair.
The minutes of the preceding meeting were read and con- firmed.
The following gentlemen were balloted for and duly elected members of the Club :— Mr. Ferdinand Coles, Mr. Alfred Howard, and Mr. R. Traviss.
The following additions to the library were announced :— " The Rotatoria of Greenland " ... By Dr. Burgendal.
" La Nuova Notarisia " ... ... In Exchange.
" The Botanical Gazette "
" Transactions of the Norfolk and \
Norwich Naturalists' Society" J From the Society. " Transactions of the Natural History")
Society of Northumberland " ) "
" Proceedings of the Nova-Scotian |
Institute of Science " ... J " "
" The American Monthly Microsco- *)
picalJournal" / In Exchange.
Journ. Q. M. C, Series II., No. 36. 4
50
The Microscope " In Exchange.
Le Diatomiste "
Annals of Natural History " ... Purchased.
Quarterly Journal of Microscopical") Science" J
The thanks of the Club were voted to the donors.
The Secretary said that the paper before them that evening was by Dr. A. M. Edwards, their oldest honorary member. It dealt with the discovery of diatoms in shales older than the Lower Miocene, and since this paper was written he believed Dr. Edwards had claimed to have found them in Silurian strata. He could not read the whole paper as received, some of the geological details being of purely local interest, but Dr. Edwards had given him permission to extract as much as he considered of value, and the salient points of the original paper were entirely preserved. Whether or no they agreed with Dr. Edwards' conclusions was a matter for them to decide when they had heard his views, but, personally, he must say that great caution should be exercised before judging on the presence of such ubiquitous organisms as fresh-water dia- tomaceae. From their small size and general distribution in running water they were liable to be carried by percolation far from their place of origin, yet, as Prof. Cleve had lately pointed out, in some cases they might be of great value in geological determinations.
Dr. Edwards' paper was then read.
Mr. E. T. Newton said he had not made diatoms a special study, but it was a well-known fact that they had been found fossil, certainly in the Chalk, and possibly in the Coal Measures, but he did not think there was any record of their presence in the older rocks. He agreed with Mr. Karop that there was always a great probability of their getting washed in, and that the very greatest care was required before it would be safe to say that they really belonged to the rocks amongst which they were found. Still, there was nothing impossible about it. Certain old rocks in Scotland and Cornwall were largely made up of Radiolarians, and some chalky-looking rock from Australia seemed nearly composed of the same small organisms. In thin sections their structure could be very well seen. He thought the subject was one worth looking into,
51
because there was no reason why diatoms should not be found in the Silurian rocks, but, on the contrary, it might rather be expected that they would.
Mr. Karop thought that the need for care which Mr. Newton had insisted upon could not be too strongly enforced in making any investigations in this direction; everything used should be perfectly free from suspicion, and new pipettes must be used, because the diatoms would cling to anything which once contained them for an indefinite time.
The President said he remembered seeing some curious diatoms in some kind of rock which was sent to them by Mr. Shrubsole.
Mr. Karop said they were common enough in the Tertiary strata, but had not until quite recently been found in strata as old as the Silurian.
Mr. E. T. Newton said it was generally accepted that the higher the grade of an animal the shorter the distance it went back in time ; and it was of course also true, on the con- trary, that the lower the grade the farther back it was found to extend; if this were true they might expect to find diatoms in the Silurian.
Mr. Karop thought it was understood that their age was great, but being formed of colloid silica, which was soluble in alkaline water, it seemed rather doubtful if they would be able to persist in the manner expected.
Mr. Newton said that the evidences of their existence would not necessarily be destroyed even if they were dissolved, because they would leave their impress in the rocks, and this might be filled up with other matter.
Mr. Morland could quite corroborate what Mr. Karop had said as to the way diatoms had of clinging to tubes, etc. No one could ever be sure that a tube was quite clear from them, even after repeated washing and wiping.
The President made some remarks upon the subject of coloured screens for use with the microscope, and pointed out the advantages to be gained thereby. These could be of a variety of tints, but all would not be found to work equally well for all purposes. Colonel Woodward's screens were made with a solution of ammonio-sulphate of copper, whilst his own were of cobalt blue glass, and Mr. C. Haughton Gill used a Zettnow
52
screen of sulphate of copper and bichromate of potash. One of the best screens was of a green glass of such a tint as to cut out the red in a bright spectrum. Those who did not possess a spectroscope could get a good spectrum by means of any coarse diatom by using a narrow pencil, and viewing the spectra at the back of the objective wlien the eye-piece was removed.
Mr. Ingpen said that a splendid spectrum could be obtained in this way with a Cherryfield rhomboides.
The President said that when diatoms were examined on a dark ground colours were often seen, red indicating a coarse and blue a fine structure. In the early days of his microscopical work he had noticed a blue line on the girdle of a Pinnularia major, and he at once recognized this as indicating the presence of fine structure. It was not long before he had resolved it into 60,000 stria? per inch. It was an interesting question whether this consisted of rows of minutely perforated structure, if so it must wait for an objective of the future to resolve it, as it was beyond the reach of the best modern objectives. It would be more difficult than the longitudinal stria? on the A, pellucida, as there were no edges and raphae for the manufacture of false ghosts.
Mr. Ingpen said that the medium piperine was irrational. There were some high refractive media he could recommend, among which he might specially mention that composed of one part of bromide of antimony, one part of bromide of arsenic, and one part of piperine. This mixture was rather yellow, but it melted easily at a low temperature.
The Secretary announced that nominations for members to serve on the Committee must be made at their next meet- ing- Announcements of meetings, etc., for the ensuing month were then made, and the meeting terminated with the usual conversazione, the following objects being exhibited : — Stephanoceros Eichhornii ... ... ... Mr. W. Burton.
Tcwdigrada (sp. ?) Mr. C. Eousselet.
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Jan cart 4th, 1895.
Cypris-stage of Balanus Mr. E. T.Browne.
Conochilus unicornis Mr. W. Burton.
Euchlanis pyriformis (mounted) ... Mr. C. Rousselet.
January 18th, 1895.— Ordinary Meeting. E. M. Nelson, Esq., F.R.M.S., President, in the Chair.
The minutes of the preceding meeting were read and con- firmed.
The following gentlemen were balloted for and duly elected members of the Club :— Mr. G. E. Awde, Mr. B. Cox, Mr. A. Harrison, and Mr. E. Hinton.
The following donations to the library were announced : —
The '' Botanical Gazette " In Exchange.
A series of reprints of papers by Herri
Lauterborn, " On the Marine and r Per Mr. Rousselet.
Fresh Water Flora of Helgoland" ) "Annals of Natural History "... ... Purchased.
The Secretary read the list of nominations by the Committee for officers of the Club for the ensuing year.
The Secretary gave notice of an alteration of the Rules, pro- posed by the Committee, to be submitted at the next Annual General Meeting, viz., that an Hon. Editor be added to the list of officers in Rules 2, 3, and 9.
The President announced that there would be four vacancies for members of Committee, and invited the members present to nominate gentlemen to fill the same.
The following nominations were then made : —
Mr. Dadswell, proposed by Mr. Hardy, seconded by Mr. Kern.
Mr. Parsons, proposed by Mr. Burton, seconded by Mr. Hembry.
Mr. Bryce, proposed by Mr. Powell, seconded by Mr. Muiron.
Mr. Morland, proposed by Mr. Soar, seconded by Mr. Scour- field.
Mr. Freeman, proposed by Mr. West, seconded by Mr. Lloyd.
The President said these names would be printed on the ballot papers in the usual way, and the election would take place at the next — which would be their Annual Meeting. It
54
was necessary for two auditors to be selected that evening, and
on behalf of the Committee they had appointed Mr. Bryce.
He now asked the members to appoint another on behalf of
the Club.
Mr. W. Chapman was proposed by Mr. Allen, and seconded
by Mr. Burton, and unanimously elected.
Mr. C. Rousselet read a paper " On the Preparation of
Rotifers as Permanent Microscopic Objects," supplementary to a communication on the same subject made about two years
ago, and detailing the improved methods discovered and adopted in the meantime. The paper was illustrated by the exhibition of a large number of slides under microscopes in the room, and Mr. Rousselet announced his intention to present to the Cabinet of the Club a complete type collection of every species. Already he had successfully mounted 130 species, and he presented to the Club that evening 77 slides, representing 72 species, as a first instalment of his promised donation.
The President thought they were extremely fortunate in the possession of such an active member as Mr. Rousselet, who had thrashed out the subject of fixing and mounting these very difficult objects so thoroughly, and had given a descrip- tion of the process in a way which would always associate it with the Club. It was hard work, like that which had been described, which would always do more than anything else to keep up their reputation. Their best thanks were due to Mr. Rousselet for his paper, and also for the valuable donation made that evening, and for the promise of a completion of the series in due course.
Thanks to Mr. Rousselet were unanimously voted. Mr. Goodwin communicated a note on an Alga found at Wan- stead Park on October 5th, at the edge of the pond, which seemed to him to be a new species of Oscillaria. The filaments were very small, and the endochrome appeared green by trans- mitted light, but under the microscope it was difficult to say exactly what colour it was, the endochrome being very much concentrated. So far as he could make out, it was a new species, but he had not yet taken the opinion of any specialist on this point, though he thought if it turned out to be new it was worth recording. No new features had been developed in it since the date on which it was found.
55
Mr. Karop said that if the object described by Mr. Goodwin was really a new species it would, of course, be interesting, but in such lowly plants as Oscillarige, where reproduction was entirely asexual, they had only morphological characters to depend upon, and therefore he thought it would be wise to wait until it had been submitted to the judgment of an expert. There was such a superabundance of species amongst the protophyta that it was most undesirable to add to them un- necessarily.
The Secretary said that the publication of the list of mem- bers of the Club would be due this year, and asked that any alterations in addresses might be communicated to Mr. Vezey.
Announcements of meetings, etc., for the ensuing month were then made, and the proceedings terminated with the usual conversazione, at which the following objects were exhibited : — Melicerta ringens ... ... ... ... Mr. J. M. Allen.
Stycoptera contaminata ... ... ... Mr. H E. Freeman.
Spirillum Mr. G. Hind.
Mr. C. Rousselet exhibited the following mounted objects under several microscopes : —
Asplanchna priodonta. Asplanchnopits myrmeleo. Brachionus pal a. Conochilus voir ox. Copeus caudatus. Diglena forcipata. Euchlanis hyalina.
,, pyriformis.
,, triquetra.
Hydatina senta. Limuias annulatvs.
,, ceratophylli. Melicerta Ringens.
Koteus quadricornis. Xotrsmmata aurita.
,, lacinulata.
Notops hracliionus. Ploesom a Ilndsoni. Proales parasita (in Volvox
globator). Bhinops (?) orbicnlodixcus. Sacculus viridis. Stephanoceros Eichhoiuii. Syuchcela iremala. Triphylus lacustris.
February 1st, 1895.
Euchlanis diletata.. Surirella fastuosa .. Cyclosis in Nitella
Mr. W. Burton. Mr. H. Morland. Mr. W. R. Traviss.
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February 15th, 1895. — Annual Meeting. E. M. Nelson, Esq., President, in the Chair. The minutes of the preceding meeting were read and con- firmed.
The following gentlemen were balloted for and duly elected members of the Club:— Mr. H. Cheese, Mr. T. S. Davis, Mr. G. J. Harris, Mr. W. J. Marshall, Dr. J. W. Measures, Mr. W. J. Wonfor, Dr. Tatham.
The Secretary announced that the " Proceedings of the Smithsonian Institution " had been presented to the library.
Announcements of meetings, etc., for the ensuing month were made, and the business of the annual meeting was then proceeded with.
The Secretary said that at their last ordinary meeting notice was given that an amendment to Rules 2, 3, and 9 would be proposed, to the effect that in future the Hon. Editor of the Journal should be a member of the Committee. This could hardly be called an innovation, because practically the Editor had always attended, as he happened to be otherwise a mem- ber of Committee, but to meet the case of anyone becoming the Editor who was not one of the Committee this addition seemed necessary. Of course, the desirability of the Editor of the Journal being present at the meetings of the Committee would be obvious to all.
The proposal to add the words " Honorary Editor of the Journal " to Rules 2, 3, and 9 was then put from the chair and unanimously agreed to.
The President having appointed Messrs. J. M. Allen and C. L. Curties as scrutineers, the ballot was proceeded with for the election of officers and four members of Committee. The scrutineers subsequently reported that the whole of the officers in the list of nominations had been duly elected, and also that Messrs. Mori and, Dadswell, Bryce, and Parsons had been elected members of Committee.
The Secretary read the report of the Committee for the past year.
The Treasurer read his annual statement of accounts for the same period.
The adoption of the report and balance sheet having been moved by Mr. Richard Smith and seconded by Mr. J. G. Waller, was put to the meeting and carried unanimously.
57
The President then delivered the customary annual address.
Mr. A. D. Michael said he rose to ask the members present to do something which he felt they were ready to do spontane- ously, and that was to pass a very hearty vote of thanks to the President for the very able and learned address to which they had just had the pleasure of listening. The subject dealt with was one of first-class importance, for there could be nothing more important to a microscopist than to know the exact amount of light with which he could till his objective in order to obtain the best possible results. It was also obvious that this ought to be intelligently done, and not by mere rule of thumb. Such an address as that, when they were able to read it carefully for themselves, would do much towards enabling them to decide as to what was the theory of microscopic vision which they could most confidently rely upon. Until they knew this they could not decide as to which was the best method for using their microscopes to the best advantage. The subject was one of leading importance to them as microscopists, and they would all agree that it had been most ably treated by their President in his address to them that evening.
Mr. W. Burton having seconded the motion, it was put to the meeting by Mr. Michael, and carried by acclamation.
The President thanked the members for this vote of thanks, and for the very kind wa}r in which it had been received and carried. He also desired to thank them very heartily for the honour which they had conferred upon him by electing him as their President for another year.
A vote of thanks to the Auditors and Scrutineers was then moved by Mr. Western, seconded by Mr. Rousselet, and carried unanimously.
A vote of thanks to the President and Officers of the Club for their services during the year was similarly honoured.
Mr. Karop said — It is my pleasant duty on these occasions to reply, on behalf of the Committee and other officers, to the vote of thanks just moved. During the Club's career of nearly thirty years it is surprising to note how few changes, relatively speaking, have occurred in its executive, a fact creditable to both Club and officers. One reporter only— Mr. Lewis— has held his post continuously since 1867, and, with very few exceptions indeed, has attended every meeting. There have been three Treasurers, Mr. Hardwicke, who died in office, Mr.
58
Gay, and Mr. Vezey, who, he hoped, would long remain ; two Librarians, Mr. Jaques and Mr. A. Smith; fonr Curators, Messrs. Ruffle, Hailes, Emery, and Browne ; and four Secre- taries, Messrs. Bywater, White, Ingpen, and Karop. In regard to the latter office, however, he thought it might be a mistake for a Secretary to continue much over ten years ; he would be apt to get into a groove and let things take their own way too much. In all concerns probably, an infusion of fresh activity was occasionally beneficial, and if the members at any time were of opinion their present Secretary had held his post long enough, he trusted they would just say so, and he should at once be willing to make room for a more efficient successor. There was another matter he should like to be allowed to refer to. Some might have thought the penultimate paragraph of the Report, concerning the non-payment of subscriptions, was rather severe, and he did not suppose for a moment it applied to anyone present that evening. At the same time it was a hard fact, and one that had to be considered by those responsible for the maintenance of the Club, but as probably very few ever troubled about the balance sheet after hearing it read, he would endeavour to show its importance by a few figures. Up to the end of December, 1894, there were 345 members on the books, and if all pay their subscriptions, these total £172 10s. Our chief items of expenditure are for rent and attendance, and the Journal, which, taking last year's figures, together amount to £150, thus absorbing the subscriptions of 300 members, leaving about £22, which, with other assets from sale of Journal, advertisements, and investments, give us at the very utmost £65 to pay for printing, stationery, postage, books and binding, extra meeting, if held, and other petty expenses. But, unfortunately, there are always a large number of sub- scriptions in arrear, and considering the advantages the mem- bers possessed of meeting in one of the best rooms in London, well warmed and lighted, a Journal, and a Library and Cabinet at their disposal for the absurdly small sum of ten shillings pel' annum, it was not asking too much that at least it should be paid with reasonable promptitude. On behalf of the officers of the Club he thanked the members for the cordial manner in which they had passed the vote. The proceedings then terminated.
i?
59
TWENTY-NINTH ANNUAL REPORT OF THE COMMITTEE.
Taking all circumstances into account, your Committee is happy to state that the Club's career during the past year has been, on the whole, satisfactory.
The number of new members is not so large as could be desired, twenty-five only having been elected in the twelve months ending December, 1894. A considerable number of resignations have also been notified, and three have been lost by deatb, leaving the total on the list somew hat smaller than usual. Your Committee is of opinion that the advantages un- doubtedly possessed by the Club, considering the extremely small amount of the subscription, might be made more widely known by members themselves, and so lead to an increase of numbers.
The attendances at the meetings, however, have been notice- ably good, aud much interest taken in the proceedings. The papers read, although perhaps falling somewhat short of the average in quantity, have been good and thoughtful contri- butions.
The following is a list of the chief : —
February. — The Presidential Address, by Mr. E. M. Nelson.
March. — " On the determination of the Foci of Microscopic
Objectives," by Mr. E. M. Nelson. " On Ammba" by
Mr. H. W. King.
May. — " Notes on Foreign Rotifers since found in Britain,"
by Mr. G. Western. June. — "On JDistyla spinifera" by Mr. Gr. Western. "On
Ilyocryptus agilis" (n. sp.), by Mr. D. J. Scourfield. September. — " On Gyrtonia tuba,'" by Mr. C. Rousselet. " Further notes on Macrotrachelous Callidince" by Mr. D. Bryce. October. — " Notes ou four Foreign Rotifers since found in
Britain," by Mr. G. Western. November. — " An addition to Beale's Reflector," by Mr. E. M. Nelson.
60
December. — ;i On the Diatomaceae older than those of Vir- ginia, etc," by Dr. A. M. Edwards.
A Special Exhibition Meeting was held at Freemasons' Tavern on May 4th, attended by 140 members and 390 visitors. The arrangements of the cloak-rooms and refreshment depart- ment were certainly very deficient, owing to the overcrowded state of the building generally on this occasion, but the incon- venience to many members and their friends, however unfor- tunate, could not be foreseen when the room was hired some four months in advance. The exhibits were generally good, and the excellent orchestra, under the direction of Dr. Dundas Grant, for whose services the Club is entirely indebted to the kind offices of Mr. J. W. Reed, was greatly appreciated by everyone present. The Committee desires to thank all who assisted at this meeting, and most particularly Mr. Reed, Dr. Grant, and the musicians. The expenses, as before decided, were defrayed by the Club.
Two Journals have been issued since the last Report, com- pleting the Fifth Volume of the Second Series. The October Number was considerably delayed owing to the loss of a portion of the MSS. in the post. The advertisements on the covers have produced the sum of £15 19s. 6d., as will be seen in the balance-sheet. As it is more than might have been expected, it is only right to say this welcome addition to the Journal fund is solely due to the energy of Mr. C. Rousselet.
Aware of the long time which necessarily must elapse before the entire revision of the Cabinet can be completed, the Com- mittee deemed it advisable to issue in the meantime a catalogue of the preparations in the Williams' bequest, a fairly repre- sentative collection of nearly 700 slides. The list of the Diatomaceae in possession of the Club and the Foraminifera in the Hailes' Collection being also finished, a catalogue of these is in the press, and will shortly be ready. The thanks of the Committee are due, and hereby offered, to Messrs. Browne, Morland, and Priest, who severally undertook the whole labour, and it is no light one, of making these lists, and also to Mr. Nelson, who, in addition to the already long list of his benefac- fcions to the Club, has most kindly undertaken the expenses of printing the catalogue of the Hailes' Collection. The finances may be said to bo in ;i Fairly satisfactory con-
61
dition ; the receipts from subscriptions are about the same as for the previous year, while the sale of Journals has brought in nearly £10 more. The item for advertisements has already been referred to. The expenditure has been very carefully watched, and the Journal kept within the sum assigned to it. Several compounding fees have been paid during the past few years, and the Committee has therefore thought it wise to add a small amount to the investment in Consols, bringing- up the total to £200.
.Many members appear to be under the impression that pay- ment of their subscription need not be made until they have received one or more applications for it. This entails an un- necessary outlay for printing and postage, to say nothing of the extra and disagreeable labour imposed on the Treasurer. Members are therefore reminded that subscriptions are due in advance on the 1st of January in each year, and should be re- mitted within a reasonable time from that date.
Your Committee desire to thank the officers for their valuable and indispensable services. In conclusion, they have every confidence in the prosperity of the Club, and that it will con- tinue to meet the requirements of the amateur and further the advancement of microscopy, the objects for which it was con- stituted thirty years ao"o.
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63
Q.M.C. Excursions, 1894.
|
I 1 I 1 |
Dates. |
Localities. |
«>5? u - 11 ■go c ® 3.C ^^ o |
on 'C I! - — ll - 0J o |
3 > o g 8 |
+2 0 |
|
1 |
April 7 |
Royal Botanic Gardens |
44 |
14 |
22 |
80 |
|
i 2 |
„ 21 |
Chingford ... |
13 |
1 |
— |
14 |
|
3 May 5 |
Enfield |
13 |
— |
1 |
14 |
|
|
4 „ 19 |
Highains |
9 |
— |
— |
9 |
|
|
5 June 2 |
Hertford Heath |
6 |
1 |
1 |
8 |
|
|
6 ,„ 16 |
Whitstable |
13 |
1 |
1 |
15 |
|
|
7 „ 30 |
Oxshott |
9 |
— |
1 |
10 |
|
|
8 |
July 14 |
Woking |
7 |
1 |
— |
8 |
|
9 „ 28 |
Richmond Park |
5 |
— |
— |
5 |
|
|
10 Sept. 1 |
Keston |
7 |
2 |
3 |
12 |
|
|
11 1 „ 15 |
Staines |
4 |
— |
4 |
||
|
12. „ 29 |
Snaresbrook |
10 |
2 |
— |
12 |
|
Names of members who sent lists of objects found by them : —
B. Burton, W. So. Southern, W. H.
D. Dunning, C. G- Th. Thompson, Percy
P. Parsons, F. A. T. Turner, C.
R. Rousselet, C. F. Wb. Webb, J. C.
Sc. Scourfield, D. J. W, Western, G.
S. Soar, Charles D.
64
List of Objects found on the Excursions.
Note. — The numbers following the names of the objects indicate the excursions upon which they were found, and the letters indicate the names of the members recording the same. When an object is frequently recorded, the initials of the names of the members are omitted.
CRYPTOGAMIA. ALGJE. Eudorina elegans Gonium pectorale . Nostoc verrucosum . Pandorina morum . Prasiola calophylla . Raphidium falcatum Yolvox globator
Desmidiacejj. Arthrodesmus incus Closterium lunula .
,, rostratum
Cosmarium margaritiferum Docidium baculum .
„ Ehrenbergii
Micrasterias denticulata .
„ rotata .
GB.AUAGEM. Chara vulgaris
PROTOZOA. Acineta mystacina . Actinophrys picta .
sol Actinosphaerium Eichhornii ^Egyria oliva . Amphileptus anser .
,, flagellatus .
gigas . Anthophysa vegetans
1, 2, W.
1, 2, 8, W. 8, T.
2, 5, 8, 11, YV. 10, 11, T.
10, 11, T.
1, 2, 3, 5, 7, 8, 9, 10, 11.
10, 11, T.
1, 2, 3, 5, 7, 8, 10, 11.
7, 10, 11, T.
8, 10, 11, T. 8, T.
11, T. 10, W.
10, T.
3, B.
1, P. 8, W.
I, D.; 7, 10, 11, 12, T.
11, T.
3, 12, P.
II, P., W.
4, P. 8, W.
5,W.; 8, P., W.; 11,12,
Arcella dentata
3, 7,T.;8, W.; 9,T.,W.;
11, w.
65
|
Arcella vulgaris |
3, 5, 7, 8, 9, 11. |
|
Bursaria truncatella |
. 1, T. ; 3, B, P. |
|
Carchesium polypinum . |
. 1, T. |
|
Centropyxis aculeata = Arcella |
b |
|
aculeata .... |
8, 9, 11, T. |
|
Clathrulina elegans |
11, P. |
|
Coleps hirtus .... |
. 1, 2, 11, 12, T. |
|
Condylostoma stagnale |
. 1, 2, P. ; 3, B. |
|
Cothurnia imberbis |
1,T.; 3, B. |
|
Didinium nasutum . |
3, P. |
|
n.s. (J. G. Grenfell) |
1, W. |
|
Difflugia corona |
9, W. |
|
„ globulosa . |
. 2, 8, 9, W. |
|
„ oblonga |
3, 11, T. |
|
,, proteiformis |
. 1, 3, 8, 10, 11, T. |
|
,, pyriformis |
. 3,B.; 8, W.; 9, T. |
|
Dimastigoaulax cornuturn |
. 11, P., T., W. |
|
Dinobryon sertularia |
3, 4, 5, 10, 11, 12. |
|
Ephelota coronata ? |
6, P. |
|
Epistylis anastatica |
1, D., W. |
|
„ flavicans . |
1, 4, P. |
|
,, plicatilis . |
. 10, T. |
|
Euglena spirogyra . |
. 8, 10, T. |
|
,, viridis . |
. 8, 10, T. |
|
Euglypha alveolata |
. 8, W. |
|
,, ciliata |
8, 10, W. |
|
Euplotes patella |
1, 3, T. |
|
Litonotus fasciola=Dileptus folium |
1,D. |
|
Loxophyllum meleagris . |
. 9, 11, P. |
|
Mallomonas Plosslii. |
7, P. |
|
Nebela carinata |
8, W. |
|
„ collaris |
8, 10, W. |
|
„ flabellum . |
10, W. |
|
Noctiluca miliaris . |
6,Wb. |
|
Opercularia nutans . |
1, 2, P. |
|
Ophrydium versatile |
9, P., T. |
|
Ophryodendron abietinum* |
6, P. |
|
Paramecium aurelia |
3, B., T„ W. ; 8, 11, T |
* Ophryodendron abietinum had some of the tentacular filaments capitate. Journ. Q. M. 0., Series II., No. 36. 5
66
|
Peridinium tabulatum |
1, P. ; 3, 5, 11, W. |
|
Phacus longicaudus , . • |
1, 3, 8, 9, 10, 11. |
|
Phialina vermicalaris ? . |
1,P- |
|
Platycola decumbens |
2, P. |
|
Pleurotrichalauceolata=Stylouichia |
|
|
lanceolata. . |
3, T. |
|
Raphidiophrys elegans . |
9, W. |
|
Rhabdostyla sertularium ? |
1, P. |
|
Rhipidodendron Huxleyi . |
7, P. |
|
„ splendidum . |
5,W. |
|
Spirostomum ambiguum . |
3, B.; 10, T., W\; 11, T. |
|
Step tor cseruleus . |
3,W.; 4, 7, 8, P. |
|
„ niger |
3, 4, P. ; 5, P., W. ; 9, P. ; |
|
11, P., T., W. |
|
|
„ polymorphous |
1, 2, 3, 4, 9, 11. |
|
„ Rceselii . |
11, W. |
|
Stichotricha remex . |
7, 11, P. |
|
Strombidium Claperedi . |
8, 12, P. |
|
Stylonichia mytilus |
1, T. ; 8, W. ; 9, 11, T. |
|
Synura uvella . |
8, 11, W. |
|
Trachelius ovum . |
2,P.,W.;3,B.,P.,T.,W.; |
|
11, T., W. |
|
|
Trachelocerca olor . |
11, T. |
|
„ versatilis . |
8,W. |
|
Trichodina pediculus |
11, T. |
|
Urocentrum turbo . |
3, 11, P. |
|
Vaginicola crystallina |
1, 3, 8, 11, 12. |
|
Vorticella chlorostigma . |
3, 4, 9, P.; 10, 11. W. |
|
„ citrina ? . |
11, P. |
|
„ microstoma |
. 1, D. |
|
„ nebulifera |
11, W. |
|
PORIFERA. |
|
|
Grantia ciliata |
6,D. |
|
„ compressa . |
6, D. |
|
CCELENTERATA. HXDROZOA |
|
|
Eudendrium insigne |
. 6, P. |
|
,, ramosum |
6,D. |
|
Obelia geniculata |
6, D., P. |
|
Plumularia halecioides . |
6, P. |
67 Plumularia pinnata = Sertularia
|
pinnata |
. |
. 6,D. |
|
Thaumantias hemisphaerica |
. 6, Wb. |
|
|
Tubularia indivisa . |
. |
. 6, D., P. |
|
ACTINOZOA. CORALLIGENA |
||
|
Actinoloba dianthus = |
Actinia |
|
|
plumosa . |
. 6, Wb. |
|
|
CTENOPHOEA. |
||
|
Pleurobrachia pileus |
. 6, Wb. |
|
|
VERMES. Rotifera. |
||
|
Adineta vaga . |
. |
. 7,8, W.; 10, P., W.; 12, P. |
|
„ var. . |
. |
. 7, W. |
|
Anureea aculeata |
. 1, 2, 3, 4, 5, 7, 8, 9, 11. |
|
|
„ „ var. valga . |
. 5, R.; 7, P., T., W.;8. P. |
|
|
W.; 12, P. |
||
|
„ brevispina . |
. |
. 3, 7, 10, 11,12. |
|
,, cochlearis . |
. 1, 2, 3, 4, 7, 10, 11. |
|
|
„ curvicornis . |
. |
. 3, 7, 8, 10. |
|
„ hypelasma . |
. 1, 9, 10, 11, W. |
|
|
„ serrulata |
. 2, 5, 7, 8, 10. |
|
|
„ tecta . |
. 3, 11, P., W. |
|
|
Anapus ovalis . |
. |
. 5, R. ;8, 11, W.; 12, R. |
|
Ascomorpha ecaudis |
= Sacculus |
|
|
viridis . |
. 3, 4, 5, 7, 8, 9, 10, 11, 12. |
Ascomorpha saltans = Sacculus
saltans 8, 10, W.
AsplanchnaBrigbtwellii . . .1, R., So. ; 10, P., W. ; 11,
P. priodonta . . 1, R., So., Th., T., W. ; 2,
So.;4,R., W.; 10, W. Asplanchnopns myrmeleo . .11, W. Brachionus angularis . . .1, So., W. ; 2, R., So. ; 3,
P., W. ; 4, R. Bakeri . . 1, R., Th., T. ; 3, 9, P.,
AY. ; 10, P.
. . 1,R, So., W.; 3, P.; 4, P.,R.;7, T. „ var. amphiceros . 1, I)., Th., T. rubens . . . . 2, So. ; 3, 4, W. ; 7, P.
68
Brachionus urceolaris
var. Callidina constricta
„ elegans
,, lata .
„ magna-calcarata
„ musculosa
,, parasitica
,, plicata , quadricornifera
, tridens
Qathypna luna
„ rnsticula .
„ ungulata . Ccelopus brachynrus
„ cavia .
,, porcellus
„ tenuior Colurus bicuspidatus
,, caudatus
„ deflexus Conochilus unicornis
„ volvox .
Copeus caudatus „ cerberus „ Ehrenbergii = labiatus „ pachyurus
Cyrtonia tuba (Rousselet) = Noto-
mata tuba (Ehr.) . Diaschiza exigua .
„ globata .
,, pseta .
„ semi-aperta
male
„ valga Diglena catellina
1, 2, 5, 6, 7, 8, 12.
2, R. 7, W. 7, W.
10, P., W.
11, P.
2, 3, W. 4, P., R.
7, 8, 10, W. ; 12, P.
8, 10, W. 8, W.
7, 8, 9, W. ; 11, P., W.
4, R.
8, R., W.
3, R., W. ; 4, 9, W.
5, 7, W.
3, W.; 5, P., R.,W.; 9,
P, W. ; 11, P. ; 12, R. 5, 10, W.
9, 10, W.
3, B. 11, W.
10, P., T., W.
5, R., W.; 7, P., T.; 8,
P., So., W. 8, W.
1, P.; 4, P.,R.;10, W.
8, P., R., W.; 11, P. T. 5, W. ; 7. P. ; 9, W. ; 10,
P. w.
11, P., w.
2, R., W. ; 3, 7, 8, 9, W.
11, W.
10, W.
4, 7, W. ; 8, R., W. ; 9, 10, 11, W. ; 12, R.
8, W.
11, W, 1,R.
69
|
Diglena forcipita . |
. 1,3, P.; 4, W.;5, P.; 10, |
|
|
W. |
||
|
Dinocharis pocillum |
. 2,3,4, 5, 9, 10, 11, 12. |
|
|
)> |
te tract is |
. 2, 3, 5, 7, 8, 9, 10, 11, 12. |
|
Diplax |
trigona |
. 8,W. |
|
Distyla |
clara . |
. 8, W. |
|
» |
flexilis |
. 7, 8, 10, W. |
|
)) |
inermis |
. 8,W. |
|
Elosa Worrallii |
. 7, 8, W. |
|
|
Eosphora aurita |
. 2, W. ; 3, R. ; 8, R., W. ; |
|
|
9, 10, W. ; 11, P., W. |
||
|
Euchlanis deflexa . |
. 4, R. |
|
|
55 |
dilatata . |
. 3, B.,T.,W.;8,R.; 11, T. |
|
55 |
hyalina |
. 11 W. |
|
55 |
macrura . |
11, P. |
|
55 |
orapha |
. 11, W. |
|
1) |
parva |
. 4, R. W. |
|
55 |
pyriformis |
. 1, 3, P. |
|
55 |
subversa . |
. 5, 7, W. |
|
55 |
triquetra . |
. 3, 5, 7, 8, 9, 10, 11, 12. |
|
55 |
„ male* |
. 12, R. |
|
55 |
uniseta |
. 3, B., P. |
|
Floscularia algicola . |
. 8, 11, P. |
|
|
55 |
campanulata . |
. 1, R., Th.; 3, P.; 8, R., W.; 9, P., T., W.; 12, P.,R. |
|
55 |
cornuta . |
. 2, P.,W.;3, P.; 7, W.;9, P.,T.;11, P. |
|
55 |
coronetta |
. 9, W. ; 11, P. |
|
55 |
cyclops . |
. 7, P. ; 10, W. |
|
55 |
longicaudata . |
. 1, w. |
|
55 |
ornata . |
. 1, Th.; 2, So., T.; 3, R. 8, P.; 9, P,W.; 11, T. |
|
55 |
pelagica |
. 10, P., w. |
|
5 |
regalis . |
. 9, P, W. ; 11, P. |
|
5) |
trilobata |
. 4, W. |
* Euchlanis triquetra, male. Mr. Rousselet describes it as loricate, of the same shape as the female, but only about one-third the size ; it has no mastax and no digestive tract, the place of which is taken by the sperm sac. This is believed to be the first male of the Euchlainda; observed.
70
|
Furculai |
•ia forficula . |
. 1, Tli. ; 9, 11, P. |
|
j? |
gibba |
. 7, 9, T. |
|
55 |
gracilis . |
. 2, W. |
|
» |
longiseta |
. 3, 5, 7, 8, 9, 11, 12. |
|
55 |
melandocus |
. 12, R. |
|
Lacinularia socialis . |
. 8, R., So., W. |
|
|
Limnias |
annulatus . |
. 1, R. ; 11, P. |
|
55 |
55 |
. 1, Th., W. |
|
55 |
ceratopliylli |
. 1, So. ; 9, W. |
|
55 |
myriophylli |
. 7, P., W. ; 8, R. |
|
Mastigocerca bicornis |
. 3, B. ; 5, P., R., W. ; 7, |
|
|
W. ; 12, R. |
||
|
55 |
bicristata . |
. 4, R.; 11, P. |
|
55 |
carinata |
. 4, W. ; 11, T. |
|
55 |
elongata |
. 4, 8, R. |
|
55 |
lophoessa . |
. 5, R.; 8, 11, W. |
|
55 |
rattus . |
. 3, P., R., W. ; 5, W. ; 8, P., W.; 10, W.; 11, P., W.; 12, P. |
|
Melicerfca conifera . |
. 7, P., W. ; 8, P. ; 9, P., |
|
|
W. ; 12, P. |
||
|
55 |
ringens |
. 1, 3, 4, 5, 7, 8, 9, 11, 12. |
|
Metopid |
ia acuminata |
. 1, T.;3,B., T.; 5, P., R.; 9, 10, 12, T. |
|
55 |
lepadella |
. 1, T., W. ; 2, T. ; 3, W. ; 5, R., W. ; 7, W. ; 8, So., T. ; 9, T., W. |
|
55 |
oxysternuui |
. 3, P. ; 4, W. ; 10, T. |
|
55 |
rhomboides |
. 4, W. |
|
55 |
solidus |
. 3, P.; 5,R., W.; 8,9, W. ; 11, P., W. |
|
55 |
triptera . |
. 11, W. |
|
Microclides orbiculodiscus |
. 8, W. ; 10, P., W. ; 12, P. |
|
|
Microcodon clavus . |
. 10, W. |
|
|
Monocerca rattus |
. 9, T. |
|
|
Monostyla bulla |
. 9, W. |
|
|
,, |
lunaris . |
. 8, W. ; 12, R. |
|
Monura colurus |
. . 6, P. |
|
|
* Limnias annulatus"? This is |
he Limnias described iu the lists of |
71
|
Noteus quadricornis |
. 3, B., R., T.; 5,R.;7, P.; |
|
8, So.; 10, P., T.; 11, |
|
|
P. |
|
|
Notholca acuminata . |
. 1, R., T. ; 3, 5, W. |
|
„ scapha |
. 1, R. ; 2, P. ; 3, B. |
|
Notommata aurita . |
. 1,P, T.;3,B.,R.,T,W.; |
|
5, P. ; 8, 10, T. |
|
|
„ bracbyota |
. 5, R, |
|
„ lacinulata |
. 3, 7, P.; 9, P., W.; 11, P.; |
|
12, P., R. |
|
|
,, longiseta |
. 11, 12, T. |
|
tigris . |
. 3, B., T. ; 7, 9, T. |
|
,, tripus . |
. 3, P. ; 4, W. ; 5, P., R. |
|
„ tuba, see Cyrtonia. |
|
|
Notops bracbionus . |
. 3,B.,R,W.;5,W.;7,f\; |
|
10, P., T., W. |
|
|
„ male .... |
. 10, P. |
|
byptopus |
. 2,3, P.; 5, R.; 7, P,W.; |
|
10, w. |
|
|
„ minor .... |
. 2, P. ; 5, R. ; 10, P., W. |
|
OEcistes crystallinus |
. 1, D., Tb., T.; 3, P.; 4, |
|
5, W. |
|
|
„ „ var. ? . |
. 1, w. |
|
,, longicornis |
. 9, W. |
|
„ mucicola . |
. 3, P. |
|
,, pilula |
. 7, P. ; 8, So. ; 12, P. |
|
,, socialis |
. 1, R. |
|
Pedalion mirum |
. 10, P., T., W. |
|
Pbilodina citrina |
. 3, P., W. ; 7, W. |
|
„ erythroptbalma |
. 1, W. |
|
„ macrostyla |
. 7, 8, P., W. |
|
„ megalotrocba |
. 2, 3, 9, P. |
|
Polyartbra platyptera |
. 1,2,3,4, 5, 7,8, 10,11. |
|
„ ,, small form |
. 10, P. |
|
Pompbolyx sulcata . |
. 4, R, W.; 10, P., W. |
|
12, R. |
|
|
Proales decipiens |
. 1, 5, W. |
|
„ felis .... |
. 7, 8,10,11, W. |
|
„ parasita |
. 5,W.; 11, T. |
|
,, petromyzon |
. 1,P. |
72
Proales sordida Pterodina patina „ reflexa ,, valvata . Rattulus cimolius . „ lunaris tigris Rotifer citrinus
,, macroceros .
,, macrurus
„ mento ?
„ Roeperi
„ tardus
„ vulgaris Sacculus saltans } gee Asoomorvha.
,, viridis ) Salpina brevispina .
,, marina ,, mucronata „ mutica „ spinigera ,, ventralis Scaridium longicaudum .
Stephanoceros Eichhornii Stephauops lamellaiis ,. muticus
,, unisetatus
Syncha^ta pectinata
,, tremula .
Taphrocampa annnlosa . n Saundersite
Triarthra longiseta .
12, P.
1, 3, 4, 7, 9, 11, 12. 11, P.
7,W.; 11, P.
2, So.
3, T.
5, 8, W.
3, 8, P.
1, Th. ; 3, P. ; 4, R. W. ;
7, 8, P. ; 9, W. ; 12, P. 1, P., Th.; 3, 8, 10,
12, P.
7, 8, 10, P., W.
8, W.
8, P.; 9, W.; 11, P. 1, 2, 3, 7, 8, 9, 10.
4, P., W.; 5, R., W.; 9,W.; 11, T.
I, 3, R.
3, 5, 7, 8, 9, 10, 11, 12.
8, R.
4, W. ; 11, P.
II, T.
4, W. ; 8, P., R, W. ; 9, 11, P., T., W.
3, P., R., W. ; 4, W.
5, R. ; 10, W. ; 11, P. 5, R.
7, P.
1, 2, 3, 4, 5, 7, 8, 10, 11,
12. 1, 2, 3, 4, 5, 7, 10, 11, 12.
9, 10, 11, 12, P.
10, W.
1, R., So., T., W. ; 2, P., So., T.;3, B.; P., T.; 5, W. ; 10, P.
73
Triophthalmus dorsualis* Triphylus lacustris .
. 11, W.
. 5, R., W. ; 8, R., So., W. ; 11, P., W. PLATYHELMINTHES. Trematoda. Cercarian stage of a trematode worm 11, P.
ANNELIDA. Oligoch^ta.
^Eolosoma variegatum t . . . 8, P.
|
POLYCHJITA. |
||
|
Polynoe squamata ? |
. . 6, P. |
|
|
GASTEOTBICHA. |
||
|
Cha3tonotus acanthophoris . . 11, P. |
||
|
„ hystrix . |
. 9, 10, W. |
|
|
,, larus |
. 2, 3, 7, T. ; 9, 10, T., W |
|
|
11, 12, T. |
||
|
,, maximus |
. 8, T. ; 11, T., W. |
|
|
Dasydytes goniathrix |
. . 3, P., W. |
|
|
CRUSTACEA. |
||
|
Carcina mamas |
. . . 6, P. |
|
|
Pisa tetraodon |
. . 6, P. |
|
|
Entomosteaca. |
||
|
Alona intermedia |
. 4, Sc. |
|
|
„ quadrangularis |
. 2, 4, Sc. |
|
|
Bosmina longirostris |
. 1,2,4, 12, Sc; 2,3, T. |
|
|
Candona fabaeformis |
. 4 1 |
|
|
„ lactea |
. 4 |
|
|
„ pubescens . |
. 1 |
|
|
Caiithrocamptus crass us |
. 1, 12 |
>Sc. |
= Attheyella spinosa Canthocamptus pygmgeus = Attheyella cryptorum
12
J
* Triophthalmus dorsualis. Mr. Western remarks that this is undoubtedly the rotifer figured and described by Gosse. The orange eye-spots on top of front processes, mentioned by Eckstein, but not seen by H. and G., were plainly visible. Of the three cervical e}*es described, the centre one only is a true eye-spot, the two outer ones being chalky masses on the brain lobes. The animal is therefore an Eosphora. Gosse's original drawing, with the above exception, is excellent.
Messrs. Rousselet and Western record from Hertford Heath an un- described species belonging to the Notommatadse.
t JEoloswna variegatum (Vejdovsky). Xew to England.
74
Cautliocamptus staphylinus = C. minutus
1, 2, 4, Sc. ; 3, B., T.
|
Ceriodaplmia quadrangula |
4, Sc. |
||
|
„ reticulata |
9, 11, W. |
||
|
Chydorus globosus . |
. 1, 4, Sc. ; 2, T. |
||
|
„ sphericus . |
. 1, 2, 4, 12, Sc. ; 1, D. ; 2, T. ; 3, B., T. ; 9, W. |
||
|
Cyclops bicuspidatus = C. |
Thomasi |
1,2 ^ |
|
|
„ fimbriatus . |
2 |
||
|
„ Leuckarti = C. simplex |
1,2,4 |
||
|
„ oithonoides = C. hyalinus |
4 |
||
|
,, serrulatus . |
. |
1,2,4 |
|
|
„ strenuns |
. |
2 |
|
|
„ „ vicinus form. |
■ 1,4 |
||
|
„ temiicornis |
2,4 |
> Sc. |
|
|
„ vernalis * . |
. 2, 12 |
||
|
„ viridis, var. brevicornis |
. 2, 12 |
||
|
„ gigas |
2,4 |
||
|
Cypria ophthalmica |
. |
1,4 |
|
|
Cypridopsis vidua . |
1,12 |
||
|
Cypris fuscata . |
. 2, 12 |
||
|
,, virens . |
2 J |
||
|
Daphnella brachyura |
. 9, 11, W. |
||
|
Daplmia hyalina |
2, Sc. |
||
|
,, longispina . |
. |
. 1, 4, Sc. |
|
|
,, pulex |
. |
2, 12, Sc; 3, T. ; 11, W. |
|
|
Diaptomus castor |
. |
. 2, 12, Sc; 3,8, T. |
|
|
„ gracilis . |
1, 2, Sc |
||
|
Eurycercus lamellatus |
9, W. |
||
|
Ilyocryptus sordidus |
4 ^ |
||
|
Leydigia acanthocercoides |
1,2,4 | |
||
|
Macrothrix laticornis |
2, 4 y Sc. |
||
|
Peracantha truncata |
, |
4 | |
|
|
Pleuroxus trigonellus |
1,4 j |
||
|
PolypL emus pediculus |
. |
8, P., T. |
|
|
Scapholeberis mucronata. |
. |
4, Sc |
|
|
Sida crystallina |
8, P., T. ; 9, W. |
||
|
Simocephalus vetulus |
1, 2, 4, Sc. |
||
|
# Cyclops vernalis has in |
previous |
years been included with C. |
|
|
bicuspid alns. |
75
Sfep*^
I* 8, So.
Simocephalus vetulus, exspinosus
form ..... 12, Sc.
ABAGHNIDA. AcarixNA. Bdellid^;.
Scirus insectoram * . . . . ^| „ vulgaris
HVDRACHNID^:.
Arreuurus buccinator $ V
„ globator 3
„ maculator ? .
„ viridis ? Arctisconidj;. Macrobiotus Hufelandi . INSECTA. D1PTERA. Simulium sericium, lava of MOLLUSCOIDA. POLYZOA Amatkia leudigera . Bicellaria ciliata Bowerbaukia pustulosa Crisia deuticulata .
,, eburnea . Cristatella mucedo . Fredericella sultana Membranipora pilosa Paludicella Ehrenbergii . Pedicellina cernua .
„ „ var. glabra.
Plumatella repens . Valkeria uva, var. cuscuta TUNICATA.
Perophora Listeri . . . . 6, D. Fredk. A. Parsons,
Hon. Sec. Excursions Sub-Committee.
|
. J |
|||||
|
• 1, |
T. |
;3, |
10, |
12 |
P |
|
. 9, |
P |
||||
|
. 6, |
D. |
P. |
|||
|
• 6, |
D. |
P. |
|||
|
• 6, |
P. |
||||
|
• 6, |
P. |
||||
|
• 6, |
D. |
||||
|
• 8, |
R., |
w |
|||
|
• 1, |
D. |
;8, |
w. |
||
|
• 6, |
P. |
||||
|
• 1, |
R. |
T.; |
8, |
P., |
R. |
|
• 6, |
D., |
P. |
|||
|
• 6, |
P. |
||||
|
• 8, |
R. |
||||
|
• 6, |
D. |
P. |
Scirus insectorum, parasitic on a springtail.
76
OFFICERS AND COMMITTEE, (Elected February, 1895.)
Edward Milles Nelson, F.R.M.S
Wxzt-*§m\ismt%.
Rev. W. H Dallinger, LL.D., F.R.S., F.R.M.S., &c.
Pkof. B. T. Lowne, F.R.C.S., F.L.C„ &c.
A. D. Michael, Pres.R.M.S., F.L.S., &c.
Prof. C. Stewart, M.R.C.S., F.L.S., F.R.M S., &c.
dxrmmittjfte.
F. W. Hembry, F.R.M.S. I J W. Reed.
G. Western, F.R.M.S. J. Spencer, F.R.M.?. E. T. Newton, F.R.S., F.G.S. J. E. Ingpen, F.R.M.S. G. Mainland, F.R.M.S. B. W. Priest.
H. Morland.
E Dadswell, F.R.M.S.
D Bryce.
F. A. Parsons
Hum. feasuwr* J. J. Vezey, F.R.M.S. 21, Mincing Lane E.C.
G. C. Karop, M.R.C.S., F.R.M.S., 198, Holland Road, Kensington, W DM*. #*r. for foreign €nTTM$onBmtt.
C. Rousselet, F.R.M.S 27, Great Castle Street Regent Street, W.
ikw. gfprter.
R. T. Lewis, F.R.M.S., 4, Lyndhurst Villa-, The Park, Ealin-, \V.
$011. ^ibrariiw. 'San, Curator.
Alpheus Smith, F. T, Buownk, F.R.M.S.
8,llanover Park, Peckhain, F.E. 141, Uxbridge Road, W.
|]foit. (irMtcrr. E. M. NaLSOK, F.R.M.S., 0(3, West End Lane, N.W,
77
On Floscularia trifidlobata, Sp. Nov.
By Geo. M. Pittock, M.B., F.R.M.S., of Margate.
Communicated by C. F. Rousselet, F.R.M.S.
{Read March 15th, 1895.)
Plate I.
Since the publication of Hudson and Gosse's great work on the Rotifera, many new species have been discovered and recorded. A list of new Rotifers found and described since that date (1889) has been furnished by Mr. C. F. Rousselet ("Journal Royal Microscopical Society," June, 1893). I have now to announce the addition of another Floscule to the list of new species given in Mr. Rousselet's catalogue.
I will endeavour to follow his advice, that " when a new species has been found, it should be figured and described in such a manner that the animal may readily be recognized when found again by a different observer, and a good figure is often worth more than a good description."
Any shortcomings in the following description will, I believe, be made up by the beautiful and characteristic drawing which accompanies this paper, for which I am indebted to my very kind friend Mr. Dixon-Nuttall, whose accurate sketches from life of many new forms are well known to many members of the Society.
This small, but very distinct species, was discovered early this year by my friend Mr. F. Daunou, of Margate, in hunting over some water moss from the Minster Marshes, Thanet, a locality which has already proved a very prolific hunting-ground to him and to myself during the past summer. (See a short paper on " Rotifer Hunting at Minster," in " Science Gossip," October, 1894.) At first sight this floscule somewhat resembles F. longicaudata, in the length of the foot, and in the shape of the long, pointed, dorsal lobe. Indeed, I sent a specimen to Mr. Hood, of Dundee, for identification, in January last, believing it to be an aberrant form of F. longicaudata.
Journ. Q. M. C, Series II., No. 37. 6
78 G. M. PITTOCK ON FLOSCULARIA TRIFIDLOBATA.
More careful examination, however, showed that it has five lobes, of which the dorsal one is long, pointed, and trifid at the apex, and crowned with three brushes of short setse. The other lobes are small, being little more than slight projections of the coronal rim, and not quite equi-distant from each other, and each crowned with a brush of short setse. The two ventral lobes are close together, and the lateral lobes close to the base of the larger dorsal lobe, leaving a wider space than usual between the lateral and ventral lobes. The setse are not continuous round the coronal rim.
Three very small antennas can be made out, one dorsal and two lateral, and the space between the integument is filled with numerous brown granules.
Before attempting to describe or to name this floscule, I first submitted it to Mr. Rousselet, Mr. Western, and Mr. Hood of Dundee, all of whom pronounced it to be specifically distinct from any other known floscule, and especially differentiated by the trifid character of the dorsal lobe, which suggested the name trifidlobata.
Spec. Char. — Lobes five, the dorsal one long, pointed, trifid at apex, crowned with three brushes of short setse, the other lobes small and inconspicuous, without knobs ; not quite equi- distant round coronal disc, each with a brush of short setas. Tube small and sometimes indistinct, antennas three, each with tuft of short setse. Jaws as in other floscules. Eyes absent. Length : total JL, of body T|_, foot twice the length of body.
79
What was the Amician Test ?
By George C. Karop, F.R.M.S.
{Read March lUh, 1895.)
In reading the earlier papers on microscopy, that is to say in the modern sense of the word, when successive improvements were being made in the construction of objectives by enlargement of their aperture and hence in their defining power ; at a time when the dilettanti were vying with one another in the resolution of diatoms by the aid of condensers, prisms, oblique illuminators and what not, one frequently comes across the phrase " Amician test." It is used so definitely as a touchstone of excellence, either in object glass or manipulative skill, that one must assume the exact nature of this " test " was the common knowledge of every microscopist of the period, but I must confess, after some amount of search and personal inquiry from those most likely to remember, it still remains to me a matter of uncertainty. I do not wish it to be understood for a moment that I have made an exhaustive, or even an extended, investigation on the subject ; I have not been able to find any statement by Amici himself or by anyone whose authority might be accepted as final, but I have looked through the few text-books of the period and papers on manipulation in various transactions, etc. It is simply for my own instruction and with a view of eliciting information from others that I have ventured to put this interesting question before you to-night.
The first, or most probable, solution that presents itself is that Amici made use of several tests of increasing difficulty as he improved the construction and resolution of his lenses. Indeed it is certain, in his earlier efforts with specula and objectives, that he employed scales of various LepiJoptera, Podurae and so forth, which were the first test objects whatsoever for comparing the quality of lenses. The use of these scales for the purpose of testing the aperture of objectives was discovered by Dr. C. R. Goring.
80 G. C. KAROP ON WHAT WAS THE AMICIAN TEST ?
Harting, " Das Mikroskop," First German edit., p. 288, says : " Mohl particularly recommends the wing scales of ? Hipparchia janira as a test, which he got to know from Amici." Although Harting gives some information about diatoms as tests, and a good deal about Amici and his instruments, there is no mention of any specific " Amician test," a somewhat curious and rather suspicious omission in a work which I regard as by far the best of its day on the microscope. I say suspicious, for I am of opinion that the test called Amician, one particular diatom as understood later, was something got up, so to speak, for the English amateur at a time when there prevailed a kind of mania here for increased apertures solely for resolving the markings on certain diatoms, which was quite without parallel on the continent, I fully recognize the value of the diatom and its reaction on the wealthy dilettante ; between them they are in great measure answerable for the modern microscope and its magnificent objectives ; but the early continental worker who employed the microscope as any other tool, came to regard the Englishman's proceedings as childish trifling, and looked upon his great, shining, complicated stand with its wonderful accessory apparatus merely as " an expensive peepshow," while he was quite indifferent to the sempiternal checks, dots, lines and little else so painfully evolved by it. An " Amician test," apparently, was not for him.
Be this as it may, however, the question for us is, which was the particular diatom considered to be the Amician test par excellence? A large number, perhaps the majority, of authorities believe it to be Navicula rhomboides. This is first figured, naturally in outline only, in Ehrenberg's "America," 1843, according to Kiitzing, who copies it in his " Bacillarien." W. Smith records it in 1849, but it is doubtful if any lens of that date could have really resolved it, unless it chanced to be a very coarse-lined variety. Mr. Ingpen informs me that he possesses a slide of rhomboides thirty-five to forty years old, by C. M. Topping, the best mounter of his day, labelled simply " Amician Test," and Mr. T. Powell has kindly sent me a similar slide and also so named. On examination it appears to have been mounted as gathered, without any preliminary treatment with acids, between two thin covers, but from lapse of time it has almost perished, and the diatoms, chiefly a very small variety of rhomboides, are quite unresolvable by any optical means in my possession.
G. C. KAROP ON WHAT WAS THE AMICTAN TEST? 81
In a paper by Mr. J. Newton Torakins " On Resolution of Diatoms by Double Prism Illumination,"* he speaks of N. rhom- boides as " the Amician test of the London, although, perhaps, not of the American microscopists," a very queer expression unless, indeed, as I suspect, the thing was a variable. Mr. E. G. Lobb, a very well-known microscopist in his day, in a paper entitled " Note on Illuminating Objects with High Powers," (" Trans. Mic. Soc," Lond., N.S. xiv., 1866, pp. 39-41), gives minute directions for using a condenser of 170° (Powell's) in resolving tests, stating the apertures and stops suitable for quite a number of diatoms. He says : " To examine N. cusjridata, N. rhomboides, P. fasciola, P. macrum, etc., use No. 11 aperture and stop No. 2, which will require a slight alteration in position only, when the checks will appear distinctly. For the Amician test use the slots instead of No. 2 stop." From this it seems quite clear that Mr. Lobb's Amician test, at all events, was not N. rhomboides.
In the first three editions of the " Micrographic Dictionary," viz., 1856, 1860 and 1875, Amici's test is given as N. gracilis, Ehr., which Smith, " Syn.," p. 75, refers, with a query, to his Pinnularia gracilis. From the figure it appears to me very un- likely. In the latest edition of the Dictionary, 1883, sub voce Test Objects is given, " N. affinis, Amici's test object, that used at the Exhibition of 1862, mounted in balsam, the transverse lines. "t Mr. Ingpen thinks this would now be considered a form of rhomboides, but both Van Heurck and Brun make it allied to N. pi'oducta, W. S. It is evidently a variable species, but I think the striation is coarser than any ordinary rhomboides ; more- over, it is figured with the central and terminal nodules of a true Navicula.
I have a, more or less, distinct recollection of a Grammatophora, probably subtillisima, being given as the Amician test ; possibly this is the American variant.
* When and where this paper was published I have been unable to find, but it is quoted at some length in the Sixth Edition of Hogg, " The M croscope," etc., 1867, pp. 175-8, and Eev. J. B. Eeade somewhere mentions that Tomkins used a double prism illumination in 1861.
t Navicula affinis, sous le nom de Test d'Amici a ete' employee d'apres le Prof. Yan Heurck a l'exposition de Londres a 1862 pour juger les Micro- scopes. Robin, "Traite du Micros, et des inject.," 1877, p. 312.
82 O. C. KAROP ON WHAT WAS THE AMICIAN TEST ?
Obviously, therefore, I have not been able to satisfy myself that there was a fixed or standard Amician test. The matter is, of course, of archaeological interest only at the present time ; but it is certainly singular how a term which thirty or forty years ago was the common property of microscopists should have become so obscure and mysterious, and I trust some here will be able to explain it.
83
M5RARY
Roots and Some Growths Upon Them.
By E. B. Green, F.R.M.S.
(Bead April 19th, 1895.)
Plate V.
The drawings upon the table are intended to represent the structure and rate of growth of some roots.
Root hairs drawn to a uniform scale ot 100 diameters, and
Parasitical and other growths, which I have found upon them.
The seeds of a large number of plants were sown in pots filled with light soil, and put into a warm greenhouse, where the temperature varied from 45° to 70°, and the seedling plants were from time to time carefully taken up with a sufficient quantity of adherent soil, plunged into a tank of water, and after gentle washing floated on to a sheet of glass, or (if intended for micro- scopic examination) upon a glass slide rather larger than the ordinary size, and a covering glass was put on before the slide was removed from the water, care being taken to exclude air bubbles.
The specimen was put upon the stage of the microscope as soon as the outside of the covering glass was dry, and it was also examined when the specimen had dried. I found this double examination necessary, as some of the more delicate organisms which could be plainly made out when first put upon the slide lost all their characteristic form and structure when they became dry, whilst others which were colourless could not be seen till all the water had evaporated.
Some of the drawings, showing the rapidity with which roots grow under favourable circumstances, are made the natural size.
A seed of maize, eight days after planting, produced 20 roots of various lengths ; the longest six inches. Another fourteen days from planting had upwards of 100 roots, and the longest of which was eight inches. A seed of barley produced 70 roots in eight days, and an oat upwards of 400 roots in 48 days ; several of them were more than fourteen inches long, and all these roots were densely covered with root hairs.
84
E. B. GREEN ON ROOTS AND SOME GROWTHS UPON THEM.
Root hairs are extensions of the walls of the outer circle of the root cells, and continuous with them ; they spread out at their base in some cases very considerably, but with this exception they are tolerably uniform. They do not branch, but in some instances divide into several short swollen projections at their extremities. The hairs upon the roots of many ferns are of a rich orange brown colour, but those of most plants are colourless or very slightly tinted ; they are beautifully iridescent when viewed with a dark ground illumination ; bright spots of organizable substance are seen abundantly in some and very sparsely in others.
They are very glutinous and attach themselves firmly to the glass slide. I have examples which have withstood much rough usage. They were put upon glass four or five years ago, and although they were uncovered they have suffered very little injury, but the roots from which they sprung have long since disappeared. They cling to grains of sand and other mineral and vegetable substances in the soil, and exercise a very powerful chemical action upon them. They differ greatly in character, dimensions, and quantity in various plants, being abundant and of consider- able length in the grasses, ferns, and most annuals, and few and short in fleshy rooted plants.
The drawings of various hairs x 70 Will give some idea of their different lengths, and others x 500 of their comparative diameters and other characters.
The dimensions of the longest hairs shown are as follows : —
|
Length |
|
|
Erica |
l 7 0 |
|
Leek . |
1 * 7 </ |
|
Oxalis |
1 ¥6" |
|
Millet |
1 • "25 |
|
Achillea |
1 • "23" |
|
Antirrhinum |
l * "577 |
|
Pteris serrulata |
1 ' "277 |
|
Pelargonium |
i * TT |
|
Rye Grass . |
1 • TT |
|
Stellar ia |
1 |
|
Rivina |
l |
|
Linum rubrum |
1 T |
|
Pteris longifoliu . |
i 7 |
|
Diameter. |
|
|
Leek |
i 4577 |
|
Pteris serrulata |
1 97777 |
|
,, longifolia |
1 1000 |
|
Maize |
TT7777 |
|
Pelargonium |
7"27777 |
|
Achillea . |
T47777 |
|
Stellaria . |
T7TT777 |
|
Pyretlirum |
W<777 |
|
Antirrhinum |
747777 |
|
Oxalis |
TS7J77 |
|
Cereua |
1 2800 |
|
Adiantum caudatum . |
55(577 |
E. ■ AMD SOKE
In : nmmavti
had c oem, bat a more c:
-aled the : farther inv fi
. were frequently attached to one specimen, and although differ- ^ere attached to plants differing
I hare not studied the subject sufficiently to g whetl re peculiar I have found
Laany of them are common to rjo found only upon individual sy may be com-
— 1 ^vhich are simp" 7 1 to and on the r ■;
hair, an : do not ceriv-: .it, and
2nd. — I uhs wh:c I and root-
:ructure.
many of thern pro- bably Algae, some of which are o: able length, a qoarter of
an inch or more, flat and tapelike, from — ! — - to a J — of an inch
* - i . . .
in the . .
ghtly coloured, chiefly . orange brown, and bearing rariously coloure; branc ninal joints, divided from the main
stem by a distinct wall. A
j\e round thread, ni upon the root hairs, until it s a dozen 01 more, and at
.gles, like those of a skein of silk. When . mted t: uriaiully b
some time 1 hare
any §j them The ::. »ftom T^nrto„
inch in diameter ; a third g I .ular core, irregular and moi ed.
.:ure and markings ; they ind flat-j . -^atly
•Tide, and abc isiderably in -.-. gring at a considers i raUel;
in mo e ^ngles lik e
links of a chain, colour bright
86
E. B. GREEN ON ROOTS AND SOME GROWTHS UPON THEM.
The second division consists of gelatinous growths which in many respects resemble fungi ; they grow from the root or hair, do not confine their attacks to the part from which they spring, bat stretch from hair to hair, or from hair to root, and completely destroy the hair and greatly injure the root ; some kinds traverse the root-hairs, tilling them with delicate threads, which emerge at intervals from it, and others nearly fill the cavity with a single thread, and on emerging from the hair become branched.
In some cases they radiate in straight threads from a central point, and in others form a dense network. The spores are very minute and appear to be formed upon the threads, or in bunches of six or more upon short stalks.
Spores are produced abundantly, and are greatly varied in shape and colour. They are round, oval, disk-shaped, and sometimes almond-like, black, white, green, brown, red or yellow in colour, occasionally quoit-shaped, showing complementary colours (red and green) in the outer and inner rings ; in some cases they appear to be enveloped in a gelatinous mass, with slight indications of a stalky attachment ; in others, smaller bunches upon short pedicels attached to, or enclosed in, filmy branches quite distinct in sub- stance and form from the stem, and divided from it by a well- marked wall ; they are also seen in considerable groups upon the stem, or closely ranged in single file upon it, or at considerable and irregular intervals.
I have found crystals of three types upon the parasites of buck- wheat, lunaria, and parsnip, each differing from the others.
The following is a list of some of the plants which I have examined, with the number of different growths upon them as shown in the drawings : —
1 2 1 1 1 I 2 2 1 2 2
|
Achillea |
. 2 |
Cereus . |
|
Adiantum caudatum |
1 |
Celandine |
|
Althea rosea . Antirrhinum . |
1 9 |
Dactylis Endive |
|
Beet Begonia Buckwheat |
. 1 1 2 |
huphorbia Flax . Gooseberry |
|
Cabbage Calendula Cranesbill |
3 2 . 2 |
Hemp . Impatiens Linum rubrum |
|
Cardamine . |
1 |
Leek |
E. B. GREEN ON ROOTS AND SOME GROWTHS UPON THEM
Lettuce . Liverwort Lin aria Lunaria Lupin . Maize . Millet . Mullein Oxalis . Parsley Parsnip Pelargonium Ph alar is Poa
|
4 2 |
Pojrpy . Pteris . |
|
2 2 |
Pyrethrum Ricinus |
|
2 |
Rivina . |
|
3 |
Rush |
|
2 1 |
Ryegrass Scabius |
|
3 |
Silene . |
|
reral |
Stellaria |
|
4 |
Tobacco |
|
3 |
Tomato |
|
1 |
Vetch . |
|
1 |
Wallflowei |
87
In conclusion the author hopes that he may be allowed to express a wish that this subject, which he thinks is novel and full of interest, may be taken up by some of your members.
Explanation of Plate V.
Fig. 1. Parasitical gelatinous growth with crystals upon roots of Parsnip, x 300.
Fig. 2. Part of the same, showing rectangular celled structure, interrupted by transparent crystals, X 1,000.
Figs. 3, 4, 5. Epiphytal growths of considerable length upon roots of Antirrhinum, x 150.
Fig. 3. Cellular cells about 30Vo-m- diameter and from 1^ to 10 or more diameters long, walls distinct, colour bright brown, direct growth.
Fig. 4. Much branched, branches united, without division, except those connected with the fructification, which is ter- minal ; outer wall very thin, pale green, enclosing irregular bright green patches.
Fig. 5. Tape like, greater diameter, about Q^^in,, much twisted, no apparent cavity, colour light brown.
Figs. 3a, 4a, 5a. Parts of the above, X 600.
88
On a New Species of Aleurodes.
By R. T. Lewis, F.R.M.S.
(Read April IWi, 1895.)
Plates II., III.
In the autumn of 1892 I received from a correspondent in Natal a spray of asparagus infested with small scale insects of a kind which he did not remember to have previously met with. The plant in question was one cultivated for ornamental purposes in the verandah of a house at Byrne, and it had become freely covered with small white spots, which, to the naked eye, had somewhat the appearance of mould, and were regarded by the owner as a great disfigurement. It was noted, however, that similar plants growing out in the open were not affected in the same way. On examination under the microscope, the objects were seen to be the pupal forms of some species of scale insect, which, though themselves perfectly black, were covered with plumes of pure white wax symmetrically arranged and present'ng a very ornate appearance, especially when seen under the binocular. The individual specimens varied as to size, but the arrangement of the waxen plumes was practically the same in each. I believe that I exhibited some specimens at one of the meetings of the Club soon after they were received, but was at the time unable either to give or to obtain much information concerning them, and on submitting them to one of our best English authorities on the subject of Coccididce, I found they were entirely new to him.
Following up the search for information, I forwarded some specimens to Prof. W. M. Maskell, whose researches into the history of the scale insects of New Zealand are no doubt well- known to many of our members through the publication of his valuable work upon the subject, as well as his numerous communi- cations to the New Zealand Institute and to the Royal Society of South Australia. Mr. Maskell had no difficulty in deciding that the creatures were not Coccididce, as at first supposed, but that they belonged to the allied family of the Aleurodidce, which may
R. T. LEWIS ON A NEW SPECIES OF ALET7RODE8. 89
be considered as intermediate between the Coccididce and the Aphides. In the adult form they are distinguished at once from the Coccididce by the fact that both males and females possess four wings, whereas the male Coccids have two only, and the females none whatever ; they also, in both sexes, are furnished with two joints to the tarsus, and with two claws, whilst it is characteristic of the Coccididce to have but one tarsal joint and a single claw. A further distinction is also insisted upon as peculiar to the adults of this family, namely, their possession of divided compound eyes, but although this is to some extent indicated in the new species, it is not so well seen as in some of the figures by Mr. Maskell of other species. In the pupa condition, however — with which alone up to that time I had become acquainted — the distinction between members of these two families is not so well- marked, since both are found attached to the leaves of the plants they affect, and both may also be covered with a floury secretion or with a more or less abundant coating of exuded wax ; hence they are not infrequently mistaken, and Mr. Maskell himself tells us that in 1878 he inadvertently placed two species of Aleurodes amongst the Coccididce under the generic name of Astero chiton. But on removing the wax and examining the dorsal surface under the microscope, with about a 1" objective, a well-defined sub-ovate orifice will be seen upon the last abdominal segment, and by this only identification is usually possible.
Still greater difficulty, however, attends the effort to distinguish between the various species of Aleurodes in their adult forms, and a comparison between the larvas and pupa? is generally necessary before a conclusion can be correctly arrived at. In the present instance, the pupa alone had been found, and although it was tolerably certain that the species was new, it could not be properly described in the absence of the adult, and my correspondent in the Colony was therefore asked to keep the plant under observation, and specially to look out for the appearance of any quantity of minute four-winged flies in its immediate neighbourhood.
In the following February the owner of the plant in question reported that the white things on the leaves had turned into flies, and my friend took the earliest opportunity of going over to Byrne to investigate the matter. He found, as stated, that the asparagus plant was now covered with minute flies, which rose in a cloud when the leaves were touched, but settled again at once if not
90 R. T. LEWIS ON A NEW SPECIES OF ALEURODES*
further disturbed. Having no doubt that these were the adult Aleurodes, he captured a quantity and forwarded them to me, and although extremely dry and fragile on arrival, there was no difficulty in determining that they were what we desired, and that males and females were present in about equal numbers.
The condition in which they came to hand prevented any very good mounts from being made, but by the examination of a considerable number it has been possible to make out all necessary details, though I regret I am unable to exhibit any specimen this evening which shows all equally well.
The larval form I have not seen in its natural conditions, bnt a few specimens of various ages, sent over mounted in balsam, and, of course, with all trace of wax removed, lead to the inference that they are inactive and that, as is the case with others of the genus, they resemble the pupae in shape.
Of the pupa, however, I can speak more confidently, having had the opportunity of examining some hundreds ; these are elliptical in shape, measuring on an average 2LT" X g^", with a thickness of y^o'' in the middle of the central longitudinal ridge ; in colour they are black when viewed by transmitted light, but when mounted in balsam and seen by reflected light they appear brown. The margin, as seen from above, appears to be beaded or corru- gated, with the exception, in some specimens, of a small space at the posterior extremity (immediately behind the ovate orifice before mentioned), from which two fine setae proceed. These apparent corrugations are, however, the extremities of a series of minute tubes, through which the wax is excreted which forms the delicate marginal fringe sunounding the pupa, but usually ob- scured from view by the overhanging plumes of the more copious secretions from the dorsal surface ; the number of these marginal tubes is found to average about 245 on each specimen. Above these and along each side are several rows of pores from which a much more abundant supply of pure white wax is extruded at an angle of about 45° to the surface of the leaf to which the pupa is attached, the numerous filaments coalesce, and before their full length is attained their extremities bend over in graceful curves until they rest upon the leaf, entirely hiding the marginal fringe, but not touching it. From the pores at the posterior end the wax is thrown out horizontally in spiral curves, which meet and overlap
R. T. LEWIS ON A NEW SPECIES OP ALEURODE8. 91
in a characteristic manner on a prolongation of the median line, those at the anterior end being projected in two parallel plumes for about the same distance as those behind. On either side of the elevated dorsal ridge other series of excretory pores are found, and from these the "wax is discharged in a nearly vertical direction in parallel lines, farming an elegant double crest above the central line. The whole appearance of the pupa in its complete condition is thus exceedingly ornate, forming as beautiful an object under the binocular microscope as can well be desired.
The perfect insects, which I am now for the first time able to describe, are very minute, the female not measuring more than -j-Jo-ths" in length and the male being about £th less. In their natural condition they are apparently a dull grey colour, with wings of rather lighter shade, both body and wings being dusted freely over with a waxy powder ; both sexes are furnished with four wings, those of the female when expanded measuring about -j^o" from tip to tip, and those of the male being slightly less. The specimens sent to me were not quite in the condition which I could have desired for successful mounting or examination, having been caught in a paper bag, killed with tobacco smoke, and then sent through the post in a small box, dry. On arrival, they were so completely desiccated as to break to pieces with the least provoca- tion, and though all attempts at relaxing them sufficiently to display in good positions proved fruitless, I secured about sixty, which, alter saturation in benzole, were mounted in balsam, and, although all were of value for comparison, it is with difficulty that I am able to exhibit a presentable slide this evening. When mounted in this medium the insects became translucent and deep yellow in colour, all trace of the waxy powder had disappeared in the benzole, and the wings were perfectly transparent. The fore- wing exhibits one median vein, with a single basal branch, the hind-wing showing the median vein only with distinctness with a 1" power ; the margin of each wing appears to be minutely beaded, and on examination with a power of about x 400 it is seen that this is due to a number of small hemispherical elevations "5 ~hnf aPai% each bearing three or four extremely fine hairs.
The eyes are compound, constricted — but not actually divided — across the middle, and there is one small ocellus above and immediately contiguous to each compound eye. The antennae are
92 R. T. LEWI8 ON A NEW 8PECIES OF ALEURODES
seven-jointed, the first two being short and thick, the others filiform and slender with many rings, the third being nearly as long as the last four. The feet are long in proportion to the body, tibia slender and twice as long as the femur, tarsus of two joints, claws two. The male and female generative organs are well made out and do not materially differ from those of other species already described. But a curious organ, apparently not hitherto noticed, is found upon the dorsal surface of the last abdominal segment in both males and females in a position corresponding to that of the oval orifice already mentioned as characteristic of the pupse of this family. These, together with the distinctive features above- named, are shown in the illustrations which accompany this paper (Plates II., III.).
In his letter to me Mr. Maskell says : "I wish somebody would take up Aleurodes seriously ; the study is difficult and has only been scratched as yet by Signoret and myself," and I venture to throw out this suggestion to members of the Club in search of a line of study a little off the beaten tracks of the diatoms and rotifers. There is but one genus in the family of Aleurodidce, and as the various species known have, for the most part, been named from the plants upon which they are found, I propose to call the one which forms the subject of the present communication Aleurodes asparagi.
In conclusion, I desire again to express my indebtedness to Mr. Maskell for the information received from him upon this little known subject, and to my Natal correspondent, the Rev. J. R. Ward, for the trouble which he has taken in the matter of collect- ing and forwarding the specimens.
With regard to the fact that this scale was only found upon an asparagus plant cultivated for ornament, Mr. Ward makes the suggestion that possibly this may be due to the protection afforded by the verandah, and it seems extremely likely that the fragile waxen plumes would speedily be broken down and washed away by the heavy rains to which an infested plant growing out in the open would be periodically subjected. In the absence of the white wax, it would, of course, be very difficult to detect the presence of so small a scale with the naked eye, and a casual observer might readily, on that account, suppose an infected plant to be free.
r. t. lewis on a new species of aleurodes. 93
Explanation of Plates.
Aleurodes asparagi. Plate II.
Fig. 1. Portion of leaf of asparagus with pupae in situ, x 20.
a, with wax intact • b, with dorsal wax removed,
showing marginal fringe. „ 2. Adult male, x 45. „ 3. ,, female, x 45.
Plate III.
Fig. 1. Pupa with wax removed, dorsal surface, x 25. „ 2. „ „ ventral „ „
,, 3. Transverse section, showing arrangement of wax. „ 4. Leg of adult. „ 5. Abdominal extremity of female, side view ; d = dorsum.
x 300. ,, 6. Abdominal extremity of male, dorsal view, x 300. ,, 7. ,, „ „ side view ; d = dorsum.
X 300. „ 8. Tarsus of adult. x 300. „ 9. Antenna of adult, x 300. „ 10. Portion of margin of wing, x 575.
Journ. Q. M. C, Series II., No. 37,
94
Examination of "Foul" Sea Water.
(From a sample given by Mr. Shrubsole, in May, 1894.)
By Walter P. Shadbolt.
{Read April \Qth, 1895).
Stroke and deep inoculations were made in agar and gelatine tubes, and kept at 19-20° C, at which temperature all the following observations were made. The growths were all aerobic, being visible along the stroke in 24 hours faintly. The organisms were fo.;nd to be mixed, and plate cultivations on gelatine for purposes of isolation were made in the usual way. After several transfers from plates to tubes, and from tubes to plates, isolation was effected. Two kinds were occasional, and probably adventitious. Three kinds were persistent.
The two occasional kinds were : —
1. A straight rod, motile during the first day, rapidly liquefying gelatine ; soon becoming motionless, and breaking up into spores, with a putrid smell.
2. Small round organisms, motile to some extent, with a move- ment like Brownian movement, breaking up into spores, and liquefying gelatine rapidly, with a putrid smell.
These were not observed further.
The three persistent kinds were all rounded bodies, of which tube cultivations on agar are produced. They all liquefy gelatine slowly. The tubes are marked respectively " Star," " White," and " Yellow."
No 1, " Star," cultivated on a plate at 19-20°.
In 24 hours showed no visible growth. In 36 hours there appeared numerous whitish spots, plainly visible under a lin. glass. In two-and-a-half days the spots were "visible to the naked eye, and in three days these had developed into star-shaped colonies, whitish, and so far without perceptibly liquefying the medium.
The colonies at first grow from one or two round organisms, which increase irregularly by budding. They are about T01oTTm> m diameter, some as large as -^-^q-q. As soon as these are numerous
W. P. SHADBOLT ON " FOUL " SEA WATER,
95
enough to form a crowded cluster of perhaps 20-30, the colony throws out numerous arms of hyaline matter radially, and these keep on increasing in length. Along the arms appear many, (say a dozen or two), nuclear spots, not at regular intervals or in regular lines, but here and there, sometimes two or more side by side, and distributed in the direction of the length of the arm These nuclei grow into round bodies like the parent, and of the same size, then arrange themselves gradually in the direction of the length of the arm or ray, and finally, as the medium liquefies after about five to six days, or less, separate.
Neither in the resulting nor any other liquid medium have I seen the star-shaped colony. In liquid the organisms divide irregularly by fission or external budding, and in a few hours break up into masses of minute spores. This organism is at no time motile, and except in the case of the radial processes above described, retains, as an individual, its rounded form.
No. 2 « White " 1 These are not visible on the plate for No. 3 « Yellow" {about 36 hours. The colonies then appear as white or yellow rounded, (sometimes kidney-shaped), spots, which gradually increase in size. In some of them the edge is definitely marked by a surrounding ring of organisms, packed closely and regularly. In others the edge shows no such bounding ring, and is fissured. These do not break up, are not confluent, and consist of masses of extremely minute rounded bodies. On being placed in a liquid medium they multiply rapidly and irregularly.
These two kinds are so similar, except in colour, and the dif- ference in colour is so slight in the earlier stages of growth, that it is not easy, especially by artificial light, to distinguish them. They are non-motile, aerobic, and liquefy gelatine but slowly.
A temporary absence during the growth on the plates when I had at last got them separated prevented my being ready with more than the above very incomplete observations as to these last two kinds. They are now, as will be seen, well differentiated in the tubes shown, and are ready for further investigation.
The hanging drop cultures, one of each of the three kinds shown herewith, are taken from the respective tubes, and are about 24 hours old.
The media have all been slightly alkaline. Trials were made on agar and gelatine media, in which fish was used instead of meat, but without any difference in the result.
96
On Scale Evolution, as shown in Ithomia diasia.
By J. E. Ingpen, F.R.M.S.
{Read May Vjth, 1895.)
Plate IV.
Variation of form in insect scales, though not considered by systematic entomologists as of much importance, has always been a subject of interest to microscopists, and the question of the line of demarcation (if there be one) between scales and hairs has frequently been discussed. The description of a specimen showing an unusual number of gradations of form may therefore be not altogether useless or uninteresting.
While hunting for illustrations of iridescence, I came across some specimens of Ithomia diasia, a clear-winged Columbian butterfly. Though not a showy form, it is very delicate and pretty, the iridescence of the clear parts of the wings being set off by the black ribs and borders. On the underside there is a dull orange and yellow margin to the hind wings, and there are a few dusky white spots on both front and hind wings. On examining the clear parts to ascertain how far the iridescence might be due to plates, lines, dots, etc., I could not help noticing the hairs thinly scattered over them. Some of these were single, others forked, some white, most of them black, the white hairs becoming transparent when mounted in Canada balsam, the black ones a dark brown. These hairs were only present on the clear parts, the ribs and borders being thickly covered with well-defined scales, but close to the ribs and borders numerous transition forms between the hairs and the scales occurred, and it is to the illustration and description of these that I desire to call your attention.
1 and 2. — Single and forked hairs, white and black. Apparently -•tubular, as shown by the character of the air bubbles expelled in tb£p. course of mounting. No appearance of interior granulation or exterior marking.
8. — The part near the fork a little wider and thicker,