ried soy Ain HAS TATE pitti is isha » sie mea K bdo 7 y 1 ie fs aN tec heuke) SPY i ’ yi Seth Ties ihe oe respecte ya woe iS pt a ous? Sete : : Sth Sosy awed mr Yh an gay SNe cre ae te : Geet eoet : nan ane — age S - ‘ * md Pe 6 og toy e = ren orn fer ae, . ‘ i * Q arnt pe = Sore on es to A ‘G4 enka ra a Sa See é . Seen “ - be era, ~ nn =: 2 a = pao ~ 2 “= ze PO een ek en = 5) vy ue Sgn aes . Yi ’ ¥ > “oak entena area etree eee seth reels one ere eR A ELIE ae # ee > THE MONTHLY MICROSCOPICAL JOURNAL: TRANSACTIONS OF THE ROYAL MICROSCOPICAL SOCKETY, AND é RECORD OF HISTOLOGICAL RESHARCH AT HOME AND ABROAD. EDITED BY HENRY LAWSON, M.D., M.R.C.P,, F.R.MS,, Assistant Physician to, and Lecturer on Physiology in, St. Mary’s Hospitat. VOLUME XIII. | LONDON: ROBERT HARDWICKE, 192, PICCADILLY, W. MDCCCLXXV. Pape es; ae ee, a Sele ) 4 : fe - eM opthly Microscopical Journsl, + carne ~ scaly” oo The Mc Be pe Jornal Jan 116" ee ine Vase 1) Se eR { a dae development of the smaller bloo dvesselsam Man. ~ \ ; = . = Royal Microscopical Society. | 3 chorion, however, showed the formation of the smaller blood-vessels not to take place, as I had observed in the former cases, by the coalescence of certain round cells, but by the fusion of spindle- shaped bodies. From this apparent discrepancy, observed in the formative process of the smaller blood-vessels of the chorion of these two different ova, it must, however, not be inferred that my former observations were incorrect, but we must rather seek for an explana- tion elsewhere. Jor this reason, too, I shall in the following pages confine myself to an accurate statement of the phenomena I observed, from which the reader may draw his own deductions. In returning now to the first ovum, containing the imperfect embryo, we shall commence our statements with a description of the structure of its wall. This consisted of two membranes, an outer and stronger one, the so-called chorion, giving origin to the villi, and an inner one, consisting of an exceedingly delicate loose fibrous tissue. The outer surface of the chorion, including its villi, was covered by a comparatively thick layer of primary epithelial cells or nuclei, imbedded in a granular matrix. In removing this layer, it was found that its base, the membrane itself (Fig. 1), con- sisted of an amorphous finely granular substance, in which, however, a considerable number of fine granular fibrillee were crossing each other in various directions. These represented the elementary form of the later fibrous or connective tissue. A considerable number of certain forms of nuclei and also cells were imbedded in the mem- brane. The most interesting of these elements were a considerable number of nuclei, distinguished by bearing on their surfaces concave depressions, corresponding to the segment of a sphere, either empty or occupied by double-contoured vesicles or cells (Figs. 1 and 3). They remind us of those mother-blood corpuscles, described in the paper before mentioned, having, as will be remembered, similar depressions on their surfaces, which, however, differed in this respect, as they were produced by the separation of a consistent, though soft body (the embryo blood-corpuscle), in the case of the nuclei in question, they were caused by the separation of a small vesicle, arising from the substance of the nucleus; in other words: in the one case, the product was an embryo blood-corpuscle, while in the other it was a vesicle or cell, destined, as we shall see, to take part in the formation of the primary embryonic blood-vessels, or to develop, perhaps, into a nucleus itself. The process of multiplica- tion of the nuclei and cell, therefore, instead of consisting in a division of the old, we find here to take place by a separation of the young brood in the form of a vesicle or bud, being in reality a process of budding or gemmation. The whole process takes place as follows: on the surface of the nucleus, and partially imbedded in its substance, a small globular body appears, which, gradually enlarging, is developed into a clear double-contoured cell. This may either B 2 +: Transactions of the remain in its place and take part in the building up of the small blood-vessels, or be thrown off from its mother-body and be developed _ into a nucleus itself. In the latter case its contents become more opaque and small granules appear within them. The concave depression which the young nucleus leaves behind on the surface of the mother-nucleus never disappears entirely, no matter how much the latter may change its original form by the production of others. For this reason the productive force of the mother-body can always be inferred from the number of depressions. Several vesicles or young nuclei may arise simultaneously from the old one (Fig. 3) ; accordingly, I observed in the chorion of the ovum in question a number of them, bearing three to four vesicles, and, judging by the number of depressions, one nucleus may even produce five to six of its kind. Along with the production of new vesicles the substance of the old nucleus seems to be rendered more dense, its double contour and the granules it contains become less distinct, and the whole body assumes at last a shining, greenish tint. This is especially the case in specimens which have been laying for a few days in a weak solution of chromic acid ; in these, the vesicle, at its first appearance, is distinguished by a reddish tint. In con- sequence of the concave depressions, produced by the formation of the vesicles, and in proportion to the diameter of the latter, the mother-nuclei appear in many fold, mostly unsymmetrical forms (Figs. 3, 4, and 5), and it is difficult to find an object of suitable comparison. In many cases the vesicle is developed, as in the formation of blood-vessels, into a large, clear, double-contoured cell. The greater now the diameter of the cell, the greater is also the depression observed on the nucleus, and it is for this reason that, after the production of a number of cells, very little of the substance of the nucleus is left. Hqually as varying as the form of these nuclei were their diameters; while, namely, those of the smaller ones only reach to about +35 mm., those of the larger attain a size of about +35 mm. in length, by 735 mm. in breadth. The latter are found in connection with the formation of the first embryonic blood- vessels. The more the entire embryo advances in its development, the more also the size and fertility of these mother-nuclei are reduced. Long before I discovered these mother-nuclei, bearing buds in the form of cells, in the membranes of the ovum, I had met with them in the nervous tissues as well as in the pia mater of those human embryos on which I had worked. But as they appeared here in a smaller form, and with smaller vesicles or corresponding depressions, I failed to recognize their true nature, and considered them passingly as old nuclei, deformed by degeneration. Never- theless, however, did I observe in their immediate neighbourhood, their offsprings in the form of small, round, and pale bodies, which, | Royal Microscopical Society. | ) as I could nowhere discover evidences of a process of multiplication by a direct division of the nuclei, almost inclined me to think more seriously of a primary formation of nuclei from the plasma, itself. It was not until I met in the epithelium, covering the villi of the chorion of a human-embryo of about 16 mm. in length, with nuclei, provided with vesicles or their corresponding depressions, that my attention was called to the process of multiplication by budding or gemmation. But further proofs in corroboration of this idea were still wanting, until chance threw the small human ovum under con- sideration into my hands, in the membranes of which I observed the whole process in full operation. Besides these mother-nuclei, a considerable number of others, of a more or less oval form and bearing no vesicles, were imbedded in the membrane; they were distinguished by a double contour and a fine granular aspect, containing a number of fine granules. A small number of nucleated cells of a granulous appearance were further observed here. The concave depressions, which many of these bodies showed upon the surface, inclined me to look upon them as mother-cells. The villi, arising from the chorion of the ovum, were tuberous bodies, connected to each other in a manner similar to that of the branches of a tree, by shorter or longer stems. (Fig. 2.) To the larger bodies, smaller pear-shaped ones were attached by means of fine pedicles. The entire tree-like body thus formed seemed to be connected bya fine stem to the membranous chorion. But by a closer examination, and after the removal of the epithelium, I found that this stem arose in reality from the membrane, by a number of fine branches or roots. (Fig. 1.) The tissue of the villi resembled that of the chorion itself; it consisted of very fine granular fibrille, with a number of more or less oval nuclei imbedded in it. The epithelium covering the membranous portion of the chorion, and extending over the villi, consisted in this small ovum of a granular matrix with oval nuclei, a considerable number of which were pro- | vided with the above-described vesicles and concave depressions. This fact proves that it is a production of the ovum itself. The inner membrane of this ovum consisted of a loose, spider- web-like connective tissue of fine, wavy fibrillee, containing a number of free nuclei and nucleated cells. Some of these latter were open, and apparently in the act of setting free their nuclei, showing that here the process of multiplication took place by the endogenous mode. Besides these, however, a number of small nuclei-bearing vesicles were also observed. No trace of epithelium could be discovered on the inner surface of this membrane. Let us now direct our attention to the formation of the primary blood-vessels, such as I observed it to occur, not only in the cho- rion of the small ovum above described, but also in that of some- 6 Transactions of the what older ova, as well as in the pia mater of the spinal marrow of a very small embryo. As has been remarked before, some of the vesicles or cells, springing from the mother-nuclei, were probably developed into ordinary nuclei, pertaining to the fibrous tissue of the membrane ; a portion of these might even assume the function of mother-nuclei and give rise to other vesicles. The rest, however, especially the larger ones, were observed to take part in the forma- tion of the embryonic vessels of the membrane. This seems to be effected by a number of these cells, arising from their respective nuclei at different points, and meeting each other in such a manner as to formarow. (Figs. 3,4,and5.) To form this row, however, they were not placed, as might be expected, in regular order, cell by cell; on the contrary, the nuclei, from which they were seen to arise, were distributed throughout the membrane without any special arrangement or order ; neither was their size and form more regular. ‘The formation of a vessel, of course, is brought about by the coalescence of cells arising from neighbouring nuclei, and oppo- site to each other. The tube of the vessel is not necessarily formed by one single row of cells; for when, by the meeting of two cells unequal in diameter, a vacancy is left, this will be filled up by a third cell, arising from the nucleus of one of the former. Rarely less than two cells were seen to arise from one nucleus, but more frequently five to six. Often, large irregularly-formed cells were met with in the course of a vessel, the nucleus of which was marked on its margin by a number of crescent-shaped indentations. In these cases, the large cell was formed by the absorption of the con- tiguous walls of a number of small ones, which originally had arisen from one and the same nucleus, of which the crescent-shaped inden- tations were indicating the place of their origin. (Fig. 4.) After the tube of the vessel is fully formed by the absorption of those portions of the cell-walls contiguous to each other, the nucleus assumes, as it seems, by a gradual rounding of its imdentated margin, a round or oval form. Very frequently, however, by the production of a number of cells, it is deprived of so much of its substance, that finally nothing of it remains but a long indentated body, which by the rounding of its angles assumes an oblong form. This form is often met with in the walls of young vessels, long after the cellular formation of the blood-vessels has ceased to occur. In some instances, especially with the smaller vessels, we meet with two cells arising from two opposite points of one and the same nucleus, the latter occupying the whole diameter of the row (Figs. 3 and 4), thus seeming to form an obstacle to the opening of the vessel. This, however, is overcome, I think, by the growth of the cells, at - the expense of the substance of the nucleus, of which at the end of the process only little will be left. Thus the absorption of the entire nucleus will sometimes be effected. In the nervous tissues Royal Microscopical Society. if of the human embryo, I observed the nuclei, belonging to the pri- mitive fibrils of the axis cylinder, disappearing during the process of development by fusing with the latter. In the small ovum under discussion, the formation of the blood-vessels, as described above, was observed to occur throughout the entire chorion to the roots of the villi, but had as yet not extended into the latter. In examining the chorion of an embryo of about 16 mm. in leneth, we still find a considerable number of mother-nuclei with vesicles, budding from their surfaces, imbedded in the tissue. The structure of the membrane is on the whole further developed, for the fibres of the connective tissue are more definite in their form, and the cells of the epithelium placed nearer to each other. The stems of the tuberous villi, arising from the surface of the mem- brane, have gained in thickness, also their epithelium, which now consists of two layers of cells. (Figs. 6 and 7.) ‘The fine fibres of the connective tissue of the villi themselves are fully developed and have lost their granular aspect. But the smaller blood-vessels, although more numerous, and having penetrated mto the villi, still consist of cells, only partially fused with each other. (Fig. 6.) Among the blood-vessels of the pia mater of the spinal marrow of embryos of about the same period as the preceding, some, especially the larger ones, were found to contain a considerable number of coloured blood-corpuscles, showing that the circulation of the blood through them had already been established ; while others, especially the capillaries, still showed their original formation by the cellular structure of their walls, and the entire absence of blood-corpuscles in their interior. The muscular structure of the heart at this period consists of embryonic muscular fibrille, each of them representing a row of simple granules. ‘The walls of the larger blood-vessels, such as the aorta, umbilical vessels, &c., consisted of a granular, amorphous, already partially fibrous matrix, in which a considerable number of oval or even round nuclei were imbedded. On their inner surface a number of clear cells, containing a coarsely granular nucleus, devoid of an enclosing membrane, were met with. These cells, being present in various other tissues of the embryo, probably stand in some relationship to the multiplication of the nuclei. Judging from the development of the heart and the larger blood-vessels of this period, it would seem that the circulation of the blood were already complete; that this is not the case is proved by the almost entire want of fully formed capillaries in a number of organs which I examined. For this reason I am inclined to believe that it occurs only through anastomosing branches of the smaller arteries and veins. Further, the fact that the smaller vessels of the chorion, and particularly those of its villi, stall mostly consist of cells, the contiguous walls of which are as yet not fused, 8 Transactions of the proves sufficiently that even here the circulation is not fully esta- blished, and that accordingly the embryo does as yet not receive its nutriment from the mother directly through the circulation of its own blood. From these observations on the formation of the primary em- bryonic blood-vessels we may infer that the larger vessels are very probably formed, in the same manner and simultaneously with other parts and organs of the embryo, from the embryonic cells of the area germinativa, while those smaller ones, imbedded in mem- branes, are formed by the coalescence of larger and smaller cells, as above described. Continuing our examination of the blodd-vessels of the pia mater of the spinal marrow, which membrane in regard to its delicate structure and. transparency is better adapted than other tissues for this purpose,—at a later period, in embryos, about eight to nine weeks old, we find that the embryo has entered another stage of development, in which these vessels are no more formed by the coalescence of cells. The pia mater here is still represented by an amorphous, granular membrane, in which, however, a thin layer of delicate connective-tissue fibres has already been developed, and containing besides a considerable number of oval or round nuclei. The latter consist of small granules, surrounded by a thin mem- brane. Among them, however, a number of mother-nuclei, with small buds arising from their surface, are also observed, showing that multiplication of these nuclei still occurs by the process of budding or gemmation. The blocd-vessels within the pia mater show different stages of development. The formation of those vessels described in the preceding pages was brought about, as we have seen, by the coalescence and subse- quent fusion of cells, and so were the greater number of those within the tissue of the pia mater of embryos from nine to ten weeks old, through which, as they were filled with blood-corpuscles, the blood had been evidently freely circulating. A smaller portion of these, however, still in process of development, were observed to be formed by another process. Where, in the former instance, the formation of the tube of the vessel was accomplished by the coales- cence of cells, it is now by the fusion of elementary fibrils. The process of gemmation, though still occurring, as far as the multipli- cation of nuclei is concerned, has ceased for the formation of vessels ; the fibrillous formative process of the blood-vessels has now com- menced. This consists in the formation of granular fibrille, lying parallel to each other, and becoming in the course of their develop- ment fused into the form of a tube. Postponing at present a more minute demonstration of this process, let us return to the already formed blood-vessels of the pia uater of the last-mentioned embryos. The greater part of the Royal Microscopical Society. 9 vessels, imbedded in this membrane, embracing, as it seemed, a con- siderable portion of the larger and smaller capillaries, consisted of tubes of about 725 to +o mm., the wall of which represented a clear, very transparent membrane. In this, a number of oval and irregular oblong nuclei were observed. ‘he irregular form of many of these bodies lead me to regard them as the remains of those mother- nuclei from which, in the chorion of the smallest embryos, those cells, forming the primary embryonic blood-vessels, were seen to arise. The larger vessels were filled with blood-corpuscles, which, by the action of a weak chromic acid solution, in which the speci- mens had been preserved, had lost their colouring matter, and thus appeared now in the form of clear double-bordered cells. The smaller ones, on the contrary, contained only a few single corpuscles, which appeared to have been forcibly pressed into their interior. This circumstance points to the probability, already mentioned in connection with the development of the coloured blood-corpuscles in man, that these bodies penetrate with every contraction of the heart only gradually into the newly formed but still closed blood-vessels. Among the blood-corpuscles, contained within larger vessels, a number of mother-corpuscles, bearing one embryo-corpuscle, were always observed. In examining the larger vessels, imbedded in the pia mater, of this period, viz. the small arteries and veins, their structure was already found considerably more complicated. Their walls, namely, consisted no more of a homogeneous membrane with large nuclei, but of two distinct layers. In place of the large nuclei, often irregular in form, a larger number of smaller ones, of an oval or roundish form, and imbedded between the two membranes, are now observed. ‘These I presume are the descendants of a small number of mother-nuclei with small vesicles budding from their surfaces, always found in company of the smaller nuclei, which they seem to have preceded. ‘The inner membrane probably represented the original tube of the vessel, while the outer one, distinguished by fine, longitudinal, fibrillous lines, represented its later fibrous coat. © In the arteries, the fibrous character of the latter was more strongly marked than in the veins. In the larger arteries and veins of the pia mater these two layers, forming the wall of the vessel, and distinguished by their regular, sharply-defined double contour, were found to be separated from each other by a third layer of irregular thickness. (Figs. 10 and 11). The latter most probably represented the muscular coat of the vessel in progress of formation. In those cases where it was found, the nuclei were imbedded in it, and a number of them were observed to assume a position in which their long axis comes to lay at right angles with the axis of the vessel. No muscular fibres, however, could as yet be distinguished. The greater number of the vessels just described were filled 10 Transactions of the with coloured blood-corpuscles, of which the greater portion had lost their colouring matter by the action of the chromic acid solu- tion, and appeared in the form of clear double-bordered cells, while the rest, comprising the younger corpuscles, had remained un- changed ; in many vessels they were crowded in such a degree that the former, by mutual pressure, had assumed a hexagonal form. A number of mother-blood corpuscles were always found among them; they had also become discoloured, while their embryo- corpuscles had retained their colouring material. In many of the larger vessels, besides the blood-corpuscles, a number of coloured molecules and also small blood-crystals were found. Sometimes even blood-corpuscles were met with, in the substance of which small crystals were found to be imbedded. Many vessels were completely coloured by the hematin escaped from the blood-corpuscles. The blood-vessels were probably found, as already mentioned, by the coalescence of cells. But besides these, I observed in the same pia mater, a number of capillary vessels in progress of formation, the fibrillous composition of which attracted my attention. The result of a series of close examinations, which I subsequently made on the smaller vessels of the pia mater of this embryo, as well as of a number of others of different periods of development, convinced me that these vessels were formed in a different manner from the preceding, to which I have already alluded. ‘This consists in the formation of granular fibrille, laying parallel to each other and becoming eventually fused into the form of a tube. (Figs. 8 and 9.) In connection with the development of the coloured blood-corpus- cles, I have already pointed to the different modes of origin and development during the earlier and later periods of embryonic life. In the development of the embryonic blood-vessels, according to these observations an analogous change in the mode of formation seems to take place. ‘The exact time at which the first or cellular process of formation is superseded by the second, or fibrillous, 1 am at present unable to state. In an embryo of 16 mm. in length, I found all the vessels of the liver still to consist of granular fibrille, while those of the chorion and its villi, as well as those of the pia mater, were formed by the cellular process, above described. It appears, therefore, that the formative process of the vessels is not always the same in dif- ferent organs. In the pia mater, as far as I am able to judge, the fibrillous formative process seems to have already commenced about the eighth or ninth week, and to be in full operation some weeks later. We will now describe its course, as I observed it in the pia mater of human embryos of about twelve weeks, where, at this period, the small arteries and veins, as well as the capillaries, prove to be quite numerous. : The primary elements of the vessels to be formed represent gra- Royal Microscopical Society. 11 nular, spindle-shaped bodies, with an oval nucleus in their centre ; they are formed by the granules of the plasma, arranging themselves into rows at the opposite poles of the nucleus. ‘The latter, there- fore, forms the basis of development. After one row has thus been formed by the mutual arrangement and attachment of these gra- nules, and attained a certain length, a second one, starting also from the nucleus, begins to be formed in the same manner ; after this, a third and fourth, until their aggregate breadth equals that of the nucleus. But, as with the beginning formation of the succeed- ing rows of granules, or fibrils, those first formed continue to elon- gate by the attraction and appropriation of new granules, a spindle- shaped body isthe result. In the formation of a vessel by a greater or smaller number of these bodies, they jom—already during their own formation—each other laterally in such a manner that a part of the length of one overlaps another; they finally are fused with each other into the form of a tube. In consequence of the various directions in which these spindle- formed bodies, or the bundles formed by them, are developed, they frequently cross or meet each other. When this occurs, it is usually found that the point of the smaller body or bundle adapts itself to some extent to the lateral border of the larger. As the result of a number of such connections, or points of fusion, the meshes of the capillaries are formed. (Fig. 8.) In this manner, capillaries, still in progress of development, are frequently observed to be fused with larger vessels, through which blood-corpuscles have already been circulating. The small arteries and veins are formed by the fusion of a number of bundles, composed of the spindle- shaped bodies. The contiguous borders of the latter can still be recognized on the vessels of the embryo of twelve weeks. (Fig. 9.) Frequently one of the larger vesssls is observed to be formed by the union of two smaller ones, the latter still being in process of development themselves. In the pia mater of human embryos of this age, the fusion of the spindle-formed primary elements into bundles, and of these into larger or smaller vessels, is observed to take place in an irregular manner, and also, as already mentioned, in various directions. It is owing to this circumstance that up to this period the form of the meshes, and even that of the vessels still in process of development, is quite indefinite. Kqually irreeu- lar are the numerous nuclei, contained in the walls of the arteries and veins, in size as well as distribution. The tube of the vessel being thus formed by a parallel apposi- tion and subsequent fusion of those fibrillous spindle-shaped bodies, is opened and distended by the blood-corpuscles penetrating into it from the neighbouring more fully developed vessels ; thus we meet in the newly-formed capillaries only a few blood-corpuscles, which have evidently been forced.into them from larger neighbouring } 12 Transactions of the vessels, as they are seen to distend the calibre of the vessel only to a certain distance. (Fig. 8.) ‘I'he further development of the ves- sels is moreover promoted by the nutrient matters contained in the liquor sanguinis. While a number of blood-vessels are thus gradually approaching their final development, and in consequence the circulation of the blood is further extended, others are still formed by the same process. | At what period the formation of new vessels in the human embryo ceases to take place I have not determined, as my examina- tions concerning this subject were extended only to the vessels of the foetus, about 54 months old, in the pia mater of the spinal marrow of which new capillary vessels were still seen in the process of formation. The further development of the newly-formed capillary vessels consists, as already mentioned, of the fusion of the granular fibrils of which they still consist, into a structureless membrane. In the small arteries and veins, formed by the fibrillous process, the gra- nular fibrils are developed into permanent, smooth fibrille of con- nective tissue, while the diameter of the vessel increases by the continuous formation of new fibrils from the plasma of the blood circulating within them. ‘The multiplication of the nuclei takes place by gemmation. In the pia mater of the embryo of about nine weeks we found, as will be remembered, the largest vessels already composed of three distinct layers, though in the middle and inner one no particular structure could as yet be recognized; the outer layer alone was composed of delicate fibres of fibrous tissue. In the succeeding periods also, it is especially this layer which is most distinctly developed. ‘The first traces of the formation of the muscular layer consist in the appearance of a larger number of oval nuclei, the long axis of which lays at right angles with that of the vessel. The inner layer, however, which in the beginning was equal in thickness to that of the outer one, is gradually rendered more indistinct, perhaps by the increasing development of the latter. In the foetus of 54 months, finally, the outer coat of the larger. vessels of the pia mater has attained sufficient consistency to permit its separation trom the loose areolar tissue by which these vessels are surrounded, thus affording an opportunity for a closer examina- tion of their respective coats. In the walls of such vessels of about +*5 mm. diameter, and freed from the loose fibrous tissue surround- ing them, only two layers, distinct from each other, are recognized (Fig. 12). The outer of these, representing the fibrous coat of the vessel, consists of delicate wave-like fibres of connective tissue, holding numerous, more or less oval nuclei, their long axis being parallel to that of the vessel. They are distinguished by. a fine double contour, and filled with small granules. The inner layer, which appears Royal Microscopical Society. 13 somewhat darker than the outer, represents the muscular coat, already tolerably advanced in development; it also contains a con- siderable number of nuclei, with their long axes, however, at right angles to the course of the vessel. A number of these nuclei, though somewhat larger and of an oblong form, show, like those of the outer coat, a fine double contour, and are filled with granules. The rest, however, represent mother-nuclei, being dis- tinguished by a greenish lustre. A number of these bear those characteristic small vesicles or buds, which show that the process of their multiplication is still in active operation: the remaining ones appear in the form of irregular spindle-shaped bodies, with crescent- shaped notches, the traces of their former activity, in their contours. The muscular coat itself appears as a fine granulous substance. © Besides those nuclei just described, a number of others of an oval form are observed on the inner surface of the vessels; these probably represent the epithelium of the vessel in the process of formation. I shall next proceed to give an account of the results obtained from the examinations made on the very small ovum, alluded to in the beginning of this article. This was the smallest specimen of the human ovum I had ever seen. (Fig. 13.) Being removed from the membrana decidua, which had come away entire, it was found to be perfectly fresh and normal. Slightly oval in shape, it only measured 13 by 11 mm. in diameter. The oval form, however, may have been produced by a stretching of the membrana decidua, which was pinned down upon a cork during the operation of its removal. Its surface was almost entirely covered by villi. The embryo it contained (Fig. 14), measuring only 6 mm. in length, was bent upon itself, the inferior part of the spinal column making a spiral turn to the left side of the body. The rudiments of the vertebrae when examined through a lens (Fig. 15), manifested themselves in the form of opaque spots. The superior portion of the body was divided into three segments, the upper and larger one of which represented the future cranium, the two others visceral arches; there was no trace of the formation of the eye or ear to be seen. LDhirectly below the visceral arches, and occupying the middle portion of the body, there were three round prominences, which, as I suppose, represented the rudiments of the heart. (Figs.15 and17.) They were of a reddish colour, and the larger of them was, by a subsequent examination, found to be hollow. Below these prominences the pedicle of the umbilical vesicle was seen to arise from the rudimentary alimentary canal ; and still lower down, within the curve of the spinal column, also the umbilical vessels. ‘The extremities manifested themselves only in the form of four small delicate buds; the upper ones laterally and behind the above-mentioned prominences, and the lower ones within the curve of the inferior portion of the spinal column. That 14 Transactions of the portion of the vertebral column situated beyond the rudiments of the lower extremities and representing principally the coccyx, formed an appendix of such a length that it might, without any impropriety, and in support of Darwin’s theory, well be looked upon as a tail. (Fig. 16.) The embryo itself was attached to the walls of the egg by a delicate membrane, which, after arising gradually from the abdominal surface, and including, but not closely surrounding, the umbilical vessels, was soon blended with the walls of the egg. (Figs. 16 and 17.) The rudimentary heart, alimentary canal, and umbilical vesicle, were not embraced by this membrane, but, laying at its right side, were projecting into the general cavity. | Referring, for a better understanding of the general form of the embryo, the reader to the drawing accompanying this article, which I carefully took from the object in its fresh condition, while immersed in water, I shall now state and consider the results of the microscopical examination, regarding the structure of the umbilical vesicle and chorion of this interesting specimen of human embryo, as they really formed the principal object of the investigation. To do so, however, I must somewhat deviate from the object, in order to recall to our mind the structure of the umbilical vesicle, in which I discovered the origin of the coloured blood-corpuscles, described in my treatise on that subject.* It will be remembered that the embryo to which it belonged had been arrested in its growth, being represented only by an accumulation of embryonic cells. Further, that the wall of this vesicle was found to be a system of primary follicles and canals, the interior of which was Imed by large hexagonal cells, in which the blood-corpuscles originated in the form of pale double-contoured nuclei. ‘The interior of the follicles and canals were occupied by considerable accumu- lations of fully-developed coloured blood-corpuscles. The examination of the umbilical vesicle of the small normal embryo, described above, became therefore a matter of interest, as its results would either disprove or corroborate the correct- ness of the conclusions which I had drawn from the observa- tions made on the former specimen. They proved to have been correct, for in examining a portion of the wall in its fresh un- changed condition, the individual follicles with their intervening canals could be distinctly recognized. As in the former case, the follicles consisted of the same large hexagonal cells (Fig. 18), which also contained, besides a number of small nuclei, one or two larger ones. But there were no fully-developed coloured blood-corpuscles to be seen either within the follicles or the canals. In place of these, however, a considerable number of free small round nuclei, containing a number of granules, were observed. The same kind * ¢M. M. J.,’ February number, 1874. Royal Microscopical Society. : 15 of nuclei I found within the cavity of the rudimentary heart and also within the newly-formed blood-vessels of the chorion. (Fig. 19.) In examining the chorion I found it to consist of an amorphous, granular membrane, covered by an epithelium, consisting of a decidedly granular matrix, in which a considerable number of small nuclei were imbedded; the villi consisted of the same elements. Within the structureless membrane of the chorion I observed, to my astonishment, a considerable number of the smaller blood-vessels and capillaries (Fig. 19), some of them far enough developed to allow the circulation of the blood, others still in process of development. They, however, extended not into the villi. As their structure showed, they had been formed by the fusion of spindle-shaped bodies. A number of those small granular nuclei, above mentioned, were met with in their interior. A considerable number of oval nuclei were distributed throughout the membrane, occupying the meshes of the capillaries. Some of these latter nuclei I discovered in the act of multiplication, not by the process of budding, how- ever, as in the chorion of the abnormal embryo, described in the first pages of this article, but, on the contrary, by that of direct division. ! In reviewing now the different facts, regarding both the mode of origin of the blood-corpuscles within the follicles of the umbilical vesicle, as well as the development of the earliest embryonic blood- vessels in the chorion, elicited. by the above examinations, and comparing them with those observed in the same parts of that ab- normal embryo, some discrepancies existing between them will become apparent, and it would almost seem as if my former observa- tions had been incorrect. But this is not the case, and for this reason we will give an explanation of the probable cause of these discre- pancies, consisting firstly in the presence of granular nuclei within the follicles of the umbilical vesicle and in the blood-vessels of the ‘chorion of the normal embryo, instead of fully-developed coloured blood-corpuscles, as were met with in those organs of the abnormal, undeveloped embryo; and secondly, in the mode of development of the embryonic blood-vessels. . In comparing the diameters of the two ova, we shall see at once, that while the former abnormal one measured 24 ctm. in diameter, the size of the latter normal one only amounted to about half of this, that is, 13 mm. in length to 11 in breadth. It becomes evi- dent, therefore, that the abnormal one, containing the undeveloped embryo, must have been considerably older than the latter. The structure of the umbilical vesicles of the two ova being found to be the same, we must presume that the fully-developed blood-corpus- cles found within the follicles of the umbilical vesicle of the older ovum, had, atan earlier time, likewise been represented by granular nuclei as in the other case, and by a gradual continuous develop- VOL. XIII. 0 16 Transactions of the ment only attained the more perfect form in which they were dis- covered. In consequence, however, of the embryo being arrested in its development at a very early period, no heart or blood-vessels were formed to communicate with the system of canals of the umbi- lical vesicle for the establishment of the provisional circulation. The primitive blood-corpuscles, in the form of round nuclei therefore, being thus prevented from escaping from the canals, accumulated there, as well as in the interior of the follicles, where they were eventually developed into perfect coloured blood-corpuscles. The development of the umbilical vesicle with its follicles, and the coloured blood-corpuscles found within the walls of the latter, of course, must be regarded as an abnormal phenomenon of nature, almost in the same light as those isolated parts of embryos, as frag- ments of jaws with teeth, &c., found sometimes in the interior of ovarian cysts. As regards the presence of round granular nuclei within the follicles and .canals of the umbilical vesicle, as well as within the rudimentary heart and the primary vessels of the chorion of the small normal embryo, it seems to indicate that at an early period, when the blood commences to circulate through the vessels of the provi- sional circulating apparatus, it carries small round granular nuclei, which are either gradually metamorphosed into coloured corpuscles, or replaced by such originating directly in the cells of the follicles. The latter seems to be the more probable, as a number of pale, smooth nuclei were observed in some of the cells. ~« The formation of the primary blood-vessels in the chorion of this embryo was observed to be effected, as mentioned before, by the fusion of spindle-shaped cells. In the chorion of that abnormal ovum, however, the blood-vessels, as my former observations showed, were formed by the fusion of certain round cells, arising in the form of buds from the nuclei, distributed throughout the membrane. Now, it might be presumed that, as the development of the embryo in this case was abnormal, the mode of formation of the blood-vessels would probably be the same; but remembering that I observed this same process still taking place in the chorion and the pia mater of much older embryos, of from 16 to 18 mm. in length, this argu- ment loses its force. With these facts before us, we can only pre- sume that the blood-vessels of the provisional circulatory apparatus, during the earliest period of development of the human embryo, are formed by the fusion of spindle-shaped cells, while somewhat later the formation of the permanent vessels is effected by the fusion - of smaller or larger cells or vesicles arising by the process of gem- mation from the nuclei, as described in the first pages of this article. At a still later period this process, too, ceases in its turn, — and the vessels are formed, as we have seen, by the fusion of granular spindle-shaped bodies. ) Royal Microscopical Socvety. LZ Of the morphological development of the embryo of the small normal ovum, I have little to say; as it was not my particular subject of study in this case. I rather directed my attention first _ to the examination of the umbilical vesicle in its fresh condition. This examination, together with the removal of the ovum from the membrana decidua and the execution of the sketches, occupying all the time which I had at my disposal until twilight, I was obliged to put the specimen in a weak solution of chromic acid for preser- vation. In resuming my examinations on the next day, the body of the embryo had so much lost in transparency by the action of the chromic acid, that I was obliged to use compression in order to render it sufficiently transparent for microscopical observation. ‘The compression of course would obliterate the form of any rudimentary internal organ. The whole embryo seemed to consist only of a multitude of small embryonic nuclei imbedded, or held together by a homogeneous plasma. With the fact of the developed blood- vessels in the chorion, however, before us, there can remain no doubt as to the existence of such within the body of the embryo; though I believe, as I have said before, that the larger vessels, as aorta, &c., being developed simultaneously with other internal organs, consist at this period, like the latter, only of embryonic nuclei imbedded in the plasma, until a differentiation of the various tissues commences. Those three prominences on the anterior side of the body of the embryo, representing, as I supposed, the rudimentary heart, were, as before mentioned, of a decidedly reddish tint, which was fading towards the body of the embryo. The question arises here, whe- ther this tint was the natural colour of the tissues, or whether it was due to the blood, which had been circulating within the tissue. As has been stated, my examination of the walls of the umbilical vesicle showed no coloured elements whatever ; still, as the specimen was examined in water, we might venture to suppose that those small round nuclei, which undoubtedly represented the coloured . corpuscles in their earliest condition, had already possessed the characteristic colouring material, and lost it again by the action of the water. This supposition would explain the phenomenon, as in the absence of any muscular fibre formed, the reddish tint could hardly be due to the embryonic tissue itself, without the presence of the colouring element of the blood. During the whole course of my researches made on embryonic tissues, I have endeavoured to discover some general law concerning the different modes of multiplication of nuclei during embryonic life ; that is, whether one or the other process of multiplication would regularly appear only during a certain period of the develop- ment of the embryo. ‘This seems to be the case, however, only to a limited extent. During the earliest periods of onpeyeme © 18 Transactions of the Royal Microscopical Society. life, the multiplication of nuclei seems to be solely effected by the process of fission, or direct division. Having observed in the chorion of the small normal embryo, above discussed, a number of nuclei in the act of multiplying only by this mode and no other, I suppose that in the human embryo this process of multiplication of cells and nuclei, beginning with the cleavage of the yolk of the egg, prevails only throughout the first weeks of embryonic life, after which it is superseded by that of gemmation or budding. I base this supposition upon the fact that, with the exception of the cells of cartilage, I have throughout all succeeding periods of development of the human embryo, never been able again to discover a cell or nucleus dividing by simple fission. In that abnormal specimen of human ovum, probably one or two weeks older than the other, I observed, as already stated, the multipli- cation of nuclei in the chorion as well as in the embryo stunted in its growth, only taking place by budding or gemmation, and the same process I observed in the tissues of other embryos up to the age of 64 months. During a certain period, however, the multi- plication of nuclei seems to be effected also by the endogenous mode. In various tissues of human embryos, of about from 16 to 20 mm. in length, as, for instance, the brain, spinal marrow, skin, &c., I met with a number of double-contoured cells, which were filled by small nuclei of a greenish lustre. On some of them the double contour had disappeared, showing the obliteration of the cell-wall for the purpose of liberating the nuclei. Another kind of clear cells, con- taining a coarse granular nucleus, which in many instances is seen dividing into a number of fragments, is met with in various tissues of the embryo; these cells stand very probably also in some rela- tion with the multiplication of nuclei. ( 19 ) Il.—On Pigment-Flakes, Pigmentary Particles, and Pigment- Scales. By JosspH G. Ricaarpson, M.D., Microscopist to the Pennsylvania Hospital. THE present paper is designed to direct attention to what I con- ceive to be an egregious error, by which several microscopists of acknowledged ability have been’ ensnared ,—namely, a belief in the importance of the “ pigment-cells” or “scales” described by Frerichs, of Berlin, as occurring in blood ;* of similar bodies found by Drs. Meigs and Pepper, of this city, under like circumstances ; t and of the “pigmentary particles” or “celloids” figured by ~ Dr. William Roberts, of Manchester, England;{ most, perhaps all of which I assert to be simply and solely accumulations of dirt (especially the remains of red blood-corpuscles) in the little excava- tions on slides in ordinary use. Such an accusation as this will, no doubt, at first excite astonishment or even ridicule, but of course no sane man would dare to bring forward a charge of this kind without strong evidence in its favour. This evidence I ask each one of my readers to furnish me after trying this simple experiment: Examine an ordinary plate-glass slide microscopically for diré- pits containing brownish-red matter which may be oxide of iron (the remains of the polishing powders used in its manufacture), or, if the slide has been long in use, old red corpuscles. If there are none already filled up with “ pigment,” rub in faithfully a little blood, by which means you can sometimes fill the shallow cavities - with the débris of the red disks, and so imitate quickly the effect probably often produced in a gradual manner by frequently wiping small quantities of blood over the glass. Lastly, clean off the slide perfectly bright (so as to be sure you leave nothing but artificial cells upon it), and examine with a power of 250 diameters. The bodies you probably find are accurately described by Dr. Roberts as follows:§$ “ Pigmentary particles; these objects deserve a passing notice from the fact that they are frequent, almost constant, if not absolutely constant, objects in urinary deposits, and have not hitherto been described. . . They never exist in such quantity as to form the entire (sic) of a visible urinary sediment ; they are only to be recognized by the microscope. They appear especially under two conditions—namely, as free amorphous par- * ‘Clinical Treatise on Diseases of the Liver.’ Sydenham Soc. Translation, London, 1860, vol. i., p. 320. Bs “Pennsylvania Hospital Reports,’ Phila., 1868, p. 108. t ‘Urinary and Renal Diseases,’ second American edition, Phila., 1872, p. 125. § Op. cit., p. 124 et seq. 20 On Pigment-Flakes Pigmentary Particles, &e. ticles and cell-like bodies (or celloids).... The cell-like particles have a peculiar appearance, very difficult to explain. They never present an unmistakably cellular character ; they appear flat, never spherical. Their outline is generally an oblique ovoid. Within this outline, which is generally of exceeding delicacy and of perfect definition, lie masses of red or orange pigment, exactly resembling the free amorphous particles already described.” Frerichs, after pointing out somewhat similar objects, says* that accurate diagnosis can be made in malarial fever by examining the blood for them, since a few drops “‘are sufficient to determine the presence or absence of large quantities of pigment.” Drs. Meigs and Pepper report finding pigment-particles in the blood of eighty-nine patients; but later these acute observers seem to have had shrewd misgivings respecting their importance, although without feeling satisfied as to their real origin. My own suspicions were excited years ago by Frerichs’s pig- ment-scales, and experiments on hundreds of specimens of blood from malarial and other cases convinced me of their delusive character. Very recently, Dr. James Tyson, of this city, whilst examining in committee some ovarian fluid, pointed out to me several of Roberts’s pigment-flakes, and said he had prepared drawings of these bodies for his forthcoming work. His statement naturally led me to a careful and prolonged study of the objects in question, and this in turn forced upon me the conviction above expressed. Excluding carbon-particles (from the air), which can generally be found in fluids which have not been secluded from the atmos- phere, I attribute the peculiar shape of pigment-flakes which Roberts finds so “ very difficult to explain” (admirably shown by Dr. Tyson in his plate), to the conchoidal figure of the minute chipped-out cavities in plate glass; which little pits have, indeed, proved veritable pitfalls to unwary travellers over the microscopic field. These same shallow shell-like excavations, before being filled up with dirt, are, probably, Frerichs’s “ coagula of a hyaline character, which resemble in form” (as they have a perfect right to do) the pigment-flakes, and are also Roberts’s “ bluish mother-of- pearl” celloids. | Dr. Roberts concludes, “I. have been in the habit of noticing these objects for many years, and have regarded them as derivatives of hematin, but how they come to assume their peculiar forms I cannot conjecture.” With him, I believe them occasionally to be “ derivatives of hematin,” but only by the rubbing process detailed above; and I trust that my “conjecture” as to how these hematin- flakes ‘‘ come to assume their peculiar forms” will be satisfactory. It seems almost incredible that the recorded appearance of these * Op, cit., p. 305. On a Modification of the “ Slit” for Testing Angle. 21 “‘ flakes” in such various and inconsistent localities—viz. in blood, urine, the brain, in tumours, and even in the breath—has hitherto aroused no suspicion of their true nature; and it is only when we remember how few investigators have minds achromatic enough to enable them to see objective facts without subjective colouring, that we can offer a plausible explanation of this remarkable pheno- menon. Does not the delusion which, if I am correct, has thus entangled several eminent observers, form one of the most curious episodes in the history of medical microscopy ? and should it not serve as a warning to future generations of students? Nevertheless, bemg always open to conviction, I hereby chal- lenge any devout believer in pigment-flakes to bring me an honest specimen of urine, or blood from any ordinary case of disease, in which can be demonstrated either pigment- flakes, pigmentary particles, or pigment-scales. PHILADELPHIA, November 7, 1874. IIlI.—On a Modification of the “Slit” for Testing Angle. By R. B. Tories, Boston, U.S.A. Ir ig only within a few days that I have used the “slit” devised by Mr. Wenham to cut off false light, as he says. Having always made the test of the verity of my measurements this condition, viz. that the object be in focus and in view with the extremest rays traversing the sector, there could remain no chance of my being mistaken. But in tracing a diagram to demonstrate the effect of aberration when the slit was used without cover and at the closed point, I hit upon a ready means of use of the slit ¢o test angle with cover, and without, almost sinultaneously. An ordinary glass object-slide, silvered on its upper surface, A. S, the slit cut through the amalgam (or silver). ¢, covering glass, with test diatoms in balsam between cover and slide, in the 22 On a Modification of the “ Suit” for Testing Angle. slit. (Also, a central portion of the cover might be a dry mount of the same diatoms.) My course is to find out, in the first place, what the field of the objective to be measured is, by means of a stage micrometer. I then cut‘the width of the field or less, as I choose, through the silvering, guiding the knife against a metal straight-edge. A little dilute acid cleans the slit-space. In the case of the {th measured in London the breadth of slit required was closely to 0:015" to span the field, an unneeded breadth for the purpose of angle-mea- surement, I will now relate my experience with the apparatus in a trial of . it on a ¢th closely similar to the one Mr. Wenham tried his inven- tion on. I induced the owner of the objective, a resident of this city, to bring it in and witness the trial. Thickness of cover used 1, inch, which the objective at “closed,” just focussed through upon the objects in the balsam, or in the dry mounted portion, with air contact. The edges of the slit trenched slightly upon the field of view in the eye-piece, a “B” of medium aperture. To get the angle as Mr. Wenham got it, the wncovered portion of the slit was brought into view. A clear air-space between, of course. The angle was less than 100°,—-scarcely 90°. The covered portion of the slit was then brought into view, cover dry. The angle was all my thin* stage would admit of, about 160°, but the aberration even with the very thick cover and contact (with brass setting of front lens) rendered the trial indecisive as to useful angle. But observe; with water contact and the object-slide having been transferred to bottom of the thin stage, the objects were nicely defined even with light incident almost exactly parallel with the surface of the slide. Furthermore, with a slit one-half or one-third the breadth of the field, the result was just as satisfactory with water contact ; but with air only intervening, the angle was reduced, accordingly as the field was reduced, from less than 100° (small enough !) to one-half or one-third that angle. : Properly used, it is evident that for taking angles a narrow slit of field-aperture is as good as more, and therefore a slit at the focus suitable for th might serve for }th. In fact, what suits a =j,th ought to serve for all powers below. The thinnest covering glass will do, that being needed merely to secure the objects, as tests of definition, in place. ‘The space may be filled up with glycerine to contact as well, ordinarily. Always, where only infinitely near to 180° of aperture is to be measured. Water has too low refrac- — tion to correct in place of glass. * Not “zinc”! stage; see ‘M. M. J.’ for August, 1874, p. 65. On a Modification of the “ Slit” for Testing Angle. 23 I may as well state here what is of real importance in using such an objective as the ith, i.e. of maximum (or large), angle and long working distance through cover. That objective goes best with the thicker covers, therefore the thin covers 3,5 to +, should be supplemented with glycerine instead of water. This gives best command of all thicknesses of cover, notably if the objective is corrected for best work through the nearly thickest covers it will penetrate. Boston, Nov. 25, 1874. ( 24) PROGRESS OF MICROSCOPICAL SCIENCE. Hawe the Lungs on their ultimate Alveoli Squamous Epithelium ?— This question has been often asked for the past thirty years, and has been answered both in the affirmative and the negative. However, now a Mr. Henry Brown, of Northallerton, seems to have decided the question. In a letter to the ‘ Lancet, of Nov. 7th, 1874, he says of this question that ‘when we find such men as Waters, Kélliker, Rossignol, Eberth, Hirschmann, and Arnold advocating its presence, and Rainey, Todd and Bowman, and Zenker denying its existence, what are we to say? With your permission I shall briefly point out how the examination of the pulmonary tissue should be conducted, and I shall explain how I and others have failed to observe the epithelium, and how by a little careful attention and manipulation any person possessing a good microscope may, with great ease and facility, demonstrate its existence. Reasoning from analogy, I con- sidered the ultimate lung tissue could not be an: absolutely bare and structureless membrane, upon the walls of which the capillaries ramified. Accordingly I obtained some lung tissue from a recently killed pig, and examined it after the least delay possible. I excised a portion from the thin edge of the lung, and, placing it over the index finger of the left hand, made slight pressure upon its upper surface, and then seized it with the thumb and middle finger of the same hand, so as to secure it firmly, and by means of fine curved scissors snipped - off small pieces. My object in so doing was to make the pieces as thin as possible, and I. have found this mode of procedure preferable to any other. The thin pieces of lung were washed in distilled water for about fifteen minutes. I used a deep watch-glass for this purpose, and by means of two needles I was able to wash the pieces most effec- tively. I then transferred the small pieces of lung to another watch- glass containing some distilled water, and, after stirring them about for a minute or so, I found that’ very few air-bubbles made their appearance ; and taking up a small piece of lung, transferred it to a glass slide, and placed upon it a thin glass cover. This I carefully examined under a power of 310. The appearance was different from what I had before seen, and I resolved to apply a very weak acetic acid solution. For this purpose I added ten drops of glacial acetic acid to one ounce of distilled water, and, by means of a Clark’s stopper, allowed a drop to pass between the cover and glass slide. The effect was truly charming. Beautiful epithelial scales with a nucleus presented themselves. ‘The reason why I have formerly been unsuccessful in demonstrating the epithelium of the alveoli of the lungs is this: that the acetic acid employed was too strong, and immersion of lung tissue in moderately strong acid causes disintegra- tion and solution of the epithelium. I think, Sir, this point should now be finally settled, and I shall most willingly send further par- ticulars to any person interested in this vexed question. I have carefully measured the epithelium, and observed its disposition, and PROGRESS OF MICROSCOPICAL SCIENCE. 29 I recommend the authors of our English Physiologies to.overlook the stereotyped engravings in their several works on the subject. Not one, with the exception of Waters, gives a faithful delineation. I shall not trouble you with a description of how dry lung is affected with acetic acid of the above strength. Suffice it to say that turpen- tine, glycerine, Canada balsam, dammar varnish, and other materials, all fail to bring out the epithelium of the alveoli.” Reproduction of Desmids.—Prof. Leidy, at a late meeting of the Academy of Natural Sciences of Philadelphia, made some remarks on the mode of reproduction and growth of the Desmids, which are reported as follows by the ‘American Naturalist, Nov., 1874. In illustration he described a common species of Docidium or Pleu- rotenium. ‘This consists of a long cylindroid cell constricted at the middle and slightly expanded each side of the constriction. When the plant is about to duplicate itself the cell-wall divides transversely at the constriction. From the open end of each half-cell there pro- trudes a colourless mass of protoplasm defined by the primordial utricle. The protrusions of the half-cells adhere together and continue to grow. The bands of endochrome now extend into the protrusions and subsequently keep pace with their growth. The protrusions con- tinue to grow until they acquire the length and form of the half-cells from which they started. The exterior of the new half-cells thus produced hardens or becomes a cell-wall like that of the parent half- cells. In this condition two individuals of Docidium are frequently observed before separation. During the growth of the new half-cells the circulation of granules in the colourless protoplasm is quite active. In a species of Docidium 14mm. long by ;, mm. broad, the erowth of the new half-cells was observed to be at the rate of about 4+ mm. in an hour. The largest Apyrencematous Blood-corpuscles.—In a paper read at a late meeting of the Zoological Society, Professor Gulliver stated that in the Apyrenemata or Mammalia the largest red corpuscles of the blood are those of the two elephants, the Aardvark, two-toed sloth, and the walrus; and that it is remarkable that the largest apyrene- matous corpuscles should occur in three such different orders as Pachydermata, Edentata, and Fere. In Pachydermata, excepting the elephants, the corpuscles are. by no means so large, not even in the hippopotamus, the corpuscles of which he had then measured for the first time. But the order Edentata is characterized by the large- ness of the corpuscles; while among the Fer there are very large and very small corpuscles, the large ones being quite characteristic of the Pinniped family, as was shown by his recent measurements of the red blood-corpuscles of Otaria and Trichecus. In the human sub- ject the corpuscles are exceeded in size by those of only eight or nine exotic Mammalia, and not equalled in size by the corpuscles of any British animal of the class. And this fact, independently of its phy- siological interest, may prove important in medico-legal inquiries ; since by it alone Dr. Joseph G. Richardson states, in the September number of this Journal, that he has correctly distinguished dried stains of human blood from those of the ox and sheep. 26 PROGRESS OF MICROSCOPICAL SCIENCE. Comparative Microscopic Rock-structure of some Ancient and Modern Volcanic Rocks.—Mr. J. Clifton Ward lately (Nov. 4, 1874,) read a valuable paper on the above subject before the Geological Society. He stated at the outset that his object was to compare the microscopic rock-structure of several groups of volcanic rocks, and in so doing to gain light, if possible, upon the original structure of some of the oldest members of that series. The first part of the paper comprised an abstract of what had been previously done in this subject. The second part gave details of the microscopic structure of some few modern lavas, such as the Solfatara trachyte, the Vesuvian lava- flows of 1681 and 1794, and a lava of the Alban Mount, near Rome. In the trachyte of the Solfatara, acicular crystals of felspar show a well-marked flow around the larger and first-formed crystals. In the Vesuvian and Albanian lavas leucite seems, in part at any rate, to take the place of the felspar of other lavas; and the majority of the leucite crystals seem to be somewhat imperfectly formed, as is the case with the small felspar prisms of the Solfatara rock. ‘The order of crystallization of the component minerals was shown to be the following: magnetite, felspar in large or small distinct crystals, augite, felspathic or leucitic solvent. Some of the first-formed crystals were broken and rendered imperfect before the viscid state of igneous fusion ceased. Even in such modern lava-flows as that of the Solfatara considerable changes had taken place by alteration and the replace- ment of one mineral by another, and this very generally in successive layers corresponding to the crystal outlines. The frequent circular arrangement of the glass and stone cavities near the circumference of the minute leucite crystals in the lava of 1631 was thought to point to the fact that after the other minerals had separated from the leucitic solvent, the latter began to crystallize at numerous adjacent points ; and as these points approached one another, solidification proceeded more rapidly, and these cavities were more generally imprisoned than at the earlier stages of crystallization. In the example of the lava of 1794, where the leucite crystals were farther apart, this peculiar arrangement of cavities was almost unknown. The third part of the paper dealt with the lavas and ashes of North Wales ; and the author thought that the following points were established : 1. Specimens of lava from the Arans, the Arenigs, and Snowdon and its neighbourhood, all have the same microscopic structure. 2. This structure presents a hazy or milky-looking base, with scat- tered particles of a light-green dichroic mineral (chlorite), and gene- rally some porphyritically-imbedded felspar crystals or fragments of such, both orthoclase and plagioclase. In polarized light, on crossing the Nicols, the base breaks up into an irregular-coloured breccia, the colours changing to their complementaries on rotating either of the prisms. 3. Finely-bedded ash, when highly altered, is in some cases undistinguishable in microscopic structure from undoubted felstone. 4. Ash of a coarser nature, when highly altered, is also very frequently not to be distinguished from felstone, though now and then the outlines of some of the fragments will reveal its true nature. 5. The PROGRESS OF MIOROSCOPICAL SOIENCE. 27 fragments which make up the coarser ash-rocks seem generally to consist of felstone, containing both orthoclase and plagioclase crystals or fragments ; but occasionally there occur pieces of a more crystalline nature, with minute acicular prisms and plagioclase felspar. 6. In many cases the only tests that can be applied to distinguish between highly-altered ash-rock anda felstone are the presence of a bedded or fragmentary appearance on weathered surfaces, and the gradual passage into less altered and unmistakable ash. In the fourth division of his paper the author described some of the lavas and ashes of Cumberland of Lower Silurian age. With regard to these ancient lavas the following was given as a general definition: The rock is generally of some shade of blue or dark green, usually weathering white round the edges, but to a very slight depth. It frequently assumes a tabular structure, the tabula being often curved, and breaks with a sharp conchoidal and flinty fracture. Silica 59-61 percent. Matrix generally crystalline, contain- ing crystals of labradorite or oligoclase and orthoclase, porphyritically imbedded, round which the small crystalline needles seem frequently to have flowed; magnetite generally abundant, and augite tolerably so, though usually changed into a soft dark-green mineral; apatite and perhaps olivine as occasional constituents. Occasionally the erystalline base is partly obscured and a felsitic structure takes ‘its place. The Cumberland lavas were shown to resemble the Solfatara greystone in the frequent flow of the crystalline base, and . the modern lavas generally in the order in which the various minerals crystallized out. In external structure they have, for the most part, much more of a felsitic than a basaltic appearance. In internal structure they have considerable analogies with the basalts. In chemical composition they are neither true basalts nor true felstones. In petrological structure they have much the general character of the modern Vesuvian lavas; the separate flows being usually of no great thickness, being slaggy, vesicular, or brecciated at top and bottom, and having often a considerable range, as if they had flowed in some cases for several miles from their point of eruption. Their general microscopic appearance is also very different from that of such old basalts as those of South Stafford and some of those of Car- boniferous age in Scotland. On the whole, while believing that in some cases the lavas in question were true basalts, the author was inclined to regard most of them as occupying an intermediate place between felsitic and doleritic lavas; and as the felstone lavas were once probably trachytes, these old Cumbrian rocks might perhaps be called Felsidolerites, answering in position to the modern Trachy-dolerites. A detailed examination of Cumbrian ash-rocks had convinced the author that in many cases most intense metamorphism had taken place, that the finer ashy material had been partially melted down, and a kind of streaky flow caused around the larger fragments. There was every transition from an ash-rock in which a bedded or fragmentary structure was clearly visible, to an exceedingly close | 28 PROGRESS OF MIOROSCOPICAL SCIENCE. and flinty felstone-like rock, undistinguishable in hand specimens from a true contemporaneous trap. Such altered rocks were, how- ever, quite distinct in microscopic structure from the undoubted lava-flows of the same district, and often distinct also from the Welsh felstones, although some were almost identical microscopically with the highly altered ashes of Wales, and together with them resembled the felstone-lavas of the same country. The author believed that one other truth of no slight importance might be gathered from these investigations, viz. that neither the careful inspection of hand-specimens, nor the microscopic examination of thin slices, would in all cases enable truthful results to be arrived at, in discriminating between trap and altered ash-rocks; but these methods and that of chemical analysis must be accompanied by often- times a laborious and detailed survey of the rocks in the open country, the various beds being traced out one by one and their weathered surfaces particularly noticed. A very interesting discussion followed the perusal of the paper. The Pathology of the Blood.—M. Laptschinsky, of St. Peters- burg, contributes a paper to the ‘Centralblatt, on the microscopic changes undergone by the blood in various diseases, which is thus given in the ‘ Lancet, October 31. He finds that in various diseases in which marked febrile symptoms are present, the microscopic aspect of the blood is essentially different from that of health. The changes consist in the blood-corpuscles not running into regularly formed rouleaux, but accumulating in heaps or clumps of various size and shape. The individual blood-corpuscles frequently appear swollen and cloudy, and their contours less distinct than natural. Small corpuscles, one-third of the normal size, are often met with, some of which exhibit a more intense colour than natural, whilst others are completely pale. In the interspaces of the clumps of red corpuscles, great numbers of white corpuscles may be seen, often coalescing to form groups of from 3 to 8. In typhus he counted from 60 to 80, and more, in one field of vision; in cholera from 110 to 130. Careful enumeration of the relative numbers of white and red corpuscles four days after death in the above cases showed that there was 1 white to 60 red corpuscles in the case of typhus, and 1 white to 23 coloured in the case of cholera. In a very anemic woman, suffering from suppuration in the knee-joint, the proportion of the white rose to 1 to 13 red. The white corpuscles in these cases presented unusually ~ active and extensive amoeboid movements. The nuclei of the colour- less corpuscles took a part in the amceboid movements, and could be seen altering their position and form in the interior of the white corpuscles. The thorn-apple or horse-chestnut like form of the red corpuscles he did not find to be unusually frequent. He found, how- ever, large quantities of granular or detritus-like material in the blood of febrile, but not much in the blood of cachectic and anemic patients. From his enumerations he feels satisfied that in febrile diseases, and in Bright’s disease, the conversion or development of white corpuscles into red is either materially retarded or is buusery arrested. PROGRESS OF MICROSCOPICAL SCIENCE. 29 Palmodictyon viride in Britain—Myr. Edward Parfit has written to ‘Grevillea’ saying that he has found this plant in the Exeter eanal. He says: “ Not knowing the plant myself, and after search- ing all the works on the subject I had at my command, I forwarded specimens to my friend Professor Dickie, of Aberdeen, who kindly writes me this: ‘The plant is Palmodictyon viride (Kiitzing), and so far as I know new to the British list.’ The plant, where it has sufficient room to develop itself, spreads over the bottom, in water about six inches deep; beyond this it comes in contact with Elodes cana- densis, over which it creeps, and extends its growth from branch to branch into deeper water. In this extension it has first the appear- ance of a Conferva, which I at first took it to be; but the moment I touched it, after taking some from the water, I found from the soft slimy feel that if a Conferva it was new to me, and the microscope soon revealed the true character. When the plant grows on the bottom it shows one continuous green membrane, stretched tight over the bottom, but when it comes in contact with other plants it throws out filaments, the thickness of which is difficult to make out on account of their adhesive nature; for wherever they touch it is matter of impossibility to separate them. 'The membrane forming the filaments is structureless, but the spherical cells form more or less moniliform threads sometimes running in parallel lines, at other times forming an irregular net-work on the inside of the filaments. These cells sometimes divide into two portions, at others into four, and in most of the mature cells may be observed four cellules.” Formation of Fibrin from the Red Blood-corpuscles.—M. Landois, according to the ‘ Medical Record’ of November 18, describes the formation of fibrin as being dependent on the dissolved corpuscles. If a drop of defibrinated rabbit-blood be brought into a drop of frog’s serum, the cells aggregate together, and become sticky on their sur- faces. The cells soon become globular, and those cells lying towards the periphery allow the blood-colouring matter to pass out. This discolouring gradually extends towards the centre of the drop, and at last only a heap of stroma remains. ‘I'he stroma-substance is very tough and viscid. At first the contours of the cells can_be detected ; and, when the stroma has been agitated to and fro, the cellular con- tours disappear, and viscous fibres and stripes are observed. Step by step the formation of fibrous masses from the dissolved mammalian cells can be observed. The author thinks this fibrin should be called “ stroma-fibrin” in opposition to the ordinary fibrin or plasma-fibrin, which is formed without solution of the blood-corpuscles. The two kinds of fibrin may possibly be chemically distinguished from each other. In transfusion, if dissolution of the cells occur, then, of course, the formation of stroma-fibrin may take place. The coagu- lation occurs the sooner, the more serous the blood. Animals ina state of asphyxia, into whom heterogeneous blood was introduced, showed the most extensive coagulation. The Anatomy of the Har.—At a meeting of the Medical Society in Vienna, in the beginning of October (a report of which is given in the ‘ Allgemeine Wiener Medizinische Zeitung’ for October 20), Pro- 30 PROGRESS OF MIOROSCOPICAL SCIENOE. * fessor Politzer gave the result of some investigations which he had recently made into the anatomy of the ear, which was thus given in the ‘ Medical Record, December 2. He finds that, in newly-born children, the cavity of the pyramid containing the stapedius muscle is separated only at the upper part by osseous tissue from the canal through which the facial nerve passes, while the lower part of the cavity communicates freely with the same canal, and thus allows, at this spot, the muscle and nerve coverings to come into actual contact with each other. In the adult, the amount of direct communication between the cavity and canal is very various, ranging from a small opening sufficient for the passage of the nerve to the stapedius, to a large irregular opening. The styloid process, he avers, arises from a cartilaginous body, which not only in the foetus, but also in the newly- born, is to be found as an isolated cartilaginous formation; and the upper end of the process does not terminate at the external visible base, but passes through a thin osseous lamella along the posterior wall of the tympanic cavity, reaching as far as the eminentia stapedii. In the adult, the process is sometimes solid, sometimes hollow, but generally there is a cellular structure with or without a central canal. Action of Electricity on Frog's Spawn.—M. Onimus, in a recent communication to the Société de Biologie, of Paris, states that by electrifying the eggs of the frog, the development of those which are in connection with the negative pole will be accelerated, whilst the hatching of those in connection with the positive pole will be either retarded or stopped. What is a Bacterium ?—Dr. W. A. Hollis has written a paper lately (Nov. 21) on the above question which may be of some interest to our readers. He says that the question, What is a bacterium? is thus answered by Ehrenberg in his great work on Infusoria:* “ Animal e familia Vibrioniorum divisione spontanea in catenam filiformem rigidulam abiens.” Dujardin accepted this definition without altera- tion, although he modified somewhat the other genera of the family. The derivation of the word itself (from Baxryptoy, a little rod) corre- sponds well with the characteristic features of the organism above given, For several years the accuracy of Ehrenberg’s definition was unquestioned; eventually, however, from the observation of the behaviour of these organisms with certain chemical reagents, and mainly also from the elaborate researches of Professor Cohn regarding their morphology, their animal nature was disputed. It was found that they were unaffected by boiling with potash water, and they were further said to behave somewhat as cellulose does when they were treated with sulphuric acid and iodine, although from their extreme minuteness any changes which take place in their tissue under such conditions are very difficult to observe. For many years past Professor Cohn, of Breslau, has published in occasional papers the results of his investigations on the subject. He has made one great step in advance of previous observers in ascertain- — ing so much of the history of the bacterium as that it arises from the * ‘Die Infusions-thierchen,’ 1838, p. 77. PROGRESS OF MICROSCOPICAL SCIENCE. 31 gelatinous scum seen floating on the top of water containing putrescent organic matter, and this he named ‘“ zoogloea.” He then described the Bacterium termo in these words:* ‘Cellule minime bacilli- formes, hyaline gelatina hyalina in massas mucosas globosas, uve- formes, mox membranaceas consociate, dein singule elapse, per aquam vacillantes;” and he considered them as of decidedly a vegetable nature, and as allied to the Oscillatoriaces. In a more recent pam- phlet he placed them amongst the family Phycochromaceex, in a natural order named Schizosporee. His last investigations have led him to divide Bacteria into four groups and six genera, as follow :—f I. Spheero-bacteria. Genus 1. Micrococcus char. emend. II. Micro-bacteria. Genus 2. Bacterium char. emend. Til. Desmo-bacteria. Genus 3. Bacillus n.g. Genus 4. Vibrio char. emend. IV. Spiro-bacteria. Genus 5, Spirillum, Ehr. Genus 6. Spirocheta, Ehr. Of these genera the Bacterium, Vibrio, Spirillum, and Spirocheta were in the original Vibrionia family of Ehrenberg. Cohn considers the ferment of contagion to be due to the presence of a variety of the Sphero-bacteria, the micrococci of Hallier. The whole group he divides into three: the chromogen, zymogen, and pathogen—the micrococci of pigmentation, of ferment, and contagion respectively. ‘These organisms are exceedingly minute, darkish, or coloured granules, so small as to be immeasurable. They frequently present the appearance of beaded chains, or the form of aggregations (colonies). They are motionless, and are occasionally found with the Bacterium termo in putrefying organic liquids. Among the pathogen micrococci I may mention the M. vaccine, observed by Chauveau and Sanderson in the vaccine lymph; the M. diphthericus, which is pro- bably the same organism as that described by Professor Eberth, of Zurich, as attacking first the epithelial elements of a part, and subse- quently the deeper tissues, and which led him to say “the metastatic pyzmia is for the most part a diphtheria with numerous localizations ;’f and, lastly, the M. septicus.§ found, according to Cohn, in the miliary eruption of typhus, pyzemia, and other diseases. ‘The chromogen, or pigmentary micrococci, have occasionally been the means of working -miracles. Several instances of bread exuding blood, under superna- tural circumstances, are related by Rivolta.|| Ehrenberg found this colour on some bread in the house of a patient who had-died of cho- lera, and he ascertained the pigment to be due to the presence of the Monas prodigiosa—small roundish bodies, which Cohn classes with the micrococci. The true bacteria Cohn divides into two species, the B. termo and B. lineola. The B. termo are small dumb-bell-shaped organisms, * Nova Acta,’ xxiv., p. 123. + Cohn, ‘ Betrage zur Biologie der Pflanzen,’ Breslau, 1872. { Eberth, * Zur Kentniss d. Bacterit'schen Mykosen,’ Leipsig, 1872, p. 15. § The Wicresporon septicum of Klebs. \| ‘Del Para itti Vegetali, Turin, 1873. VvOL. XIII. D oo PROGRESS OF MICROSCOPICAL SCIENCE. having a slowly vacillating motion, and about g 59” or ys45y” in length. I have elsewhere given Cohn’s description of these micro- bacteria and their zoogloea. They are essentially the ferment of putrefaction, and it is doubtful whether putrefactive changes can take place without them. It is probable that Ehrenberg confounded this Bacterium with the Vibrio lineola in his plates in the work before noticed. The B. varicosum of some writers is possibly this species, although, when fresh names are introduced in classification without sufficient description, some doubt will always be cast upon the accu- racy of the investigation. The B. lineola is somewhat larger than the preceding species. It is endowed with stronger and more rapid to-and-fro movements. It is rod-shaped, and is essentially the ferment of sour milk. It is equivalent to the Vibrio lineola of Ehrenberg, the V. iremulans and B. triloculare of the same author, and to the V. lineola of Dujardin. The Desmo-bacteria, or “ linked rods,” are distinguished, as their - name implies, from the true bacteria by being occasionally united together in chains. They are thus separated: the filament trans- versely lined—Bacillus ; the filament cylindrical and curved—-Vibrio. The Bacilli Cohn divides into three species : The first, the B. subtilis, is the Vibrio subtilis of Ehrenberg. It is a slender supple thread found in stale boiled milk. Its length is about =4,". It moves with a pausing motion, “like a fish forcing its way through reeds.” The B. anthracis of Cohn is the Bacterium carbuncolare of some writers. It is described by Rivolta * (following Davaine and Delafond) as an immovable, oblong, highly refractive body, found in the blood of animals affected au the CEE Its size (according to Davaine) varies much, from +5355 tO gaoy OF CVE appa lt is unaffected by water, alcohol, ether, acetic, nitric, or phosphoric acid, or soda, potass, or ammonia. Sulphuric acid readily destroys it. It is occasionally found united in chains of two or three links. Lastly, the Bacillus ulna is distinguished from the B. subtilis by the greater thickness of its filaments and by its rigidity. Its length is about z1,”. Cohn found it in a stale infusion of boiled egg. The Vibrios are distinguished from all the preceding genera by their rotary motion. This motion, which most writers had restricted to the Spiro-bacteria, Cohn, I think, rightly applies to the movements of the Vibrio. The V. rugula is generally seen with one or two curves in the form of the signs ) or §. A flexible thread, 5;',9"' to t300 long; rotation slower than in the following species. This organism was found in the evacuations of cholera and diarrhcea by Leeuwenhoek, and by Davaine in the pus of balanitis also.t The second species, the V. serpens, is distinguished by the greater number and regularity of its curves, by the rigidity of the filament, and its more rapid rotation. The thread is also considerably thinner than the V. rugula, and its length is about zag". The motion is ser- pentine in appearance. The Spirilla (including the Spiroche taplicatilis, for I do not * Rivolta, op. cit., p. 47. t Davaine, ‘ Entozoaires,’ 1860, p. 5. NOTES AND MEMORANDA. oe think Cohn is justified in separating the two genera) of Dujardin * are distinguished by the greater regularity and closeness of the curves of the spiral, and their uniform corkscrew motion. The distinguishing character of the flexibility or rigidity of the threads in the genera Spirocheta and Spirillum respectively, insisted upon by Ehrenberg and followed by Cohn, is rightly set aside by Dujardin as superfluous. All the Spirilla, of which Cohn gives three species —S. tenue, S. undula, and S. volutans—were found by him in the decomposing tissues of a fresh-water snail. They are distinguished mostly by their size from each other. ‘The S. volutans is by far the largest of all the bacteria, if we apply the name to the genus at all. It is thus described by Khrenberg, “ Filis valde tortuis robustis et elongatus.” Cohn fancies that he has found traces of organization within it. He states that having above given a short résumé of the labours of the most trustworthy naturalists upon the morphology of bacteria, he will now only add a few remarks upon the limitations we should place on the term. _ In the first place, then, it seems right to consider bacteria as strictly forming part of the vegetable kingdom, and this, as I have before remarked, is the opinion of all the most trustworthy authorities of France, Germany, and Italy. I should have included our own country in this geographical list had I not lately been somewhat startled to find a learned Professor in a recent lecture at the Royal Institution t reported to have represented bacteria to be “ animal- ecules.’ Secondly, I think the name bacteria ought to be restricted to those minute rod-like hyaline bodies, the B. termo and B. lineola of Cohn. “They have a more or less rapid to-and-fro motion. The so- called “ locomotive bacteria” of some physiologists are probably in many instances specimens of the larger V. reguia. Rivolta considers that the true bacteria have no proper locomotive powers, only the vacillatory movements common to all small particles of matter sus- pended in liquids. Thirdly, we must, I think, always associate the presence of the true bacteria (especially the B. termo) with putre- factive or analogous changes in organic liquids. At some future period I hope to give a short account of the etiology of these organisms, and the part they play in the causation of disease. NOTES AND MEMORANDA. The Society’s Universal Serew.—We quote the following re- marks from ‘Science Gossip, as they are of some importance. They are made by M. A. de Sonza Guimaraens. There is a general com- plaint among microscopists respecting the so-called “universal screw. Ihave myself felt great annoyance when finding that the screw is not universal. Some of my friends’ object-glasses (having the “ universal screw”) do not screw home in the nose-piece of one * ¢ Tnfusoires,’ p. 209. + See report in ‘Illustrated London News,’ Feb. 14, 1874, p. i D 34 NOTES AND MEMORANDA. of my microscopes, while others fit loosely the nose-piece of my other instrument, although both microscopes have been supplied by the makers with the so-called “universal screw”! Moreover, I have seen modern object-glasses (manufactured since the introduction of the universal screw ), by one of the leading opticians, having different gauges of universal screw, and by another not only object-glasses, but adapted for analyzers, Brooke’s nose-pieces, &c. When using high powers with a microscope having a concentric rotating’ stage (which is now considered almost a necessary addition), these variations of gauge render the stage eccentric, and no doubt very often the rotation of a stage is condemned, and the workmanship considered imperfect, when the fault lies in the inaccuracy of the so-called universal screw of either the object-glass or of the microscope’s nose-piece, and fre- quently of both. Iam quite aware that the smallest particle of dust in the object-glass screw will cause eccentricity, but this drawback is not a permanent one; it is bad enough to have it when it occurs— there is no necessity to make eccentricity both a feature and a fixture! With a universal screw, if we could not get in every instance perfect concentricity when rotating the stage, we should certainly approach it much nearer than we do now; of course, accurate workmanship being always taken for granted. Besides the above inconveniences, there is another—the great difficulty and trouble in centring achro- matic condensers of large angle of aperture with high powers, by different makers, having different universal screws. The Royal Microscopical Society have undoubtedly conferred a great boon upon microscopists by introducing the present “universal screw”; but could not an effort be made to render the screw really universal by causing the Royal Microscopical Society’s gauge to be adopted by all the London opticians? Some technical and practical reasons may be adduced as to the difficulty of making universally true the “universal screw”; but, even admitting the next to impossibility of such an accuracy, why then call the screw universal when in reality nearly each maker of microscopes in London has his own gauge of the “ universal screw”? It would be also a great convenience to have a universal gauge for the sub-stage fittings, eye-pieces, &c., so that the apparatus of any one maker should fit the microscopes of the others. At present there is a great discrepancy in the diameter and length of microscope-tubes and the gauge of sub-stage fittings of some makers, compared with those of others. Why not make these also wniversal ? Gilded Glass in the Construction of the Camera Lucida.—It is known that the construction of the camera lucida is founded upon the simultaneous perception of two images—that of the object, and that of the pencil. Various means have been employed to arrive at this result. In that of Soemmering it is a metallic mirror smaller than the pupil; that of Amici is constructed on the principle of reflexion on a plate with parallel faces; that of Wollaston, at present most in use, consists in a prism, of which the edge, dividing the pupil in two parts, permits the object to be seen by the upper half, and simul- taneously the pencil by the lower portion. In all these systems the fusion of the images is somewhat difficult to seize, especially for PROCEEDINGS OF SOCIETIES. 35 certain points of the reflected image. Signor Govi, Professor of Physics at the Royal University at home, proposes to cover with a thin layer of gold the reflecting surface of a prism, and to apply upon this, with Canada balsam, a second prism with like angles. Although this layer of gold is sufficiently transparent to allow the luminous rays to pass, its power of reflexion is considerable, and it gives images of great brightness. We have thus a perfect means of super- imposing, without fatigue to the eye, two different images—the one direct, and the other reflected. The principle is the application of that property of thin plates—metallic or otherwise—to transmit simul- taneously direct rays, and to reflect rays which arrive obliquely from another source. CORRESPONDENCE. “Some Onze ”—Aw ApvocaTE For THE 180°. To the Editor of the ‘Monthly Microscopical Journal.’ Srr,— With an anonymous correspondent in the ‘ American Natu- ralist’ I shall not revive a discussion, that has been closed on an optical question. When I guessed that some one might come forward to argue Mr. Tolles’ 180° to be right, I hardly expected that an advocate would appear. This enlightened one states, that with a dry object on the cover with 180° no distance is involved, ignoring the fact that 180° below the surface must be the result of 180° on the front lens; and if there is no distance in the one case, there can be none in the other. But as there is a front distance :013 in the ith, the triangle is a practicable fact. This advocate having, either not the sense or the will to see this, rather than risk his credit, conceals himself; his defence is, however, a superfluous one, for I have no wish to deprive Mr. Tolles of any honorary degrees that his policy may tempt him to claim; and if “Some One” proposes that 180° is to be emblazoned upon his escutcheon, I will be the foremost to raise my hand to vote that it shall be done. Yours truly, F. H. WenHAM. PROCEEDINGS OF SOCIETIES. Royat Microscopicat Soctery. Kine’s Coniecn, December 2, 1874. The minutes of the preceding meeting were read and confirmed. A list of donations to the Society. since the last meeting was read, and the thanks of the Fellows were voted to the donors. The Secretary announced that the Council had unanimously re- solved to support .a proposal that Col. Dr, J. J. Woodward, of the United States Army Medical Department, be elected an honorary. 36 PROCEEDINGS OF - SOCIETIES. Fellow of the Society. Dr. Woodward’s name was well known to most of them from his many communications, as well as by the nume- rous photo-micrographs for which the Society was indebted to him. The President having put the proposition from the chair, it was unanimously resolved that Dr. Woodward’s name be suspended in the usual manner, and that it be brought before the Fellows for election at the next ordinary meeting. The President said that a number of photographic likenesses of their former President, the late Rev. J. B. Reade, had been sent to the Society by Dr. Wallich, for distribution amongst the Fellows. They would be placed upon the table, and the Fellows were invited to take one each at the termination of the meeting. They would doubtless be very glad to avail themselves of the opportunity of pos- sessing a memento of Mr. Reade, and would feel greatly obliged to Dr. Wallich for his kindness in enabling them to do so. A cordial vote of thanks to Dr. Wallich for the photographs was unanimously carried. A paper by Dr. Hudson, “On the Discovery of some New Male Rotifers,” was read to the meeting by the Secretary, who expressed his great regret that owing to an attack of bronchitis the author was prevented from reading it to them in person. The paper was illus- trated by a number of extremely beautiful drawings in white and coloured chalks upon a black ground, representing the rotifers as they would be seen by the paraboloid illumination. The Secretary called the special attention of the Fellows to the drawings, several of which were exhibited from the chair, whilst the particular portions of the paper relating to them were re-read. He much regretted the absence of Dr. Hudson, and the more so because he believed that there were other illustrations and sume additional particulars which would have been brought before them had he been able to come there that evening. The subject was one of very great interest, and he observed that in a note appended to the paper Dr. Hudson mentioned that in all the males figured and described he had seen the motion of the spermatozoa within the testes. The thanks of the meeting were unanimously voted to Dr. Hudson for his valuable and interesting paper. Mr. C. Stewart (Secretary) said that they had just received a paper from Dr. Schmidt, of New Orleans, on the Development of the Smaller Blood-vessels in the Human Embryo. Unfortunately the paper had only been placed in his hands that evening, so that he had not had any opportunity of reading it through or becoming acquainted with its contents ; under these circumstances he felt that he might be doing it an injustice to attempt to make an abstract then. The better course, he thought, would be to take the paper as read; the text would then appear in the next number of the Journal, together with the very beautiful illustrations by which it was accompanied. The paper was then taken as read, and a vote of thanks to Dr. Schmidt was unanimously passed. The Secretary reminded the Fellows that their next scientific evening would be held on December 9, and requested that intimation PROCEEDINGS OF SOCIETIES. ov might be sent to the Assistant Secretary if any special arrangements were required for purposes of exhibition by any of the Fellows of the Society. The President having expressed a hope that as many of their number as possible would attend on that occasion, and bring with them matters of interest, the proceedings were adjourned to January 6, 1875. Scientific Evening, December 9, 1874. On this occasion an unusual number of remarkable objects were brought together for exhibition, as the subjoined list will show. The illustrations of minute anatomy excited special admiration. It will be seen that Dr. Urban Pritchard contributed a valuable and instructive series of preparations and models showing the comparative anatomy of the cochlea, rods of Corti, and other portions of the ear; while Mr. Loy’s modestly-mentioned “ Dissections of lepidopterous larve,” comprised a large collection of objects, prepared and mounted with extraordinary skill. The two marine creatures exhibited by Mr. Browning have not yet been identified by any authority. The “insect” may be a larval form. It has apparently only six legs, and jaws well adapted for biting. Both these creatures are reported to be serious foes to electric telegraph cables, one assailing the hemp, and the other the guttapercha. M. de Souza Guimaraens exhibited the ovum, larva, and pupa of the Phylloxera vastatria, the cause of so much damage to the vines. He also exhibited the Phylloxera of the oak, including the male, illustrating Balbiani’s researches, which will be found in the ‘ Revue Scientifique,’ June 6, 1874. Messrs. R. and J. Beck exhibited a microscope made for a surgeon in New Orleans. It was on the design of their large best portable stand, with a complete series of object-glasses and apparatus. ‘The limb was made of solid silver, as also the bodies. The pillars and stand were of aluminium bronze, and the movable parts and apparatus of alu- minium. The fittings for rack work and the slow motion were of steel. The distribution of the various metals was arranged so as to endeavour to obtain the greatest stability, freedom from tremor, and minimum of friction. The whole of the apparatus was packed with the stand in an elaborate rosewood case, every block being screwed into an inner carcase. They also exhibited a beautiful specimen of Spirogyra dubia, showing the anatomy of the cells, prepared by Dr. J. G. Hunt, of Philadelphia. Messrs. Powell and Lealand exhihited two glasses on a new formula; one, 7th, showing the lines of Amphiplewra pellucida; and the other, 4th, showing Pleurosigma angulatum ~ 4000. This object was illu- ~ minated by direct light. The effect was to show the interspaces re- markably magnified, and the beads comparatively small. They stood out like minute spheres of pink coral on a white ground. Messrs. Ross and Co. exhibited a new portable microscope of elegant appearance. The stem of the arm to which the body is at- tached slides through a socket, forming a coarse adjustment. This 38 PROCEEDINGS OF SOCIETIES. slides within another socket with a delicate rack-and-pinion movement for a fine adjustment. It has a revolving stage like Nachet’s, packs in a very small compass, and has sufficient range of motion to work with a 4-inch objective. Mr. Moginie showed a new microscope of large size, arranged with folding legs, to pack in a narrow box. From the stretch of the legs when open, and the disposition of the weight in relation to the points of suspension, it is remarkably steady. The type slide of Holothuria plates by Moller, exhibited by Mr. Baker, afforded a fresh proof of the artist’s remarkable skill, and, like his type diatom slides, will be found highly instructive. Sections of Dictyoxylon from the Lancashire coal-measures, shown by Mr. How, and asection of fossil wood belonging to the genus Arau- caria, from Edinburgh, exhibited by Dr. Millar, may also be signalized, and also a piece of limestone wonderfully rich in polyzoa. In selecting the above for mention, it must on no account be con- cluded that many others were not well worthy of special description. The Society was indebted to Mr. Baker and Messrs. How for the loan of excellent lamps. Exhibitors and Objects. Mr. James Bell: Coffee pure, and adulterated with mustard husks and with locust-bean. Mr. John Browning : Worm found in hemp of the deep-sea cable, and an insect found in the guttapercha of ditto. Mr. Charles Baker: Type slide of Holothuria plates, by Moller. Mr. John Badcock: Melicerta ringens, Floscularia~ ornata, and Actinophrys sol, alive. Mr. W.G. Cocks: Triceratium favus (hexagonal form). Mr. Thomas Curties: Dissections of spider, beetles, &c., by Mr. Tatem, and cuticle of Onosma taurica. Mr. Frederick Fitch: Earth mite and acarus. Mr. J. F. Gibson: Acarus of bat. Dr. W. J. Gray: Portion of skin from the neck of a fowl, to which in a space not more than one-third of an inch square, are firmly — attached, by the insertion therein of their piercing ag nearly one hundred fleas! from Ceylon. M. A. de Souza Guimaraens: Ovum, larva, and pupa of Phylloxera vastatrixc and the Phylloxera of the oak. Mr. F. Hailes: Selected foraminifera, from Jersey. Messrs. How: Section of Dictyoxylon, from the coal-measures, Lancashire ; and section of human liver. Mr. W. T. Loy: -Dissections of lepidopterous larve; salivary glands of Java cockroach, Periplaneta orientalis. Mr. Henry Lee: Young cray-fish, Palinurus vulgaris. Dr. Matthews: Canadian lichens, illuminated by sub-stage mirror. Mr. Moginie: Skin from the finger, showing fat-vesicles, &c. Mr. 8. J. McIntire: Foot of West Indian spider, Test Podura scale, with Wenham’s reflex illuminator and Nachet’s 1th objective. Dr. Millar: Section of fossil wood from Edinburgh ; fossil polyzoa, PROCEEDINGS OF SOCIETIES. 39 and corals from the upper carboniferous limestone, Scotland; and fossil foraminifera. Mr. Thomas Palmer: Sections of ivy and cane and seaweeds, mounted in balsam. Messrs. Powell and Lealand: Pleurosigma angulatum (4000 dia- meters), with 4th immersion object-glass, on a new formula ; Amphi- pleura pellucida, with 4th immersion object-glass, on a new formula. Messrs. Ross : Rough diamond used for turning glass; and the molecular movement of particles in fluid cavities of quartz; and their new educational microscope. Mr. W. W. Reeves: A fungus on rotten wood, Siemonites typhoides. Mr. Charles Stewart: Gyrinus, showing two of the four sets of compound eyes; those on the upper surface of the head for seeing in air, and those on the lower for seeing in water. Mr. J. W. Stephenson: Crystals of sulphur. Mr. H. J. Slack: Vesicular and other forms of silica depcuted from silicic fluoride on wet cotton threads. Mr. Amos Topping: Section of jaw-bone and teeth of hedgehog, injected ; ditto of mouse, injected ; ditto (transverse) of rabbit, imbibed. Mr. J. 8S. Townsend: Leaf of Oxalis stricta, showing cell structure most beautifully. Mr. E. Wheeler: Some whole insects, and some nice slides of Diatomacex, including new species of Triceratium, Coscinodiscus, and Aulacodiscus. Mr, T. C. White: Salivary glands of cockroach; head of cysti- cercus: and a section of the pad of kitten’s foot, doubly stained with picric acid and carmine. Dr. M. Pritchard: Cochlea of human foetus, showing organ of Corti, containing air-cells, rods, and membrana reticularis in section ; human adult cochlea, showin g nerve-fibres and ganglion-cells ; cochlea of cat, showing the ciliated cells of Corti; cochlea of kitten, showing membrane of Reissner in position, and the general arrangement of ductus cochlea; cochlea of dog, showing rods; cochlea of guinea- pig, showing a row of outer rods; cochlea of parrot, showing the general view of the straight cochlea of a bird; cochlea of a porpoise, showing immense spiral ganglion and ganglion-cells, &e.; some beautiful models and diagrams. Mr. W. Fell Woods: Living organisms from the cockle. Donations to the Library, &e, since Nov. 4, 1874 :— From IN ne MCE liaise. Selo S20) oa envi ses Sees ee bay aa) LNG Hatton, PARAM TIC MIME CIN sie e ek aad wiaeds | sek Liwieh (tae os Vat, eeu vam Ditto, Society of Arts Journal. Weekly ae as OPER Te NCE tance werimny eelaeFISOCLC LYE Journal of the Linnean Society, No.58 ... mapsirscrantd ices Ditto. Quarterly Journal of the Geological Society, No. 120 ae 5 Ditto. Seventy photographic likenesses of the late Rev. J. B. Reade, for distribution amongst the Fellows.. .. ; a Dr. Wallich. Ross’ instrument for measuring thin olass UG Ko accom tne 7, Mallar The following gentlemen were elected Fellows of the Society :—- John H. Martin, Esq.; John Badcock, Esq.; Alfred Coles, Esq. Water W. REEVES, Assist.-Secretary, 40 PROCEEDINGS OF SOCIETIES. Mepicat Microscoprican Society. Friday, November 20, 1874.—Jabez Hogg, Esq., President, in the chair. Dr. Goodhart read a paper “On Ichthyosis Lingue.” He had observed two cases, both men above middle age, both with a history of syphilis, and in both the disease ended in epithelioma; in one the ichthyotic condition had lasted ten years. The naked-eye appearance of the disease is that of a thick hard white coating to the tongue in patches on its dorsum, and sometimes on the cheeks. In one case the patches were of the character of local warty excrescences, a milli- métre in height, consisting microscopically of a number of vertically- set papille, of fusiform shape and ragged surface ; the surrounding epithelium was twice its normal thickness. In the plaque the epithe- lium was much thickened, as also the cutis vera and sublying fibrous tissue: at times the epithelial layer was of uniform thickness, at others it was seen dipping down into the interpapillary spaces and sublying fibrous coat, and was surrounded by a small cell growth: to all these changes the warty appearance was due. All this was ex- plained by over activity of the rete Malpighii, the supply of cells produced being greater than the demand created by wear and tear required. He had not observed the colossal papille described by Mr. Hulke, nor the shrunken papille described by Mr. Fairlie Clarke; which latter might be explained by the normal papille having been cut obliquely ; still, if the interpapillary depressions are for long clogged with excess of epithelium, then the papillae would seem to be less prominent. The thickening of the subcutaneous fibrous tissue was especially noticed in the condensed fibrous band that normally may be seen running along immediately below the bases of the papille. The muscular fibre of the tongue had not been found diseased. In order of sequence it was difficult to state which ought to be placed first: the epithelial growth or the excess of subcutaneous fibrous tissue ; but probably the former. The incurability of the disease might be owing to its being gene- rally seen when almost in the condition of epithelioma. With regard to this latter affection, it was hard to trace, microscopically, its exact relation to ichthyosis; the general infiltration of the subjacent fibrous tissue of an ichthyotic patch with indifferent cells indicating its presence; in fact, this condition was generally characteristic of epithelioma in this situation, it being comparatively rare to see the so- called “ birds’ nests” of epithelium. LHven before the onset of epithe- lioma the greatest difficulty in treating an ichthyotic patch with the idea of curing it, would be from the altered habit that the cells must have acquired after a long time, which would have to be counter- acted before the normal state of things could be resumed. In ichthyosis the normal tissues were only in excess; but in epithelioma this was not only the case, but the epithelial cells infil- trated parts foreign to them, and from their very rapidity of growth acquired the characters of “indifferent” cells. A second condition PROCEEDINGS OF SOCIETIES. 41 rendering the cure of ichthyosis doubtful—and at the present time impossible—was the increase of fibrous tissue. At first excessive epithelial growth was found: this meant increased blood supply, and this in turn increased development of tissue supplied by the blood: hence the one condition reacted on the other. The President discussed the paper generally, criticising the use of the term ichthyosis; he thought that of tylosis better. He had not had the opportunity of observing a case pass on to epithelioma ; and quoted one where there was no history of syphilis. Mr, Fairlie Clarke remarked, he had, in adopting the term tylosis linguze, only reproduced the original name, and that there were strong arguments, clinically, against that of ichthyosis. He had found, microscopically, a thinning and wasting of the papille ; for not only is there increase of cell structure towards the surface, but it even dips down and spreads laterally between the papille themselves ; this especially appearing as it approaches the condition of epithe- lioma. Sooner or later an “ichthyotic” tongue became epithelio- matous; but there is a condition where white patches (“ white fibrous cicatrices”) are seen on the tongue, which, though incurable, does not lead to epithelioma, and hence requires carefully distin- euishing from tylosis hnguz. Hpithelioma supervenes in two ways : either by extension of cell growth from the surface, which growth not only is in large quantity, but penetrates into tissues to which it is naturally foreign; or, secondly, it may commence in the underlying structures, as the result of prolonged irritation from the ichthyotic patch. Palliative measures may relieve in the disease, but as yet we are ignorant of any cure, short of that by surgical interference. Mr. Henry Morris questioned the connection of cancer and ichthyosis lingue, remarking that though, in his opinion, quite distinct diseases, yet that both depend upon modified nutrition; this being the production of excessive epithelium, in the case of cancer, heterologous, but not so in ichthyosis. He had observed, at least once, epithelioma follow, as a direct result of irritation to an ichthyotic patch that had shed its scale, the red raised spot becoming a cancerous ulcer. Where epithelioma has followed, it does not spread more rapidly than if it had started quite independently, even though the ichthyosis may have been of long standing. He believed the disease to be like ichthyosis elsewhere; he had seen it on the tongue, while the neck around was similarly affected. Dr. Allchin asked whether the secondary conditions described were not rather extensions of the ichthyotic growth, and not true epithelioma, in a histological sense, although clinically malignant. Mr. Needham, in two cases operated on where epithelioma was commencing, had observed hypertrophy of the papille, and of the cutis, which was infiltrated with large granular cells; the vessels were also enlarged. He had traced the epitheliomatous growth to the original ichthyotic patch. Dr. Goodhart, in reply, preferred retaining the term icthyosis linguz, as one well understood now. Had but once seen the white 42, PROCEEDINGS OF SOCIETIES. cicatricial patch described by Mr. Fairlie Clarke; he did not think it cicatricial in character, for it could be scraped off; and suggested its being owing to some chemical change on the mucous surface. It was not the rule to find the “ birds’ nests” of epithelium in epithe- lioma of the tongue; but he had usually observed an abundant infil- tration of small cells under the epithelium, as in ichthyosis lingue. The second cause for cancer following this disease, given by Mr. Fairlie Clarke, was useful in explaining those cases where the direct extension of the disease from the original patch could not be observed. He had never verified Mr. Needham’s observation of hypertrophied papillew, though he had heard that condition described before. Microscopican Society oF Victor1A, AUSTRALIA. The usual monthly meeting of this Society was held September 24, 1874, at eight o'clock. There was a good attendance of members, and Mr. Ralph took the chair. Dr. Sturt exhibited some Gippsland limestone, containing fora- minifera, pointing out many of its characteristics and demonstrating the mode of manipulation for preparing and mounting the stone. He said the indications it presented showed the deposit had been accumu- lated close to the beach, but he could not state the exact locality. He did not profess to have examined it thoroughly, but hoped the slight account he had given might induce members to give that and other similar deposits a careful examination, which could be accomplished without much special skill. Dr. Sturt said he had received some specimens from Geelong, and also exhibited some crystalline limestone from the interior, extremely pure in character, and he hoped that persons throughout the colony would forward to the Society any specimens for examination. Mr. Sydney Gibbons, F'.R.MLS., exhibited the cuticle of synapta, with anchors in situ—a small marine animal allied to the holothuride, or sea cucumbers—oune of which was a known article of commerce, under the name of béche-de-mer. The synapta differed from the other echinodermata in not having ambulacra—the little feet by which star- fish, &c., move about. Its motion was vermigrade, creeping along by contractions and elongations, ike those of a worm. This mode of progression was facilitated by the skin being studded with minute calcareous plates, in each of which a minute anchor was socketed. Knowledge of the animal in a state of nature was limited, and there was uncertainty as to the species, owing to the difficulty of preserving it for observation, the creature having a trick of committing suicide by bursting itself to pieces when caught. Mr. Gibbons also introduced to the Society the echinococcus (a hydatid), the immature form of a kind of tapeworm, which was only found in the mature state in animals of the dog family. In the larve form it was a common tenant of cysts or hollow tumours formed in various cavaties of the human body. He said there could be no doubt that much disease occurred as a conse- quence of the very common practice of dogs licking the faces and PROCEEDINGS OF SOCIETIES. 43 hands of children, and being kissed by them. The tenia was the smallest of the kind, being only about a quarter of an inch long, and the larve were often as small as 1-200th of an inch. He showed a specimen about 1-150th of an inch, demonstrating the extremely fine hooklets or barbs which evidenced the creature’s presence. They were abundant in the preparations, which were stated to have been recently taken from the human subject. . Mr. Robert Robertson exhibited a tetrarhynchus, an entozoon from the flathead. Mr. Robertson explained that it lodged in the flesh and intestines of the fish, and was supplied with four probosces covered with circular rows of hooks, which were employed for boring through the flesh and tissues of the fish. Mr. Robertson likewise presented some berg-mehl, a mountain meal, from Swan-hill, con- taining numbers of diatoms. Some diatomaceous deposits from New Zealand were exhibited and distributed to the members by Dr. Sturt. The Chairman, on behalf of Mr. Johnson, exhibited an apus found by the latter gentleman at St. Kilda, observing that these creatures existed on tadpoles. At the conclusion of the exhibits the following gentlemen were elected officers of the Society for the ensuing year :—President, Mr. T. L. Ralph; Committee, Dr. Sturt, Messrs. W. H. Archer and F’. Barnard; Hon. Secretary and Treasurer, Mr. Robert Robertson (re-elected). The meeting then proceeded with some arrangements for the annual conversazione of the Society, to be held in October, and several members present promised their aid on the occasion. It was decided to admit friends (ladies and gentlemen) of members, and for this purpose to give a liberal distribution of tickets; and that the applica- tion for tickets of any ladies or gentlemen interested in microscopical research be made to the Hon. Secretary or any of the members. Members were also requested to forward to the Hon. Secretary lists of objects which they would exhibit on the occasion. The meeting then adjourned. THe Mermpuis Microscopic Society, U.S.A. The Society met at the usual hour on the night of 3rd December. Dr. J.T. Marable, and A. J. Murray, City engineer, were elected active members; and Dr. J. J. Woodward, Assistant-Surgeon, United States Army, in charge of the Army Medical Museum at Washington ; Dr. W. B. Bizzell, of Mobile, and Dr. Sterling Loving, of Ohio, were elected corresponding members. Contributions of unmounted material were received from Rev. E. C. Bowles, of Salem, Massachusetts, consisting of different vegetable fibres used in the manufacture of textile fabrics in India; also, six slides from B. F. Quimby, of Philadelphia, two being crystals of salicine, one crys- tals of phloridzin, one crystals of chloride of copper, one of fresh-water algee from the Adirodacks, &e. Mr. G. W. Morehouse, of Wayland, New York, contributed one 44 PROCEEDINGS OF SOCIETIES. dozen slides of fossil and recent diatoms. The specimens contri- buted by both these gentlemen were much admired for their skilful mounting. A hearty vote of thanks was returned to each of the donors. Encouraging letters were read from a number of practical working microscopists, expressive of the kindest hopes regarding the future of the young Society. A paper, contributed by J. Edward Smith, of Ashtabula, Ohio, on the use of dammar varnish as a mounting medium for test objects, was read to the Society. Mr. Smith has found, from numerous expe- riments, that the varnish renders objects much more difficult of reso- lution than balsam. ‘The increased transparency obtained by the use of the varnish seems to him to be the chief cause of the difference. The dammar mounts, according to Mr. Smith’s experiments, utterly defeated a Tolles’ immersion jth three system objective, which would readily resolve the same Sieaiangas when mounted in balsam. A Tolles’ new four system jth objective, however, readily resolved the dammar slides, though the same result could not be obtained by the use of any of the old objectives from 75th to oth. A paper was also read from G. W. Morehouse, of Wayland, New York, on the comparative results obtained by the use of Tolles’ old three system, =),th, and the new four system, ,,th. Mr. Morehouse states that the best work of the former was unequivocally oes by the performance of the latter. This is a great gain, as the j1,th gives a great increase of light and a better definition, as compared ‘with the sth. The most remarkable point in Mr. Morchouse’s investigation is this: That the optician can, by a new and simple combination of lenses, with a focal distance as low as ;4,th of an inch, secure better performance than can be obtained by the old system, jth of an inch focal distance. This seems to be the greatest triumph of the optician’s art, as regards the construction of objectives. A communication from J. Edward Smith fully corroborated the comparative statements of Mr. Morehouse. Mr. Dod, secretary oe the Society, stated that he had ordered one of the new four system ;),ths, and that the members could soon have an opportunity of judging from practical demonstration of the value of this new objective. The Board of Managers reported to the Society that they had purchased one of J. W. Queen and Co.’s students’ microscopes, with accessions to the amount of one hundred and fifty dollars, in accord- ance with the expressed wish of the Society. The Society then adjourned, and the members proceeded to an examination of the slides lately received, and to a test of the perform- ance of a Gundlach’s +1,th objective on the Moller probe platte. This was followed by an interesting discussion of the theory of “ultimate atoms,” as set forth by the president, Dr. Cutler. ae ho BT cs hy ae ae Sey ae Lacs >, zy i ons. Q Feb 1 185, af = alse La al Jour c Wier OS COn1C male Wrest & Co. see a SdONEN., . ones * > s&MaleF lantopanel Cc 4T A os linc COMIN AT THE MONTHLY MICROSCOPICAL JOURNAL. FEBRUARY 1, 1875. I.—On some Male Rotifers. By C. T. Hupson, LL.D. (Read before the Roya Microscopican Sovrrty, December 2, 1874.) . Puate XCI. It is a trite and very obvious truth, that, in consequence of the great growth of science, anyone who wishes to add to the common stock and to enjoy the pleasure of original discovery, must be content to confine himself not merely to one branch, but even to one twig, or, it may be, to a mere twiglet of the great tree of knowledge. It is true that there are some whom great natural capacity and the happier accidents of fortune enable not only to keep themselves well acquainted with what has been done and is doing by others, but also to take up with success first one subject and then another : bringing to the investigation of each minds disciplined and en- larged by the knowledge of many others. But such cases are rare. The great majority of us have neither the leisure nor the talents necessary for playing such a part. With ordinary brains, and under the ordinary circumstances of life, anyone who wishes to study natural history, and yet is not content with doing over again what others have done before him, must of necessity be a specialist. And to be a specialist is to lie under several sreat disadvantages : it tends to make a man a tedious recounter and a bad listener; for a specialist finds it equally difficult to take an interest in other peoples’ hobbies, or to get others to take an interest in his. He is apt too to lose all sense of proportion: to estimate his discoveries DESCRIPTION OF PLATE XCI. Fic. 1.—Ventral view of Notommata Brachionus ; female. 2.—Dorsal view of the same, to show the muscles. a, curved cilia at the base of the buccal funnel. 3.—A sete-bearing cushion from the head of above. ‘ —Enlarged view of the sete fringing the side of the buccal funnel. 5.—Dead male of Mloscularia Campanulata—dorsal view. 6.—Side view of male of Notommata Brachionus, 7.—Ditto ditto of male of new species of Asplanchna. 8.—Ditto ditto of male of Lacinularia socialis. 9.—Enlarged view of (6) in Fig. 8. iy \ in Figs. 5, 6, 7, 8. c. Atrophied cesophagus d, Arm-like processes | in Fig. 7. é. Third process VOL. XIII. 46 Transactions of the rather by the difficulty they have caused him, than by their intrinsic merit; and to be quite amazed to find that the scientific world are as little startled with his corrections of some predecessor’s errors, as the mathematical world was by the laborious gentleman who rightly proclaimed an error in the two-hundredth decimal place of the ratio of the circumference of a circle to its diameter. Fortunately we are all as well provided with “ flappers” to bring us to our senses, as were the sovereigns of Laputa; and though in our case the “‘ flappers” are amateurs and not officials, yet they are not the less efficient on that account. These excellent but unsym- pathetic friends do good service in preventing us from over-estimating our labours, and in bringing us back from the realms of science to the work-a-day world. Even a man’s own household will now and then gently flap him “as though they loved him;” but the outside world knows no such tenderness (at least in the case of Rotifer- hunters), and flaps with the most wholesome vigour. It was only a few days ago that I was hawking with a lens over a bottle of port- wine-coloured water that I had dipped from a farmyard pond, when I became aware that I was being watched by a stout labourer leaning on his pitchfork and standing on the dung heap which had stained the water I was examining. His face was a picture of pity- ing contempt, and said as plainly as a face could do, “ Well! he looks harmless, poor fellow !—but I’m glad I’ve got my pitchfork :” in fact, a naturalist who goes about with bottles, hunting for little creatures in ponds and ditches, may think himself lucky if he is silently treated as little better than an amiable lunatic; for the great majority of mankind seem to make ignorance of natural history a positive merit, by adopting to those who study it a tone of calm superiority, which is at once both amusing and irritating. To an audience however like the present a naturalist, even if he is a specialist, may turn with no little comfort; for he is sure to find among the members of such a Society many who are familiar with his own subject, and some who have obtained distinction in it ; while even those to whom it is comparatively new have minds trained by similar investigations to appreciate his new facts, and to exercise a most useful criticism on his new theories. It is therefore with great pleasure that 1 bring before your notice one or two discoveries concerning male Rotifers (“a poor thing, but mine own”), quite free from any of ‘Touchstone’s anxieties as to being understood and appreciated, though at the same time thoroughly agreeing with him that “ When a man’s verses are not understood nor a man’s good wit seconded with the forward child understanding, it strikes a man more dead than a great reckoning in a little room.’ For ten years after the publication of Ehrenberg’s ‘ Infusion- sthierchen,’ it was supposed that the Rotifera were all hermaphro- Royal Microscopical Society. 47 dite; and it was not till 1848 that Mr. Brightwell of Norwich discovered a Rotifer with separate sexes in the genus Asplanchna. In 1850 Mr. Gosse announced his discovery of the male of another species of the same genus, Asplanchna priodonta, and in 1854 Dr. Leydig discovered that of a third, Asplanchna Sebold. Two years later Mr. Gosse published a paper in the ‘ Philosophical Transactions’ “On the Dicecious Character of the Rotifera,” and in it he described and figured the males of several species of Brachionus, of Poly- ae platyptera, Synchxta tremula, and Sacculus viridis ; besides _ stating that he had discovered certain unusually shaped ova (which were possibly male ova) in Melicerta ringens. ‘There were also strong grounds for believing that the males of Hydatina senta and Notommata Brachionus, had been seen and described as new species of female Rotifers. So the case stood in 1856; and I am not aware of any further addition having been made to our knowledge except my own dis- covery of the male of Pedalion mirum. Now on looking at the list of species given above in which the males have been observed it strikes one at once that, with the single exception of Melicerta, they all belong to one group; namely, to that of the free-swimming Kotifers: moreover, as it is probable from Mr. Gosse’s description that the ova he found in Melscerta were winter eggs and not male ones, the thought at once occurs that it is possible that the Rotifers may be divided into two great groups, the one dicecious, the other moncecious—the first including all the free- swimmers both loricated and il-loricated, and the second the tube- making Floscules and Melicertans, and the creeping Philodines. Indeed Professor Huxley, in his paper on Lacinularia socialis, made this probability a very strong argument for considering the Rotifers as permanent forms of Echinoderm larvee—as in these larvae a similar difference in sexual character accompanies a difference of structure, very like that which separates the free-swimming Rotiters from most of the others. The argument was one that was hard to answer, for it rested on . the supposed moncecious character of some of the largest and most common Rotifers, of creatures that are constantly being watched and studied in consequence of their great size and beauty. Indeed it does seem strange that no one should have seen during the last eighteen years the males of Stephanoceros or of the Floscules, if these creatures have any; for the adult animals are fixed to the plants on which they are found, are of comparatively large size, and, what is still more to the purpose, have tolerably transparent tubes in which their eggs are deposited and hatched. Melicerta presents a difficulty in the opacity of its tube, and Conochilus in its roving habits; but Lacinularia is free from each drawback, and yet hitherto its male has escaped observation. E 2 48 Transactions of the It was only a few weeks ago that Mr. Bolton of Stourbridge very kindly sent me a group of Lacinularia socialis on a small piece of myriophyllum; and after spending some time in enjoying the beautiful sight (quite a new one to me) of a fully-expanded healthy cluster of Lacinularia, seen with a dark-field illumination under a low power, I changed the objective and illumination, and began a systematic inspection of one of the group. I soon discovered that the animals were loaded with eggs, and almost at the same instant saw a young Rotifer playing round one of the females in the usual male fashion. I at once endeavoured to catch and isolate it, and on suc- ceeding found that it was a male, in the usual aborted condition, but _ differing in shape and proportions from any that I had seen before. As the weed was perfectly clean, and had nothing on it but this cluster of Lacinularia, I had no doubt that it was the male of that rotifer ; but to make quite sure I clipped away everything from the group, and then dropped it into a small tube of clean water. In this the eggs hatched day after day, supplying me with dozens of the same male, so that I had every opportunity of studying its form and structure. Fig. 8 is a side view of this creature. It will be seen that it consists of little else than a large testis (a) ending in a hollow cylindrical penis (b), and nearly filling the whole internal space of the body. Of mouth, cesophagus, mastax, or stomach, it has not even a vestige. ‘There is a large nervous ganglion (c) giving off nervous threads to two red eyes, and a dorsal antenna (d). Tortuous tubes with vibratile tags were visible above the testis, and could be traced partly down the animal’s sides ; while above the testis between it and the ganglion (c) I repeatedly thought that I caught sight of the delicate outline of a contractile vesicle. At first sight this seems a most unusual position, but, if I am right as to its existence, it really holds its normal position with respect to the testis, and is only apparently thrust out of its proper place by the monstrous size of that organ. Large cilia could be seen lining the passage through which the penis could be protruded, as well as the cup which terminated the short pointed foot. My good luck with Lacinularia encouraged me to make a deliberate effort to find the male of Mloscularia Campanulata, which was I knew growing in fair abundance in a pond not far off, and I have at last been successful in finding it, and in seeing it (when newly hatched) force its way through its mother’s tube. The Floscules were growing on alge attached to the stems of water-lilies, and the first thing to be done was to cut up the stems in lengths at the pond’s side, and by the aid of a lens to pick out — the pieces where there were good-sized clusters of them; for these tube-dwellers have a choice as to depth and light, and even as to ~ Royal Microscopical Society. 49 the side of the stem to which they adhere. Next, every piece had to be hunted over with a low power, in the hope of detecting some specimen with eggs differing in size, shape, or number, from the ordinary female ones. Unfortunately the stems of the water-lily were very thick, and I had to put them in a trough so deep that I was often prevented from using a power sufficiently high to detect differences of size—and as for those of shape or number I could at first find none. After two or three days of this work, and of finding none but the usual-looking eggs, I at last came upon an empty tube with three eggs in it, and these eggs were perceptibly smaller and rounder than usual. Moreover, one of the eggs already showed the two red eyes quite distinctly, but not a sign of any teeth. I com- pared this with a female egg close by, and in which the eyes were in much the same state, and in it the teeth were distinctly visible. _ This was at three o'clock in the afternoon, so I left the sup- posed male ege in the middle of the field of view, and at seven returned to see what progress had been made. ‘The frontal cilia were now visible, and the young animal could twitch itself about in its shell—but still there was no sign of teeth. Feeling certain that it was a male, I sat down before the instrument, book in hand, determined to wait patiently for the happy moment. But I reckoned without my Rotifer. It developed rapidly enough during the next four or five hours, and I could distinctly see through the shell, and at the same time the cilia of both the penis and the foot. But at half-past one it was still twisting about im its shell. It was as an “ unconscionable time a-hatching” as Charles the Second was “a-dying”; and as the little wretch would neither hatch nor apologize, I went to bed and left him to his fate —namely, to be dried up. I confess that I was a little reluctant after such a failure to go back to the pond and begin the whole thing over again ; but I did, and I was rewarded by finding on my return home, on almost the first piece of stem I looked at, two Floscules, each with six or seven. of the same smaller eges in their tubes, and with others in their ovaries. None of the eggs had eyes developed in them, so I knew that I need not trouble myself about them for twenty-four hours ; but next day, soon after I began to look over the eggs in one of the cases, I saw a newly-hatched young one in the other, trying to drill his way through his mother’s case into the water. I say “drill,” for the word exactly expresses the process. With its - wreath of powerful frontal cilia it swept its way through the tena- cious stuff of which the tube is composed ; stopping every now and then to take breath, as it were, and to hitch up its foot to get a fresh purchase for a new assault. Its progress was very slow, for nearly twenty minutes elapsed before the head fairly emerged from 50 Transactions of the — the side of the case. The instant it had done so the cilia flashed — round in a grand whirl, and in a second the whole animal glided swiftly through the opening. I had seen the testis and penis, and the entire absence of teeth or stomach, and could safely say now that Floscularia Campanulata was dicecious. Soon after I saw another newly-hatched male attempt the same means of exit into the world from the other tube. But he was not so fortunate. Whether the case were tougher or the young one weaker it is hard to say, but I watched the poor fellow working away till he was fairly exhausted; and then he crept back to the side of his mother, and died. Fig. 5 is a portrait after death of this unlucky Floseule. The dioecious character of at least one of the Floscules, to wit Campanulata, and also of one of the Melieertans, viz. Lacinularia socials, having been. thus established, it is worth while to revert to Professor Huxley’s argument, to state it a little more amply than I have done already, and to show how it is affected by these two dis- coveries of male Rotifers. The argument is as follows. The Rotifers have a nervous ganglion (their only one) situated on what is usually ealled the dorsal surface of the body, and m one group of Botifers—viz. that of the free-swimmers, creepers, and Floscules—the trochal disk has been so unsymmetrically developed as to thrust the mouth to the opposite side of the body from that on which the ganglion lies, and the anus to the same side as the ganglion; while in another group —viz. that of the Melicertans—the disk has been so developed as to push the mouth to. the same side as the ganglion, but the anus to the opposite side. Moreover, “so far as the sexes of the Rotifera can be considered to be made out (approximatively) the dioecious forms belong” to the first group, and the monoecious to the second. © “Tt is this circumstance,” says the Professor, “which seems to me to throw so clear a hght upon the position of the Rotifera in the animal series. In a report in which I have endeavoured to har- monize the researches of Professor Muller upon the Echinoderms, . I have shown that the same proposition holds good of the latter in their larval state, and hence I do not hesitate to draw the conelu- sion (which at first sounds somewhat startling) that the Rotifera are the permanent forms of Echinoderm larve, and hold the same relation to the Echinoderms that the Hydriform Polypi hold to the Medusz, or that Appendicularia holds to the Ascidians.” There are other weighty arguments in the same paper for placing the Rotifera among the Vermes, but this 1s one on which, as will be seen from the above extract, Professor Huxley lays great stress, and which the discovery of the male of Lacinularia socialis weakens considerably. For now it has been shown that dicecious Rotifers exist among those whose anus is on the opposite side to Royal Microscopical Society. — d1 that of the ganglion as well as among those who have it on the same side. Besides, there is now a great probability that all the Melicertans are dicecious, for they resemble each other so much that Mr. Gosse, in the ‘ Popular Science Review,’ has proposed to reduce the whole family to a single genus. To sum up then we may say that the Rotifers can be divided into the five families, the Flosculariza, the Melicertadea, the Brachionza, the Hydatinza or Notommatza, and the Philodinza, and that among the first four of these five, dicecious genera have’ been discovered. The family of the Philodina is the only one in which as yet no males have been found. , It may possibly still be held desirable to rank the Rotifera among the Vermes, with which it must be admitted they have many points in common; but among the reasons for so doing, that of their sexual resemblances to the Echinoderms can scarcely hold a place. : Indeed the very peculiar males of the Rotifers lend no little assistance to those who, like Gosse and Leydig, would place the Rotifera among the Crustacea; for a parallel case to that of their rudimentary condition is only to be found among some of the Cirripedes. The males of the Entomostraca are often smaller and rarer than the females, and (as among the Rotifera) one impregnation suffices for a succession of generations of females. ‘There are female parasitic Isapods too that have minute imperfect males parasitic on themselves; and among the Vermes there are curious rudi- mentary males much smaller than the females; but in all the above cases the males possess some sort of mouth and stomach, and are capable of taking nutriment, whereas in that of the Rotifera, and of the males of the parasitic Cirripedes Alceppe and Cryptophialus, the males have not even a rudiment of mouth or stomach. As Darwin (in his monograph of the Sessile Cirri- pedes) has pithily said, “ they exist as mere bags of spermatozoa.” As the male Rotifers spend their short lives in incessantly chasing one female after another, they are provided with cilia, muscles, eyes, nervous ganglion and nerve-threads (as well as with a depuratory apparatus), all of which the males of Alcippe and Oryptoplialus lack; but in the remarkable absence of any means of procuring nourishment, these Rotifers and Cirripedes at the same time most closely resemble each other, and differ from almost everything else. It is beyond the scope of this paper to discuss the question of the affinities of the Rotifers, or that of their true position in the animal kingdom; but I may be permitted to add that there is at least one Rotifer—viz. Pedalion—which it seems to be impossible to class among the worms, for it has six hollow limbs worked by o2 Transactions of the striated’muscles, some of which pass freely through the cavity of the body. | Among the males figured in the Plate is that of Notommata Brachwonus, Vig. 6. I found the females, Figs. 1 and 2, of this very curious Rotifer for the first time some two years ago, in a large rain puddle lying in a woody hollow at the top of Nightingale Valley. The pool was not more than two or three yards across, and it was often dried up, and very little light could reach it through the over- ‘hanging trees; yet when I first found it, it contained swarms of this Notommata, many specimens of large Bursaria, and a few half-developed ova of some fresh-water zoophyte. The latter were evidently accidental additions to its inhabitants, for none of the adult Polyzoa could have survived a single drying up of the water, and this pool was often dry for a fortnight at atime. It is hard to say how the ova could have got into such a place. Perhaps some ~ bird bathing at the edge of Abbot’s Pond (where Plumatella repens was then abundant) had entangled the ova in its feathers, and had then washed them off again in the pool, or they might have been carried there in the coat of a roving spaniel. Any way it was curious, for the two places are more than a mile apart ; and though stato-blasts might travel a long way without injury, it does not seem likely that soft ova could be: taken far, or could survive after having been dried up. : On one occasion, when I had been disappointed by finding the pool empty, I thought I would try to rear my own Rotifers at home; so I carried away in my tin box a thick sandwich of leaves and soil trom the bottom of the pool, and put it into an aquarium full of soft water. In three days’ time the Notommata made their appearance, as I had hoped, though not in any great numbers; the experiment however was rather too successful if all the creatures that came to life are to be taken into account; for one evening I saw such a forest of long white worms waving backwards and for- wards over the rotten leaves, that I hastily emptied my aquarium, and resolved to be contented in future with my pool, no matter how often it might fail me. The female of Notommata Brachionus is so good an example, of a typical Rotifer, that its structure requires no further explana- tion than that given by Fig. 1, which shows the ventral surface. This Notommata has however two peculiarities which are well worth notice. First, that its external shape might almost make one fancy it a hybrid between a Hydatuna and a Brachionus ; for it has the peculiar head of the former, and an illoricated body tucked up to resemble the lorica of the latter: while in the second place the setee and cilia surrounding the mouth, and the funnel- shaped cavity leading to it, surpass in number, size, and variety, those of any other Rotifer that I have ever seen. ee OO eal ei al Royal Microscopical Society. aod 53 Three hemispherical cushions (as in Hydatina) crown the head ; and the setz: on them, Fig. 3, have distinct bases from which they spring, and through which they grow. In the young Notommata only the tip of each seta can be seen just above the top of its cylin- drical base. Similar partly sheathed cilia are to be seen ranged parallel to one another on each side of the buccal funnel; an en- larged view of these is given at Fig. 4, which also shows a fan of small seta situated just above the base of each of the larger ones. At the bottom of the funnel also are large curved cilia (figured at (a) im Fig. 2), and I have more than once thought that I could detect the presence of minute cilia over the whole surface of the cavity. I have added to the Plate, Fig. 7, the male of a new species of Asplanchna. The female resembles Asplanchna priodonta, but differs from it in having an unusually large contractile vesicle, which is kept constantly in motion to and from the ovary with a sort of semi-contraction, but without the distinct spasmodic col- lapse that usually characterizes this organ. The vibratile tags too are numerous, and arranged in a long straight line down the whole length of the body, as in A. Brightwelli. It is, however, only half the size of A. Brightwellw, and its peculiar male also shows it to be a different species. I should have thought it to be A. Szeboldie, were it not that the male of A. Szeboldi has four arm-like processes, and this male has only two. The male is wonderfully transparent and empty; for such organs as it has are small, and its skin 1s so delicate that it is often difficult to detect the creature in the water with a lens, in spite of its being of the respectable size of ?jth of an inch. Its two arms (d) and an odd hump (e) are only seen when it retracts its head; on doing this they start out stiff from the body in the most comical fashion, and collapse again as the relax- ing muscles allow the head to resume its usual position. The atrophied cesophagus is seen at (¢) attached by a thread to the conical hump: of the mastax, stomach, or salivary glands, there is not a trace. The vibratile tags and contractile vesicle are as well seen as in the female, but 1 have met with a specimen in which the tags appeared to be quite empty, with the exception of two or three near the contractile vesicle in which the usual cilia were vibrating. It is hardly possible to consider so rudimentary a creature as this male Asplanchna without speculating on the steps that have brought it into so strange a condition. When we find an atrophied oesophagus, closed at both ends, without either mastax or stomach attached to it, but in precisely the same position as the oesophagus of the female, it is difficult to imagine that we are looking at the original state of things: the mind naturally pictures to itself a time when the cesophagus was of real use, when it led from a mouth to a stomach, and when the male, as capable of feeding as the female, 54 Transactions of the lived a much longer life than it does now, as well as a very dif- ferent one. What then can have led to so remarkable a degeneration ? What can have reduced the male to the rare, rudimentary, short- lived creature that he is at present? It might be suggested that an abnormal development of the special male organs has taken place in some specimens at the expense of the other organs of the body, and that an unusually numerous and vigorous offspring has descended from such specimens; inheriting the peculiarities of their parents, and supplanting the feebler and normal tribes ; such a process, if continued, leading in time to the conversion of the male into what is now little more than a movable “bag of sper- matozoa.” But this guess, if accepted as an explanation, only meets half the difficulty. How is it that parthenogenesis among the females accompanied degeneration among the males? For, of course, if the males occur only at certain seasons of the year, and live but an hour or so, parthenogenesis is a necessity among females whose lives are so short that scores of generations succeed each other between two appearances of the males. Then too is there any connection between the degeneration of the male and its rare occurrence? And how comes it that some female Rotifer, in no way distinguishable from hundreds of others, should, unlike them, lay male eggs instead of female ones? And why should the same female never lay eggs of different sexes ? (uestions such as these are much easier asked than answered ; and yet it is the hope of finding a satisfactory answer to them that constitutes the chief charm of natural science, which without its speculations and hypotheses would become a barren record of com- paratively uninteresting facts. I cannot pretend to offer any solution myself of these difficul- ties ; and, indeed, in the case of the Rotifers it seems almost hopeless to expect ever to get a solution of them: for the small size of these creatures prevents us from studying them except under conditions that are very unfavourable both to life and health. Royal Microscopical Society. 5D TI.—On the Invisibility of Minute Refracting Bodies caused by Excess of Aperture, and upon the Development of Black Aperture Test-Bands and Diffraction Rings. By Dr. Roysron-Picorr, M.A., F.RB.8., &. (Read before the Rovau Microscoricau Society, Jan. 6, 1875.) Tue invisibility of minute bodies, subtending a sufficient visual angle to be readily seen if properly defined, is a highly curious and important fact, to which our Hon. Secretary, Mr. Slack, has already drawn the attention of the Royal Microscopical Society. This invisibility depends upon several causes, which it is now intended to examine. Minute bodies are often solely distinguished by the sharpness and decision of their outline. The question is—can this outline be obliterated by the conditions of vision and by any relation between the refractive index of the substance and the aperture of the objec- tive employed ? A few experiments will now be related which may perhaps help to unravel these points. First starting with gas bubbles found in plate glass (probably nearly vacuum bubbles)—if glass of very fine quality be chosen, (having surfaces true enough to exhibit Newton’s rings* under pres- sure,) and these be examined with a horizontal microscope placed opposite the window, a very perfect picture of the prospect will be seen in miniature, surrounded by a black band ; the field of view will be found precisely three-fifths of the diameter of the bubble, or the band one-fifth. The curious fact is, that for this hollow lens the breadth of the band is the same for all objectives, whatever be the aperture. Not so, however, with a solid spherule of the same size and of the same glass. ‘Two conditions regulate this breadth. I. The band increases in breadth from nothing till it occupies the whole spherule as the aperture is diminished. IJ, The degree of aperture at which this black band first appears varies with the refractive index of the bead. It results from these principles that the aperture of an objective regulates the appearance or disappearance of the circular black out- line of minute refracting spherules, and consequently the black bands of refracting cylinders. Having thus stated the points to be attended to in observing such bodies, I proceed to describe more in detail the facts from which these conclusions have been deduced. I. In the case of the air bubbles, in plate glass, care must be * Of course it is only when one of the surfaces is truly spherical that Newton’s rings are developed: in nearly flat surfaces these rings take eyery imaginable shape under pressure.and every variety of prismatic hue. 06 Transactions of the taken to choose them lying near the surface, and as small as possible. The writer published an article in January, 1870, from which the following passages are now selected. “Remembering that when a pencil of parallel rays passes through a denser into a rarer medium (supposing common air were enclosed), the focal point for a refractive index 1°5 would be found to lie on the posterior surface of the minute hollow sphericle, 1. e. on the surface farthest from the eye of the observer. If the con- tained gas or air were much attenuated it would approach the centre. . . . The field of view presented is independent of the aperture of the objective, whilst change of aperture has a very sur- prising effect upon the visible characters of the solid glass spherule. This change, so decided and important in minute research, has been a cause of much surprise and pleasure to the writer, as it appears to open a new mode of changing and selecting definition under novel conditions.” .... “Remarkable is the result that large aperture destroys the black ring-outline of refracting spherules and black borders of cylindrical fibres. In innumerable instances the only possibility of distinguishing the molecules of organized particles depends upon shadow. . .. A fundamental defect of excessive aperture is the disappearance of these invaluable characters of minute spherules and of fibres capable of refracting light.” “In some cases, therefore, they appear jet black with a small aperture, but most frequently invisible with an excess of aper- ture.” * The appearances of Mr. Slack’s invaluable silica films most opportunely illustrate the effect of aperture. He has observed quite independently that the most minute beading visible with a — glass of low aperture vanished under increased aperture. Now if aperture must be diminished in order to develope the black test-band, it is evident that excess of aperture may destroy it, so that in the case of direct illumination by parallel rays the blackness and breadth of the test-band may wholly depend upon the two conditions already stated. I have used in these experiments an “iris diaphragm” (con- structed for me by Messrs. Beck in 1869); by this instrument the aperture can be instantly reduced from 3ths to y¢oth inch. Eaperiment 1.—Select very fine threads of glass, and, holding them’ like an open fan, rapidly pass the ends through the blue edge of the steady flame of a wax light. On examination with the microscope { under parallel rays from the plane mirror before the window in a good light, fused spherules of glass will be seen, of various sizes and degrees of spherical perfection, in each of which a minute image of the window appears surrounded by a black * «Quart. Journ. Micro. Sci.,’ Jan., 1870. t It is best to begin with a low aperture objective. —————— ee Py Royal Microscopical Society. 57 annulus, which I shall call the black test-band. If the object-glass aperture be reduced, or if another object-glass be used of much less aperture, this circular blackness will appear much increased in breadth. And upon careful micrometrical measurements being made, it will be found for the same aperture that the breadth of the black ring is exactly in the same proportion to the diameters of the spherules. Indeed this phenomenon is so striking that the angular aperture is at once shown by the breadth of the pacture displayed within the spherule or spherical lens. Upon increasing the aperture the picture becomes larger and larger, and more and more indistinct and confused, until with a large aperture the ring is attenuated exceedingly ; but of course as the aperture is increased the spherules chosen must be smaller in proportion to the power of the glass. : Upon diminishing the aperture exceedingly, the aperture test- band widens so much that only a minute picture is left in the centre, which can be further diminished to a bright dot. This aperture test-band has a remarkable effect upon definition. If we are observing very minute spherules in a mass, with excessive aperture the aperture bands become almost invisible. The forms of closely-packed beading if refractive and transparent cannot be deseried. Hach bead under large aperture-vision forms a confused picture; and if there be brillant illumination the forms under inspection are completely obliterated. Haperiment 2.—Globule of glass sq'5oth of an inch in diameter. Aperture 140°, dry {th, 1862. Aperture band invisible. A stop is now placed behind the back set of lenses 735th of an inch in diameter ; a large, broad, black annulus is instantly produced. The breadth of the aperture band measures the reduction of aperture. IT. Another principle affects the breadth and distinctness of the test-band, viz. the refracting power of the spherule itself. This band will not be developed in a spherule of water with a greater angle than 60° 16’ of angular aperture.* A minute spherule of plate glass will begin to show the aperture band at so high an angle as 83°; blue sapphire at 124° 30’. But’ a heavy glass bead, consisting of two parts lead and one of flint, will begin to develope the aperture band at 164°. The aperture bands are shown equally well in cylindrical threads as in spherules. Tt is evident that, conversely, a coarse measure of the refractive index of any proposed substance can be got from the breadth of this band, provided the substance can be formed into minute spherules © or cylindrical threads. There is, here, a nice distinction to be made as regards microscopical definition, in the double effects of variable zs ae the mathematical consideration of this point, see the article already quoted. 58 — Transactions of the refractive power and variable aperture upon the character of the defining band developed. Thus the peculiarly pale appearance at the edges of some silicious forms found im sponges under ordinary apertures is de- pendent upon their very low refractive index. Indeed, Tabsasheer will not develope the defining band at a greater objective aperture than 25°. I have not as yet measured the refractive index of Mr. Slack’s silica beads, but suspect it is very low. For this reason alone, a very high-angled objective would fail entirely to detect the circular defining band of a very minute spherule. That gentleman has kindly presented me with several of his slides, and left in my care an excellent Zeiss + from Jena. Considering the fine performance of this glass notwithstanding it has no adjusting collar, I have in- stituted experiments on its aperture: and at the same time measured that of Powell and Lealand’s glasses. Objective, ieee Rae Character. LU STISISTROG NAGY Worse Rene + 68° Dry lens. Powell and Lealand .. 2 98° Dry, latest construction. : ; 124° Immersion, ditto. oa fae 3 { 124° Immersion without water. The angular aperture was measured by laying a tube, into which was screwed the objective, upon a large flat board, then two night- lights were placed at about a foot distance from the nose of the object-glass: the lights were then gradually separated till, upon looking through the tube, both appeared distinctly in miniature at the extreme edge of the field. On replacing the eye-piece and alternately hiding each, the field of view was symmetrically ilumi- nated. ‘'wo lines were then carefully ruled from the centre of the front to each light, and the angle subsequently measured by a pro- tractor. In the case of Powell and Lealand’s “1872 eighth,” the angle was first measured dry, and then a small piece of covering glass being wetted was attached to the front lens: in each case, ag might . be expected, the same oblique rays reached the observer's eye at the same position of the lights, viz. 124°. I may remark here that one of Andrew Ross’ finest “ quarters ” had about the same angle, tested in this way, as Zeiss’ “ sixth.” This mode of testing is altogether different. from measuring the angle at which a ray of light emanates from a brilliant particle itself immersed in a highly refracting medium: the two things are totally distinct. ie Royal Microscopical Society. — 59 There is another point of view worth considering, viz. the appearance of brilliantly reflecting particles under illumination from above. The peculiar invisibility of minute beading under ordi- nary wide-angled glasses under reflected light is quite as striking a result as that given by transmitted light. A brilliant scene is lit up upon dark ground. The appearances presented remind me of the beautiful effects displayed in the field of view of a first-rate telescope directed to a dew-drop glittering in the morning sun- shine. No glass yet constructed, whether microscopic or telescopic, has yet been adequate to present to the eye the real size of the image of the sun seen on a small spherule.* The study of Mr. Slack’s films by reflected light on a black ground indeed well repays the observer. Rich fields of sparkling beauty, variegated with tiny stars of various magnitudes down to exquisite groups of star-dust as it were closely resembling resolved nebule and cloudlets of nebulosity, doubtless indicating beading still more minute and undefinable—such are some of the lovely pictures formed by these films. Precisely in the same way, thus illuminated, the spherical silica beads present very beautiful diffraction rings according to the quality of the glass, and the Zeiss “sixth” certainly gave very finely formed concentric ones. On trying a_ badly -corrected eighth objective, and thought “ fine” at the time by the makers, the brilliant speck reflected by a single bead presented an exact representation of Saturn and his ring as it were viewed perpendi- cularly to the plane of the ring, no division being visible: in fact there were no delicate diffraction rings whatever. Now in wide aperture glasses it is possible many images may be embraced by the extreme rays of the objective: just as each person views at one and the same time a different set of solar rays reflected from the falling rain-drop. It would seem that an extremely wide-angled objective is not adapted for defining brilliant points of light reflected from minute spherical surfaces. Nor is it so well adapted for developing the aperture test-band of solid highly-refracting particles. On the con- trary, it completely hides it. I shall beg leave to conclude this note by a further quotation from the article already cited,} (in the case of transmitted hght)— “From these effects of aperture it may now be assumed that * With the telescope a disk which ought to be the two-thousandth of an inch . appears something like the fortieth of an inch in diameter: or the spurious disk is 500 times larger than the reality. It is my opinion, however, from many care- ful experiments that microscopic object-glasses are more finely constructed than the telescopic, and that great improvements are still necessary in that direction. f ‘Quart. Journ. Micro. Sci.,’ Jan., 1870, ‘Researches on the Errors of Micro- scopical Vision and on New Methods of Correcting them,”’ by Dr. Royston-Pigott. VOL. XIII. EK 60 Transactions of the Royal Microscopical Society. with a small aperture a spherical refractive particle exhibits a dark even jet black terminal annulus. If a body be studded with such beading it will necessarily appear dark from an assemblage of shadows ; when the definition is exalted, these beads considered as lenses exhibit in general too small a central point of illumination to be detected in ordinary glasses. ven if perfectly refracting and unembarrassed with other substrata, beads so small as the thirty-thousandth of an inch form an image of a radiant source of light inconceivably minute.’”* “Supposing the glasses free from annular aberration, greater depth of vision with black out- lines is given by a reduced aperture with direct light.... . On the other hand, enlarged aperture appears to illuminate a dark object, if transparent; it converts apparently, in many cases, opacity into translucence, transforms a reddish-brown scale into a brilliant object, reveals interstitial sparkling, and developes new but often delusive appearances in eidolic forms.” * “1 The image of a brilliant flame is in all such cases swelled out by the imperfection of the glasses into an exaggerated spurious disk.” The Monthly Macro scopical Journal Feb.1. 1875. i! | yi! i) AW vi) Vi 4 Il A nG j A / [ fi f on /) f f MMM OA LS, iy’ 906; ES > S IAM hi i ani j W West & C2 hth ie Sie ane tb =e an 2 Way). Jor a L——— Sed SSS = SSS : SS ty) @, 61.) III.—On Bog Mosses. By R. Brarrnwarrs, M.D., F.LS., &. Puatrts XCII. anp XCIIT. 18. Sphagnum intermedium Hoffmann. Deutschlands Flora II. p. 22 (1796). Pirate XCII. Syn.—Sphagnum palustre, molle, deflecum, squamis capillaceis. D1uu. Hist. Musc. p. 243, tab. 32, fig. 2 a (1741).—Sph. recurvum P. Beauv. Prodr. p. 88 (1805).— Brip. Bry. Univ. I. p. 13 (1826).—Linpbs. Torfm. No. 3 (1862).— BERKELEY Handb. Br. Mosses, p. 808 (1863). Sph. cuspidatum Nuss, Hscu. & Sr. Bry. Germ. p. 23, Tab. IV. Fig. 9 (1823).—C. Mutu. Synop. Muse. I. p. 96 (1849).—Scupr. Torfm. p. 60, Tab. XVI, fig. 1 (1858). Synop. p. 675 (1860). Russow Torfm. p. 55 (1865).—Mitpz Bry. Siles. p. 383 (1869).—et p. p. aliorum auct. Sph. cuspidati- forme Brevtet Bot. Zeit. 1824, p. 407.—Brip. Bry. Un. I. p. 752. Sph. Mougeoti Scupr. in Moug. & Nestl. St. Crypt. Vog.—Rhen. fase. XIV, No. 1306. SpA. flexuosum Dozy & Mok. FI. Batav. p. 76, tab. III. Sph. cuspidatum and var. B, recurvum WILSON Bry. Brit. p. 21. Dioicous. Plants robust, straight, in large, dense or lax tufts ; yellow-green, pale green or sometimes pale ferruginous above, pale brown or whitish below. Stems 6-12 in. high, greenish white ; the cortical cells small, thin, not porose, in 2-3 layers; woody zone narrow, pale yellowish. Cauline leaves reflexed, rather small, ovato-triangular, minutely auricled, without fibres or pores, EXPLANATION OF PLATES. Puate XCII. Sphagnum intermedium. a.—Female plant. a ¢—Part of male plant. 1.—Part of stem with branch fascicle. 2.—Male inflorescence. 26.—Bract with antheridium. 3.—-Perichstium and fruit. 4.—Bract from same. 5.—Stem leaf. 5aa.—Areolation of apex. 6 5.—Stem leaf of var. riparium. 6.—Leaf of divergent branch. 6’—The same in a dry state. 6*.—Section. 6 p.—Point of same. 6c.—Cell from middle x 200. 7.—Basal intermediate leaves. 8.—Leaf of a pendent branch. 9 x.—Part of section of stem. 10.—Part of a branch denuded of leaves. Puate XCIII. Sphagnum cuspidatum. a.—Female plant. ad.—Male plant. 1.—Part of stem with branch fascicle. 2 b.—Bract with antheridium. 4.—Pericheetial bract. 5.—Stem leaves. 5aa.—Areolation of apex. 6.—Branch leaves. 62.—Section. 6.—Point of same. 6c.—Cell from middle S2008 ay: : ; 7.—Basal intermediate leaf. 94.—Part of section of stem. B.—Var. plumosum. 6 8.—Bryanch leaf of same. y.— Var. hypnoides. § 6.—Branch leaf of var. Torreyi. «62 On Bog Mosses. broadly bordered with narrow cells, the apex somewhat obtuse with 3-5 small teeth, not involute at margin. Branches 4-5 in a fascicle, two divergent, and arched down- ward, the rest pendent, attenuated, closely appressed to the stem and concealing i; those of the coma numerous, short, obtuse, squarrose-leaved, forming a large dense capitulum ; retort-cells elongated, perforated and slightly recurved at apex. Branch leaves densely imbricated, erecto-patent, broadly lance- olate, involute m the upper part, when dry with the margins undulate and points recurved; apex with 2-3 minute teeth. Border of 2—4 rows of extremely narrow elongated cells ; hyaline cells of the upper half elongated, filled with annular and spiral fibres, and with a few small pores; of the lower half very long, with annular fibres only and no pores ; chlorophyll cells free on the posterior surface, trigono-compressed in section. Male amentula fusiform, subclavate, ochraceous, the bracts ovate, acuminate. Capsules numerous in the capitulum, exserted, and also in the upper fascicles. Perichaetium yellow-green, the bracts broadly oval, pointed, concave, without fibres or pores ; lower ovate, acumi- nate, recurved at apex, upper elliptic oblong, emarginate. Spores yellow. Var. £. be Sph. riparium Anesr. Ofvers. Vet. Ak. Férh. XXI, p. 198 (1864). Sph. cuspi- datum Var. majus Russ. Plants taller, dull brownish green. Cauline leaves shortly tri- angular, erose ‘and somewhat fringed at apex. Branch leaves ovato-lanceolate, without fibres in the apical cells. Var. y. speciosum Russow. Plants robust 10-18 in. high, deep green. Capitulum very large; branches gradually attenuated from the middle. Cauline leaves large, elongated-triangular, often deeply frmged at apex. Branch leaves longish lanceolate, with a subulate point, recurved when dry, without fibres in the upper cells. Hab.—Open moorlands, wet heaths and spongy mountain bogs. Frequent. Fr. July. £, in deep pools. Upland and Westro- bothnia. In the Riesengebirge, Labiau in Prussia, Livland. Wool- ston Moss, Cheshire (Wilson). yy, Eastern Europe; sparingly 1 in Silesia, Estland, Courland and Prussia. Prof. Schimper unites this plant with the following as Sph. cuspidatum Ehrh., regarding the present as the type of the species, and the other as a submersed variety, and moreover describes them as monoicous. The habit, texture and general facies of the two are so dissimilar, that they appear to me always separable by these characters alone, and in all the specimens I have examined the reproductive organs in both are on separate plants. The points On Bog Mosses. 63 especially noteworthy in Sph. intermediwm are, the pendent branches quite concealing the stem; the indistinct cortical cells, which scarcely differ from those of the woody layer; the branch leaves undulated and more or less squarroso-recurved when dry, the broadly oblong, apiculate, more densely areolate perichetial bracts, and the pale yellow spores. The indefatigable Lindberg has satisfactcrily settled the nomen- clature of both Sph. cuspidatum Ehrh. and Sph. intermedium Hoffm. from an examination of original specimens of both authors preserved at St. Petersburg ; Hoffmann’s description is otherwise far too brief for correct determination, and his Var. £, of entermedium s ‘a stated by the same authority to belong to Sph. acutifoliwm rh. 19. Sphagnum cuspidatum Ehrhart. Decades Crypt. No. 251 (1791). Puate XCIIL. Syn.—Sphagnum palustre, molle, deflecum, squamis capillaceis, B fluitans, Dru. Hist. Muse. tab. 32, fig. 2, B.(1741). Sph. cuspidatum Enru. |. c.—Horrm. Deutsch. Fl. If. p. 22 (1796).—Smiru FI. Brit. p. 1147 (1804). Eng. Bot. t. 2092 (1809). Turner Musc. Hib. p. 6 (1804).—Bripet Sp. Muse. L. p. 17 (1806). Mant. Muse. p. 2 (1819). Bry. Univ. I. p. 14 (1826).—Werzer & Mour Bot. Tasch. p. 74 (1807).—Scuwaer. Supp. I. P. I. p. 16, tab. VI (1811).—Scuxunr Deutsch. Moose p. 16, Tab. 7 (1810).—Rouutine Deutsch. FI. III. p. 35 (1813).—Scuuitrz Supp. FI. Stargard. p. 65 (1819).— Fl. Dan. Tab. 1712 (1821).—Htzen. Muse. Germ. p. 29 (1833).—Dozy & Moukens. FI. Bat. p. 79.—BrrKeu. Handb. Br. Mosses p. 307 (1863).—Linps. Torfm. No. 1 (1862). Sph. laxifolium C. Miu. Synop. I. p. 97 (1849). Muxpz Bry. Siles. p. 385 (1869). Sph. cuspidatum Var. y, Bry. Brit. Tab. IV. Sph. cuspidatum B submersum Scurr. Torfm. p. 61, Tab. XVI. fig. 1 8 (1858). Synop. p. 676 (1860). Sph. laricinum Ancsrrom, Ofver. Vet. Ak. Forhandl. XXI, p. 197 (1864). Moicous. Plants very soft, im loose submersed or floating tufts; light green, deep green, or more or less tinged with yellow or brown. Stems slender, flaccid, pale green, 6-18 in. or sometimes several feet m length; cortical cells not porose, larger, well defined, in 2-3 strata. Stem leaves ovate-oblong, pointed, with the margins involute at apex, broadly bordered with very narrow cells, the hyaline cells of the upper half with numerous spiral fibres. Branches 3-5 in a fascicle, longer, often turned to one side and faleate at points ; all divergent, or 1-2 pendent but not concealing the stem, those of the coma few and more lax. Branch leaves laaly imbricated, narrowly lanceolate, flexwose when dry, often somewhat falcato-secund, 3-6 toothed, and with a broader border of narrow cells; chlorophyll cells free on the posterior surface, trigono-elluptic im section. Capsules in the capitulum, or more frequently scattered on the stem, the peduncles being often much elongated. Perichetial bracts 64 On Bog Mosses. distant from each other, very broadly oval, involute at apex, laaly areolate, with fibres in the upper cells. Spores ferruginous. Male plants more slender, amentula fusiform, the bracts ovato-lanceolate. Var. 8. plumosum. Sph. subulutum Brip. Sp. Muse. I, p. 19. Mant. p. 3. Br. Univ. I, p. 18. Scuwen. Supp. 1, P. I, p. 18. Spa. acutifolium 8 subulatum Bry. Germ. I, p. 21, T. III, fig. 8***. Rora Fl. Germ. III, P. I, p. 120. Buanpow Fase. V, No. 204. Sph, cuspidatum Muse. Brit. p.4,T.1V. Sph. cuspidutum B 6 plumosum Scuimp. Submersed, slender, elongated ; branches decurved, all uniform and divergent, their leaves very long and narrow. Var. y. hypnocdes. Sph. hypnoides BRAUN in Bot. Zeit. 1825, No. 40. Brip. Br. Univ. I, p. 752. Short, densely tufted; stem simple with simple branches, hooked at apex. Leaves uniform, strongly undulated, narrowly lanceolate, falcato-secund. Var. 6. Torreyt. Sph. Torreyanum SULLIVANT, Mem. Amer. Ac. n. s. IV, p. 175 (1849). Mosses of Un. States, p. 13, No. 16 (1856). : Robust, rigid 10-16 in. high, of a dirty brown colour; branches 4-5 flattened. Branch leaves very large, involute at point, elongated lanceolate-acuminate, spreading, straight, broadly margined, minutely eroso-denticulate at apex ; stem leaves without fibrils. Hab.—Stagnant pools in moorlands, frequent. Fr. July. £, in deeper water. yy, in Lake Hornsee (A. Braun). 6, ponds in pine barrens of New Jersey (Torrey). | The chief points of distinction between this species and the last are these ; in Sph. cusprdatum the plants are more slender, the pendent branches not closely appressed to the stem so that it is more or less visible ; the cortical cells of stem well defined from the thicker woody layer; the longer branch leaves not recurved when dry but slightly flexuose ; the stem leaves with larger cells, fibrillose in the upper part, and narrower more elongated ones at the margin ; the more obtuse perichzetial bracts ; and lastly the brown spores. It must also be borne in mind that the two plants not unfrequently grow together, yet each retaining their special features. A gradual transition may be observed between the typical plant and the Var. plumosum, a form of which (Var. mollissemum of Russow) with densely placed fascicles is remarkable for its yellow, soft, spongy texture, and was found by Nowell near Todmorden. C. Miller regards the Var. hypnoides as an abnormal condition of seedling plants. es) ® 1V.—On the Similarity between the Red Blood-corpuscles of Man and those of certain other Mammals, especially the Dog ; con- sidered in connection with the Diagnosis of Blood Stains in Criminal Cases. By Dr. J. J. Woopwarp, U.S. Army. ty his recent paper ‘On the Value of High Powers in the Diagnosis of Blood Stains,”* Dr. Joseph G. Richardson, of Philadelphia, affirms the possibility of distinguishing the blood of man from that of the pig, ox, red-deer, cat, horse, sheep, and goat, by the measurement of the red blood-corpuscles, even in dried stains such as the micro- scopist is called upon to examine in criminal cases. The circumstance that Dr. Richardson does not mention any animal whose blood-corpuscles cannot be thus distinguished from those of man, and the warmth with which he combats the prudent counsels which Virchow,t Casper,{ and Taylor,§ in common with other experts,|| have offered to enthusiastic microscopists in connec- tion with this subject, led me, on perusing his paper, to fear he would be understood as teaching in a general way, that it can be * « American Journal of the Medical Sciences,’ July, 1874, p. 102; also the ‘Monthly Microscopical Journal,’ September, 1874, p. 130. This paper has attracted considerable attention. See, for, example, the ‘Lancet, August, 1874, p- 210; the ‘Medical Times and Gazette,’ August 8, 1874, p. 151; and the ‘ London Medical Record,’ September 9, 1874, p. 560. The last of these journals is the only one to raise a warning voice: “ Dr. Richardson’s paper is interesting, but we are afraid the question often put, ‘ What is the source of the blood ina stain?’ must still go unanswered. In questions where capital punishment hangs on scientific evidence, that evidence must be of no doubtful or questionable nature.” + Rud. Virchow, “ Ueber die forensische Untersuchung von trockenen Blut- flecken,” Virchow’s ‘ Archiv,’ Bd. xii. (1857), s. 334. t J. L. Casper, ‘Handbook of Forensic Medicine.” Translation of new Sydenham Society, London, 1861-5, vol. 1., p. 138, et seg.; also p. 198, e¢ seg. See also the new and enlarged German edition of the same by Dr. Carl Liman, ‘ Practisches Handbuch der Gerichtlichen Medicin,’ 5te aufl. Berlin, 1871, Bd. ii., s. 173, et seq. § A. S. Taylor, *The Principles and Practice of Medical Jurisprudence,’ 2nd edit., London, 1873, vol. i., p. 548. || Among others, I may mention E. Briicke, “ Ueber die gerichtsarztliche Unter- suchung von Blutflecken,” Wiener ‘Med. Wochenschrift,’ Jahrgang, 1857, s. 425 ; Hermann Friedberg, ‘ Histologie des Blutes mit besonderer Riicksicht auf die forensische Diagnostik,’ Berlin, 1852; Andrew Fleming, “Blood Stains,” ‘The American Journal of the Medical Sciences,’ vol. xxxvii., N.S. (1859), p. 84; Wharton and Stillé, ‘Medical Jurisprudence,’ 3rd edit., Philadelphia, 1873, vol. ii., p. 696; M. Z. Roussin, ‘“‘ Examen Médico-Légal des taches de sang,” ‘ Annales d’ Hygiene, tome xxiii. (1865), p. 139. For an elaborate history of the growth of our knowledge on this subject, up to 1860, the reader may consult B, Ritter, ‘“* Zur Geschichte der gerichtsarztlichen Ausmittelung der Blutfiecken,” in Henke’s ‘Zeitschrift fiir die Staatsarzneikunde,’ 1860; Drittes Vierteljahrheft, s. 31. The chief authority in favour of the possibility of distinguishing the blood-cor- puscles of man from those of other mammalia is Carl Schmidt, ‘‘ Die Diagnostik verdachtiger Flecke,” Mitau u. Leipzig, 1848. Ihave not yet obtained a copy of this paper, but find abstracts of it in Schmidt’s ‘Jahrbiich’ for 1849, p, 258, and Ritter’s history, just cited. The reader will also find liberal extracts in Fleming’s paper, cited above. The extravagant views of Schmidt are especially confuted by Briicke and Virchow in the papers cited above. ’ 66 On the Similarity between the Red Blood-corpuscles of Man determined by the microscope with certainty whether a given stain is composed of human blood or not; and this fear has been justified by some of the notices of his essay which have since appeared in the medical journals. Now, this subject is one which, from time to time, becomes of great importance in criminal cases, and justice, no less than scientific accuracy, demands that the microscopist, when employed as an expert, shall not pretend to a certainty which he does not possess. I suppose no experienced microscopist, who has thoroughly investi- gated this subject, will be misled by Dr. Richardson’s paper, but there are many physicians who possess microscopes, and work with them more or less, to whom a partial statement of facts on such a subject as this is peculiarly dangerous; and the object of the present paper is to point out to this class of readers that Dr. Richardson's statement of the case, even if all he claims be granted as true, is, after all, not the whole truth: that there are certain mammals— among them the dog, the constant companion of man—whose red blood-corpuscles are so nearly identical in size with those of human blood, that they cannot be distinguished with any power of the microscope, even in fresh blood, much less in dried stains; and that, consequently, it is never in the power of the microscopist to affirm truthfully, on the strength of microscopical investigation, that a given stain is positively composed of human blood and could not have been derived from the blood of any animal but man. I must do Dr, Richardson the justice to state, at the outset, that these facts are well known to him, although, from motives of prudence, he has thought proper to be silent with regard to them. In a note dated October 19th, 1874, in reply to one in which I in- formed him of my intention to write the present paper, he says, “T should be very much obliged to you if you would add to your remarks (in a foot-note or otherwise) that, on communicating with me, you found me fully aware of the difficulty of making anything more than a differential diagnosis even in the cases I specified, and of the impossibility of distinguishing the blood of man from that of a monkey or dog, but that I had refrained from giving prominence to these facts,” lest an improper use should be made of them in the defence of criminals. I must, however, entirely dissent from this view of the matter. I cannot forget that on more than one occasion in the past, wit- nesses summoned as scientific experts have been so misguided as to go into courts of justice and swear positively, on the strength of microscopical examinations, that particular stains were human blood,* and I think the danger that others may do so in the future, * Passing by certain American cases, I may refer, in illustration of this state- ment, to the celebrated English case, Reg. v. Thomas Nation (Taunton Spring Assizes, 1857, p. 279), with regard to which the editor of a London medical journal and those of certain other Mammals. 67 to the prejudice of innocent men, is more to be feared than the pos- sibility that an acquaintance with the true limits of our knowledge on this subject may sometimes be made use of in the unscrupulous defence of real criminals. I have, therefore, no hesitation whatever as to my duty in speaking of this subject at all, to speak the whole truth so far as it is known to me, and in so doing, I am happy to say I follow the practice of many of the best writers on medical jurisprudence. ! In the instance of the dog it might at first sight be supposed from the estimates of the average diameters of the red corpuscles in this animal and in man, as given by Gulliver and Welcker, the authorities most frequently cited in the modern text-books, that a certain small, but constant and measurable, difference existed, which might serve as the basis of a distinction in legal cases. This in- ference, however, is not only contrary to the facts of the case, but an examination of the original essays of the authors cited, shows that it is not borne out by their observations. The mean diameter of the red corpuscles of man, according to Gulliver,* is s55 of an inch (= ‘00794 millimeter), while that of the red corpuscles of the dog is gz'¢z of an inch (= 00716 mm.). With regard to his estimates for the human corpuscle, Mr. Gulliver says:; “ We are only speaking now of the average size; for they vary like other organisms ; so that in a single drop of the same blood you may find corpuscles either a third larger or a third smaller than the mean size, and even still greater extremes.” According to this statement, the human red blood-corpuscles may vary in a single drop of blood from zsy5 of an inch (=°00529 mm.) to szo5 (=:01058 mm.). Mr. Gulliver tells us further, in the same para- eraph, “ My own estimate of the average size has been deduced from numberless measurements, frequently repeated during the course of several years, of corpuscles quite fresh and swimming in the blood, and in various artificial mixtures, as well as in the dry state.” I have not, however, been able to find, in those of his papers which I has pithily said, that the testimony of the expert must be looked upon “as most dangerous clap-trap, and rather what we might expect to hear at some popular lecture, where the ‘ wonders of the microscope’ form the theme of declamation to a gaping audience, than the solemn asseveration on oath of a man of science in a court of justice.”—‘ Medical Times and Gazette,’ April, 1857, p. 366. * George Gulliver, F.R.S., “Lectures on the Blood of Vertebrata,” ‘ Medical Times and Gazette,’ vol. ii., of 1862, p. 101, et seq.; ‘*On the Red Corpuscles of the Blood of Vertebrata,” &c., ‘ Proceedings of the Zoological Society of London,’ 1862, p. 91; the Sydenham Society’s edition of ‘The Works of William Hewson,’ London, 1846, p. 216, e¢ seg.; Appendix to ‘Gerber’s Elements of the General and Minute Anatomy of Man and the Mammalia, London, 1842, p. 31, et seg.; ‘“Ob- servations on the Blood-corpuscles or Red Disks of the Mammiferous Animals,” ‘London and Edinburgh Philosophical Magazine,’ vol. xvi. (1840), pp. 23, 105, and 195; also vol. xvii., pp. 189 and 325; also vol. xxi. (1842), p. 107. For a list of other papers referring to the blood-corpuscles of various animals, see ‘ The Works of William Hewson,’ above cited, note to p. 236. + ‘Medical Times and Gazette,’ vol. ii., of 1862, p, 157. 68 On the Similarity between the Red Blood-corpuscles of Man have examined, any of the numerical data from which this average size was deduced. In the table of measurements appended to Gerber’s ‘ Elements,’ in which, for the first time, he gave “mean or average sizes” (in previous papers he had only recorded “ common sizes,” occasionally supplementing these by the extremes observed), Mr. Gulliver ex- plained his method of arriving at the average size, as follows: “The common-sized corpuscles are first set down, then those of small and large size, and lastly the average deduced from a computation of the whole.”* In this table the measurements for the common dog are given as follows: 7 1-4000 of an inch. Common sizes .. .. 41-3500 es 13200) 5 y, Small size .. .. .. 1-4570 ie Large size .. .. .. 1-2900 s Average .. 41-3542 5 Where the “average” is simply the arithmetical mean of the several fractions given above, it can hardly,’I think, be accepted as the true average size, since as much weight is given, in this mode of calculating, to the rarer as to the more frequent forms. Ac- cordingly, it is not surprising that we find in a former papert measurements which do not accord very closely with this average. “Domestic dog, old mongrel. Common diameter of corpuscles, 1-4000th to 1-3200th of an inch. Foxhound puppy, one day old, a bitch, 1-3000th and 1-2666th, the most common diameter of the corpuscles. Foxhound puppy, twelve days old, a bitch. Most common diameter of the corpuscles 1-3000th and 1-2885th of an inch. Extreme sizes 1-4000th and 1-2666th. Mongrel puppy, four months old, a bitch ; all the following diameters common, viz. 1-3698rd, 1-8554th, 1-3429th, and 1-8200th.” The measurements for the second and third of these animals are about as much larger than those for the human species as the others are smaller. It is interesting to know just how Mr. Gulliver’s measurements were made. He tells us he used a glass eye-piece micrometer so adjusted that the divisions had a value of zo'yoth of an inch each. “Tf one space and a quarter of this micrometer were occupied by a single globule, this would of course measure 3z¢a5th of an inch ; if three equally-sized particles lying in a line, and touching at their edges, covered three spaces and a half, the diameter of each of these would be szs5th, if four spaces zq'yoth of aninch.”§ The objectives used were an eighth by Ross and a tenth by Powell.|| It is not * Appendix to Gerber’s ‘Elements,’ cited above, p. 1. t+ Loc. cit., p. 38. ; ¢ ‘ London and Edinburgh Philosophical Magazine,’ vol. xvi. (1840), p. 28, § ‘London and Edinburgh Philosophical Magazine,’ vol. xvi., p. 24. \| Loc. cit., pp. 24 and 105, and those of certain other Mammals. . 69 stated whether these objectives were provided with the screw-collar adjustment for thickness of cover, but they probably were, and if so, doubtless all the measurements were somewhat vitiated, like others of the same date, by the failure to allow for the variations in magni- fying power produced by turning the screw-collar. Moreover, it must be clear that practically the fractions of a division of the eye- piece micrometer were only estvmated, for the case in which a number of “equally-sized’’ corpuscles would be found “lying in a line,’ and just “ touching at their edges,’ without overlapping, must have been rare. As to the accuracy of the value assigned to the eye-piece micrometer, Mr. Gulliver himself says: “ In the absolute accuracy of any micrometer applied to objects so extremely minute it is difficult to place implicit reliance,” and he only claims “ rela- tive exactness” for his results.* Turning, now, to the original essay of Welcker, we find that his observations give even less support than those of Gulliver to the notion that the blood of the dog can be distinguished from that of man by the microscope. Welcker’s measurements, as ordinarily quoted in the text-books, are ‘00774 of a millimeter for man, and °0073 for the dog. I find, in his original paper, +} that the mean for the dog was derived from the measurement of but ten corpuscles in the blood of a single terrier, the variations in this case beg, minimum °0065 mm., maximum ‘0082. Now, if we turn to the table¢ of his own measurements of human blood, we find that in the last measurement of the blood of Dr. Schweigger-Seidel, fifty corpuscles gave the following results: mean, ‘00724 mm. : minimum, ‘0051; maximum, ‘0085, in which case the mean is a trifle less than that found for the dog. I would commend this table of Welcker’s to the study of those who may be disposed to underrate the diversity of size which may be observed among the human red corpuscles; the minimum mea- surement recorded in it is ‘0045 mm.; the maximum, ‘0097 mm. The author remarks: “I have always, both in animals and in man, found the transverse diameter of the blood-corpuscles of one and the same individual vary from one-fourth to one-half of the mean mea- surement; and it appears that all the sizes lying between the two extremes are present in tolerably equal numbers, with the excep- tion of the smallest corpuscles, which occur for the most part singly and at intervals.” I may mention further that the mean dimensions of the human red corpuscles so often quoted from Welcker, viz. 00774 mm., with a minimum of ‘0064 mm., and a maximum of ‘0086, were y VEO, dic Jos 7B + H. Welcker, “ Grosse, Volum und Oberflache und Farbe der Blutkorperchen , hei Menschen und bei Thieren,” ‘ Zeitschrift fiir Rationelle Medicin,’ 3te R., Bd. xx. (1863), s. 237. { Loe. cit., p. 263. 70 = Omthe Similarity between the Red Blood-corpuscles of Man not derived from the whole of this table, but from four sets of measurements of his own blood only, of which two were from dry preparations and two from the moist blood. He tells us that he selected the mean -00774 mm. because it was derived from his own blood, which he had used in a previous research on the number of blood-corpuscles, and thought best, therefore, to use also in the computation of their volume, which is one of the chief subjects discussed in his paper. The mean of eight other measurements from five different individuals was ‘00768 mm. ‘The blood of a chlorotic woman gave ‘00656 mm, as the mean of the cor- puscles examined moist, and -00693 mm. as their mean when examined dry. _ Welcker made his measurements with Kellner’s System III., ocular II., magnifying about 620 diameters, and by a delicately ruled eye-piece micrometer, each division of which, with the power used, had a value of ‘001723 mm., as determined by the stage-micro- meter. A human blood-corpuscle fell within four or five of these divisions, while, on account of the great delicacy of the ruling, fifths or even tenths of a division could be estimated with tolerable exactness. The stage-micrometer itself was a millimeter in one hundred parts ruled by Lerebours, and which Welcker had verified by comparison with a standard scale, in a manner which he describes in full, and which is worthy of study. He measured, as a rule, 50 blood-corpuscles from each sample, and these were not selected, but taken indiscriminately one after the other, as they came under the scale while the specimen was being moved along. Other observers besides Gulliver and Welcker have recorded minute differences in the average size of the red corpuscles of man and the dog. Thus, Carl Schmidt * estimates the average dia- meter for man at -0077 mm.—for the dog at -0070 mm. A. Kolliker + fixes the mean for man at ‘0033 of a Paris line (= ‘0751 mm.)—that of the dog at ‘0031 of a Paris line (= 00709 mm.). On the other hand, Friedberg} makes the blood-corpuscles of the dog the largest, stating that he finds the human corpuscles measure from -0070 to -0058 mm.—those of the dog from -0054 to -0080. For myself, after repeated measurements of the blood of the dog and of human blood, I can only say that I find no constant difference between them, whether the fresh blood or thin layers dried on glass be selected for measurement. The mean of fifty corpuscles taken at hazard is seldom twice the same, and sometimes that of human blood, sometimes that of dog’s blood, is a trifle the largest. The following measurements, intended to illustrate these facts, t OR Menu of Human Microscopic Anatomy,’ London, 1860; pp. 519 and 525. t Op. cit. and those of certain other Mammals. 71 were made with a glass eye-piece micrometer ruled in two hundred and fiftieths of an inch, and with such a magnifying power that. each division corresponded to the fifty thousandth part of an inch (0005079 mm.). The objectives used were an immersion yg of Powell and Lealand, and an immersion No. 13 of Hartnack, either of which permitted the above value to be given to the divisions of the eye-piece micrometer by properly adjusting the draw-tube. The stage-micrometer used in effecting this adjustment is an excel- lent one in ydoths and ypoaths of an English inch, in which the several hundredths and thousandths, as nearly as I can measure, are equal to each other, and the ten divisions of the latter value to any one division of the former, a quality in which the stage micrometers in the market are generally deficient. I have com- pared this micrometer with a standard scale ruled on silver—a centimeter in millimeters and tenths—the property of the United States Coast Survey, kindly loaned for this purpose by Mr. J. E. Hilgard, who assures me that it is “very accurate.” I made several comparisons both by means of an eye-piece micrometer, and by the contact method described by Welcker. ‘These comparisons showed that the divisions of my stage-micrometer were nearly two per cent. (exactly 1°945 per cent.) larger than they ought to be, and this correction was accordingly applied in adjusting the value of the eye-piece micrometer. The value assigned to the divisions of the eye-piece micrometer for these measurements cannot, therefore, I think, differ from their absolute value by a quantity large enough to modify the results appreciably. As the divisions represent a value twelve and a half times less than that of the divisions of Mr. Gulliver's eye-piece micro- meter, and more than three times less than those of Welcker’s eye- piece micrometer, I did not find it necessary to estimate fractions of a division, as they did, but read the nearest number of whole divisions corresponding to each corpuscle. Fifty corpuscles, or about that number, were measured in each sample of blood. An assistant noted the number of eye-piece divisions corresponding to each corpuscle as the measurements were made, and the mean was obtained in each case by adding together all the values and dividing by the number of corpuscles measured. Of course, the number of eye-piece divisions found only required to be multiplied by two to convert it into decimals of an inch. I endeavoured at first to make these measurements with a dry Powell and Lealand’s soth of an inch, with the draw-tube so adjusted that each division of the eye-piece micrometer should equal one hundred thousandth of an inch, but I found the outline of the corpuscles, with this power, was not sharp enough to permit me to measure them as exactly as I wished, and I therefore gave the preference to the immersion objectives above mentioned. — ‘ 72 On the Similarity between the Red Blood-corpuseles of Man Of course, in arranging for these measurements, the effect of the screw-collar adjustment of the objective on the magnifying power had to be taken into account. This was done in the following manner: some thin glass covers, not varying more than a thou- sandth of an inch from *012 inch in thickness, were selected from a lot of so-called s$oth inch covers by means of a suitable lever of contact.* Some blood being placed under one of these covers, the best adjustment of the screw-collar for definition was found by trial. The stage-micrometer, which is an uncovered one, was then temporarily covered with another of the selected thin glasses, and being duly focussed upon the desired value was given to the divisions of the eye-piece micrometer by the adjustment of the draw-tube, after which the measurements were proceeded with, and the screw-collar was not turned again until they were com- leted. ; | ; The following tables present the several means deduced from these measurements in decimals of an inch, to which, for con- venience, I have added the equivalent values in decimals of a milli- meter. The number of corpuscles from which each mean was deduced is also given. The measurements made with the Hartnack No. 13 immersion are marked (H), the others were made with Powell and Lealand’s immersion +,th : MEASUREMENTS OF Human Rep BLOOD-cORPUSCLES, FROM Five INDIVIDUALS. Number of Mean Diameter. orpuscles : : Dec D j -Meseored, | pesto aon | jae DA Widry) SL eee B50 - 000304 -00772 2. Dos moist: eS: Lee ee 49 -000292 °00742 3. Dottiudo. (CEL) wins aiice ounce 50 *000300 00762 4. DO G0. SCE) ae, 50 -000289 00734 DADE MeO dry 3.20 Vea he hs . 90 *000288 *00731 6. Dos undostte: aera 50 -000294 *00747 70 DOS MOI coc ses lagen! ole 50 -000301 -00765 SMES Wy: ic tis) dee) eyelet 00 “000298 °00757 oh Do. do.*C) rn. ees. 52 *000297 *00754 LO. Mare Teel dont: «chiar Go eu 50 -000290 *00737 11, Do, dio. GED) aicch doras he 50 -000292 00742 De Te Bs) Os: (piss eee Ue Metis 50 °000296 *00752 13. Do.’ do? GED) UA Oe 50 *000297 00754 In each of these measurements of human blood the great majority of the corpuscles ranged from twelve to seventeen divisions of the eye-piece micrometer ; that is, from 00024 to :00034 of an inch. Out of the whole number measured, six were as small as * The instrument used was made by Stackpole and Brothers, of New York, after the pattern of the instrument designed by Mr. Ross, which is figured in ‘Carpenter on the Microscope,’ 4th edit., London, 1868, p. 203. and those of certain other Mammals. 13 ten divisions, and one as large as eighteen divisions; large and gmall forms were not searched for, however. The size most frequently measured was fifteen divisions, or -00080 of an inch. MEASUREMENTS OF THE RED CoRPUSCLES OF THE Doc, FROM FIvE INDIVIDUALS. Nuraber of Mean Diameter. Corpuscles : c Pea aaieeiut tach |e Muletse 1. Mongrel terrier, dry .. .. .. 50 000292 ~°00740 2 sameanimal)* do... 3... 54 -000299 *00759 3. Another mongrel terrier, dry (H) 50 -000290 °00737 4, Same animal, moist (H) .._... 50 °000288 °00731 5. Scotch terrier do, (H).. .. 50 -000291 °00739 6. Same animal do. (H).. .. 50 -000289 00734 le Do. do: SCE) e.2 3: 49 000287 *00729 8. Spitz dog, dry CE) ces ah 92 °000285 00724 9. Black-and-tan, moist (H) Me 00 -000290 °00737 In each of these measurements of dogs’ blood, precisely asin the case of those of human blood, the great majority of the corpuscles measured from twelve to seventeen divisions of the eye-piece micro- meter (*00024 to -00034 of an inch); out of the whole number measured, four were as small as ten divisions, but nine larger than seventeen were encountered. As with the human blood, however, large and small forms were not searched for, but all the perfectly formed corpuscles brought into view by the movement of the stage, were measured as they passed under the micrometer without selec- tion, until the required number was recorded. The size most frequently measured was fifteen divisions, or 00030 of an inch, precisely as in the case of human blood. It will be observed that three of the above means for human blood, Nos. 1, 3, and 7, are a trifle larger than any of those of dogs’ blood; and two of the latter, Nos. 7 and 8, are a trifle smaller than any of those for human blood. All the other means for the dog are within the range of the values found for human blood, and the majority of them are each identical, even to the last decimal place, with some one of those found for man. I may, moreover, remind the reader in this place, that the varia- tions between the mean diameter assigned to human blood by different observers are quite as great as the variations recorded by any of them between the blood of man and the dog, or even greater. Passing by the older measurements, some of which, as a matter of curiosity, | have given in a foot-note,* I may cite, besides * A list of the more important of these older measurements will be found in the Mensiones Micrometrice of R. Wagner (‘ Partium Elementarium Organorum que sunt in Homine atque Animalibus Mensiones Micrometrice,’ Erlangen, 1834), Most of these are included in the more complete list given by Louis Mandl 74 On the Similarity between the Red Blood-corpuscles of Man ‘the measurements of Gulliver, -00794 mm., Welcker, -00774 mm., and Kolliker, -00751 mm., which have been already quoted in this paper, the following values: Robin,* ‘0073 mm.; Harting, °0074 mm.; Valentin, | ‘0071 mm.; and Austin Flint, junr., t °00726 mm. (goo inch). I have thus shown that we are not justified, either by the facts of the case or by the authorities supposed to favour the possibility of doing so, in attempting to distinguish between the blood of man and that of the dog by the measurement of their red corpuscles. Mr. Gulliver himself, indeed, appears to have come to a similar conclusion, not only with regard to the dog, but of other animals, for he tells us that the corpuscles of the quadrumana “differ but little from those of man, being only just appreciably, or sometimes not at all, smaller, both in the monkeys of the Old and New Conti- nents,’ and that “in the seals, otters, and dogs, the corpuscles are about as large as in man.’§ I myself have not made systematic measurements of the blood of any of these animals, and am there- fore unable to speak as authoritatively with regard to them as I can about the dog. From Mr. Gulliver’s detailed measurements, appended to Gerber’s ‘ Elements,’ however, I am led to believe that there are several other animals whose blood, even in the fresh state, could not be distinguished by the dimensions of the red corpuscles from that of man. Among the domestic animals I may especially mention the rabbit and guinea-pig as belonging to this category. To these, besides most of both the monkeys of the Old and New World, the seals and the otters, we may add the kangaroo, the capybara, the wombat, and the porpoise. In the case of all these animals we not merely find that the ‘‘ average size,” calculated in Mr. Gulliver’s peculiar way, approximates dangerously to the average assigned to man, but the classic ..,9th of an inch figures among the “common sizes” recorded by Mr. Gulliver for each. The foregoing remarks and measurements refer especially to the fresh blood of the animals mentioned, and to thin layers quickly (‘ Mémoire sur les Parties Microscopiques du Sang,’ Paris, 1838, p. 10), from which I take the following, reducing the values which both Mandl and Wagner give in vulgar fractions of a Paris line to decimals of a millimeter: Leeuwenhoek (1673), -00902; Ib. (1720), -01327; Jurin (1717), °00789; Tabor (1724), 00723; Senac (1749), :00820; Muys (1751), 01128; Weiss (1760), -01085; Della Torre (1763), “00301; Blumenbach (1789), :00789; Villar (1804), -00564; Sprengel (1810), “00902; Kater (1819), 00677; Bauer and Home (1818), :01504; Young (1819), -00451; Rudolphi (1821), -00902; Prevost and Dumas (1821), :00705; Edwards (1826), 00814; Hodgkin (1827), :00902; Wollaston (1827), 00525; Weber (1830), -00525; Miiller (1834), °00525 to :00902; Schultz (1836), -00667 to -00836 ; Wagner (1838), -00645 to ‘00752; Mandl himself gives -00800. * Charles Robin, “ Note sur Quelques Points de l’ Anatomie et de la Physiologie des Globules Rouge du Sang,” ‘ Journal dela Physiologie,’ tom. i. (1858), p. 283. + I cite the estimates of Harting and Valentin from Welcker’s paper, cited above, p. 258. t ‘The Physiology of Man,’ vol. i., New York, 1866, p. 111, § ‘Proceedings of the Zoological Society,’ 1862, p. 96. and those of certain other Mammals. 79 dried on glass, as is generally practised in making preparations of blood for permanent preservation. In such preparations the cor- puscles have almost exactly the size they possess in the perfectly fresh blood. The great majority of Mr. Gulliver’s measurements were made upon blood prepared by this method, and at the time he appears to have regarded the results as the equivalent of measure- ments made on perfectly fresh blood. ‘“ In some instances,” he tells us, “there was certainly a slight enlargement in the dried corpuscles, as compared with those seen in their own serum imme- diately after they were taken from the animal. In the greater number of trials, however, the sizes of the wet and dry disks corre- sponded accurately.”* ‘Twenty years later he seems to have modified this opinion somewhat, for he states, “ When the cor- puscles of man and other mammalia were dried on glass, however quickly, they were usually just appreciably larger than in the liquor sanguinis.” + Welcker also found that the mean dimensions obtained by measuring the corpuscles dried in a thin layer was apt to be rather greater than that obtained from the measurement of moist blood, and explains it by stating that “the very smallest, mere spherical corpuscles spread out a little in drying.” He regards the difference, however, as so trifling, that he uses measurements of dried specimens indiscriminately with those of moist in obtaining his average. I myself am not satisfied that there is any constant difference, and find, on comparing the mean diameter of fifty cor- puscles dry, with fifty moist, from the same individual, that some- times the one, sometimes the other, is a trifle the largest. ‘The dried corpuscles are very apt to be deformed, and often many of them are quite oval. If the long diameters of a number of such corpuscles are measured, the mean will be of course too great. I do not find it so if the measurement is confined, as it should be, to those corpuscles which have dried systematically and are quite circular. How is it, now, with regard to blood dried en masse when sprinkled upon weapons, clothing, wood, &e. Dr. Richardson admits in this case that a slzght contraction takes place, but evidently | regards it as too trifling to interfere with the diagnosis. Carl Schmidt, on the other hand, found the blood-corpuscles under such circumstances contracted to nearly one-half their original size; and gives ‘0040 mm. as the mean diameter of the corpuscles of human blood thus prepared, while he assigns ‘0077 mm. as the mean of human corpuscles dried in thin layers on glass.{ It is not necessary for the purpose of the present paper to go into a detailed discussion of this subject, for no one will pretend that it can be any easier to make the diagnosis of such stains than it is in the case of moist blood or — * “London and Edinburgh Philosophical Magazine,’ vol. xvi. (1840), p. 25. + ‘Medical Times and Gazette,’ August, 1862, p. 158. { I quote from Fleming, op. cit., p. 111. VOL. XIII. & 76 Similarity between the Red Blood-corpuscles of Man, &c. of thin films dried on glass; and if it is impossible in the latter case to ascertain by the microscope that the sample submitted is human blood, it would be absurd to hope to do better in the former. I cannot, however, refrain from expressing my conviction that Carl Schmidt was quite as accurate in measuring his samples as Dr. Richardson in measuring his, and that the latter has underrated the variations in size which the dried corpuscles may present under various conditions. I may also call attention, in this connection, to the effect of water on the diameter of the corpuscles. Mr. Gulliver has pointed out that if “water be mixed with blood, the disks immediately become much enlarged and spherical, quickly losing their colouring matter; and yet if the whole of this be thus removed, after a while the outlines of the disks, very faint indeed, may frequently be recog- nized, diminished considerably in diameter and apparently quite flat.” * | , ‘In another place he relates that “some human corpuscles having an average diameter of 355th of an inch measured only th of an inch in diameter. But they were found afterwards to be a poor and insignificant substitute for sun miniatures, at this season so difficult of attainment. The experimenter on these methods will occasionally be surprised at the very curious results obtained by viewing the same miniature with equal magnifying powers used differently. For instance : Experiment. A miniature landscape was formed by a small convexo-plane lens =5th focal length and a lineal aperture of yéoths, 0-03”, placed on the stage, the tube of the microscope being directed * The formula calculated by the writer is there given: from which it follows if m be large, q m= -——2, where m ig the minimizing power and d the distance between object and miniature. Testing Object-glasses. By Dr. Royston-Pigott. 151 to an open window disclosing a lovely foreground. Highth O.G. A low eye-piece: power 400. Result. Landscape dark and hazy. The deficcency of light was most remarkable. The same power was now got from a half-inch and D eye-piece. New result. An exquisite picture brilliantly lit up, even the slittering foliage twinkling in the sunbeams, and the garden details were marvellously displayed. This difference is truly surprising. Increased light and superb definition with diminished aperture and same power. To those who have not yet tried this method, and are desirous of becoming acquainted with the peculiar effects of over or under correcting their glasses as far as their construction is capable, I may be permitted to recommend the following commencement with these experiments : A. Haxperiment for spherical aberration. Remove the front glass of the observing objective. Examine the miniatures of the illuminated globules. B. Remove the internal glasses and replace the front only. C. Replace all the glasses and close up the screw-collar for the mark “covered ” if there be one. D. Open the collar for “uncovered” position. At the last point for the first time the miniatures will begin to more nearly resemble their original. The various changes of the appearances of the miniature, to the student of this department of optics, form a most interesting study. These phenomena, varying from a mild brilliance to a gorgeous splendour, according to the quality of the light, and its mode of exhibition, may be greatly varied by the reverse process, viz. changing the lenses of the m¢nzatwre-forming glasses, just as done with the observing. Some of old Pritchard’s exquisitely minute lenses mounted by him give very charming miniatures. But these form no test of the quality of the objective in use, because their aperture is extremely limited. I now may be allowed to describe what has not before appeared before the Society—the singularly beautiful phenomena displayed by miniatures of sun-lit mercurial globules. It is well known that the surface of minute globules of mercury becomes more nearly spherical as they diminish in weight. The law of the curvature of these surfaces, dependent upon the specifie attraction of mercury, has been investigated by Professor Bash- forth, though not yet published ; and according to this law they seem incapable of forming a perfect image by reflexion. But under direct illumination (not that wild bull’s-eye side illumination of the globule hitherto employed) a minute spectrum of the sun 152 Transactions of the Royal Microscopical Society. may be descried. The use of a good prism as a reflector gives a pure beam greatly superior to a quicksilvered plane mirror. On one occasion the subtle delicacy of the interference-waves of light was thus revealed, for the whole of a series of magnificent phenomena was wholly obliterated by substituting a plane ordinary mirror for the prism.* | In the ‘Proceedings of the Royal Society,’ the appearances of a minute miniature of the solar disk, republished in this Journal, are so fully described, as dependent upon the quality and condition of the objectives employed, that I may be excused the trouble of re- capitulation here. I proceed therefore to treat of the miniatures of illuminated globules of mercury. ‘These may be dismissed with. the general statement that the symmetry, beauty, and fineness of the diffraction rings are severe tests of the objective. And finally : These rings are either wholly above or wholly below the focal point with a bright haze on the other side; or else equal and similar on both sides of the focal point; or altogether ill-defined. The experimenter will soon ascertain for himself these various appearances. I therefore pass on to the effects of obliquity. If the miniature-forming objective be slightly inclined, so that its axis has a few degrees of obliquity, a new order of effects dis- play themselves of extraordinary beauty and complexity. Sun-lit globules suffice; but of course a minute focal disk of the sun in miniature gives more brilliant effects. The conditions of over or under correction are beautifully seen, and the best possible adjustments still give very peculiar forms, some of which are shown in the accompanying drawings. The most extraordinary of all is the curiously winged butterfly form: the cometary, double vase, and conical diffractions are well worth development. These very beautiful solar phenomena, as shown by a miniature of the illuminated globule, vary their exquisite forms according to the quality of the glasses, and according as they are over or under corrected,. and according to * The same destruction of beauty and symmetry occurs with a badly con- structed screw-collar, whose movements decentre the component lenses: a very little error in this mechanical adjustment produces huge derangement. Better is a glass of lower aperture without such source of error, than a large aperture and loose adjustment... Indeed, a trifling difference of thickness in the glass cover introduces much milder error than the shake of the adjusting screw causing central displacements. Besides, if the glass be a little thicker than before, a slight extension of the draw-tube will compensate for thickness with extreme nicety. Lengthening the tube ‘‘ over corrects,’ whilst a thicker glass intro- duces “‘under correction.” In the case of telescopes with fixed glasses, I have never been able to persuade an optician to clean old glasses and reset them: it is almost always a total failure: nothing is more delicate and difficult than exactly — centring the lenses of a telescope, an instrument which seldom magnifies more than 500 times. How much more difficult then must be a movable construction of the » many lenses of a microscopic object-glass, which is used for much higher powers! Testing Object-glasses. By Dr. Royston-Pigott. 153 the obliquity at which the miniature is formed in the field of view by inclining the sub-stage. The surpassing beauty and pertfec- tion of these figures thus obtained by the magnified miniature of the mercurial solar star, render it probable that the obliquely ulumined mercurial globule, viewed dvrectly in close proximity to the front of the object-glass of the microscope, and placed upon the stage, 1s a very imperfect test; and the methods here described are submitted as possessing very superior delicacy and convenience. The perfection of the diffraction lines cannot be displayed at all by the old method. Eidola. With such instances of wonderful variation of the spectra formed by the miniature of a sun-lit mercurial globule, we may well suspect that innumerable diffraction images may be developed : (1) By obliquity of illumination. (2) By erroneous correction of the glasses. (3) By erroneous focussing. I. An absolute knowledge of structure cannot be probably ob- tained by obliquity of illumination. Those structures which can only be thus seen are liable to distortion and misrepresentation. Hexample (1). Display very fine gauze by oblique light and a low power a little out of focus, a complex structure is seen bearing very little resemblance to the reality. Hample (2). Treat the transparently-mounted eyes of an insect in the same way. ‘The eidolic forms of delusion are endless. The diffraction effects are the most exaggerated when the illumina- tion is most oblique. Il. Hxample (1). Uluminate perforated metal from behind in a darkened room ; view an exquisite miniature of these perfora- tions. ‘The holes will appear enlarged; black dots take the place of apertures; haloes join haloes, and the images are altogether disguised and transformed according to the correction of the observing objective and the focal plane of vision employed. Haxample (2). Fine copper wire gauze thus treated loses its apparent solidity. The meshes appear chequered with black dots, sharply defined, and the wires appear translucent. Thus in an unknown structure these false eidola might readily be mistaken for the true images. In this way a variety of forms having no reality start occasionally into almost tangible form and existence. IIT. Erroneous focussing. Microscopists are not always agreed in viewing an unknown object which is the correct focal plane. And it is just possible that different observers with the same instrument and adjustment view a different focal picture. 154 Transactions of the Royal Microscopical Society. The most peculiar difficulty of all is the existence of two sets of false images, viz. the one above and the other below the focal reality. This is seen beautifully in miniaturing (by the method now advocated) two distinct structures placed the one behind the other. In the case of the perforated metal the false images or e¢dola were made to exist in front of the true image. If therefore another structure were placed behind the first, the eidolic images of the one, as it were, will be mixed and confused with the real image of the other, and vice versa. | The earnest microscopist, remembering the results he has obtained from miniatures of the sun-lit or lamp-lit globule, that the false image lies wholly above or below the best focal point according ‘as’ the object-glass is over or under corrected, can have no difficulty in perceiving that also when viewing a duller object, a false image will similarly lie wholly above or below the real according to the corrections. A corollary may be drawn from these principles, viz. that in duplex structures the upper may be best seen by throwing the false wmage wholly below, for then the eidola of the lower structure does not mingle with the true image of the upper. And conversely the lower structure is best seen when the false images are wholly above, for then the,eidola of the upper does not mingle with the true image of the lower. In such cases under-correction best displays the upper and over-correction the details of the lower structure immediately subjacent. I now search among the Quadrata diatoms, and with a half- inch by Wray, of three lenses, I just discover a waviness like the early stage of Podura definition, of somewhat. irregular pattern, two of these objects lying exactly over each other at right angles. Another half-inch by the same maker, with a C eye-piece, sharply defines these dark waves, and upon entering with a D. the pecu- liar structure of these markings becomes delicately visible. A Ross 41,1851, resolves them ; but the 1870 water-lens of Powell and Lealand’s 4th now exhibits a more remarkable pattern than the Angulata. On applying the finest powers of definition I possess, these markings disappear almost entirely, and the view is wholly confined to the upper surface; then alone clearly beaded. I have just seen a beautiful example of illusion. On examining this evening a fine specimen of Moller’s Angulata plewrosigma, I succeeded in finding* several instances where two diatoms overlay each other at a favourable angle. On carefully illummating with a small achromatic pencil of direct rays, with a blue shade, I dis- * With Powell and Lealand’s dry eighth and © eye-picce about 800 diameters. Testing 7 Ce By Dr. Royston-Pigott. 155 cerned very Peal well-defined dark bars nearly parallel, with four rows of beads between each. The pattern is exquisite, and varies with a change of the screw-collar, but they look quite as real as the other structure. Here is a remarkable case of eidola. The images of the lower structure mix with those of the upper. These false images are best seen when the objects are overlaid at a slight obliquity. If they cross each other at a large angle, then these eidola change to large bright beading twice the natural s1ze. The transformation of appearances under the microscope by the application of a series of powers in order of power and merit, is a subject now worthy of special interest and development. For instance, the various plates and engravings of objects still extant, accumulated within the last fifty years, would upon patient in- vestigation yield instructive results as to the causes of these optical misrepresentations, for such, with the extraordimary ad- vances made in the goodness of modern glasses, we are now compelled to pronounce them. © I have the pleasure of recording here that just about four years ago I had the honour of first exhibiting to Mr. Slack many examples of eidola at my house. _ The diagrams accompanying this paper represent various forms of interference cievon eae developed by sun-lit mercurial globules, miniatured either by a 14-inch Ross or a+ Ross. ‘The sub-stage of the microscope employed has several movements, made by the writer about ten years ago, which enable the operator to manage the miniature as easily as an object on the stage, and also to give great obliquity. The examination of oblique pencils coming from the miniature, as to their conditions of achromatism or aplanatism, whether well or ill corrected, is thus rendered particularly easy and interesting. The figures given represent some of the many forms developed by different conditions of correction and obliquity, I should state that the Figures 3-14 were copied from sun-lit globules at my house by Mr. Hollick, of 135, hare Park Road, Holloway, N. : | VOL. XIII. : N “ET 6 29 | Ill.—On a Method of obtaining Oblique Vision of Surface Structure, under the Highest Powers of the Microscope. By F. H. Wenuam. (Described before the Royau MicroscopicaL Society, March 3, 1875.) Ir we take a thin semi-transparent object; such as a slice of melon, for the purpose of examining its structure, instinct directs us to hold it aslant to the light, and also to view it im an oblique direc- tion. Experience has taught us that if we oppose the object to very strong rays, and look straight through it, the minutiz of con- figuration will be obliterated by a flood of light. It is in this way that we see objects under the microscope, as their mounting lies square with the axis of the object-glass. For resolving the striated structure of the most difficult tests, extreme obliquity of the illuminating pencil is requisite, and numerous adaptations to the microscope have been invented for this special purpose. Let angle a, Fig. 1, represent the aperture of the object-glass, b the angle of the illuminating pencil for an object in the focus. It is evident that the portion of the object-glass brought most strongly into action under these conditions, is that opposite to the direction of illumination ; the near extreme will be in compara- tive darkness, and it is questionable whether this gives any material aid, by collecting mere radiations necessarily feeble, from surface con- figurations. This favours the hypothesis that, besides oblique light, oblique vision is an important condition for discovering the closest striations on microscope tests, and that their development does not probably depend so much upon a large aperture as the degree of obliquity at which they are viewed. Oblique vision is thus obtained by the extreme marginal and most imperfect image-forming rays of the object-glass. The best or central ones come so little into action, that they even mar the result; for, if obscured by a central stop, the exterior light is not overpowered, and greater distinctness in Oblique Vision of Surface Structure. By F. H. Wenham. 157 the appearance of the structure is the consequence.- The closeness of the high powers to the covering glass will not permit the slides to be tilted, to an extent sufficient to cause any appreciable differ- ence in the appearance of the object. The following arrangement will produce an extreme obliquity of vision obtained with the axial pencil of the object-glass. a, Fig. 2, is a slip of glass about 745 wide, ground and polished off to an angle. Objects to be mounted, such as diatoms or lepidopterous scales, are scraped up with the knife-edge, so as to be distributed thereon along the sloping plane. Those situated near the edge may be viewed with the highest powers, as the glass is of course thinner here than any cover. ‘The thickness of the remainder of the prismatic slip is of ~ no-consequence, and it may be of the same gauge as an ordinary thin slide. The slip is tacked on to a 3x1 slide with a dot of balsam or cement. Another similar slip, b, is then pressed endways against it, so as to lay the objects flat between the two inclines. The lamer prism is necessary; for without it, a deal of offensive colour enters the object-glass from the decomposition of the trans- mitted light. This is recomposed or neutralized by the under prism, which also greatly increases the obliquity of the illuminating ray by refracting this to the same angle as that of vision, from the deflection of the axial ray of the object-glass, The conditions are as follows. a, Fig. 3, is the central ray of the object-glass. This ray, after leaving the upper inclined surtace, is refracted in the direction b. If the surface is inclined near 40°, the upper side of the object will be viewed from a small elevation of between one and two degrees, according to the refraction of the glass; conversely, an illuminating ray thrown up axially with the microscope will strike on the object at the same degree; both the visual and illuminating angles will therefore be similar, as represented by line ¢, ¢’. - The degree of inclination of the facets of the prisms for dry objects should be less than 40°; for on holding before a flame a slide having this angle, and tilting it slightly, the width of the junction of the prisms appears as a dark band impervious to light— the effect of total reflexion. About 35° is therefore more suitable for objects mounted dry. If balsam is run between the inclines, of course total reflexion is eliminated, and refraction nearly so, and Pee ate 158 Transactions of the Royal Microscopical Society. we then only see the object at an angle the same as the incline; therefore for objects in balsam 45° would be preterable. In using Re with these prismatic or inclined mounts, it must be borne in mind that nearly every object lies under a different thickness of glass, according to the distance from the keen edge; therefore, having selected a suitable one, the objective is to be care- fully adjusted to give proper definition, and a thickness of glass over the scale may probably be found that will best suit its correc- tion. For dry mountings, the object-glass must be used dry, as water would run in and spoil the object. If this is in balsam, of course the immersion system can be employed. In the dry slide, a direct illuminator is used—such as the ordinary achromatic condenser; for, as shown by the diagram, axial light becomes that of excessive obliquity on reaching the object. At first sight, it might be urged that colour would arise from this extreme refraction or deviation of the axial ray of the object-glass ; but such is not the case, because distance must be an element in chromatic dispersion or separation ; and as the object is on the refracting surface, the outline is as free from colour as if seen through the usual covering glass. Nor is there any difference in the appearance, whether the object is adherent to the face of either the upper or lower prism.” * As there is no chromatic appearance, dense flint glass might be used for the prisms, as this medium having a higher refractive power, more acute angles would give the required obliquity of vision, Oblique Vision of Surface Structure. By F. H. Wenham. 159 These prismatic mounting slips may be cheaply and easily made by any ordinary glass-grinder, in the following manner: Thin well-polished sheet glass (such as is used for microscope slides) is cut into pieces, three-quarters of an inch long by four-tenths wide. Hight or ten of these are cemented together with hard Canada balsam, and their step-like projecting edges adjusted against a bevel, set at the desired angle, say 35°, as shown by Fig. 4. They must be pressed in very close contact, as it is important to have the edges worked fine and clean, and any thickness of balsam stratum between them will prevent this, for during the work close edges mutually protect each other. Having got a sufficient number of blocks together in this way, any quantity of them are cemented on to a runner or metal plate, as in Fig. 5, with the usual cement of IIIT pitch and wood ashes. They are then ground and smoothed on a flat metal lap, till all the steps are gone and keen edges shown, and are then finally polished. Thus hundreds may be made at a time. Discussion as to the effects of this suggestion of mounting for oblique vision, and its probable value, is at present premature. The author has done but little more than enunciate the optical principle. It may, however, be stated that the object selected should either lie in a parallel direction with the faces of the incline, or at right angles to it. If it occupies an intermediate position, rather a curious confusion of cross striation results. Oblique mounting affords a very marked means of discriminating whether the ribbings are on the upper or lower side of the scale, two of which adjoining sometimes showing the series in one very distinctly, and in the other confused, simply because they are relatively inverted. 160 . Transactions of the Royal Microscopical Society. One of the first objects observed was the scales of the common Be Soos saccharina (the active “window fish” of our childhood). The late Richard Beck announced that the markings on the lower surface of this scale consisted entirely of fan-like radiations starting from the quill—a. structure by some considered illusory ; but with axial vision thus refracted obliquely, the accuracy of this careful observer was confirmed, as these radiating lines were shown very distinetly, as if graven in black and white. hes hGH sso) LV.— On the Connection between F luorescence and Absorption. , By H. C. Sorsy, F.R.S., &., President R.M.S. Txovex the relation between fluorescence and absorption has already attracted a good deal of attention, there are some important facts which appear to be often imperfectly known. I have been surprised to find that even some of those who have paid considerable attention to such subjects have so far misunderstood the question as to suppose that the light of the fluorescence consists of rays which are as it were reflected by the solution, and do not penetrate through it, so that the spectrum of the fluorescence would show a bright band in the same place as some dark band seen in the spectrum of the transmitted light. This is certainly an error. A much nearer approximation to the truth is the conclusion arrived at by Lubarsch, who has recently published a paper on this subject in Poggendorff’s ‘ Annalen, * of which a good outline is given in ‘Der Naturforscher, 1875, Feb. 6th, p. 52. It is the appearance of this paper which has induced me to describe some of my own observations. He gives a table showing the connection between the fluorescence and absorption of eight different substances, all of which show that the spectrum of the light of fluorescence extends some distance on the red end side of the principal absorption band in the spectrum of transmitted light, commencing very nearly at that part which corresponds to the centre of the aksorption band, or maximum point of absorption. He expresses this law by saying that “ the spectrum of fluorescence of a substance can never contain rays which are more refrangible than those which are most readily absorbed by a very dilute solution.” To express this in wave-length phraseology, I should say that if a fluorescent solution gave by transmitted light a spectrum having a well-maiked absorption band, whose centre corresponded to light of some particular wave-length, as, for example, 600 millionths of a millimeter, the spectrum of the light of fluorescence would extend from nearly that point towards the red end, so as to include a band of light of wave- lengths varying from 600 to some other greater length, according to each particular substance. This is certainly such a common fact, that for a long time I was disposed to believe it to be general, but I have now had the opportunity of examining a greater number of fluorescent substances, and find that there are very decided exceptions. It appears to me important to know what is the true state of the case ; since, as I shall show, the study of the spectra of. fluorescence may often be of great value in deciding whether any solution contains a number of different substances in solution, or only one. In studying the spectra of fluorescent solutions, I often find it * Vol. cliii., p. 420. 162 On the Connection between convenient to examine them in the small glass cells used in all my chromatological inquiries, cut from barometer tubes, having a length of 4 inch and an ‘internal diameter of 3th inch. ‘The spectrum of the light of fluorescence depends a good deal on the kind of illumination. Of course transmitted light must be entirely excluded, and the solution illuminated by strong light thrown perpendicular to the line of vision. For this purpose I use a bull’s- eye condenser, which for the study of some substances is better if made of quartz, but for very many may be of glass. J then con- centrate direct sunlight on the uppermost part of the solution in the cell, so as to get very bright fluorescence, and at the same time to avoid letting the light of fluorescence pass through any such material thickness of the solution that it would lose any portion by simple absorption. The effect of this may easily be seen by con- centrating the sunlight on the lower part of the cell, and allowance made for any slight action due to this cause. Having observed the spectrum of the light of fluorescence, it is easy to examine that of transmitted light, by removing the condenser, screening off the side light, and reflecting light up through the solution by means of the usual mirror below the stage of the microscope. __ Whilst thus describing the general phenomena of fluorescence, it would, I think, be well to allude to what looks like it, but is entirely spurious. ‘There are some cases in which we appear to have a perfectly clear coloured solution with strong fluorescence ; and yet the substance is not really dissolved, but disseminated through the liquid in such extremely minute particles that they do not subside, and can be seen only by high magnifying powers, moving about tumultuously in currents due to slight alterations in temperature. On illuminating such a liquid by concentrated sun- light, passed through a solution of some salt of didymium, the spectrum shows all the bands due to this substance; whereas, if the liquid were quite clear and possessed genuine fluorescence, no trace of the didymium bands would be seen. The existence of some true fluorescence along with much spurious, due to minute disseminated particles, may be recognized by the presence of some of the didymium bands, and the comparative absence of others from those parts of the spectrum where the light of true fluorescence exists. By adopting these methods of observation, I have found that in: the case of some substances the light of fluorescence does contain rays of greater refrangibility than those most readily absorbed by a dilute solution, and extends from the red end a little beyond the centre of the main absorption band. This is, however, only when the illumination is strong and near the upper surface, and, if weaker or lower down, so as to increase the effect of absorption, the spectrum of the light of fluorescence extends only to the centre of the main absorption band, or may even stop considerably short Fluorescence and Absorption. By H. C. Sorby. 163 of the centre, and be bounded by the limit of absorption towards the red end. We may thus easily explain why there is a slight difference in the case of different substances ; since, if the intensity of absorption be greater in proportion to the intensity of fluores- cence, all other circumstances being equal, the limit of the light of fluorescence will lie more towards the red end than the centre of the main absorption band, than if the absorption be relatively weaker. The result is that in the case of the substances I have examined, the average limit of the light of fluorescence lies a very little on the red side of the centre of the main absorption band, which is in exact agreement with the observations of Lubarsch, t ough there is a very decided variation in different cases not shown by the substances named in his published list. | The knowledge of this law is very important in studying such mixtures of different colouring matters as are obtained in examining animals and plants. For example, when the superficial mem- branous coloured layer of some such species of fungi as Russula nitida and vesca is digested in alcohol, a purple fluorescent solution is obtained, which gives a spectrum with a well-defined absorption band, having its centre at wave-length 554 millionths of a milli- meter, whilst the spectrum of fluorescence extends far beyond that towards the blue end, up to wave-length 440. This led me to conclude that the coloured solution was a mixture of a purple non- fluorescent substance with one that is pale yellow and fluorescent ; and after trying various methods, I at length succeeded in separating two substances of exactly that character. If it had not been for such theoretical considerations, I might never have suspected that there was any such mixture. Another admirable illustration is furnished by the beautiful purple fluorescent solution obtained by keeping Oscillatoriz in water, described by me in this Journal, vol. m., p. 229. This gives a spectrum with two well-marked absorp- tion bands, having their centres at wave-lengths 620 and 569. The spectrum of fluorescence shows two bright bands, having their centres at 647 and 580, and their limits towards the blue end at 632 and 571, which bright bands are thus manifestly related to the absorption bands, as though they were due to two independent fluorescent substances mixed together. Now by heating this solu- tion to the point of the coagulation of albumen, a pink substance is deposited, and the clear solution gives a spectrum with only the band at 620, thus proving that the original solution is a mixture— a conclusion borne out by many other facts. In a similar manner. I was led to find that the higher classes of plants contain a mixture of two different kinds of chlorophyll (blue chlorophyll and yellow chlorophyll), by observing that the spectrum of the light of fluo- rescence of the solution showed two narrow red bands related to two absorption bands, and that on exposure to the sun one of these 164 Fiuorescence and Absorption. By H. C. Sorby. bands rapidly disappeared, on account of the unaltered yellow chlorophyll being decomposed by sunlight far more rapidly than the product of the action of acids on blue chlorophyll.* Though a knowledge of this connection between fluorescence and absorption may thus often cerve to indicate whether any coloured fluorescent solution is or is not a mixture, yet I must say that I do not think it furnishes conclusive evidence; since I have found a few cases in which what appears to be a single substance — gives a spectrum with fwo or more bright bands of fluorescence. The most decided case is that of the green colouring matter found in the annelid Bonellia viridis, described by me in a ‘paper in the current number of the ‘Quarterly Journal of Microscopical Science ’ (April, 1875). . This substance, which I have called bonelleie, is sreen and has strong fluorescence, and the spectrum of the light of fluorescence of a solution in-alcohol shows two bright bands,— one red and the other green,;—whose centres.are at wave-lengths 643 and 588, and their limits towards the blue end at 632 and 582, corresponding to two well-marked absorption bands, having their centres at 636 and 584, the latter being much less intense than the former. One might therefore suppose that it was a mixture, but on adding an acid the spectrum is materially changed, by the removal of some bands and the development of others, so that there is only one well-marked absorption band at wave-length 614, and a single red band of fluorescence, having the limit towards the blue end at 612, as though it were a single substance. Independent of the two bands of fluorescence, there is nothing to lead us to suppose that this colouring matter is a mixture. be Similar facts are met with in the case of the product of the action of acids on blue chlorophyll, but the limit of the band of fluorescence in the green is a considerable distance towards the red end from the connected absorption band, which agrees with the ~ general law, when, as in this case, the fluorescence related to the band in the green is comparatively weak. ‘The yellow substance obtained from some Aphides, which I have named aphedilutee, gives fluorescence with three bright bands, as described in my paper in the ‘ Quarterly Journal of Microscopical Science,’ x1., 1871, - . 352, : My conclusions therefore are, that though, on the average, the law adopted by Lubarsch is approximately correct, yet there are important differences in individual cases, depending on the relative intensity of the absorption and fluorescence, and in some instances it is necessary to modify the law very materially, so that it may express the connection between the fluorescence and more than one dominant absorption band. ; * «Proceedings of the Royal Society,’ vo]. xxi., p. 453. VEO 105 77): NEW BOOKS, WITH SHORT NOTICES. The Micrographic Dictionary. Third Edition. Edited by J. W. Griffith, M.D., Professor Martin Duncan, M.B., F.R.S.; assisted by the Rev. M. J. Berkeley, M.A., F.L.S., and T. Rupert J ones, F.R.S. Parts XVII., XVIII., XIX., and XX. London: Van, Voorst, 1874. (Szconp Notice.) We much regret that our remarks on the subject of the above work were “crushed out” of the last number of this Journal, as it neces- sarily makes our present observations more brief. We shall now run shortly over the Nos. XVII., XVIII., XIX., and XX.,—the last two being merely one number in reality, containing the remainder of the plates, and the various portions, as the preface and title-page, which are usually reserved for the final portion of a work which comes out in serial parts. And in the first place we must observe, that it seems to us the authors and their assistants have taken more care of the articles as they have approached the completion of the work, so that our criticism is less marked than it was in our review of the earlier parts. Imprimis, we have noticed several short paragraphs on the subject of Herr Haéckel’s work. These have been all new, and though brief, yet they are clear and to the point. Such are, for example, the several words Protista, Protogenes, Protohydra, Protomonas, Protomysxa. Protozoa is not lengthy, nor is it bad, but we think the writer has been much to blame in dismissing the important subject of biblio- graphy with the words “works on Comparative Anatomy.” He must have known very well that the great majority of works on the subject referred to, contain nothing in the shape of observations upon the Protozoa ; and it would not have occupied further space than he has occupied with the misleading reference he has given, to have referred to the best, and indeed the only book on the subject, the exceilent ‘Manual of Protozoa,’ hy Professor J. Reay Greene. Another point on which we have to take the authors to task is their reference to the ‘Microscopical Journal. Such a term might have been employed with indifference in the older editions, when there was but one periodical devoted to microscopy. But now it is absolutely inexcusable. For how is anyone to know whether the ‘ Monthly’ or the ‘Quarterly’ is the Journal referred to? It is exclusively the fault of one of the editors, for the other, when he cites either Journal, is always careful to distinguish between the two pericdicals. As we said in our former notice, the Fungi and Alge are excel- lently done, and so we must say of the last three numbers of the work. As a type of this we may take the article on Puccinia, which gives an excellent account of these peculiar fungi. Herepathite, too, is a good ~ paper, describing at length this peculiar salt and its polarizing properties. Raphides is not so good a paragraph as we should have expected. - Much work has been done on this point in our own country of late, and we should have expected that the ‘ Micrographic Dictionary ’ would certainly have taken notice of it. Rhizopoda is a 166 NEW BOOKS, WITH SHORT NOTICES. short but nevertheless a good contribution, and Rock Structure is also very fully given. _ However, we think that the writer might have given less space to his article on the latter subject, and withal have composed a fuller paper. For instance, we think he should have avoided the quotations which he has made, and he should have read Forbes’ paper to which he has referred. By doing so he would have been able to attempt something better in the shape of classification than he has given. Sotation or cyclosis 1s a good paragraph ; but Rotatoria is certainly too short a contribution for the ‘ Micrographie Dictionary.’ We had expected a tolerably long paper on the wheel-animalcules, but we are sadly disappointed, and we cannot urge a reason for this treatment of a class which is perhaps more than any other essentially the microscopist’s. Assuredly it is a mistake. Salivary glands is fairly done, and the notice contains allusion to Pfliiger’s remarkable discovery (?) of the nerves, which run, s0 to speak, into the very secreting cells of the gland. Sarcina, too, is a good contribution, but we hardly agree with the writer in his supposition that when it is formed in any quantity in the stomach, it is perfectly harmless. Is it not the case that many instances of gastric catarrh arise solely from the presence of this alga in the stomach ? The Scales of insects is, we think, but poorly done, and Mr. McIntire’s work is not at all fully given. Shell is fairly done, and so is Silica; in this instance the writer has evidently considered carefully the researches both of Messrs. Slack and Sorby. Spermatozoa and Spheroplea are excellently given, and will well repay perusal. ‘The articles on Spiral structures in plants ; Spores; Staining tissues ; Stomata; Vaucheria; Volvox, and Vorticella, are all good; they are, as a rule, modern, concise, and to the point. But, on the other hand, Teeth is a paper by no means so fully dealt with as it merits; mdeed, much of this subject is totally left out. But our most severe remarks have to be made upon one, and. only one contribution, that on the spinal cord. This is an eminently © bad paper, which by no means gives even a reflex of the splendid work achieved, both at home and abroad, on this important subject. It is really the only exceedingly badly executed portion of the entire work; but that it by no means indicates the great advance that has been made in this subject is but too evident. It were better to say nothing of the cord than to leave it and the brain in the condition in which they have been disposed of by whoever has had charge of this part of the Dictionary. And now we have to speak of the paper on Test objects, which, though it precedes some of the others, we have left to the last. On the whole, we look on this contribution as a very good one, for the remarks are terse and to the purpose; and there is a good deal of practical information on the subject of objectives (though not on immersion ones), which will prove immensely useful to the student who is commencing to work with the microscope. Still we must observe that the writer appears to us to state opinions in regard to the optical quality of penetration which are not universally held. Of course we may have misinterpreted his observations, but so far as we — have been able to gather from his remarks (and in regard to angular apertures we thoroughly agree with him) we do not see the force of © PROGRESS OF MICROSCOPICAL SCIENCE. 167 his opinions on the subject of penetration. To us it appears to be an optical defect, but one which is to a certain extent needed in anato- mical work, or indeed in any observation where one wishes for more than the mere superficial detail. _ However, it will, we hope, be seen that the ‘ Micrographic Dic- tionary’ is by no means the very imperfect work which it was represented to be by some critics; and though we could have wished for an improvement in the plates and in some of the articles, still we -are bound to offer our best thanks to the authors for what we consider on the whole a successful re-issue of a very elaborate work on the wide field of microscopical research. PROGRESS OF MICROSCOPICAL SCIENCE. How does the Ameeba Swallow its Food ?—According to the recent re- ‘searches of Professor Leidy (in ‘Silliman’s American Journal, Feb., 1875), some important facts have been arrived at. This observer remarked that he had supposed that the Amceba swallows food by this becoming adherent to the body, and then enveloped, much as insects become caught and involved in syrup or other viscid substances. He had repeatedly observed a large Ameba, which he supposes to be A. princeps, creep into the interstices of a mass of mud and appear on the other side without a particle adherent. On one occasion he had accidentally noticed an Amceba with an active flagellate infusorium, a ‘Urocentrum, included between two of its finger-like pseudopods. It so happened that the ends of these were in contact with a confervous filament, and the glasses above and below, between which the Amceba was examined, effectually prevented the Urocentrum from escaping. The condition of imprisonment of the latter was so peculiar that he was led to watch it. The ends of the two pseudopods of the Amceba gradually approached, came into contact, and then actually became fused, a thing which he had never before observed with the pseudopods of an Amoeba. The Urocentrum continued to move actively back and. forth, endeavouring to escape. At the next moment a delicate film of the ectosare proceeded from the body of the Amceba, above and below, and gradually extended outwardly so as to convert the circle of the pseudopods into a complete sac enclosing the Urocentrum. Another of these creatures was noticed within the Amoeba, which appeared to have been enclosed in the same manner. This observation would make it appear that the food of the Amceba ordinarily does not simply adhere to the body, and then sink into its substance, but rather, after becoming adherent or covered by the pseudopods or body, is then en- closed by the active extension of a film of ectosare around it. The Microscopic Anatomy of Sponges.—Infusoria has been very fully given with abundant illustrations in the February number of the ‘American Naturalist, by one of the editors, Mr. A. 8. Packard, jun. 168 PROGRESS OF MICROSCOPICAL SCIENCE. To these pages we would commend all who desire to know something of our recent knowledge of these important groups of animals. ‘We can only state the results arrived at, which are as follow in the case of the Infusoria. The writer says: “There are, then, two modes of development among the Infusoria (Ciliata): 1. By fission. 2. By pro- duction of internal ciliated embryo arising from eggs. We have, then, for the first time among the Protozoa, if the observations of Balbiani be correct (though this is denied by good observers), truly sexual animals, producing true eggs and spermatic particles. 'The same animal repro- duces both by fission and by the production of ciliated embryos. Most of them before producing embryos undergo fission. This is comparable to the alternation of generations among the Hydroids, Aphides, &e.” In the same manner he gives the following summing upas regards the stages of the life-history of sponges: 1. Fertilization of a true egg by genuine spermatozoa; both eggs and sperm-cells arising from the inner germ-layer. 2. Total segmentation of the yolk, or proto- plasmic contents of the egg. 3. A ciliated embryo. 4. A free-swim- ming “planula’-lke larva, with two germ-layers, not, however, originating as in the true planula of the acalephs. The planula becomes sessile, spicules are developed in the hinder end of the body, afterwards a gastro-vascular cavity appears, constituting the—5. Gas- trula stage. 6. A mouth and side openings appear and the true sponge characters are assumed, The Power of Motion which Diatoms possess.—In a recent paper before the Academy of Natural Science of Philadelphia (‘ Proceedings,’ p. 118), Professor Leidy made some remarks on the moving power of Diatoms, Desmids, and other Alge. While the cause of motion re- mains unknown, some of the uses are obvious. The power is con- siderable, and enables these minute organisms, when mingled with mud, readily to extricate themselves and rise to the surface, where they may receive the influence of light and air. In examining the surface mud of a shallow rain-water pool in a recent excavation in brick-clay, he found little else but an abundance of minute diatoms. He was not sufficiently familiar with the diatoms to name the species, but. it resembled Navicula rvaciosa. The little diatoms were very active, gliding hither and thither, and knocking the quartz sand grains about. Noticing the latter, he made some comparative measurements, and found that the Navicule would move grains of sand as much as twenty-five times their own superficial area, and probably fifty times their own bulk and weight, or perhaps more. How Pigment-cells are influenced by the Nerves.—We are glad to see that M. Pouchet, who published one of his first papers on the sub- ject in these pages, has been awarded the Montyon prize by the French Academy for his researches. The following abstract of the Commission’s report appears in the ‘Medical Record, Jan. 18, 1875: The memoir is in two parts, one purely anatomical, the other physiological. The former contains new facts, but it is the latter that has chiefly engaged the attention of the Commission. From this point of view the work is almost without precedent, | De tok 6 a ae ‘PROGRESS OF MICROSCOPICAL SCIENCE. 169 It was widely believed, indeed, that the skin of certain fishes took the colour of the bottom on which they lived; but exaggeration often de- prived statements to this effect of their value. In 1830 certain experiments on the subject, by Star k, were described in the ‘ Edinburgh New Philosophical Journal.’ Putting fishes in vessels enclosed in dark or in bright cloth, he perceived that the colour of the animals changed in the same direction, becoming darker or brighter; but he abstained from giving an opinion as to the internal conditions of production of this phenomenon. It has been shown by physiologists, further, that the colour of the frog's skin may be modified from various causes, section or stimulation of the nerves, various conditions of habitat in water or air, &c.; but it was pretty generally agreed that these changes might be explained by disturbances in the circulation, due to the various modes of treat- ment, and bringing about in their turn a change in the state of dilatation or of contraction of the pigmentary cells. The special feature of M. Pouchet’s experiments is that they show the pigmentary cells or chromoblasts to be in direct and immediate dependence on the nervous system; so that they must be added to the list of anatomical elements, in which nervous excitation is transformed into mechanical work. The nerves determine contractility of the chromoblasts, as well as that of striated fibres of voluntary muscles and fibre-cells of the muscles of vegetative life. The author first verifies the fact that certain kinds of fish, such as young turbots, placed successively in water on bright and dark bottoms, show very rapid changes of colour, or tone, produced by dilatation or contraction of the chromoblasts charged with dark pigment, more especially those having the réle of changing to brown, or abating more or less the proper colouration of neighbouring parts. As theve are also, however, contractile cells charged with coloured pigments vary- ‘ing from red to yellow, it may happen that, by the state of relative contraction of these different elements, the shade of the animal may be modified in a certain measure. : If in most of the species presenting these changes it is difficult to ‘make out the influences which cause them, there are other species in which the determining conditions may be ascertained with ease. Let a turbot, measuring only twelve to fifteen centimeters rest for some minutes over a light bottom, such as one of sand, and it hccomes pale in unison with the sand; let it rest, on the other hand, over a rocky bottom, and it grows brown like that. One has only to contrast two animals placed under such conditions, to ascertain that the brightness of their colouration corresponds exactly to that presented by the colour of the two bottoms. We may thus produce indefinitely, in the same animal, a considerable change of colour, which does not require more than twenty to forty minutes for its production, and is sometimes much more rapid. M. Pouchet calls this power which the animal has, its chromatic function. It is subject, within variable limits (according to species), to the influence of the nervous system. The colour of several species of fish was observed to change when they were irritated, or on simple 170 PROGRESS OF MICROSCOPICAL SCIENCE. sight of an external object. And since the changes depend on the greater or less absorption of light by the bottom, they must be regarded as true reflex acts, having their centre in the brain, and their starting-point in retinal impressions. ‘The fundamental experi- ment in M. Pouchet’s work is that in which he suppresses the chro- matic function by removing the ocular globe, or simply cutting the optic nerve. The blinded animal loses its power of changing colour according to the bottom. | | Having thus first established that the dilatation or contraction of the chromoblasts does not depend on local conditions produced in these elements at that point in the organism which they may occupy (as was previously thought), but is determined at a distance, by ante- cedent change of the elements of the central nervous system, it remained to find out by what route this transmission takes place, from the brain to the pigmentary cells of the periphery. The author made various sections of nerves, and he has demon- strated that the spinal cord is not the nervous conductor, nor yet the lateral nerve, to which it seemed natural to attribute a réle in this func- tion. The trigeminus, on the other hand, has a direct action. Turbots taken from off a brown bottom, and, after section of the trigeminus, placed in a basin with sandy bottom, grow pale over their whole sur- face, except the face, which remains shaded, as if covered with a mask. Section of the spinal nerves gives results no less distinct. It confirms what has been said about the negative réle of the cord. For the section of spinal nerves to influence the chromatic function, it is necessary that it be made below the point where they receive the thread of the great sympathetic. The result is a transverse dark band marking the region under the influence of mixed nerves receiving the cut sympathetic fibres. my | It is, then, the great sympathetic which governs the chromatic function. It forms the route of transmission for the influence going from the brain to the cutaneous chromoblasts. The disposition of this nerve in fishes, lying as it does in the same osseous canal with the principal artery and the principal vein of the body, does not allow of the section being made with advantage directly, as grave disorders ensue, which spoil the experiment. But the result of section of the mixed nerves, as above, sufficiently attests the influence in question. The author has not confined himself to fishes; he has shown that the chromatic function also exists in some articulata; more particu- larly in Palemon serratus, It may be demonstrated in the way that has been indicated for fish. Removal of the eyes, also, suppresses the function ; at least till these organs are regenerated. But M. Pouchet did not succeed in finding what route the nervous influence took in crustacea, from the cerebral ganglions. M. Pouchet’s observations establish, it will be seen, a series of new facts, which have, moreover, a remarkable character of generality. They open up an unexplored region, by revealing a series of reflex actions, of which the retina is the starting-point, and which irradiate | over the whole system. ) These researches were prosecuted at Concarneau, in the laboratory PROGRESS OF MICROSCOPICAL SCIENCE. 171 founded by M. Coste, which has already yielded various important scientific results. Effects of Concentration on the Movements of White Blood- corpuscles.— A very interesting paper recording experiments on the blood of the frog and newt, is that of Herr R. Thoma, which appears in Virchow’s ‘Archiv. * It has been abstracted in the ‘Medical Record’ of December 30, 1874, by Dr. W. Stirling. Herr Thoma divides his experimental inquiries into three sections: 1. Influence of the Concentration of the Surrounding Fluid on the Ameboid Movements of the Colourless Blood-corpuscles removed from the Body.—Blood of the frog, placed in a gas-chamber, and from which water was removed by the passage through it of a stream of air, showed that, in the portion of blood poor in water, the number of round, motionless, colourless corpuscles surpassed considerably the number of those showing changes of form. In blood in which the quantity of water was increased, the greater number of the colourless corpuscles showed the branched forms, such as are produced by the flowing movement of protoplasm. These corpuscles which adhere to the cover-glass are more spread out, show clearly three or four nuclei, and bear more richly branched processes, oftener contain vacuoles, and show more lively changes of form than those floating free in the fluid. This is, without doubt, due to the action of the surface, and is pro- duced by strong adhesion of the body of the cell to the surface of the glass. ‘This property also belongs to a series of other solid bodies, and also to the intima of the vessels. The white blood-corpuscles become more sluggish in their changes of form with increase in the concentration of the fluid, and the greater number change into rounded cells, which sometimes have fine processes on their surface. This is not due to death of the corpuscles, for on increase in the quantity of water they again become lively in their movements, and resume the properties of freshly-drawn white blood-corpuscles. ‘These observations were made in the blood of Rana temporaria and esculenta ; but the same is also true for that of Salamandra maculosa and Triton cristatus, and also for that of warm-blooded animals; at least for the guinea-pig and dog. - Under the influence of water, the contents of the white corpuscles may be increased four times, and this can only be regarded as an imbibition phenomenon. 2. Hxperiments on Colourless Corpuscles circulating in the Blood, produced by injection of water into the circulation of the frog.— Besides unchanged colourless corpuscles, there are a large number which show forms such as can be produced in blood under the influence of water outside the body. Those which lie upon the walls of the vessels exhibit very lively changes of form. In an opposite experi- ment, frogs were exposed for several days to evaporation. Microscopic observation showed that in the tongue, under these conditions, no — amceboid movements were to be observed in the corpuscles circulating in the blood, and also in those touching the walls of the vessels; and the injection of a 3 per cent. solution of common salt into the veins showed that increase of the quantity of salts acted quite in a similar * Vol. Ixii, Heft I. VOL. XIII. \ ce) 172 : NOTES AND MEMORANDA. manner to the regular concentration of the blood by the evaporation of water from the surface of the skin. 3. Experiments on the Wandering Cellsin Living Tissues.—The ques- tion was, whether colourless corpuscles which have wandered outside the vessels are influenced in a similar manner by differences in concen- tration of the tissue-fluids. The cells which have wandered out into the tissue show the lively amceboid changes of form and place, whilst, by infusion of a 3 per cent. salt solution and evaporation from the skin, the amceboid movements of the wandering cells becomes lower and very soon cease altogether. The same was observed with a 1°5 per cent. solution, the colourless corpuscles becoming round and shining, and changes of place could no longer be observed of them; whilst with a 0:5 per cent. solution the changes both of form and place were very lively. Irrigation of the frog’s tongue with salt solution of various strengths also produced important changes in the calibre of the blood-vessels and therefore on the rapidity of the blood-current. Under irrigation by a 0°5 per cent. solution, a very plentiful out-wan- dering, specially from the small veins, takes place, while in the same organ with a 1°5 per cent. solution, the wandering out of the colour- less corpuscles is completely suppressed. This solution acts first on the blood-vessels, producing a pronounced dilatation of the arteries, and therewith an acceleration of the blood-current in the arteries, capil- laries and veins, as Wharton Jones had already proved, and which, as H. Weber, F. Schuler, Buchheim, Vierordt, &c., showed, depends essentially on the diffusion of the blood-plasma with the salt solution. The acceleration of the blood-current is so considerable, that the venous current takes on part of the characteristics of the arterial one. Specially, the marginal position of the colourless corpuscles dis- appears. ‘The second effect of the 1:5 per cent. solution of common salt is its influence on the changes of form and place of the colourless corpuscles. | NOTES AND MEMORANDA. Notes on Recent Objectives.—The following observations are by Dr. J. A. Thacker, the editor of the Cincinnati ‘Medical News’ (January, 1875), and have a certain interest for our readers: “ Dr. J. G. Richardson, Microscopist to the Pennsylvania Hospital, read a paper before the Biological and Microscopical Section of the Academy of Natural Sciences, entitled ‘ Notes on the Performance of Two One-Fiftieth Objectives.’ One of the glasses was an immersion, by Tolles, and the other a dry one, by Powell and Lealand. Whether the object of the comparison was to determine the relative merits of the work of the makers is not stated; but if it were, certainly the mode adopted was very improper. An immersion lens should be com- pared with an immersion, a dry one witha dry one. It is as unfair — to compare a wet with a dry objective, as it is to compare an eighth NOTES AND MEMORANDA. 173 with a quarter. The drop of water gives an immersion lens a larger angle of aperture and more light, besides other advantages, and it has therefore, other things being equal, greater resolving power. The Doctor says that his skill, or unskilfulness, as a microscopist, were all constant factors, so that the superior performance seemed certainly due to the superior qualities of the higher power lens. Now, certainly, no greater fallacy could be than such an hypothesis. In unskilfulness chance is constantly occurring to deceive, and cannot be provided against. We think we can almost say, without exaggeration, that in the majority of instances an unskilful microscopist will select the poorer of two objectives as the one he can do the most with. And this is not very strange when we come to consider; for the finer a lens is, the more perfect must be the conditions for it to perform well, and the greater is the skill required in its management. A tyro, who is filled with admiration with the conduct of a French commercial objective that a microscopist would regard of no value whatever, would probably not be able to see anything with a fine Powell and Lealand ;,th, so perfect must be all the conditions in order for it to disclose its exquisite powers. Dr. R., in comparing the resolving powers of the two =),ths, found that the transverse strie of Surzrella gemma were easily shown, but that the finer longitudinal striz were not distinctly visible by gaslight. On our part, we never find any difficulty in bringing into view the transverse strice, with any ordinarily good quarter or even half inch, and we have no trouble in showing,. by lamplight, the longitudinal lines with our Powell and -Lealand’s qth, Verick’s No. 10, Gundlach’s German No. 7, Seibert and Krafft’s Ath, &., &e. ‘Under the employment of monochromatic sunlight, the Doctor goes on to say, ‘ these faint markings, which Frey says are “only to be aoe with much pains,” are clearly visible, even under Wales’ );th. Now, we are not the owner of a Wales’ sth, but we are of an eighth by him, and from its performance we do not think that with a little skill in its management there would be any difficulty in the .th mastering the longitudinal strize without the aid of mono- chromatic sunlight. Not only does Seibert and Krafft’s .4th bring out these faint lines without the aid of the blue cell, but even their ith does it with proper amplification. In testing with the Podura scales, the result of his comparative trials with central ight was that the (eee of the note-of-exclamation-marks afforded by the Tolles’ =th immersion was somewhat superior to that gun by the Wales’ immersion szth, and the Powell and Lealand’s dry =,th, although the advantage over the latter was very slight. We do not think that the Doctor’s judgment in this matter would have much weight with micro- scopists. The failure to define the longitudinal lines of the Surirella gemma with the glasses of such eminent makers. as Tolles, and Powell and Lealand, implies such a want of skill in manipulating very fine © lenses of high power, as to render an opinion valueless in regard ‘to any comparative merit. In the use of the microscope in the study of pathology, Dr. Richardson has undoubtedly done a great deal of work, and, in that department, has used the instrument to advantage, as the results of his labours have shown ; but, to judge from his paper, as a Qn 174 CORRESPONDENCE. manipulator in ‘advanced microscopy, he has not yet attained to a very high standard. Nor do we think that his knowledge of the capacity of glasses of different powers is sufficient for him to fully appreciate the comparative merits of high and low powers. In a recent article in the ‘Monthly Microscopical Journal’ he undertook to prove that high powers, as a =th and upwards, were valuable in that by their means the differences in the size of the red blood- corpuscles of man and the lower animals, by the greatly increased amplification rendering their comparison easy, could be so clearly made out that there need be no difficulty in discriminating one from | the other. Now, as has been pointed out in previous numbers of the ‘Medical News,’ all the advantages of increased magnitude can be obtained by means of amplifiers, in any lens of sufficient power to bring an object into view. To be more definite ; with a 4th, or at the most with a ;,th, with a high angle of aperture, the utmost limit of defining power is attained, and, having reached that, it is a matter of indifference at which end of the microscopic tube amplification is made. A .th, with an A eye-piece, magnifies 1250 diameters ; a +),th, with deeper eye-pieces and other means of amplifying, can be made. to magnify several thousand diameters, without material loss of sharpness of outline. Where, then, is the advantage of the latter over the former? In fact, it has been proven that the capability of the highest powers is less than those that are lower. For instance, Dr. Woodward has proven that a Powell and Lealand’s ;,th will show more than their =1,th.” : The Advantages of High and Low Powers—An American Diffi- culty.—The editor of the Philadelphia ‘Medical Times’ thinks that a committee of several microscopists should be appointed to settle the matter in dispute between Dr. J. G. Richardson and Prof. Hunt, of the Woman’s Medical College, as to the comparative merits of the former’s th and the latter’s ~)th—or the advantages of high over low powers. CORRESPONDENCE. OBSERVATION OF Test Diatoms. To the Editor of the ‘Monthly Microscopical Journal.’ Lonvon, February 8, 1875. Sir,—It may interest students of the diatoms most difficult to re- solve, to note a few of these objects as recently shown to me by Mr. W. J. Hickie, and I shall confine myself to a brief announcement of the principal results. I, Stauroneis spicula; with a »1,th immersion very little could be made out, but with a ~,th immersion objective the lines were dis- tinctly observable. This seemed to be a very delicate and useful test. PROCEEDINGS OF SOCIETIES. 175 The object was very flat, and I conceive that it would require very careful manipulation to display it. 2. In Navicula crassinervis the lines were distinct when viewed under a 54th immersion objective. 3. Two specimens of Frustulia Saxonica were shown with a >,th immersion glass, in one of which the lines appeared somewhat coarse, _ while in the other (mounted by Rodig) the lines were remarkably fine. 4. A select slide of Surirella gemma displayed fine markings under the 1,th objective, while with another slide of the same (taking the objects just as they came) under the same objective, the lines were less finely seen, though tolerably distinguishable. All the above objects were viewed by very oblique light. Some diatoms were then shown to me by straight candle-light, which I had never before seen so displayed. Under a 4th dry objective the following were noteworthy : ‘1. Navicula cuspidata, dry; two different slides by Lind, and another slide of the same in balsam, by Topping. 2. Nitzschia sigmoidea, mounted dry by Norman. 3. Hyalodiscus subtilis, mounted in balsam by Topping. 4. Navicula rhomboides, dry, by Norman. The above four diatoms were distinctly seen, to my surprise and pleasure, by a foreign }th. The same objective was brought to bear on Papilio janira (known to the readers and friends of Dr. Frey), but here it proved a comparative failure with direct light, while under oblique light the cross markings were clearly seen. | 1 will not take up additional space with further details on the above, or on less remarkable exhibitions of less difficult diatoms. Your humble servant, J. R. Lerronizp, PROCEEDINGS OF SOCIETIES. Royat MicroscopicaAL Society. Kinq@’s Cottece, March 3, 1875. H. C. Sorby, Esq., F.R.S., President, in the chair. The President, having been introduced to the meeting by his predecessor in office (Mr. Chas. Brooke), said that in taking the chair for the first time as President of that Society, he begged that the Fellows would allow him to express how much he felt the honour. which they had done to him. He had heard it said that there could be no greater honour than being elected President of an important scientific Society, since those on whom the election depended were of all men the best qualified to judge of the fitness of him who was chosen for the office. It would be affectation on his part if he were to say that he had not adequately devoted himself to the microscope, 176 PROCEEDINGS OF SOCIETIES. since he had made it his constant companion for something like twenty years; but at the same time he had applied it in such a different manner, and to such different subjects from those which were usually brought before the Society, that he felt himself in many respects very imperfectly qualified to preside at their meetings. His ereat aim had always been to occupy himself with those branches of research which had been neglected by others, and this had necessarily occupied so much of his time that he feared he was very imperfectly acquainted with much of what had been done by other observers. For his own part, he was inclined to believe that the development of new lines of inquiry and the application of new methods would conduce as much or more than anything else to advance science; but still, anyone devoting himself. to such subjects had necessarily to contend against many difficulties. He might say that in no respect did the fact that the Fellows had chosen him for their President give him more satisfaction than in its proving that the Society approved of new methods and of new kinds of investigation, and that in econ- sideration of that, they were willing to overlook many deficiencies and shortcomings in other respects. The minutes of the preceding meeting were read and confirmed. A list of donations to the Society since the last meeting was read by the Secretary, and the thanks of the Fellows were voted to the donors. Mr. H. J. Slack said that most of the Fellows saw a short time ago a curious living organism which was exhibited there by Mr. Badcock, and which was thought at the time might be the same as Bucephalus polymorphus. It was thought that it might have come from a fresh-water mussel. As some considerable interest attached to it, he thought it might be desirable to publish in connection with Mr. Badcock’s observations extracts from Von Baer’s paper and also some descriptions of similar organisms from the ‘ Annales des Sciences Naturelles, and from ‘ Comptes Rendus. Mr. Slack then gave a résumé of the extracts to which he referred (and which will be found printed at p. 141), illustrating the subject by drawings on the board. In reply to an inquiry from Mr. Beck as to the size of the creature, Mr. Slack said that it was quite small, but still in its free-swimming state visible to the eye. Drawings—which will be published with the paper—showing the natural size and also enlargements x 20, were handed to Mr. Beck for inspection. Mr. Badcock said that for some considerable time after he had een observing them, he could not find out that anyone else had described any similar creature, until Professor Huxley suggested that it might possibly be the Bucephalus of Von Baer. But having seen Von Baer’s remarks and drawings, and having carefully compared them with his own observations, he thought it impossible to identify them as the same from the description given. The mode in which Von Baer proceeded to dissect them out showed them to be tough and not easily injured, but his own specimens were so excessively brittle that it was most difficult even to take them up. They had been shown to numbers of scientific men who had not recognized their identity, PROCEEDINGS OF SOCIETIES. 177 and he would simply point out that Professor Huxley himself had since doubted whether the creature was the Bucephalus polymorphus of Von Baer, from certain appearances and observations which had been described to him, and also from the circumstance of its being found free swimming. ‘The resemblance to an ox he could not at all make out. | Mr. Slack suggested that Von Baer only used a magnification of 20 diameters. It was a mistake to suppose the creatures he found were tough. Mr. Badcock said that his own impression was that the creature might belong to the same class of animals as that of Von Baer, but might be a different species. Mr. Slack thought if most probable that higher powers might be required in order to determine the species. The thanks of the meeting were then voted to Mr. Slack and to Mr. Badcock for their communications. 3 A paper by Dr. G. W. Royston-Pigott, “On the Principle of testing Object-glasses by the Coloured Images produced by Reflexion from a Globule of Mercury ; and on Hidola,” was read by the Secretary. The subject was illustrated by numerous diagrams, which were ex- plained by Dr. Pigott as the reading of the paper proceeded. -. The President said that looking at the subject from an a priori point of view, he thought it might be very useful when applied to the study of forms of minute bodies which were well known, in order to see what kinds of false images were produced, so that it might be by analogy inferred what was the real nature of other bodies which were only known to us possibly by such kinds of images. Mr. Browning said he had followed the paper with considerable interest, but he had been rather puzzled by the statement that when a prism was used good images were obtained, but when a mirror was made use of they became confused. Dr. Pigott had, however, ex- plained this to him by saying that the mirror was a glass one having the back surface silvered. Dr. Pigott had often seen with a silvered glass mirror of this kind as many as half-a-dozen images of the flame of a candle, so that when this was used as a reflector, there were perhaps five or six images thrown one over the other in such a way as to obliterate the sharpness of outline. Mr. Elphinstone inquired if Dr. Pigott had seen in an early number of the ‘Quarterly Journal of Mathematics’ an article by Mr. Munro, “‘ On the Final Interference of Light,’ which bore upon these questions. It was well known that if they put two things marked in the same way one behind the other, and then looked through them, they would immediately get patterns, as in the case of two pieces of wire gauze, and it had often occurred to him that there were things seen in this way which, though described as real, were in fact only false images of things which showed two sets of lines, one behind the other. If they went to a pond and threw in two stones, and looked at the rings obliquely where they crossed each other, they would see a series of hyperbolas. No doubt the things they should 178 PROCEEDINGS OF SOCIETIES. see would be two series of circles, the one well defined and the other ill defined, and crossed by a series of hyperbolas. He thought there were often very erroneous appearances produced by seeing two series of markings one behind the other. Mr. Beck said that it was for that very reason that they had such difficulty in making out the nature of such fine structural markings as those on the diatoms, which were probably not simple structures, for nature did not deal in simple structures ; so that when looking at the structure of the Podura scale, it was not easy to say what it was they really did see; and he thought it was not so much by examining these objects themselves as by taking similar structures of a simple kind and arguing from analogies, that they would be able to form a correct idea of what really existed. The reference to a wire-gauze blind reminded him that if light were passed through it upon a sheet of white paper, by varying the distance they could get the effects of all the markings of the Diatomacez, but it was clear that none of them really existed. He must express his dissent from the statement that they did not learn anything from oblique light. He should quite agree with the opinion that if they were to settle questions of structure merely from what they could make out by means of oblique light, they would fall into a series of errors; but oblique light was of great value in many respects, particularly when sections had to be examined. They had not been told the size of the globules of mercury employed by Dr. Pigott; this was, however, not of great importance, as the real object in view was to produce an artificial star, the most minute point of light with which they were acquainted. Dr. Pigott said that Mr. Beck had very properly remarked that he had not said anything about the size of the globules. His practice was to pour out a small quantity of the metal, and then to keep sweeping the globules away until he got them sufficiently small for the purpose. Globules about {th of an inch were small enough to form a miniature, to be reduced by the objective employed. The thanks of the Society were voted to Dr. Pigott for his paper. Mr. Wenham then explained to the meeting a new method of viewing objects at extreme angles, and illustrated the manner of mounting and observing them by means of drawings on the black- board. Several mounted specimens were also placed in the hands of the Fellows for inspection. (Mr. Wenham’s observations will be found printed at p. 156). The thanks of the meeting were unanimously voted to Mr. Wenham for his communication. The President remarked that all observers were well aware that illumination was half the battle in microscopy. In many cases he had no doubt but that Mr. Wenham’s method would be a very valuable aid to investigation. Mr. Browning suggested that as the glass must be ground to a perfect knife-edge, the greatest care must be taken of the edges, as they would certainly break if touched. Mr. Wenham said he did not think there was much difficulty about that; the edges could be butted together, and would be pretty PROCEEDINGS OF SOCIETIES. 179 safe ; but of course they must be quite sharp, or the appearance of the jagged edge would be very unsightly. Any glass-grinder would be able to prepare them. Those he had brought to the meeting were made of the ordinary slip glass. Mr. Slack thought it mene be termed an oblique unilateral illu- mination. Mr. Wenham said it was the only plan by which the object could be obliquely viewed by the central portion of the object-glass. At the suggestion of the President, Mr. Wenham then drew a more enlarged diagram, showing clearly the method of mounting and the position of the object upon the slide. The President announced that the Council was endeavouring to arrange for a scientific meeting to be held on Wednesday, April 14— subsequently changed to 21st; also that at the next ordinary meeting of the Society he hoped to be able to read a paper “ On some New Contrivances for the Study of Spectra, and for apply pe the mode of Spectrum Analysis to the Microscope.” The Secretary, Mr. Stewart, called the paeell attention of the Fellows to some extremely beautiful preparations of Polycistine exhibited in the room by Mr. Stephenson. Some of them were new, and some were very delicately mounted, preserving the spines in a very perfect manner. Donations to the Library since February 3, 1875: From INLINE RICCI Giese =. ar tel (tae oe Ora Peres a al. Phe mditor: Athenzum. Weekly .. Bee ine mar trtre sence sett Mpa meta Noe Ditto. Society of Arts J: china. Weekly edi hbs Cities gy ten Ogi Usa ay OCLC. Journal of the Linnean Society. No. Ta AO ee es Ditto. The Cincinnati Medical News. Quarterly Journal of the Geological Society. No. 121 .. Ditto. Transactions of the Natural History Society of N orthumberland and Durham: Vol. Vie ..°. .. Ditto. Bulletin de la Société Botanique de France... Ditto. Microscopical Notes regarding the Fungi found present in Opium Blight. By Dr. D. D. Cunningham .. Author. A Report on the Microscopical and Physiological Researches into the Nature of the Agent producing Cholera. By Drs. Lewis and Cunningham .. ee. Authors: The Pathological Significance of Nematode Heematozoa. By Dr. T.R. Lewis... oe Author, Proceedings of the Literary Society of Liverpool. 1874s hee Society. A Monograph of the British Spongiadz. Vol. III. By Dr. Bowerbank Author. Charles Dexter Barker, Eisq., was elected a Fellow of the Society. Water W. REEVES, Assist.-Secretary. MicroscopicaL Society oF VicTorta, N.S.W. The first annual conversazione of the members of this Micro- scopical Society was held on the evening of October 29, 1874, in the Royal Society’s hall. There were about 200 ladies and gentlemen present. His Excellency the Governor, accompanied by Major Pitt, 180 PROCEEDINGS OF SOCIETIES. private secretary; Archdeacon Stoke, of New Zealand; and Mr. Samuel Johnson, arrived at the hall shortly before eight o ‘clock, and the proceedings were at once commenced. There were a great number of microscopes exhibited, some of them being of great power. Among the principal objects of interest shown during the evening were the following: Diatoms, or minute fossilized vegetable deposits, showing beautiful markings on their surface; foraminifera, or small marine animals—those found on Australian and New Zealand shores are very beautiful ; infusoria, animalcules generally prevalent in infusions of organic matter; rotifera, having cilia on their bodies, giving the appearance of wheels in action ; polyzoa, animals for the most part microscopic in their dimensions, found in most pools, streams, and on the shores, very interesting objects for anatomical examination, as well as for observation in the living state—some supposed new species will be exhibited ; insect dissections, which form a large and interesting branch of microscopy, plant cells and seeds; circulation in foot of frog and water worms, aud the ciliary motion in the gills of the mussel; one of the greatest curiosities was the cocoon of the leech; crystals shown with the polariscope; microphotographs, of which wonderful results have been effected ; wool-classifying apparatus. Some very fine microscopes of great magnifying power were also exhibited by Messrs. F. F. Balliere and Co., of 104, Collins Street East. There were alsosome handsome cases of Australian and exotic beetles, which were a source of great attraction during. the evening. Mr. Ralph, the President of the Society, having taken the chair, the Secretary (Dr. Robertson) read the following report : - The committee of the Microscopical Society of Victoria, in presenting their first annual report, are pleased to be able to give such good accounts of the state of the Society, both in its working and financial aspects. The Society was formed twelve months ago, and held its inaugural meeting in this hall on the 10th October, 1873. At that time it consisted of thirteen members. The number has now increased to thirty-six. The subscriptions amount to 54. 12s., and the expenses to 23/. 19s. 10d., thus leaving a balance in hand of 301. 12s. 2d. The committee desire in the first place to express their thanks to the council of the Royal Society for the kindness and liberality in granting the free use of this hall, both at the inaugural and this their first annual soirée; also to acknowledge with thanks the following presentations to the Society in their order: Microscopical drawings, by Dr. Sturt; a collection of Victorian insects, by Mr. Wooster, of Narree Warreen ; vol. vi. ‘ Flora Australiensis,’ by Bentham and Mueller, from the Government; a number of valuable books as a loan to form the nucleus of a library of micrographical works, by Mr. Sydney Gibbons ; some deep-sea soundings from H.MLS. ‘ Challenger,’ by Professor Wyville Thomson and Mr. Murray; some deep-sea soundings from the neighbourhood of King’s Island, by Mr. 8. S. Crispo, of H.M.C.S. Victoria; also some beautiful stalactites from the same gentleman. Besides these, numerous objects, mounted and un- mounted, have at various times been presented, and others promised, PROCEEDINGS OF SOCIETIES. 181 from various parts of the colonies. During the past twelve months: eleven meetings have been held, and the papers read and objects exhibited have been generally of great interest. At the inaugural meeting our late President, Mr. W. H. Archer, gave a very able address, which the leading papers of the colony thought fit to publish. in extenso, and which was reprinted in the ‘Monthly Microscopical Journal’ of England. Among the principal subjects at the subsequent meetings was a very interesting paper by Mr. T. 8. Ralph, our new President, “On the Fungus affecting the Rye-grass,” which proved to be Isaria gramimiperda, and this was borne out by Mr. Sydney Gibbons, who had investigated the same parasite. Mr. Archer brought forward some living specimens of Hydra viridis, and a fresh-water polyzoon, found in a pool on the banks of the Yarra, which he considered a new species allied to the Fredericella. Some entozoa found in-sheep and rabbits on a run near the Werribee, and which had proved very fatal to those animals, were kindly sent to the Society by Dr. Youl. Mr. Ralph and Dr. Wigg undertook to examine and report upon the same,’ and they were found to be a species of tapeworm—filaria and hydatids. Mr. Sydney Gibbons reported on some deposit found near Bacchus Marsh, consisting for the most part of diatoms. The microspectro- scope—the advantages derivable from the use of it in microscopic researches, especially in plant chemistry, toxicological, and medico- legal inquiries, were pointed out by Professor Ellery, and the committee trust at some future date to hear more upon this subject from such an able exponent. Mr. Gibbons read a paper “On a Mode of Detecting Sewage Contamination in Water,’ and mentioned an interesting fact as a proof of the purity of the Yan Yean, that the fungi found in impure water would not live in Yan Yean. of an inch in diameter. Hence, therefore, until further discoveries are made, a microscopist’s best efforts at revealing crime can only serve the cause of right and justice in those cases where the criminal’s attorneys, in spite of being forewarned, and consequently forearmed, are unable to prepare or suborn testimony to show that one of the creatures just enumerated has been killed in such a way as to produce blood stains, which are likely to be confounded with those from the murdered victim. Of course, however, a change in the prisoner's story, so as to attribute the blood spots to a dog, monkey, &c., after consultation with shrewd lawyers for the defence, or scientific friends, as in the case mentioned below, must have great weight with the jury, and go far to put them on their guard against the crafty trick attempted upon their intelligence. That I was led to avoid reiterating and emphasizing this failure of our science by no unfounded apprehension of the evil likely to arise from dinning such knowledge into the ears of rogues, is proved by the fact that after my testimony was delivered in the Lambee trial at Franklin, Venango Co., Pa., the prisoner’s “ keen, sharp-witted lawyer ” brought two female witnesses into court who testified that on a certain occasion about the time of the murder, when the defendant’s boots (on which were the suspected blood spots) were standing in the corner of a particular room, they were engaged in clipping the ears of a terrier dog, and just as they got one ear done the baby cried, and they were obliged to let go the dog, which ran round the apartment shaking its head, and thus sprinkled the boots with its blood. Further to substantiate this tale, a dog with one ear clipped was exhibited to the jury, and sworn to as the very one from which the blood was shed. For- tunately, however, it so happened that I had examined one or two spots upon the prisoner’s pantaloons, finding them to be human blood in contradistinction to pheasant’s blood, as he first explained VOL, XIII. R 216 Note on the Diagnosis of them to be; and since the contrivers of this dog story apparently forgot that the pantaloons were not standing up in the boots, and consequently had no chance to become sprinkled along with them, their ingenious theory failed to gain credence with the jury, who brought in a verdict of guilty of murder in the first degree. I venture to predict that from Dr. Woodward’s paper and this note to my own essays will spring, as from the dragon’s teeth of ancient fable, a host of bloody dog tales to account for suspicious stains on the clothing, &c., of murderers, until even attorneys for the defence become themselves ashamed to put forward this worn- out plea. Sometimes, as in a recent case wherein I was engaged,* the large amount of blood might enable us to expose some ingenious falsehood, attributing the tell-tale spots to one of the smaller animals, as, for instance, the rat, mouse, rabbit, or even lapdog. The other criticism of Dr. Woodward to which I wish to advert is his remark that he suspects I have underrated the amount of contraction which the dried and remoistened corpuscles undergo, estimated by Carl Schmidt at about 48 per cent. of their diameter. Numerous experiments made to settle this point lead me to remark that I stand ready to prove the greater accuracy of my measure- ments of the least deformed corpuscles examined by my method in the thin films of BLoop stains, but not in masses of dried blood clot. When the blood forms a stratum of some thickness, its cor: puscles during desiccation generally become crenated, and thereby diminish in diameter to two-thirds or less of their original size. It seems probable that some at least of the measurements of Carl Schmidt and others have been made upon red disks in this con- tracted state. , I wish to insist most emphatically that all my statements in regard to the diagnosis of blood stains are applicable to “ stains” only, and not to masses of dried. blood clot. In this conviction I reply to the chief point made by my critic in the London ‘ Medical Record, Sept. 9, 1874, that bearing in mind this possibility of the disks diminishing in size by crenation, I would—in the extraordinary and, I believe, as yet unreported case where a man might be convicted if a given stain were pro- nounced horse’s blood, and acquitted if it were human _ blood instead of the contrary—positively decline to say it was the blood of a horse, even if the corpuscles ranged from go'oo to sooo Of an inch in diameter. Two questions very properly suggested or urged by the learned counsel in the Lindsay case above referred to, during cross- * Trial of Owen Lindsay for the murder of F. A. Colvin. See Syracuse ‘Daily Standard,’ Jan. 30, 1875. ~ Blood Stains. By J. G. Richardson. 217 examination, I have made the subjects of repeated experiment, the results of which may be useful to future observers. First, as to the action of freezing upon the red disks, I find that drops of blood from my finger exposed upon pine wood for twelve hours to a’ temperature of about 15°F. so as to be frozen ito solid lumps, and then thawed and dried in a moderately warm _ room, present their corpuscles as distinct and uninjured as do ordinary blood stains. Second, similar drops of blood dried in about fifteen minutes by mere exposure in my office upon a hemlock chip, and also upon a fragment of oak bark, such as is used for tanning leather, like- wise exhibited the corpuscles with exactly the same characters, usually seen in those from common blood stains on paper or muslin ; and I therefore conclude that the amount of tannic acid taken up by the serum from the bark, and a fortoort from any kind of wood, under analogous circumstances is insufficient to alter these red blood disks. () 218%) NEW BOOKS, WITH SHORT NOTICES. The Pathological Significance of Nematode Hematozoa. By T. R. Lewis, M.B., Staff Surgeon H.M. British Forces. Calcutta: Office of Superintendent of Government Printing, 1874. The Government does well to attach to its Sanitary Commissioner in the Government of India so painstaking and industrious an observer as Dr. T. R. Lewis. For assuredly he has done much more excellent work than many who have had similar opportunities. Some couple of years ago we re- ceived the first part of Dr. Lewis’s essay on a Heematozoon inhabiting human blood, which was a most valuable monograph on the subject it dealt with. Now we have the second part of this memoir, in which the author completes the evidence he has already offered, and conclusively shows that the peculiar disease in which the most marked symptom is chyliferous urine, is caused by the presence in the blood of numbers of the particular entozoon which he has described and figured so minutely in this essay. And here we may refer the reader who is interested on the subject to Mr. F. H. Welch’s able paper on the subject of “ Filariz in general, with an account of the species in the Dog and in Man,” a paper of great importance, which appeared in this Journal for October, 1373. Dr. Lewis in his present essay has gone fully into the anatomy of the worm and into the history of its origin, as well as that of its position in the human and the dog’s bodies. From his researches on these points he appears to be led to the conclusion that though the two parasites resemble each other, and though their habitat is precisely similar, yet they are perfectly distinct. And this distinction appears in great part to depend on the possession by the human form of a distinct sheath, which is totally absent from the dog’s nematode. The disease appears to be perfectly common in the Indian dogs, at least one-third of the animals examined by Dr. Lewis being found infected. He describes the following as the pathological appearance found in the afflicted animals. “1. The most striking feature is the existence of fibrous-looking tumours, varying from the size of a pea to that of a filbert or walnut, along the walls of the thoracic aorta and cesophagus, both tubes being affected, or only one. 2. Minute nodules in the substance of the walls of the thoracic aorta, from the size of a duck-shot to that of split peas. They can be felt as tubercles, and usually project somewhat on the outer surface of the vessel; a depression or slight extravasation of blood, corresponding to the nodule, being visible on the inner surface of the aorta, and frequently a slight abrasion of the lining membrane. 3. A pitted or sacculated appearance of various portions of the in- terior of the thoracic aorta with thinning of its walls at some parts ; the lining membrane roughened at the spots affected; the roughening, however, is not of an atheromatous character, but due to the mem- brane being thrown into delicate rugs, as if from contraction of the middle and outer coat. 4. Enlargement and softening of some glan- dular body adjoining the vessels at the base of the heart.” NEW BOOKS, WITH SHORT NOTICES. 219 The structure of the worms is most minutely gone into, and in a set of three plates and various woodcuts the author minutely illus- trates the subject. With reference to the question whether these worms are associated with the so-called chyluria and elephantoid conditions Dr. Lewis makes the following observations. “Tt might be desired that I should express briefly (1) the chief reasons for the belief that chyluria and the elephantoid state of the tissues, referred to on a previous page, are associated with the pre- sence of a microscopic hematozoon ; and (2) in what manner, such connection being satisfactorily established, this fact can aid us in offering an explanation of the evidence we possess that the disease is due to mechanical interruption to the flow of the nutritive fluid in the capillaries and lymphatics: “1. With regard to the first clause, it may be sufficient to state that detailed histories of a considerable number of individuals affected in this manner have been published by me, and that in all the Filaria _ sanguinis hominis have been detected. I have now traced the Filaria to the blood direct in eleven, and detected them in one or other of the various tissues and secretions of the body in more than thirty indi- viduals. The history of one of these persons could not be ascer- tained, but all the others were known to suffer or to have suffered from chyluria, elephantiasis, or some such closely allied pathological condition. “2. With reference to the second clause, our knowledge is not so exact, and almost all the inferences have to be drawn from obser- vations made in connection with the hematozoon described in previous pages as occurring in pariah dogs. Judging from what may be seen in these, and frem data which the only post-mortem examinations which I know to have been made of individuals affected with this parasite, I think that the interference with the flow of fluid in the lymphatic capillaries and smaller blood-vessels may not unreasonably be attributed to one or other of the following causes: a. ‘To tumours, produced by encysted mature entozoa along the course of the blood- vessels and lymphatics, impeding the flow of fluid in them by pressure either directly or indirectly by interfering with the functions of the nerves supplied to the part. b. To the active migration of the imma- ture, or rather partially matured parasite; the act of perforating the tissues—nervous or vascular—producing more or less permanent lesions. ¢. To the activity of the liberated embryos in the capillaries causing the rupture of the delicate walls of these channels in which possibly ova may have accumulated owing to their size, or an aggrega- tion of active embryos taken place, either accidentally or by the parent having migrated to the capillary termination of a blood-vessel, and there given birth to a brood of microscopic blood-worms. Once the walls of the capillaries have given way the embryos pass into the adjacent lymph channels, the boundaries of which are so extremely delicate as practically to offer no impediment to the further progress of such active organisms. Should the lymphatic spaces be situated in intimate relation with a secreting surface, the escape of the minute filarie, as well as the escape of fluid from the lymphatics 220 PROGRESS OF MICROSCOPICAL SCIENCE. with the ordinary secretion of the part, would seem to be a natural consequence.” It will be seen from the foregoing quotations what this author endeavours to prove in the pages of his essay. So far as we can see, he has abundantly shown, if not the connection of elephantiasis, at least the undoubted relation of chyluria to the presence of these parasitic nematodes. PROGRESS OF MICROSCOPICAL SCIENCE. The Fecundation of Certain Fungi.i—The ‘Academy’ (March 13) [which by the way is a thoroughly able paper| has an interesting note on M. von Tieghem’s researches on the above subject. ‘This savant has recently brought before the French Academy some interesting experiments on the fecundation of certain fungi (Basideomycetes), con- firming the statements of M. Reess, to which he refers, and throwing fresh light on the interesting question of sexuality in these lower organisms. M. Reess made his observations. on the common dung fungus Coprinus stercorarius, and M. von Tieghem selected for his Coprinus ephemeroides. Placing a spore of this little agaric in a de- coction of dung, and confining it in a cell, under the microscope, he found it soon germinated, producing a branched cellular mycelium, anastomosing, not only from branch to branch, but from cell to cell, along each branch; the branches being about 0-003 mm. in diameter. In most cases the mycelium tubes produced, in the course of five or six days, tufts of narrow rods (baguettes), springing, sometimes to the number of twenty, from the tip of a short lateral branch. Lach of these rods divided itself into two smaller ones (bdtonnets). The upper one detached itself and fell away; the lower one grew at its base and divided again. When this had gone on two or three times, the basilar joint fell off, and there remained only a pedicel and a great number of small white rods lying by it. These were 0°004 mm. to 0-005 mm. long and 0:0015 mm. wide, and often having a brilliant granule at each end. When these rods were sown in the dung decoction they did not germinate. In another set of similar experiments, no rods appeared, but about the seventh or eighth day—that is to say, when the little rods in the contemporary experiments had separated from the stems, certain lateral branches swelled at their summits, forming large vesicles, separated by partitions from the pedicels bearing them. Sometimes these vesicles, which contained a dense protoplasm and usually exhibited three vacuoles, grew in loose tufts. M. von Tieghem, having thus obtained the little rods and the vesicles in separate grow- ing cells, brought them together, and saw the “rods” attach them- selves to the vesicles, and empty into them their contents. The vesicles thus fecundated lost their vacuoles, formed two internal PROGRESS OF MICROSCOPICAL SCIENCE. DOA divisions, and transformed themselves into large tubes composed of three superimposed barrel-shaped cells. The basilar cells, which were the longest and narrowest, soon pushed out curved lateral branches, and were followed by the median cells. The branches, which were multicellular and ramose, pressed against each other and formed a little white tubercle, the beginning of the fruit. The “ Membrana Nuclei” in the Seeds of Cycads.—At the meeting of the Linnean Society, on March 4, Professor Thiselton Dyer read a brief note on the structure of the so-called ‘‘ membrana nuclei” in the seeds of Cycads. Heinzel had described this as a cellular struc- ture, the cells of which had thick walls penetrated by ramifying tubes. There is reason, however, for believing that the membrane only represents the wall of a single cell, and is, in fact, probably the greatly enlarged primary embryo-sac. What Heinzel had taken for tubes seemed really to be solid. They are arranged all over the membrane after the fashion of what carpet manufacturers call “ moss- pattern.” They are possibly the débris of the thickened walls of the cells of the nucleus which had been destroyed by the enlargement of the primary embryo-sac. In the discussion which ensued a remark- able diversity of opinion was displayed among the microscopists present, as to whether the reagent magenta exhibits the largest amount of its characteristic reaction on the cellulose wall of the cell, or on its protoplasmic cell-contents. Where do the White Corpuscles get through the Blood-vessels ?— This question is answered by M. L. Purves in a recent number of a Utrecht Journal, which has been abstracted in the ‘ Medical Record’ lately by Dr. W. Stirling. It states that M. Purves, in order to in- vestigate the place where the white blood-corpuscles pass through the wall of the vessel in Cohnheim’s experiment on inflammation, injected a solution of silver into the vessels of a frog prepared after the manner of Cohnheim. The colourless corpuscles, without ex- ception, wander out between the boundaries of the epithelioid cells. They never pass through the substance or through the nucleus of an epithelioid cell. According to the author, the red corpuscles only pass out by those channels which have been previously made for them by the colourless corpuscles. The author found no stomata of any kind on the epithelium of the vessels. Natural History of the Diatomaceew.—Dr. M. C. Cooke states in ‘ Grevillea’ (March, 1875), that Dr. Edwards has sent him a copy of the chapter from the Reports of the Geological Survey on the above subject, which is written in a popular style for general readers, and extends over nearly 100 quarto pages. The sections into which it is divided are: 1. Introduction. 2. Movements of the Diatomacez. 3. Mode of growth of the Diatomaces. 4. Reproduction of the Dia- tomacez. 5. Modes of occurrence and uses to man of the Diatomacee. 6. The Diatomaceze and Geology. 7. Directions for collecting, pre- serving, and transporting specimens of Diatomacee. 8. How to prepare specimens of Diatomacez for examination and study by means of the microscope. This enumeration of the sections will give an 222, NOTES AND MEMORANDA. idea of the scope of the “ History,’ which will doubtless be of eminent service in the direction for which it is intended. “ Unfor- tunately the general public know but little, and care less, about the lower Cryptogamia, except for Alge grouped as pretty objects for tke drawing room, or ornate diatoms arranged in groups to please soirée hunters, or stewed mushrooms, and Perigord pies.” NOTES AND MEMORANDA. The Belgian Microscopical Society——This Society, founded last year on the model of the Royal Microscopical Society, is rapidly growing into importance, and bids fair to perform its part in micro- scopical research. It has, we are informed, just conferred, through its President, Professor Miller, the honorary Fellowship of the Society upon Mr. Jabez Hogg. The Compound Microscope in the Examination of Patients.— Dr. H.G. Piffard has devised a simple contrivance by means of which the binocular microscope can be employed in the ordinary “ out- patient room,’ for the examination of the skin of patients suffering from skin affections. The inventor’s remarks in the last number of the ‘ Archives of Dermatology ’ are, as to the subject of the aberration of lenses, utterly unimportant. But his idea of employing the binocular is a good one. He says: “The objectives which I employ are a 6”, 2", and 1” of Grunow, a 4” and 4” of Ross. The 4” is made with taper front, specially constructed for use with reflected light. The advantages of this arrangement over the single lens, are enlarge- ment of the field of view, absence of spherical and chromatic aberra- tions, convenient distance of the observer's eye from the object observed, ten times the amplification practically attainable with the simple microscope, and lastly, the very great advantage of true stereoscopic vision. With the mstrument described any portion of the integument from the scalp to the sole of the feet can be conve- niently examined, and a prolonged examination can be made without fatigue to the observer. ‘The ordinary diffused light of a bright day affords ample illumination with all the objectives except the 4”. For this we need direct sunlight. If the examination be made at night or in a dark place, the light from a Tobold or other good illuminator, concentrated upon the object with a mirror or bull’s-eye condenser, will answer every purpose.” _- (2228) CORRESPONDENCE. An Exepnanation From Mn. Toes. To the Editor of the ‘Monthly Microscopicul Journal,’ Boston, February 13, 1875. Sir,—In your last issue Mr. Wenham grievedly says: “ That dis- cussion with Mr. Tolles is useless, is proved by his article, page 21 of this Journal for January, 1875, where, in order to show that I am wrong, he first tries the slit without and then with water contact, in the last case measuring not the internal cone, or immersion angle, but the increased emergent angle from the under surface of the slide,” i.e. the air angle of the immersion objective. Just what and all I was talking about. Now drolly enough he says, in closing his commentary, that even if this, the focal point, “falls exactly on the under surface of an intervening plate of glass in water contact, it will still cut off stray rays within the glass, and give the true air angle, as one of final emergence.” Very well said. Now let Mr. Wenham interpose the thin plate of glass, viz. “cover” so near to 0°013 of an inch thick as the ith sent Mr. Crisp will work through with water contact at “ closed” adjustment of the objective and then putting the light down through the micro- scope tube accordingly as he says is the correct way, then measure the emergent pencil and report “the true air angle as one of final emergence.” This will be very fair, and I pointedly invite it in accordance, if you please, with your own suggestion appended to my article of August last, ‘M. M. J.,’ p. 65. I repeat,—what seems unnecessary to say again,—I talk here (as in my last) of the emergent air angle of that immersion objective only,— and I promise him more than 112° ! But again,—“ ONE HUNDRED AND EIGHTY DEGREES!” In quoting from Mr. Wenham’s article, p. 113 this Journal, March, 1874, I, in my reply, alluded to the above-quoted inscription as being given by Mr. Wenham in “small caps,” and Mr. Wenham thought I meant his “stops” over the ith.—My fault. I suppose they are “screaming capitals” more descriptively. All this about 180° I abate for the present. Jf it should ever happen to be proven to Mr. Wenham that more than 82° of corrected “ balsam ”’ angle existed in an objective, say 90°, I presume he would admit that such an objective must have an air angle “ up to 180°.” But now let all that be apart. Mr. Wenham admits the thin plate of glass which before he did not use, and, water contact. Let us know then (and thus) if the “true air angle” of “final emergence” is 112° only, or a “rational and wholesome angle ” somewhat above that. Yours respectfully, R. B. Toutes. 22.4 CORRESPONDENCE. Note by Mr. Wenham. Anyone taking the trouble to interpret the above curious letter will admit that controversy should cease concerning apertures pecu- liar to Mr. Tolles. IJ have tried the 4th as in paragraph 3rd with lenses closed, and the focus on the front of a thickness of glass in water contact. As might have been expected, the aperture is the same, whether the glass is there or not—a practical exemplification of the first rule in optics. I have done with the 1th, which is here ac- cessible for trial by others if asked for. I am confident that the apertures will be found as I have stated and that the extra immersion angles claimed have no more real existence than the 180° engraved on the object-glass to the delectation of such as are ready to believe, in spite of the focal distance and small diameter of front lens. ANGULAR APERTURE. To the Editor of the ‘ Monthly Microscopical Journal.’ Boston, March 11, 1875. Srr,—In your Journal for March.current, p. 131, Mr. Wenham says, “I repeat (as I have stated before) that I did try the 1th of Mr. Tolles with several thicknesses of glass in front, and whether these were superadded in water-contact or not, the aperture or ulti- mate emergent pencil was alike with all.” The clause, “as I have stated before,’ is a mistake. I deny, with challenge, that he has ever so stated before in the pages of your Journal. This is what he has said, ‘Monthly Microscopical Journal’ for November, 1874, p. 223: “In measuring varying angles of aperture by the usual method, we take them at all points of the adjusting collar, and do not place in front a thickness of glass suitable for that correction, because with a parallel plate of glass there is no per- ceptible difference. The angle at the crossing point of the rays is the same whether it is there or not. I stipulate that the edges of the stop shall be in the crossing point. If anyone thinks proper to introduce an intervening plate of glass, serving no purpose, he must focus through it, so as still to get the stop in the focal plane.” Here is strong implication at least that he did not use ‘‘ cover” to fill up the interspace. I suggest that he try it, or tell us what hap- pened when he did try it. He has not reported accurately. Let him use cover, the thickest the 4th will focus through at “closed” the edges:of the slit thus “in the crossing point”’ of the “ corrected” rays, and I will bide the result. Because I know the state of the case from irrefragable proof, in the first place, in my own hands, and I naturally expect he will get like results. Something more than 112°! Yours respectfully, R. B. Touss. CORRESPONDENCE. DI 5 Note by Mr. Wenham. Though I have received an intimation from the Editor that the discussion concerning the aperture of Mr. Tolles’ “180°” ith is closed, I have asked for the insertion of the above that he may not complain of injustice, that the last item of his defence has been sup- pressed. What is the character of that defence? The science of the question having been exhausted, it has degenerated into a search for inconsistencies in my writings, with the view of imputing to me false statements concerning things measured and observed. Had Mr. Tolles quoted a few more lines to the end of my sentence, I there stated that the aperture was found to be the same if parallel plates were inter- posed. I have a vivid recollection of selecting a thickness of glass that the lens would just focus through. I now take from my note- book as follows: “‘ Maximum distance of dry focus 013. Will pene- trate a cover °018 thick (at adjustment on its under surface). With the slit in focus in each case this plate did not increase the aperture. I decline to argue on a principle so obvious as this. The date in my note-book is January 17, 1874. So for near fifteen months argument concerning this 1th has dragged out its weary length, by Mr. Tolles requiring me to answer his “ challenges ” in defence of the wonderful apertures engraved thereon. I can testify that Mr. Tolles commands a high degree of manipulative skill, and deserves every success in a somewhat hard and profitless line, for his industry and persevering experiments for improving object-glasses ; and the tone of his letters when left to his own diction speaks favourably for his good nature. |The controversy as to Mr. Tolles’ 1th objective must now end.— Ep. ‘ M. M. J.’] Urinary Derrostrs—A Note sy Dr. Orp. To the Editor of the ‘Monthly Microscopical Journal.’ March 9, 1875. Drar Sir,—In referring to some papers by Dr. Bence Jones relating to urinary deposits, I find that beyond recording the influence of chloride of sodium in modifying the form and increasing the solu- bility of urate of ammonia, he, in a paper contributed to the Medico- Chirurgical Transactions in 1844, relates experiments which agree with and therefore anticipate some of the experiments related in my paper read before the Royal Microscopical Society in January last. At page 111, he records that he heated needles of urates of ammonia for some hours at about 212°, so that decomposition took place ; boiling water was then poured on and filtered whilst hot. A deposit obtained at the end of forty-eight hours consisted of globules, and globules with projecting angular crystals and crystals of uric acid. ‘This experiment is very like my second experiment with urate of ammonia in principle and in results; though Dr. Bence Jones used the experiment for a different object from mine. At page 113 he writes: “A large excess of needles was boiled 226 PROCEEDINGS OF SOCIETIES. with distilled water and filtered while hot, a little salt was added, and after some hours largish globules were deposited, and no needles.” This is clearly an anticipation of experiment 6 on urate of am- monia, and of the general principle of many others. I think it right to draw attention to these experiments, first in justice to Dr. Bence Jones’s most valuable work ; second, in order to point out the remarkable agreement of these experiments with my own, although the two sets of experiments were undertaken with different objects, and certainly lead to diiferent thought and applica- — tion ; third, in order to clear myself from any charge of intentional plagiarism. I am, Sir, your obedient servant, W. M. Orgp. ——__—___ CARPENTER ON THE MIcROScOPE. To the Editor of the ‘Monthly Microscopical Journal.’ March 18, 1875. Sir,—Mr. Stodder has called my attention to an error in p. 213 of the above work, where Mr. Tolles is spoken of as having made the 3th objective, so highly commended by Dr. Woodward. This glass was made by Mr. Wales. The binocular eye-piece ascribed to Professor H. L. Smith should have been placed to the credit of Mr. Tolles. Your obedient servant, Henry J. Stack. PROCEEDINGS OF SOCIETIES. © Royat Microscorican Society. : Kine’s CoLteGe, April 7, 1875. H. GC. Sorby, Esq., F.R.S., President, in the chair. The minutes of the preceding meeting were read and confirmed. A list of donations to the Society was read by the Secretary, and the thanks of the meeting were voted to the donors. The Secretary said that a very important paper had been received, entitled “ Further Researches into the Life History of the Monads,” by the Rev. W. H. Dallinger and Dr. Drysdale, in which they con- tinued the subject treated in their previous papers, and gave a complete life history of a new species found by them in a maceration of cod’s head. Other engagements would not permit of the paper being read that evening in extenso, and therefore after briefly alluding to its con- tents, he proposed that it should be taken as read; it would then be a PROCEEDINGS OF SOCIETIES. 227 printed in the next number of the Journal, and the Fellows would be able to read it before the next meeting, at which any discussion arising out of the subject could be taken. (The paper will be found printed at p. 185.) The paper was then taken as read, and a vote of thanks to the authors unanimously passed. The Secretary announced that in consequence of the large hall of the college being required for other purposes, the Society would in future hold its meetings in the library. The scientific evening would also be held in the library and adjoining suite of rooms on the 21st instant, and the Council hoped that as many as possible of the Fellows would bring their instruments and objects of interest on that occasion. The President, H. C. Sorby, Esq., F.R.S., then read a paper “ On some new contrivances for the study of the Spectra, and for applying the mode of Spectrum Analysis to the Microscope.” He first exhibited and explained the apparatus used in his experiments and investi- gations, showing the new arrangement for employing an ordinary eye-piece in connection with a slit and prisms; and also the con- struction of the binocular spectrum microscope, and the method of comparing the spectra of two objects in the field of that instrument. The importance of obtaining equal illumination in both spectra was pointed out, and the means of regulating the light was also described. The measurement of the position of absorption bands by means of the quartz interference scale, the spot method, and the wave-length method, were explained, and the relative advantages of each were set forth. After some interesting observations upon the meaning of the absorption bands and the variations produced in their positions by acid or alkaline additions to the same solutions, illustrations were given by means of coloured diagrams of a few remarkable Spectra which had recently engaged the attention of the author, and he inti- mated his intention to exhibit and further oo the apparatus and objects at the forthcoming scientific evening. Mr. Slack having proposed a vote of thanks to the President for his paper, it was put to the meeting and carried unanimously. In consequence of the lateness of the hour the discussion upon the President’s paper was postponed until the next meeting. (The paper will be found printed in eatenso at p. 198.) Donations to the Library and Cabinet since March 3, 1875: PN EMTIC MMIC CES V ionic Meld ces Meare Saat Mee ite mes MEE aha Phen Ban toy: PAwyMeNce TIM GNMCCKLY oe EE eg ea ele Rls Meee ale Ditto. Soclenmonanierournal.) \Weelkly) oi.) ae) th constructed by him was of about that aperture. Immersion lenses, Dr. Abbe says, allow of good correction to an air valve of 180°, giving, according to Zeiss’ catalogue, from 104° to 108° in water ; and an objective that corre- sponds with our English sth has the power of working through a covering glass $th mm. thick.* With regard to Zeiss’ immersion systems, 3th, ~;th, and 5th, of about 100° aperture in water, he says: ‘“ Personally, I am con- vinced that even in immersion systems, for the normal requirements of science, there would be no loss, but in many respects a gain, if they were constructed with smaller angles of aperture, although we cannot suppose that practical opticians will exert themselves in this direction while, according to a universally spread opinion, such objectives would be valued as of only second rank.” It is this absurd mode of valuing objectives that is now the greatest hindrance to further progress. An optician can get great credit for giving a 4 inch an angle too much for a ='sth, but might get no credit for constructing a quarter of moderate angle so perfect in correction as to possess the resolving power associated with a large-angled ';th, and yet to accomplish the latter would be a feat of higher skill and of much greater usetulness. No English optician is known to the writer as now attempting this task, and we must refer to Zeiss’ productions for illustrations of what has already been accomplished. There are, however, small- * The millimetre is equal to 0:039 of an inch, one-fifth of which is nearly 4 si inch. On Angle of Aperture. By H. J. Slack. 237 angled ths in existence by our great makers, of remarkable merit, and their resolving powers would probably be found very consider- able if new modes of illumination were applied to them. Dr. Pigott possesses a 1th of Andrew Ross’s, angle about 68°, which with E eye-piece and 16 inches of tube can show his famous Podura beads, which are certainly fine tests, whatever disputes may continue as to the structure that causes their appearance. In Professor Abbe’s paper there is a reference to Dr. Pigott’s “ Aplanatic Searcher,” which is condemned, not on the ground taken by certain objectors here, but for a reason that its inventor will be the first to endorse, namely, that the corrections it can make ought to be effected by the optician through an improvement in the combinations he employs. Some years ago Dr. Carpenter showed that excess of angular aperture led to great distortion of objects seen with the binocular microscope, converting spherical bodies into ovals, &c. He stated that he “had caused Messrs. Powell and Lealand to construct for him an objective of half-an-inch focus, with an angular aperture of 40°, and found it to answer most admirably.”* If we take this angle of 40°, as best suiting magnifications of from 90° to 120° or a little higher, what angle will best suit higher powers so as to avoid dis- tortion? This is a question for which it is difficult to find the data for a mathematical calculation, but we may perhaps arrive at it approximately by well-conducted experiments. It is often supposed that an object: that requires very oblique illumination must also require a large-angled glass to view it; but the better the spherical correction and the less false light—that is, light not concerned in forming an optical image—that is admitted, the smaller seems to be the angle of aperture necessary for seeing an obliquely illuminated set of surface markings well. Professor Abbe observes that “chromatic aberration for large angles of aperture not only depends upon the focal differences which affect the image-making light cone, by reason of the unequal passage of the different coloured rays through crown and flint glass, but also upon incurable inequalities in recomposing the coloured rays of differently refracted pencils, so that an objective achromati- cally corrected for direct illumination must be more or less over- corrected for oblique rays.” He makes similar observations on spherical corrections, and points out that increasing angles of aperture beyond narrow limits augments the outstanding deficit of correction and damages defini- tion. It is probable that many favourite objectives have had their definition damaged in this way, and it is curious that large angles do not work well with the silica films described by the writer, and that with suitable illumination small angles will resolve them. * Note to ‘The Microscope,’ 5th edit., p. 72. 238 Transactions of the Royal Microscopical Society. The new 4th by Powell and Lealand must, if fairly considered, be regarded as a convincing proof that a comparatively low power can be made to do work for which the highest that can be con- structed have been supposed necessary. It likewise indicates the narrow limits within which a fine large-angled glass, working near the object, can be made to operate with advantage. If this remark- able objective is compared with an ordinary 3th, no admiration of its merits will prevent complaint of its limited amount of penetra- tion ; but it is in fact an improved substitute for afar higher power, and in that respect deserves high praise. Few, if any, of the finest powers previously made would give a clear view with anything like the magnification which deep eye-pieces afford with this objective. By the kindness of Mr. Lettsom, who was one of the first to order and obtain one of these glasses, the writer has been able to experi- ment with it. The I eye-piece of Ross’s series, giving a magnifica- tion of about 2000 linear, suits it as well as the lowest eye-piece suits ordinarily fine glasses; and the view that can be thus obtained of such an object as P. angulatwm surpasses in beauty and bril- liancy anything seen before. With appropriate illumination there is a marvellous stereoscopic rotundity of the beads, the interspaces are remarkably large, and the shadows are wonderfully sharp. It would obviously bear a much deeper eye-piece than HK, and was exhibited to this Society with one stated by Messrs. Powell and Lealand to bring it up to 4000 x. ; Under special conditions this objective may serve the naturalist and physiologist in a remarkable manner. It has enough penetra- tion to show the internal structure of small rotifers, and it, together with previous high powers by the same optical artists, proves that Professor Abbe is quite wrong in his dictum that no microscope can show anything beyond that which a sharp eye can detect with 800x. To say nothing of lined objects, Messrs. Dallinger and Drysdale have been indebted to the much higher magnification obtained by #,ths for some of the most valuable information con- cerning minute germs they have laid before us. It may be impossible to obtain such enormous magnification and resolving power as this glass will give without an angle of aperture and an approximation to the object which is incompatible with much penetration, and in using it we must compare it with asths and jyths rather than with an ordinary }th. So compared, its working distance will be pronounced large, and its penetration con- siderable for the power. There is with it, however, a rapid, almost violent, transition from perfect performance when all its conditions are complied with, to bad performance, and no performance, if the object is not sufficiently flat, placed exactly in the best position, — and illuminated in the best way. It would be well worth trying whether the same principle of ‘On Angle of Aperture. By H. J. Slack. 239 construction applied to an ith of some thirty degrees less aperture would not work still better, even upon surface markings, as it certainly would upon objects requiring much penetration. ‘This suggestion is equivalent to asking whether the proportion of angle of aperture to focal length is such as to admit of the best cor- rections, bearing in mind Professor Abbe’s remarks. Zeiss’ 1th, not at all competing with the new Powell and Lealand glass in its specialty, shows how much more than has been expected can be done on the plan of a small angle and great working distance. This glass stands C and D eye-pieces well, and has a very remarkable amount of penetration, united to more than usual resolving powers. To sum up the results of experiments with various powers of different constructions: In the first place it appears that opticians have been encouraged to make excessive apertures substitutes for good corrections; 2, that naturalists and physiologists have been too contented with feeble resolving powers, under the belief that any more capacity for resolution must mean less penetration: and they ought to demand more penetration than they have been accustomed to, and far greater resolving power in addition; 3, that better illumination, and specially Mr. Wenham’s Reflex Illu- minator, adds greatly to the resolving powers of really good small- angled glasses; 4, that microscopists, and especiaily this Society, should so act as to secure opticians from the unfair treatment alluded to by Professor Abbe, and cause all the honour that is deserved to be awarded to those who will bring comparatively small- angled glasses to the highest degree of perfection in resolving as well as in penetrating power. (i ee ITI.— Measurements of the Moller Probe-Platte. By J. Epwarps Surra, Esq., Ashtabula, O., U.S.A. Som twelve months since my friend Professor Edward W. Morley, of Hudson, O., at my request made careful and accurate measure- ments of his Méller Platte (No. 258), and kindly forwarded to me the results obtained. I have cross-questioned pretty severely some of the figures as given by Professor M., by “throwimg down” the images on paper with camera lucida, and comparing the various markings each with the other graphically, and find the Profesgor’s results to harmonize very nicely. In making the measurements Professor Morley used the superb Houghton and Sims’ micrometer, belonging to the Hudson Equa- torial. The objective was a very fine Tolles’ 4th. Monochromatic sunlight was also employed. With pleasure I forward you the results obtained by Professor Morley, as per table annexed. | 7 I have had occasion to examine several of these Probe-Plattes of Moller, and found them all singularly even as to the “ markings.” This being the case, the Platte becomes at once valuable as a stage micrometer, using the camera and tracing the marking on paper— hence these values would at once be obtained by consulting the table. The whole process is so plain that it is quite unnecessary for me to go through the details. It will sometimes be better to ~ trace several of the markings from the camera, as by example given. Take shell No. 3 (Nav. lyra), and throw, by camera, its markings on paper. Selecting now the lines best tabulated and tracing off the space. occupied by sw of these, the distance obtained should equal the distance similarly obtained from shell No. 1; or we may trace from No. 1 the distance occupied by six hexagons, and dividing this by six graphically, get a more correct result than could be obtained by measuring a single hexagon. After a little practice the observer becomes expert with the camera, and will be able to deal with the finer shells. Mono- chromatic sunlight will now be found of advantage. Again, the observer may subdivide the distances given by the coarser shells, and thus obtain finer comparison scales, i.e. taking the distance already obtained from the tracings of T. favus (No.1), and with a fine lithographic pen divide this into three parts; each of these parts will represent the yo'ooth of an English inch; all this is plain enough. Professor Morley assures me that he can readily measure N. crassinervis (No. 18) of the Platte with his psth, wsing lamplight. When we bear in mind the high magnifying power of the H. and S. micrometer, and also the delicacy required for this kind of work, The Moller Probe- Platte. By J. Edwards Smith. 241 we must regard the measurement of No. 18 by lamp as little less than a feat. Numbers ae 0° counted, Eng. inch. 1. Triceratium favus 4 .... centre to centre of hexagons . 3°06 4, Sener teats 3°08 Biss SE Der NE eens et eat BOS 2. Pinnularia nobilis .. 14 .... at edge from centre -- top 10°8 IES awe i A aha bottom 10°5 18 .... midway from centre to end . top 12°5 TS Sia fe te bottom 12°1 3. Navicula lyra 24 .... from centre along axis top 16°3 PATS oie 4s D 3 bottom 17:1 29 .... short lines between marginal top 17°3 LNA a Bs bottom 18°5 4, Navicula lyra 36 .... from centre along axis .. top 25°0 36%. . 43 bottom 25-0 36 .... short lines 2 top 23h BO Cee Pe MSA Nea hotles bottom 27:1 5. Pinnularia interrupta 20 .... along each edge from centre .. top 26°8 LO ce 9 56 bottom 25°5 6. S. Phenicenteron 44 .... along axis .. top 33° Ee aie i bottom 32°7 Ga LMR alone edge top 31-1 7. Gramm. marina SAA ee .. 36°3 8. P. Balticum .. 48 .... near ‘end : ae) 50 .... including middle . 34:3 17 .)+ longitudinal... . . 31°5 9. P. accumenata 52 .... including middle along axis ec ang 10. Nitzschia amphoryx 46 . 45 Ps convex edge 42°9 20ers concave edge 45°3 11. P. angulata .. ea diagonal near centre (angles of dpe onels AA ens OME nn neu iAnBA 5a) Chess} 12. G. subdil, 58 . . 61°7 Sree MOVER anny Ot . 61°2 13. Surirella gemma 51 .... at axis from centre . 04°8 48 .... atedge.. . . ole4 30 see. longitudinal’ <2) 7. . 63°5. 14, Mitzschia sigmoidea 63 .... including middle 63-0 64. uh 5 .. 63°3 64 . i ‘3 oom 15. P. fasciola st Olre A -. 06°5 42 =. 06°2 AO oc. Bb oreleugrlalstiahi es 2 00° D 16. Surirella gemma 16 .... near middle of length 64-2 20 . a mn A .. 63°0 ZOM ens: s So ipo elle eae 24 .... almost half-way from middle to end 2 Of 3 19 .... nearer to end than middle.. . 70°4 17. Cym. elliptica 35 .... along edge from centre . . 63°3 OLS cei. (probably was + 80—doubtfal) 65°1? 18. Navicuia crassinervis 47 .... 82°2 Pa OD Is 81-1 Di aaiats 79°4. 19. Mitzschia curvula .. 50 .... : 84°7 Bue (counted number not given J. ELS. ) 84°5 20. Amph. pellucida .. 42 .... counted three times : 92°9 EF Ueio os “s 92°7 MEASUREMENT OF MOLLER Prope-PuatrE, No, 258. 242 The Moller Probe-Platte. By J. Edwards Smith. Remarxs.—lIt will be noticed that the figures corresponding to the last three or six shells are considerably below those formerly published ; it is, however, probable that the figures above given will not be materially changed. Professor Morley’s determination of A. pellucida as above given, agrees very well with Colonel Woodward’s observations.—A Paper read before the Memphis Microscopical Society, reported in the ‘ Cincinnati Medical News,’ February, 1875. (243:3,) PROGRESS OF MICROSCOPICAL SCIENCE. Diatomacecee in the Carboniferous Epoch, by Count Castracane. ‘Transactions of the Academia dei nuovi Lincei.’ Rome. February, 1875.—The remains of several species of Diatomacex were discovered in coal by the following method. A portion of the solid interior was reduced to a coarse powder, and burned in a small porcelain vessel in a glass tube, through which a stream of oxygen was passed, but the temperature was kept as low as possible, in order to avoid any fusion of the ashes. These were then heated in a mixture of nitric and hydrochloric acids with some chlorate of potash, in order to remove, as far as possible, all impurities. On carefully examining the residue thus obtained from various specimens of coal from different localities, mostly British, Diatomacez were invariably found, though usually only in small numbers. All agree with known living species in form and in the number of the markings, and in fact in every particular. Some specimens yielded marine, but the greater number fresh-water species. ‘he author appears to have taken every precaution to avoid being misled by the presence of accidental impurities, and he points out the importance of the facts in connection with the origin of coal,. and as showing that such low organisms have continued to exist with the same constant characters for such a vast geological period. In conclusion, it may be named that the author has kindly sent for exhibition at the meeting of the Royal Microscopical Society, two mounted specimens, showing well-marked Diatomacee and other interesting minute organic remains. On “ Personal Equation” in Microscopy.— Those who are familiar with astronomical matters will readily understand the above expression. But to the microscopist it will be almost entirely new. Mr. J. Ingpen, the Secretary of the Quekett Club, has a very important paper on this subject in the last number (March) of the ‘ Journal of the Quekett Club. He points out the many varieties of this “ equation,’ which must be taken into consideration in every instance, and he explains by numerous examples the several optical differences of observation under the heads of colour, focus, and form. 'The paper must be read itself, as it is impossible to briefly abstract it. The discussion to which it gave rise is also of much importance, the President’s (Dr. Matthews) remarks being of much interest. Influence of Light on Development.—This subject has been examined from time to time with the most contradictory results, and in nearly all cases it is the young of the frog that has been examined. M. Thury has been recently examining this question. He took the eggs of Rana temporaria and placed them all under precisely the same favour- able circumstances, except that while part received light through colourless glass, another part received it through green glass. The former developed rapidly, and by the end of May had a length of four centimeters, and well-developed hind legs in most of them; while the latter were slowly developed, blackish in colour, hardly had a length VOL. XIII. T 244 PROGRESS OF MICROSCOPICAL SCIENCE. of two centimeters by the end of May, and were without a trace of the hind legs. By the 10th of June the former had their fore legs, and some were changed to frogs; the latter, still black, had no trace of legs, and breathed almost exclusively by means of their gills. By the 15th of July all the former had become frogs; but those of the latter still had no legs, and by the 2nd of August they were all dead, without a trace of legs haying appeared. Some of the young of the latter lot transferred to the vessel of the former on the 15th of July finished their metamorphosis. At the same time, some of the former transferred to the vessel containing the latter continued to develop, showing the influence of the first impulse in their development. The Eozoon Question—An American Mistake.—In a notice of a book on the geology of New Hampshire, in ‘ Silliman’s American Journal,’ March, 1875, the writer makes the following remarks: “On the question of the animal nature of the Hozoon, Professor Hitchcock writes judiciously, excepting in a single remark. He observes that ‘those who disbelieve the organic theory are mostly better skilled in mineralogy than biology.’ But Messrs. King and Rowney, the chief contestants, are not mineralogists, but zoologists, and Mr. Carter, of England, another strong opponent of the ‘organic theory, is also a zoologist, and one particularly versed in the lower orders of animal life. There are probably mineralogists that doubt, as there certainly are zoologists, but we can recall no articles by any such on the sub- ject, excepting one or two which aim to show that the limestones containing KHozoon are sometimes of igneous origin, an observation which, whether sustained or not, cannot be attributed to mineralogical prejudices.” To this we may observe, that Professor King is essentially a geologist, and not a student of microscopic structure; whilst Pro- fessor Rowney is exclusively a chemist. The Poppy Fungus.—The ‘ Academy,’ in a late number, points out that Dr. Cunningham (whose memoir we have not received) states that this fungus, which is so destructive to the opium crop, is a near relative of the potato blight, and is named Peronospora arborescens. Dr. Cunningham found that soaking fine sections of the poppy leaves in carmine solution enabled the mycelium threads, which took up the colour, to be traced running between the cells, but not in any case perforating them. The conidia, which crop out abundantly from the fertile filaments on the under surface of the leaves, he states, “ appear very rapidly to lose their power of germinating.” He was unsuccessful in his search for the oogonia and oospores, supposed from analogy to exist in these fungi and spring from the mycelium in the tissues of the plant. Oospores can preserve their germinating power for months, and are conjectured to be important means of propagating the Perono- spora moulds. As the Peronospora arborescens, or poppy mould, is common on wild poppies in this country, English microscopists may contribute to the further elucidation of its life history. The Dimorphic Development of the Cladocera. — le ey ger Atheneum. Weekly .. OY! eer ae oa) Ditto. Society of Arts Journal. Weekly _ bo eee) ae Dae err ae Journal of the Lannean Society... No, 79)... 4.4.4. as) eee Ditto. The Canadian Journal .. seat 2 hate) eee mee OIL pia La Teoria della Riproduzione delle Diatomee. By Conte Francesco Castracane.. Mey Nk hake ely 7 oye Le Diatomee nella eta del Carbone. Memoria del Sig. Conte Francesco Castracane .. Ve Te ale | os Ditto. Le Diatomee in relazione a la Geologia. Memoria del Sig. Conte Francesco Castracane .. Ditio. A box of minerals, and some Giatounceous, seen in ie solid state. Mr. Hanks, H. W. Jones, Esq., was elected a Fellow of the Society. Water W. REEVES, Assist.-Secretary. Scientific Evening, April 21, 1875. On this occasion the libraries of King’s College were placed at the service of the Society by the kindness of the authorities, and the attendance was very good in spite of violent rains. Hxcellent lamps were lent by Messrs. Baker, How, and Parker, and the display of objects equal to any former occasion, as the subjoined list will show. Hahibitors and Objects. The President, H. C. Sorby, Esq.: Some new apparatus for the study of the spectra, and showing its application. Messrs. Beck: Podura scale under an immersion 3th, with a pecu- liar illumination, showing corrugations and fine black lines from end to end of 'the scale. All sign of the note of exclamation markings had disappeared. Mr. W. A. Bevington: The fructification of Trichomanes radicans. Mr. Thomas Bolton: A new species of Ophrydium (0. pediculum). Dr. Braithwaite: Section of leaf of BRhopala Pohlii, showing lignified trabecular cells between the upper and lower surface; also cuticle with immersed stomata, Mr. John Browning: The specula of nitrate of didymium and thallium. Mr. Frank Crisp: Ahren’s binocular microscope, with prisms of Iceland spar. Mr. F. Fitch : Tongue of Norway ant (under side). Mr. Fitzgerald: Selenite flowers under a new form of polariscope. Mr. Henry Hails: Internal casts of Foraminifera, Cliona borings, &c. PROCEEDINGS OF SOCIETIES. DA Messrs. How: Recent Foraminifera, the chambers becoming filled with glauconite from Australia. Mr. Thomas Howse: Section of caryopsis of wheat; section of pistil of vegetable marrow, showing pollen tubes, &c. Mr. J. F. Gibson: The Colorado potato-beetle, Doryphora decem lineata. Mr. J. W. Goodinge: Acari of bat. Mr. John HE. Ingpen: Clava squamata, from the Mediterranean. Mr. William T. Loy: A series of dissections, showing the entire anatomy of the large and small water-scorpion, Ranaitra linearis and Nepa cineria. Mr. 8. J. McIntire: Podure alive, Templetonia nitida, and some of the smaller species. Mr. W. W. Reeves: Young spongilla alive, sent from Chester by Mr. Thomas Shepheard. Messrs. Ross: Scale of Lepisma saccharina, mounted between prisms of 35°, showing radiating lines by oblique vision with a 5th object-glass. Mr. Sigsworth: Stellate crystals from office gum. Mr. J. W. Stephenson: Some new forms of Polycistina. Mr. Charles Stewart: Section of venereal wart and dilated lymphatics of the skin. Mr. H. J. Slack: Surirella gemma displayed in beads with 1th objective by Zeiss, angle of aperture 68°, and Wenham’s Reflex Illuminator, to show what resolving power could be obtained with a small angle. Mr. Swift: Podura scale shown with his low-angle 34th objective, and a new portable microscope lamp. Mr. Topping: Injected transverse section of hoof of horse, and sections of skin of horse from various parts of the leg. Mr. F. H. Ward: New British species of Lepisma (Lep. inguilinus). Mr. John Young: Sections of fossil plants from the Lancashire coal measures. Mr. Tuffen West: Some nice drawings of microscopic objects. Mr. Parkes: His new patent reading and microscope lamp. Mepicat MicroscopicaL Socrery. Friday, March 19, 1875.—Dr. J. F'. Payne, President, in the chair. Spinal Cord in Infantile Convulsions.— Dr. Sydney Coupland exhibited specimens from the case of a child, aged six months, dying in convulsions, secondary to cancrum oris. He described great dilata- tion of the capillaries and small vessels of the cord, especially in the commissural part of the grey cornua, and enlarged perivascular spaces, the maximum of enlargement being in lower part of medulla, par- ticularly near the central canal, but the canal itself and its epithelial lining seemed perfectly healthy. He considered the perivascular dilatations to be most probably secondary to the convulsions, and not their cause, but due to over-distension of the vessels during hy- peremia of the cord; and drew attention to the similarity of the appearances now seen to those described by Dr. Dickenson in cases of ~ 274 PROCEEDINGS OF SOCIETIES. diabetes. Mr. Needham had observed the same changes in the brain in cases of hydrophobia, and in cases of heart disease where there had been much congestion. The President thought the changes described not uncommon; they were mentioned long ago by a French writer as owing to wasting of the brain in old age, and lately by Dr. Lockhart Clarke in paralysis of the insane. ‘These appearances may not be pathognomic; and Dr. Dickenson could not find them in the parts of the brain which when injured cause a diabetic condition ; they are found too in seemingly healthy brains. His first-described perivascular spaces are by some considered lymphatic; but may they not be the tunica adventitia of the artery separated, and under diseased conditions filled with blood or inflammatory material ? In the case given it was not likely they were owing to simple me- chanical distension of the vessel, for, if so, why should the vessel not remain distended ? it would scarcely again collapse. They were more easily explained by wasting of the brain substance, and consequent filling of the perivascular spaces—whether tunica adventitia or not— with serum, since a vacuum cannot exist, and this wasting a severe illness or bad feeding might bring about. Dr. Greenfield had always observed a catarrhal condition of the central canal of the cord in cases of convulsions, and what the Presi- dent described as tunica adventitia he thought an additional struc- ture to help support the vessel. ; Dr. Coupland in reply stated he had in preparing the spinal cord prepared it first for twenty-four hours in spirit and water, and then in weak chromic acid. He did not know if the child were badly nourished, nor how long it had been ill. Urate of Soda in the Heart.—Mr. Ward exhibited a specimen where in a gouty subject the coronary artery was found plugged, the plug containing acicular crystals of urate of soda. Death was sudden, from rupture of left-ventricle ; the heart substance was friable. The President had seen sudden death in cases of plugging of the coronary artery. Dr. Greenfield stated that fatty change in the heart was said to follow plugging of the coronary arteries: he had not observed it uniformly. He quoted Dr. Quain’s cases of plugged coronary artery ; in all death was from ruptured heart. ~ Mr. Golding Bird asked if any chemical test had been applied to the crystals. He had once succeeded in obtaining under the micro- scope, by the addition of weak acid, crystals of uric acid from the acicular crystals of urate of soda contained in a section of “ gouty ” cartilage. Mr. Ward, in reply, had not applied any chemical test; the heart substance was not fatty, and he did not know which coronary artery was plugged. The crystals did not polarize. Blood-crystals of Rat, exhibited by Dr. Pritchard, were obtained after killing the animal with ether; a drop of the blood with water is placed on a glass slide and covered at once; on coagulation the crystals are seen in the spaces between the fibrin. If cemented thus they keep a long time, being “in vacuo.” Myxoma.—A specimen exhibited by the President, in which the PROCEEDINGS OF SOCIETIES. 275 connecting filaments were apparently tubular, and not merely, as described, flat processes folded to form a “gutter.” The preparation was in glycerine, but the same appearance was seen when fresh. Sout Lonpon MicroscopicaL AND NaturAt History Cuus. At a meeting of this club, held on Tuesday, February 16, at the Angell Town Institution, Brixton, a lecture was delivered by Dr. Huggins on “Spectrum Analysis and its Astronomical Results.” A large attendance of members and their friends testified to the interest which the subject excited, and the lecture, which was illustrated by many interesting experiments, was listened to with the greatest atten- tion by those present. The annual meeting of the club was held at the above Hall on Tuesday, March 16. Dr. Robert Braithwaite occupied the chair. Two new members were elected, and thirteen proposed for election at the next meeting. The following officers, proposed for the ensuing year, were unanimously elected: As President, Charles Stewart, M.R.C.S., F.L.S.; as Vice-Presidents, Hector Helsham, M.D., F.R.C.S.; W. T. Suffolk, F.R.M.S.; and Robert Braithwaite, M.D., M.R.C.8.E., F.LS., ¥.R.MS.; as Treasurer, Henry Robinson; as Committee, B. D. Jackson, ¥.L.S., F.R.M.S.; B. Neighbour; T. Rogers, F.LS., F.R.M.S.; N. Stowers, M.R.C.S., L.S.A.; J. W. Stephenson, F.R.A.S,, F.R.MS.; C. W. Stidstone; W. J. Parks; J. F. Wight, and E. Dadswell; as Honorary Secretary, Frederick Hovenden; and as Honorary Reporter, Thomas G. Ackland. The Treasurer’s report for the year just closed showed a balance in favour of the Society of 771. 19s. 2d. The report of the Committee was then read by Mr. B. D. Jackson. From this it appeared that 38 members had been elected into the club during the past year, the total number of members now being 245. The death of Mr. Henry Deane, the first President of the club, and one of its founders, was alluded to, and a tribute paid to his scientific knowledge, and the amiability of disposition which placed it at the service of the youngest student. It was reported that a collection of Lepidoptera had been acquired by the club; and the report concluded by an appeal to the members to help still more, by practical work and original investigation, towards the attainment of the objects of the club. The President (Dr. Braithwaite) then gave his annual address, in which he passed in review the advance of microscopical science during the past year, noticing in some detail a paper read by Dr. Hooker on *‘ Carnivorous Plants,” and also the researches of Sir John Lubbock, Dr. Darwin, and others, into the question of the fertilization of plants. He concluded by some interesting remarks upon the deep-sea sound- ings carried on by the ‘Challenger, under the direction of Dr. Carpenter. Votes of thanks having been accorded to the officers of the club for their services during the past year, the meeting separated. VOL. XIII. x 276 PROCEEDINGS OF SOCIETIES. On Tuesday evening, April 6, the annual soirée of the club was held in the tropical department of the Crystal Palace. About 1500 were present on this occasion ; and the various courts of the Palace were occupied by a brilliant company, who divided their attention between the interesting objects exhibited under the microscopes, and the larger and livelier, but equally interesting, objects shown in the aquarium, while sweet music was discoursed to the visitors by a con- tingent from the Crystal Palace band. The exhibitors were 270 in number, and included representatives of the Royal Microscopical Society, Medical Microscopical Society, Old Change Microscopical Society, and the Tower Hill, Quekett, Croydon, Greenwich Amateur, Sydenham and Forest Hill, Blackheath, West Kent, and New Cross Microscopical Clubs, in addition to those objects exhibited by members of the South London Microscopical Club. 'The microscopes were judiciously arranged in different parts of the Palace, the representa- tives of each club being, as far as was possible, placed in the same group. ‘The reading room was a centre of considerable attraction, the microscopes in this room being principally devoted to objects illustrative of pond-life, among which we noticed the familiar Rotifers, Melicerta, Conochilus, Stephanoceros, and the like; Volvox globator was admirably exhibited under several of the microscopes; and Hydras were also well shown. ‘The circulation in plants was shown, the objects chosen being Nitella, Anacharis, and Vallisneria. The Colorado potato-beetle and Trichina spiralis excited interest from the public reputation which these creatures have obtained. Circulation was shown in the blood of a newt, tadpole, carp, gold fish, and frog. The arrangements of butterfly scales and diatoms in the form of flowers were much admired; and groups of natural flowers received much attention. Foraminiferous shells from China, Australia, and the Mediterranean, were exhibited under different microscopes, as also was Atlantic mud from a depth of more than 2000 fathoms. Of miscellaneous objects we can only mention the Lord’s Prayer, written on the twenty-thousandth part of an inch, and an exhibition of the metal thallium under the electric spark. To pass from “food for the mind” to “food for the body,” refreshments were provided by the Crystal Palace contractors; and the counters loaded with refreshments testified that this department was ably conducted. The soirée would appear to have been in all respects a perfect success, and the visitors did not separate until a late hour. An ordinary meeting of the club was held on Tuesday, April 20, Mr. Charles Stewart, M.R.C.S., F.LS., in the chair. Twelve members were balloted for and duly elected, and the certificates of six mem- bers, proposed for election, were read. The President then made an interesting address on Respiration, which subject was illustrated by the objects exhibited by the members. A paper having been an- nounced for the next meeting on “ Nonvascular cryptogams,” the meeting separated. F PROCEEDINGS OF SOCIETIES. Die Souta AUSTRALIAN Microscopr Cuups. Although the number of microscopists in a limited population like that of South Australia is necessarily small, it is gratifying to know that a Microscope Club has been recently formed in Adelaide, under favourable auspices. ‘The idea of forming it arose from a successful exhibition of microscopes and objects by members and friends of the Philosophical Society. It was found that some fine instruments and objectives were in the hands of private gentlemen resident in the colony, and it was suggested that it would be useful to form a club for the purpose of mutual improvement. About eighteen gentlemen united to form the club, and during the last year monthly meetings have been regularly held at the offices of one of the founders. The plan of proceeding has been simple. The first half hour of each meeting has been spent in examining new or interesting objects and any novel piece of apparatus received by any member since the last meeting. The remaining portion of the evening has been spent in the study of some special subject notified by the chairman appointed at the previous meeting. Mr. Smeaton has acted as secretary and convener of the meetings, and during the year the following subjects have been studied, viz. insect preparations, mounting in balsam and resinous media, polarization of light, spectrum analysis, dental tissues, starches, preparation of diatoms, and photography as applied to the microscope. Numerous objects have been exhibited, those collected in South Australia having attracted special attention. The stands brought under the notice of the club have been Beck’s large binocular, Beck’s educational, Collins’s Harley binocular, a medium-sized Powell and Lealand, Hartnack’s model, and one or two others of smaller con- struction. The objectives examined by the members have been a complete series of Beck’s dry objectives, up to .,th inch; Collins’s objectives; a 5,th inch by Ross, working wet or dry without change of front ; a ~,th inch Powell and Lealand, with immersion arrange- ment ; and some very good objectives made in France. It will be seen that the.club has found ample material for work ; -and although it cannot hope to rival the great societies at home, it has been proposed to imitate them by giving a public exhibition during the year, whereby it is expected that a large accession of members will be attracted to the club. Memenis Microscopical Socrety. The Society met at the usual hour and place, with a large atten- dance of members, attesting an increasing interest in its objects and proceedings. Dr. W. A. Edmonds was unanimously elected to active member- ship, and Dr. J. V. Herriott, of Valparaiso, Indiana, as a corresponding member. A donation was received from Dr. Chris. Johnston, of Baltimore, consisting of finely preserved specimens of deutzia leaf, cuticle of ladies’ slipper, section of lignite, fossil diatoms, &c. Also from Henry x 2 278 PROCEEDINGS OF SOCIETIES. Mills, Esq., of Buffalo, three specimens of filterings from Niagara River water, accompanied by a brief but interesting account of what they contained. For all which a hearty vote of thanks was passed. The President, Dr. Cutler, read an account of the microscopical examination of a pathological specimen sent the Society from a neighbouring city. The case seems in many respects a remarkable one, baffling the best medical skill. And the microscope, although demonstrating that the disease was not cancer, as was supposed, fails to discover its exact nature, A paper was also read from J. E. Smith, Ksq., of Ashtabula, Ohio, giving the measurement of all the numbers on the Moller Probe-Platte, as made by Professor Morley, of Hudson, Ohio, and compared with his own observations. Letters of ac- Inowledgment were also read from T, W. Starr, Esq., and Henry Mills, Esq. The President then read his paper on the microscopic examina- tion of water from a pond, “Happy Hollow,” of yellow fever notoriety. In this water he found a number of curious and interesting species of infusorial life, and several new and hitherto undescribed forms. This water proved so rich in life that a description of all it contains could not be condensed within the limits of one paper, and a portion is reserved for a future meeting. A vote of thanks was then tendered the President, after which the Society adjourned until the next regular meeting, February 4. San Francisco Microscopican Society. The annual meeting of the San Francisco Microscopical Society has been held some time since, but the report has only now reached us, and it seems it was well attended by resident members, and the reports of its various officers show a thriving and energetic state of affairs. : 3 . Mr. Hanks, who has been President of the Society since its organization, read a very full and complete paper, giving a brief . history of the Society, showing what had been done by the members during the past year, and which contained many valuable suggestions, extracts from which we give a place below. The report of the Treasurer, Mr. Ewing, was very satisfactory indeed ; and the assets of the organization,{in the way of instruments, library, furniture, objects, &c., with the cash on hand, show what a few determined ones can do when they are in earnest. After the reading of reports, the election of officers for the ensuing year took place, resulting as follows: President, Wm. Ash- burner ; Vice-President, H. C. Hyde; Recording-Secretary, C. Mason Kinnie; Corresponding-Secretary, Charles .W. Banks; Treasurer, Charles G. Ewing. Louis Rene Tulasne, of Paris, was elected a corresponding member of the Society. Mr. J. P. Moore donated a pamphlet entitled ‘ New Mexico, which was valued as containing a list of hot springs in that country, and from which he hoped to present, from time to time, samples of animal PROCEEDINGS OF SOCIETIES. 279 and vegetable life. ‘The Secretary announced additions to the library in the way of six volumes of the ‘ Monthly Microscopical Journal and Transactions of the Royal Microscopical Society.’ Dr. Harkness donated a sample of the Palmella cruenta (gory dew), stating where it could be found in this city at the present time. Mr. J. P. Moore donated a bottle of caoutchouc, stating he had found it useful for making cells and fixing covers; a sample of wild cotton, from Barbacoas; a sample of Liber used by the natives of the above locality for blankets, and two slides mounted by him with fibre of the same. Mr. Scupham presented samples of rock composed of tertiary shells, from near Folsom, California ; rock composed of fresh-water shells and protozoans, Cache Valley, Utah: silicified oakwood, Rose- ville Junction; Arenaceous slate, showing crystals of peroxide of manganese, Green River, Wyoming ; and specimens of the Tillansia usneoides with seed pods, from Galveston, Texas. President Hanks’ Report. San Francisco, Feb. 4, 1875.—To-night ends the third year since the organization of the San Francisco Microscopical Society. It is with pleasure that I announce to you that it has been a ‘year of great prosperity. None of the members have died, none have been seriously sick, an increased interest has been manifested in microscopical science, not only by the growth of our Society and by the deep interest of our fortnightly meetings, but generally throughout the state. A desire has been shown to assist the earnest workers of this Society by sending objects for examination, and by calling attention to many strange and beautiful things that would otherwise have been lost. — Not only has the Society increased its apparatus, but many members have furnished themselves with first-class instruments, with which they pursue the fascinating science at their homes, bringing the result of their labours to the meetings, there to exchange ideas and to comment upon the result of their investigations. It has been stated by persons of great experience that few cities in the Union were so well provided with good instruments as San Francisco. This is owing directly or indirectly to the influence of our Society. Although I have said that we have greatly advanced in the study of microscopy, yet, in effect, we have only just begun. If we have much, very much to learn yet, we may feel that we have laid a good foundation upon which to erect the superstructure. We are particu- larly fortunate in one respect—we are in a new and undeveloped country. Unlike Europe, every inch of which (figuratively speaking) has been placed in the field of the microscope, we have vast unex- plored regions within our grasp, and the seientifie world is looking to us for results. Tt has been the custom of our Society to give entertainments to: our friends from time to time. During the year three of these have been given. One large reception was held on May 4, at Mercantile 280 PROCEEDINGS OF SOCIETIES. Library Hall, and was well attended. Two of less magnitude were given at our rooms. ‘These meetings not only give pleasure to our guests, but foster a taste for microscopical study, by giving our friends an opportunity to see what they could only otherwise guess at or remain in ignorance of. ‘There are many people in San Francisco who have no idea of the power of the modern microscope; to them our meetings must be instructive as well as entertaining. Our future receptions must be more instructive than those past, from the fact that our members are more generally provided with good instruments and objects, and have learned to display them in a manner more satisfactory. I believe we can in no way do so much for the cause of science, as by the continuance of these exhibitions. Finding our rooms too small for our growing Society, the question arose whether we should remove to another location, or enlarge the rooms we already occupy. The latter course was decided upon, and the result has been our present cosy quarters. In closing this report, I wish to call the attention of the Society to the importance of publishing our proceedings. By doing so we can by exchange obtain those of other societies, and thus learn what is being done elsewhere. If our first publication should not be all we could desire, we have another year before us, in which we may hope to improve. The regular meeting of the San Francisco Microscopical Society was held on Thursday evening last, with a good attendance of mem- bers. President Ashburner in the chair. Messrs. A. W. Jackson, of the University of California ; H. Scamman, of Downieville ; H. Molli- neux, Theodore H. Hittell, Charles Troyer and Dr. J. M. Willey of this city, present as members. Dr. Gustav Hisen, Professor of Zoology, University of Upsale, Sweden, was elected a corresponding member. The Secretary announced the receipt of six additional volumes of the ‘Monthly Microscopical Journal, completing the series, and the February number of the ‘ American Naturalist.’ Mr. H. G. Hanks donated a copy of the ‘ Cincinnati Medical News’ containing notices of meetings of microscopical societies.— Cincinnati Medical News, April. BronocicAaL AND MuicroscopicAL SECTION OF THE ACADEMY OF NatuRAL Scrences of PHILADELPHIA. Dr. J. Gibbons Hunt made a very interesting verbal communication upon the subject of aniplifiers for the microscope, in the course of which he remarked that from the time of the first observation by the aid of — more than two convex lenses, an almost constant effort had been made by opticians to fit in the best intermediate glasses, and yet further improvement in this respect was confidently to be looked for. The amplifier which he had upon the table consisted of a concavo-convex lens, with its concave side turned towards the eye, and so placed within the body of the microscope as to stand at a considerable distance from PROCEEDINGS OF SOCIETIES. 281 the objective. This adjustment of position was best accomplished by having the amplifier screwed to the end of a tube arranged with rack- work in such a manner as to traverse six or eight incnes, because we could thus compensate for a want of complete correction in the objec- tives employed. The advantages obtained by tising an amplifier were, in the first place, gain in magnifying power, as could be seen in his microscope upon the table, when, with an amplification of only 800 diameters, afforded by a four-tenth of an inch objective, he had on exhibition the Navicula angulatum resolved into dots all over the field, which was apparently more than sixteen inches across. By the aid of an amplifier we also gain a greater focal distance, and an increase of flatness of field. : Amplifiers have been employed in telescopes for the past fifty years, but ten or twelve years ago they were only adapted to micro- scopes, in this city at least, by one or two amateurs. Subsequently, Mr. Tolles, of Boston, saw them in use here, and on his return home made one, apparently with gratifying success, as he has since kept them in stock. Some few years since, Mr. Dickinson, of New York, wrote a paper upon amplifiers, claiming that by their aid he could obtain a power of 100,000 diameters; but objects thus magnified are visible only as dim shadows, similar to those shown by the solar microscope, quite unfit for data in scientific work. Such amplification, however, may be employed upon diatoms, the resolution of which does not require definition. Dr. J. G. Richardson inquired of Dr. Hunt whether, in his opinion, the ;4,th objective associated with his amplifier, as he had it upon the table, and eye-pieced so as to give a power of 800 diameters, was equal to his Powell and Lealand’s ;1,th immersion lens, combined with the A. eye-piece. Dr. Hunt replied that on histological work the results were not quite so good, but on Plewrosigma angulatum he considered them fully equal. The combination of amplifier and objective which he used was, however, a merely accidental one, so that a skilful optician would probably be able to arrange the lenses more efficiently, and thereby enable microscopists to obtain this greater amplification at a much lower cost, and yet with definition good enough for scientific work. Dr. Pigott’s aplanatic searcher appeared to be a modification of the amplifier, but had proved so unsatisfactory in his hands that he had entirely laid it aside. Dr. Hunt also exhibited a beautiful specimen of the Protococcus nivalis, or red snow, which he believed had been discovered for the first time within the United States, by Mr. Harkness, of California, who found it growing upon the Sierra Nevada mountains. For a long time it was a matter of dispute whether this organism belonged to the animal or the vegetable kingdom ; but from observations made upon specimens brought from the polar regions by Captain Parry in 1815, and which grew in bottles of snow, its vegetable nature had been demonstrated. In the growing stage this plant is of a green colour, and it is only the resting spores which present the brilliant red hue 282 PROCEEDINGS OF SOCIETIES. from which it derives its name. Dr. Hunt stated that on examining portions of the Protococcus nwwalis under the micro-spectroscope he had found that its colouring matter entirely blotted out the violet end of the spectrum, leaving the red, yellow, and orange untouched. Dr. J. H. McQuillen showed a specimen of muscular fibre from the sheep, which, after the simple method of preparation of allowing it to remain between two of his own teeth for five hours, he had placed in glycerine and teased out with mounted needles, thus obtaining a mag- nificent view of the ultimate fibrille of the muscle. Dr. J. G. Richardson exhibited a fine specimen of a vertical section from the mucous membrane of the tongue of a calf, mounted in balsam, which at his urgent request had been loaned to him from the Army Medical Museum. He desired to call the attention of members to the fact that each individual epithelial cell, throughout almost the whole thickness of the membrane, displayed its outline and nucleus with perfect distinctness, and that therefore the statement made when balsam preparations were last under discussion, that they showed hardly anything, was inaccurate. Dr. J. G. Hunt exhibited a similar specimen of his own mounted in glycerine, and remarked that when thus prepared the epithelial cells were displayed, not shrunken, but of their full size, and that those important elements, the connective-tissue fibres, were clearly visible, instead of being lost to view as in the balsam preparation. Dr. Richardson observed that even if the fresh glycerine prepara- tions exhibited these delicate fibres more plainly, yet the specimen preserved in balsam displayed the muscular-fibre cells with far greater distinctness, and the absolute permanence of objects mounted by the balsam method constituted one of its most important recommendations. Dr. H. C. Wood, jun., stated that the glycerine preparation ap- peared to be superior to that mounted in balsam, and moved that in order to settle this question, about which there had been so much dispute, these specimens should be referred to a committee composed. of Drs. J. H. McQuillen and James Tyson, for examination and report. Dr. J.G. Hunt exhibited an exquisite specimen of the liver of a common fly, showing with remarkable clearness the arrangement of | the hepatic cells and ducts, and stated that he proposed mounting a series of preparations displaying the structure of the liver from its simplest form in the Articulata up to its most complex arrangement in the human organism. ERRATUM. In the description of the woodcut Fig. 5, at p. 207 of this volume, the words “ Lobelia” and “ Cineraria” have been transposed and placed opposite the wrong spectra. (2 Son) INDEX TO VOLUME XIII. A. AsBE, Professor, of Jena, on a New Illuminating Apparatus for the Microscope, 77. Address of the President, 97. Amoeba, How does it swallow its Food ? By Professor Lrrpy, 167. Angle of Aperture in Relation to Sur- face Markings and Accurate Vision. By Henry J. Siack, 233. Angular Aperture of no Importance, 129. a an American View of the Advantage of High, 257. Animal Kingdom, the Classification of the, 85. B. Bacteria in Organic Tissues protected from Air, 126. Bacterium, What isa? By Dr. W. A. HO.uIs, 30. Bapcock, Mr. Jonn, Some Remarks on Bucephalus polymorphus, 141. Birds’ Eggs, the Colouring Matter of, 253. : Blood, the Pathology of the, 28. Corpuscles, the largest Apyre- nematous, 29. of Man and those of certain other Mammals, especially the Dog, on the Similarity between the Red; considered in connection with the Diagnosis of Blood Stains in Criminal Cases. By Dr. J. J. Woopwarp, U.S. Army, 65. Effects of Concentration on the Movements of White, 171. — Stains, Note on the Diagnosis of. By Jos. G. Ricuarpson, M.D., 213. Vessels, on the Development of, in the Human Embryo. By Dr. H. D. Scumipt, of New Orleans, U.S.A., 1. Bog Mosses, Dr. BRAITHWAITE on, 61, 229, ee Brairuwatre, Rosert, M.D., on Pog Mosses, a Monograph of the European Species, Sphagnum intermedium, 61; Sphagnum cuspidatum, 63; Sphagnum laricinum, 229 ; Sphagnum Pylaiei, 231, Brown, Mr. Henry, Have the Lungs on their ultimate Alveoli Squamous Epithelium ? 24. Brun'ron and Fayrer, Drs., on the Action of Crotalus-poison on Micro- scopic Life, 249. on Muscle, 251. Bucephalus polymorphus, some Re- marks on, by Mr. JoHn Bancocx: together with Translations from Papers of Von Baer, Lacaze-Duthiers, and Alf. Giard, on B. polymorphus and Haimeanus. By H. J. Suack, 141. C. Camera Lucida, Gilded Glass in the construction of the, 34. Cancer of the Bones of the Head, 254. CasTRACANE, Count, Diatomacee in the Carboniferous Epoch, 243. Cladocera, the Dimorphic Develop- ment of. By Dr. G. Sars, 244. Conjunctiva, Cup-cells of the, 85. Correspondence :— . Camera Lucrpa, 134, Cox, C. F., 132. GUIMARAENS, A. DE Souza, 90. Hicxiz, W. J., 265. LEIFcHILD, J. R., 174. Orp, W. M., 225. Pigott, G. W. Roysron-, 266. Suack, H. J., 226. Toutes, Rosert B., 90, 130, 223, 224. WENHAM, 225. Crotalus-poison, its Action on Micro- scopic Life. By Drs. Brunton and Fayrer, 249. Cycads, the “Membrana Nuclei” in the Seeds of, 221. F. H., 35, 90, 131, 224, 284 D. Datiincer, W. H., and Dr. J. Drys- DALE, Further Researches into the Life History of the Monads, 185. Deep-sea Researches, Professor Wit- KINSoN’S, 126. Desmids, the Reproduction of, 25. Development, Influence of Light on, 243. Diaphragm, the Use of a V-shaped, 260. Diatomacee in the Carboniferous Epoch. By Count CasTracane, 243. Natural History of the, 221. Diatoms, the Power of Motion which they Possess, 168. EK. Ear, the Anatomy of the, 29. Hchinoderms, Mode of Development in, 2538. Kozoon Question, the—an American Mistake, 244. Error, a Serious, 255. Erysiphe Tuckeri, 121. Exploring Expedition, the French, 262. F. Fibrin, Formation of, from the Red Blood-corpuscles, 29. Filarize, a Skin Disease caused by, 247. Filaria in the House-fly, 253. Fluorescence and Absorption, on the Connection between. By H. C. Sorsy, F.RB.S., 161. Frog’s Spawn, Action of Electricity on, 30. Fungi, Certain Parasitic, on Plants. By Tuomas Taytor, 118. —— the Fecundation of certain, 220. Fungus-foot of India, the so-called, 247. Fungus in a Flamingo. Levy, 255. H. Harpwicks, Mr. Roprrt, the Death of, 141. Hous, Dr. W. A.,. What is a Bac- terium ? 30. Hupson, C. T., LL.D., on some Male Rotifers, 45. I. Illuminating Apparatus for the Micro- scope, a New. By Professor ABBE, Th By Professor INDEX. L. Lerpy, Professor, on some New Species of Rhizopods, 86. on a Fungus in a Flamingo, 255. Light, its Influence on Development, 243 Liver, Structure of the Lobules of the, 246. Lungs, Have the, on their ultimate Alveoli Squamous Epithelium ? 24. M. Micro-cabinet Club, an American Pos- tal, 262. Micro-polariscope and Lantern, 264. Microscope, the Compound, in the Ex- amination of Patients, 222. Microscopical Society, a New Local, 88. the Royal, the President’s Address, 97. the Belgian, 222. Microscopy, on ‘ Personal Equation ” in, 243. Monads, Further Researches into the Life History of the. By W. H. Dat- LINGER and Dr. J. DRysDALE, 185. N. Nematoids, the Peripheral Nervous System of Marine, 247. New Books, witH SHort Novices :— The Micrographic Dictionary, 83,165. The Pathological Significance of Nematode Hematozoa. By T. BR. | Lewis, M.B., 218. O. Object-glasses, on the Principle of Testing, by Miniatures of luminated Objects examined under the Micro- scope, especially of Sun-lit Mercurial Globules; and on the Development of Hidola or False Images. By Dr. RoystTon-Picort, 147. Objectives, Notes on Recent, 172. Oblique Vision of Surface Structure under the Highest Powers, on a Method of obtaining. By F. H. Wenuam, 156. Ophidia, Structure and Development of the Teeth in. By Mr.C.8. Tomes, 248. Orp, W. M., M.B., Studies in the Natural History of the Urates, 108. INDEX. Pp. Palmodictyon viride in Britain, 29. Peronospora, Is it the cause of the American Onion Blight? 246. “ Personal Equation” in Microscopy, 243. Pigment-cells, how they are influenced by the Nerves. By M. Povcuet, 168. Pigment-flakes, Pigmentary Particles, and Pigment-scales. By Dr. G. RicHarpson, 19. Picort, Dr. Royston-, F.R.S., on the Invisibility of Minute Refracting Bodies caused by Excess of Aperture, and upon the Development of Black Aperture Test-Bands and Diffraction Rings, 55. on the Principle of testing Object-glasses by Miniatures of Illu- minated Objects examined under the Microscope, especially of Sun-lit Mer- curial Globules; and on the Develop- ment of Kidola or False Images, 147. PLowrRicHT, CHarLes B., Some Re- marks upon Spheria morbosa, 209. Polariscope and Lantern, a Micro-, 264. Poppy Fungus, the, 244. PoucuEer, M., How Pigment-cells are influenced by the Nerves, 168. Powers, the Advantages of High and Low, 174. President, the Address of the, 97. Probe-Platte, Measurements of the Moller. By J. Epwarps Smits, Esq., 240. PROCEEDINGS OF SOCIETIES :— Academy of Natural Sciences, Phila- delphia, 280. Medical Microscopical Society, 40, 93, 139, 273. | Memphis Microscopical Society, 43, 183, 277. Microscopical Society of Victoria, 42, 179. Quekett Microscopical Club, 95, 139, 184, Royal Microscopical SODIY, 39, 91, 135, 175, 226, 268. San Francisco Microscopical Society, 278. South London Microscopical Club, 228, 275. South Australian Microscopical Club, 277. R. Refracting Bodies caused by Excess of Aperture, on the Invisibility of Minute, and upon the Development of Black Aperture Test-Bands and Diffraction Rings. By Dr. Roysron- Pigort, 55. 285 Rhizopods, New Species of. By Pro- fessor LEtwy, 86. —— the Ameceban, Actinophryan, and Difflugian. By Dr. Waturcn, 210. Ricuarpson, Dr. JoserpH G., on Pig- ment-flakes, Pigmentary Particles, and Pigment-scales, 19. Note on the Diagnosis of Blood Stains, 213. Rotifers, on some Male. Hupson, LL.D., 45. By C. T. S. Sars, Dr. G., on the Dimorphic De- velopment of the Cladocera, 244. Scumipt, Dr. H. D., on the Develop- ment of the Smaller Blood-vessels in the Human Embryo, 1. Screw, the Society’s Universal, 33. Stack, Mr. H. J., Translations from Papers of Von Baer, Lacaze-Duthiers, and Alf. Giard, on B. polymorphus and B. Haimeanus, 141. on Angle of Aperture in Relation to Surface Markings and Accurate Vision, 233. “Slit,” on a Modification of the, for Testing Angle. By Roprrtr B. Toss, 21. Small-pox, the Lymph of, 254. SmitH, Mr. J. (U.8.A.), on the Illumi- nation of Difficult Test-objects: the Use of Blue Glass, 88. J. Epwarps, Esq., Measurements of the Moller Probe-Platte, 240. Sorsy, H. C., F.R.S., on New and Improved Microscope Spectrum Ap- paratus, and on its Application to various Branches of Research, 198. Soundings, the ‘Challenger.’ By Dr. WYyvILLE THOMSON, 245. Spectrum Apparatus, on New and Improved Microscope, and on its Application to various Branches of Research. By H. C. Sorsy, F.R. 8., 198. Spheeria morbosa, 118. some Remarks upon. By Cuarues B. PLlowricut, 209. Sphagnum intermedium, 61. cuspidatum, 63. laricinum, 229. Pylaiei, 231. Sponges, the Microscopic Anatomy of, 167. : T. TayLor, Tuomas, on certain Fungi Parasitic on Plants, 118. Teeth, Development of the, in Reptilia and Batrachia, 89. 286 Teeth, Development of, in Mammals, Birds, and Fishes. By Mr. C. S. Tomes, 252. Test-objects, the Illumination of Diffi- cult, 88. Tuomson, Dr. WyVILLE, on the ‘Chal- lenger’ Soundings, 245. To.LuEs, RoperT B., on a Modification of the “Slit” for Testing Angle, 21. Tomes, Mr. C. S., on the Structure and Development of the Teeth in Ophidia, 248. on the Teeth in Fishes, 252. Traps of the Mesozoic Basin, Thin Sections of the, 254. Tripoli, the Locality of the Bermuda, 258. Turn-table, a Self-centering. By C. F. Cox, 132. Development of Mammals, Birds, and —— U. Utrates, Studies in the Natural His- tory of the. By W. M. Orb, M.B., 108. INDEX. ¥, Voleanic Rocks, the Comparative Mi- croscopic Rock-structure of some Ancient and Modern, 26. W. Watticu, Dr. G. C., on. the Amceban, Actinophryan, and Difflugian, 210. Warp, Mr. J. Cuirron, Comparative Microscopic Rock-structure of some Ancient and Modern Volcanic Rocks, 26. Wenuam, F. H., on a Method of obtaining Oblique Vision of Surface Structure, under the Highest Powers of the Microscope, 156. White Corpuscles, Where do they get through the Blood-vessels ? 221. Wiu.iamson’s, Professor, Deep-sea Re- searches, 126. Woopwarp, Dr. J. J., on the Similarity between the Red Blood-corpuscles of Man and those of certain other Mam- mals, especially the Dog; considered in connection with the Diagnosis of Blood Stains in Criminal Cases, 65. END OF VOLUME XIII. LONDON: PRINTED BY WILLIAM CLOWES AND SONS, STAMFORD STREET AND CHARING CROSS. Fees Rene: Ppa ne ewe: Moen wade Serle mtn) te ee ON ee ae <> , Re See = fase a -* Seay on : ane Yh ee ee, : 5 ! ee 3 iS = Se z Y % md poe Seir® Siaee wer SOF ais x . : 2 eae < : % re : ok + z s = 5 oe : : z pee rete = -" = 5 ¥, 2 is So - = *. 5 _ %; . s San tel 3 Se era an) : 2 < ne “ = mee : ; m : ~ ; : ey : 2S ; . < We : nae Tint oa ee me eee Dott J AEA, | is GL LLL apdose Tie i AL ‘ He a SP4ob/I¥ Taggly) yas if RES — Coenen at = eee ” ; Koes i fre a? ib oo natin