SAE ASTRON ‘ Cea sees Soars ~ pny i, a) st vo — o es See ec te Seas ctl: wd. Ke wee = pegeye ween ¢ Sas tye 2 Sey Aon pe eb oY is Rice x oS hitaseaidy a) $s 7 eat & Hat eo if" 4) r eat Beret neh rh ba oe ee, me, oe 6a + Retutes eS ay — Pores ee te oF fae ‘ i] arenes Phi th — : £8 3 eae : 4 ae at einer hats ENE BH nt aie) ie eee re me ee te SR et . a sree a ms pa ae rae Ny oie ek es ro Rane eet iiny pat ty Biley arif “4 a Sey wk Patrietsyennten bea aN ifaAy it} ae ig Ban shh Gare aneen ~ iP 282 Gulliver, George, F.R.S., on raphides as natural characters in the British flora, ,1. H. Hackney Microscopical Society, 194. Hesse on a new crustacea, 255. Hyperosmic acid, on the action of, on animal tissues, 39. I. aed, on, by EH. C. Mecznikow, 241 Tlumination, Count Francisco Castra- cane’s new method of, 48. Tlumination, stops recommended for oblique, by B. Wills Richardson, F.R.C.S.T., 10. Intestine of the child, on the nervous plexus in the, 39. Irid, histology of the reproductive organs of the, by P. Martin Dun- can, M.B. Lond., 12. L. Larval eyes, 88. Leptothrix-swarms, and their relation to the vibriones, 155. Light reflected from transparent sur- faces, 167. M. Macalister, Alexander, on the anatomy of Ascaris dactyluris, 79. Manchester Literary and Philosophical Society, oe of, 73. 130. Mecznikow, E. C., ‘on the development of Ascaris nigrovenosa, 25. on Icthydium, &c., pet on Rhapcocera, 25. Meinert on Cecidomyie, 265. Microphotography with high powers, 164 Microscopical Society, proceedings of, 53, 108, 170. Moxon, Dr., on motor nerve termira- tion, 235. N. Nervous laminze, on the, of motor fibres, 42. INDEX TO JOURNAL. O. Ordonez on connective-tissue, 257. Oxford Microscopical Society, 137, Ii : ipa in an undescribed animal, 43. Pediculus, on the structure of the mouth in, 95. Phreoryctes Menkeanus, on, with re- marks on the structure of other annelids, 37. Polyzoa, on the development and fat- corpuscles of the, by F. A. Smit}, 99. Prussic acid, effects of, by T. S. Ralph, 163, 225. : Q. Quekett Microscopical Club, 119. R. Ralph, T.§., on the effects of prussic acid, 163, 225. Raphides, on, as natural characters in the British flora, by George Gulli- - ver, F.R.S., 1 Raphides, 46. Rhabdocela, Mecznikow on, Rhynconella Geinitziana, on the micro- scopic structure of the shell, 45. Richardson, B. Wills, on stops recom- mended for oblique illumination, 10. ye on an additional stop re- commended for oblique illumination with the achromatic condenser, Robertson, Charles, on a new species of Acarus, 20. Robin and Legros on Noctiluca, 258. Royal Society of Tasmania, 36. S. Spermatozoa, on the, and their deve- lopment, 89. Stanhoscope, 8. P. Barkas on, 263. Sympathetic cord, researches on, 154. a Tubes, on cleaning glass, 49. V3 Nerve, on termination of motor, by | Vorticellidan parasites, anatomy and Dr. Moxon, 235. Noctiluca, Robin and Legros on, 258. physiology of, 159, Vulcanite cells, price of, 168. PRINTED BY J. FE. ADLARD, BARTHOLOMEW CLOSE. TRANSACTIONS OF THE MICROSCOPICAL SOCIETY OF LONDON. PLL LI SP DIDI NEW SERIES. VOLUME XIV. LONDON: JOHN CHURCHILL AND SONS, NEW BURLINGTON STRERT, 1866. re wag % A vw t. 2 . eT hy @ pe 7 : FS Pk ieee a i 1 Shwe 18 ay r 4 -. TRANSACTIONS. Descriptions of New and Rare Diatoms. Series XVIII. By R. K. Grevitiz, LL.D., F.R.S.H., &e. (Communicated by F. C. 8S. Roper, F.L.S., &.) (Read Nov. 8th, 1865.) (Plates I & II.) PLAGIOGRAMMA. Plagiogramma decussatum, nu. sp., Grev.—Valve elliptic- oblong, with 2 central costz and numerous pervious strize composed of minute granules, so arranged as to form decus- sating lmes. Length :0022”. (Figs. 1—2.) Hab. St. Helena, in fifteen fathoms ; Dr. Wallich. Shark’s Bay, west coast of Australia, in stomachs of Ascidians ; Dr. Macdonald. Zanzibar; Professor Hamilton Smith. This species 1s so exceedingly hke P. Gregorianum (Den- ticula Staurophora, Greg.) that it requires careful examination to detect the difference. One character, however, is amply sufficient to separate them. In P. Gregorianum the pervious strie are merely obscurely moniliform, whereas in_ the ‘species under consideration, under the same magnifying power, they are seen to be composed of distinct, somewhat transversely oblong granules, so regularly arranged that they form distinct longitudinal and transverse decussating lines. The valve is also considerably more robust than that of P. Greyorianum. ‘The discovery of this species is due to Dr. Wallich, in whose notes and sketches it is clearly indicated. Plagiogramma Barbadense, n. sp., Grev.— Valve narrow, elongated, contracted in the middle, then dilated, and again contracted into linear subacute extremities ; costz 2, strong, centrical; structure showing exceedingly fine longi- tudinal and transverse lines (dots) and another series of numerous very fine transverse pervious striz. Length 0085”. (Fig. 3.) VOL. XIV. a 2 GREVILLE, on New Diatoms. Hab. Barbadoes deposit, Cambridge estate; in slides com- municated by C. Johnson, Hisq.; exceedingly rare. I regret to say that no perfectly entire valves of this species have been obtained ; but the only deficient part is the striation of the inflated portion of the valve. The sutural ends of the striz are, however, quite evident, and there can be no reason to conclude that they differ from those of the narrower portion. In form it is allied to P. lyratum. In structure it varies from the other members of the genus, having, in addition to a groundwork of exceedingly delicate decussating rows of dots, a series of transverse pervious strie. Fine illumination and careful adjustment is required to bring out the characters. MASTOGONIA. Mastogonia Actinoptychus. (Fig. 4.) Ehr., ‘ Bericht. d. Berl. Akad.,’ 1844, p. 269; ‘ Mikrog.,’ pl. xvi, fig. 19. Kiitz., ‘Sp. Alg.,’ p. 25. Ralfs, ‘in Pritch. Infus.,’ p. 814, pl. v, fig. 59. As the figure published by Ehrenberg is not quite satis- factory, I have been induced to offer one taken from a fine example in my friend Mr. L. Hardman’s cabinet. The station given by Ehrenberg is Virginia. Mr. Hardman ob- tained his specimens from the celebrated Monterey deposit in California. They exhibit a minutely punctate structure, and a very variable number of radiating lines or segments. Ehrenberg fixes them at 13, but his own figure has 19. The valve I have copied shows 25, and I have seen another with as many as 30. It is evident, therefore, that number in this case is not a trustworthy character. XANTHIOPYXIS. Xanthiopyxis ? umbonatus, nu. sp., Grev.—Disciforme, cir- cular, broadly umbonate, the umbonate portion more or less covered with strong short sete. Diameter about -0040”. (Fig. 5.) Hab. Monterey deposit; cabinet of L. Hardman, Esq. ; Lita GS G ahs eet Of this fine diatom, which is by no means rare in the Monterey deposit, I have seen no specimen with the valves im situ, and I am consequently by no means certain that it is a genuine Xanthiopyxis. The curve of the umbo is vari- able, as well as the proportion of the disc which it occupies ; and the setz, although generally confined to the centre, some- GREVILLE, on New Diatoms. 3 times occupy two thirds of the radius. The substance appears to be fragile. CoscINODISCUS. Coscinodiscus elegans, n. sp., Grev.—Disc small, with a smooth irregular umbilicus; granules rather large, equal, in radiating, not very close lines, which terminate in a narrow belt of minute crowded puncta; border strong, finely striate. Diameter about :0030”. (Fig. 6.) Hab. Monterey deposit; Laurence Hardman, Esq.; R. K. G. Allied, apparently, to C. Lune and gemmifer of Ehren- berg, having, in common with those species, a smooth um- bilicus and a narrow belt of minute puncta between the termination of the radiating lines and the border; but dif- fering from both in the strong, finely striated border, which appears double in consequence of a fine dividing line. The narrow punctate belt is scarcely so broad as the border. Granules large, circular, conspicuous, about 8 in -001” in the radiating lines. Coscinodiscus pulchellus, n. sp., Grev.—Large; valve con- vex, largely reticulate ; cellules hexagonal, somewhat smaller near the margin, the last row more or less oblong; border strong, rather broad, with strong, subremote striz. Diameter about ‘0050”. (Fig. 7.) Hab. Barbadoes deposit, Cambridge estate ; C. Johnson, Esq. A fine species, with a regular, somewhat delicate hexagonal cellulation, which becomes smaller only near the margin, the cellules of the last row being not wider, but only longer. The strong striz of the border pass for a short distance into these oblong cellules. Coscinodiscus robustus, nu. sp., Grev.—Large; disc convex, cellulate; cellules large, roundish-hexagonal in the middle, becoming smaller, rounder, and more remote towards the margin; border very strong, broad, elevated, with irregular strie. Diameter 0045” to 0055.” (Fig. 8.) Hab. Monterey deposit; cabinet of L. Hardman, Esq. A rather singular species, strong and robust in its general aspect with a broad elevated rim. ‘The cellulation is coarse, and the hexagonal spaces are continued nearly equal in size to the margin ; but the cellules themselves have a roundish appearance, large in the central region, then becoming gra- dually smaller as they approach the margin. The walls, of course, become correspondingly thicker, until at length the cellules look like mere circular perforations in the middle of A GREVILLE, on New Diatoms. the hexagonal spaces. In the centre of the disc the cellules are 4—5 in ‘001”. Coscinodiscus oblongus, n. sp., Grev.—Disc more or less oblong, having the centre depressed, and an umbilicus con- taining a number of subremote granules; surface filled up with radiating granules, which diminish in size next the umbilicus and towards the margin, where they resemble minute puncta. Length :0028” to ‘0050’. (Figs. 9, 10.) Hab. Barbadoes deposit, chiefly in Springfield estate ; C. Johnson, Esq.; L. Hardman, Esq.; R. K. G. This beautiful little species is liable, on account of its similarity in form, to be taken for a variety of C. punctatus of Ehrenberg; but on a close examination it appears to be essentially different from the figures of that diatom im ‘ Mikro- geologic.’ The granules forming the radiating lines, for example, become smaller as they approach both the margin and umbilicus. The latter is not smooth, but always con- tains a number of granules, which, in the more elongated valves are generally arranged in lines. The centre of the valve is also much depressed. C. punctatus itself, however, is not very clearly established. Ehrenberg gives two figures (‘Mikr.’ Tab. xvu, figs. 40, 41), the first of which is oval, but neither of them exhibits the slightest indication of one of the most conspicuous characters contained in the descrip- tion, viz., cellules “very densely crowded at the margin, and forming a broad yellowish-white border.” At present I am under a very strong impression that two or three oval or oblong species belong to the American deposits, one of which may be the diatom Ehrenberg had in view. BRIGHTWELLIA. Brightwellia Johnsoni, Ralfs, MS.—Valve with the border composed of radiating lines of cellules diminishing in size from the coronal circle to the margin, and of ridge-like ribs at subregular intervals. Diameter about ‘0035.” (Fig. 11.) Hab. Barbadoes deposit, Cambridge and Springfield estates, most abundant in the latter; C. Johnson, Esq. ; L. Hardmann, Esq.; R. K. G. This exquisitely beautiful diatom is similar in size to B. elaborata, but is at once distinguished by the radiating lines of cellules becoming smaller towards the margin, and by the dark ribs which radiate, at short intervals, parallel with them. The coronal circle of larger cellules and the spiral arrangement of the central cellules are very like the GREVILLE, on New Diatoms. 5 same parts in the species above mentioned. It is seldom that a good view of the spine-like character of the ribs can be obtained; but the disc now figured happened to be tilted up in such a way as to show it very conspicuously. ACTINOPTYCHUS. Actinoptychus minutus, n. sp., Grev.— Minute; valve 8-rayed; the compartments alternately slightly raised and depressed, very minutely punctate; umbilicus in the form of a minute cross, with the ends truncate. Diameter :0017”. (Fig. 12.) : Hab. Monterey deposit; cabinet of L. Hardman, Esq.; very rare. The smallest species of the genus, with the surface nearly even, and the cellulation so minute as to justify the term punctate. HELIOPELTA. Heliopelia nitida, nu. sp., Grev.—Dise with six compart- ments, the cellulate ones with 4—5 marginal spines ; central space obtusely hexagonal, containing a circular umbilicus; margin narrow, with a fine line running through it, and no perceptible striz. Diameter 0040”. (Fig. 18.) Hab. Deposit at Los Angelos, California; L. Hardman, Esq. ; very rare. To my friend Mr. Laurence Hardman we are indebted for the discovery of what appears to be an unquestionably new species of this fine genus, and individually I have to thank him for enriching my cabinet with a specimen. Whatever view may be taken of the species described by Ehrenberg, the Californian disc differs from all of them in the non-striate rim and in the well-defined non-stellate centre. The latter is an hexagonal umbilicus, containing a circular nucleus, and of a thicker and more opaque substance than the stellate central space in the other Heliopelte. The margin is rela- tively narrower, and the cellules larger. EUPODISCUS. Eupodiscus minutus, n. sp., Grev.—Small; disc slightly convex, obscurely cellulate, with four circular, submastoid processes, distinguished by a prominent lip on their marginal side. Diameter about 0020”. (Fig. 13.) 6 GREVILLE, on New Diatoms. Hab. Barbadoes deposit, Springfield estate; cabinet of L. Hardman, Haq. Considerably smaller than EH. odscurus, and, like that species, possessing four processes, but is not otherwise allied to it. I place our present little diatom provisionally in Eupodiscus, but am doubtful whether that be its true posi- tion. The processes, which are situated near the margin, are somewhat similar to those of the genus Craspedoporus, having the edge next the margin of the disc considerably raised, and with a thickened lip. The structure is rather obscure, but can be made out to be a faint, uniform, minute, roundish cellulation. | , AULISCUS. Auliscus Hardmanianus, n. sp., Grev.—Large; valve circular, with two processes; whole surface more or less granulose ; umbilical space four-angled, the angles attenu- ated, two of them passing to the base of the obovate ridges within which the processes are placed, the other two passing into rough transverse lines, terminating in a sort of capitate mass of radiating short lines and granules. Diameter ‘0040’ to 0055”. (Fig. 17.) Hab. Monterey deposit; cabinet of L. Hardman, Esq. There is no genus of diatoms in which a greater variety of sculpture occurs in proportion to the number of species than in Auliscus. The present most remarkable disc, of which I have seen a number of examples, 1s quite unlike any of those previously described. The most striking peculiarity is the attenuation of the angles of the umbilicus, especially those which are intermediate with the processes, which are pro- longed into more or less distinct linear channels, ending in intra-marginal knobs or rough clusters of short radiating lines. These knobs are connected with the ridges surmount- ing the processes by a few fine, sometimes obscure lines, stretched, as it were, across from one to the other. BIDDULPHIA. Biddulphia Johnsoniana, n. sp., Grev.—Large; frustules oblong, turgid; valves broadly oval, very minutely scabrous, destitute of spines, with large, very shortly produced, broadly truncate processes. Diameter of valve 0040” to 0055”. (Figs. 14, 15.) Hab. Moron deposit; very rare; C. Johnson, Esq. This very rare species has considerable affinity with B. ¢ur- GREVILLE, on New Diatoms. 7 gida, which it resembles in general form and dense structure, and especially in the short, broad, flat processes. I have been unable to perceive any trace of spines, nor is there any indication of a rough line or fringe of apiculi, like that in the valve of B. turgida. Like most of the other members of the genus, our new species varies greatly in size. Biddulphia ? mammosa, n. sp., Grev.— Valve in front view produced at the angles into large, elliptical, mammeeform, minutely punctate processes ; median surface slightly convex, and transversely remotely striate; the rest of the surface smooth. Length of valve 0040”. (Fig. 16.) Hab. Barbadoes deposit, Cambridge estate ; in slides com- municated by C. Johnson, Esq. We have here another of the dubious forms of which so many occur in the Barbadoes deposit, and of which it is desirable to place on record. It is fortunate that although, in the absence of the end view of the valve, we cannot describe the exact contour, characters amply sufficient for the determination of species are obtained from the front view. At least this has been found to be the case in the fossil Biddulphie and Hemiaulide from Barbadoes. The end view of the valve of the present species must be very beautiful, being apparently composed of a series of long, linear, trans- verse cellules, traversed by a median line. TRICERATIUM. Triceratium Robertsianum, u. sp., Grev.—Large; valve with gibbous sides and subobtuse, slightly produced angles, a short, horn-like process at each angle, and I1—2 strong spines, arising from the surface within the margin on each of the sides ; cellulation hexagonal, large, equal; margin broad, elevated. Distance between the angles (0042”. (Fig. 22.) Triceratium grande ?—‘ Brighton Mic. Jour.,’ vol. 1, p. 249, pl. iv, fig. 8. Hab. Woodlark Island, South Pacific; in a dredging com.- municated by Dr. Roberts, of Sydney. For nearly two years I have refrained from making any use of the drawing of this diatom, in the hope that I might be enabled to come to some satisfactory understanding rela- tive to T. Favus and its varieties. In the mean time multi- tudes of that species have come under my observation, and I have met with no form which tended to unite the one under consideration with that species. J. Favus frequently occurs with the sides of the valve “ slightly convex,” in accordance 8 GREVILLE, on New Diatoms. with the specific character adopted by Mr. Ralfs (‘ Pritch. Inf.,’); but a slight convexity is very different from the prominent gibbous curve in the valve now before me. The presence of strong spines also, by themselves of very uncer- tain value, contributes, in connection with the other charac- ters, to confer upon it great primd facie distinctness. Size alone is of little importance, but it may be well to state that it is scarcely more than half that of T. Favus, as figured in the ‘ Synopsis of British Diatomacez.’ At the same time the margin is far more decidedly defined, and the reticulation more delicate. After all, however, it may turn out to be nothing more than an extreme form of 7. Favus, to which Mr. Ralfs seems disposed to refer T. grande of Brightwell. Triceratium Stokesianum, n. sp., Grev.—Large; valve with slightly concave sides and subobtuse angles; surface with subremote, roundish, irregularly radiating cellules, minute in the centre, becoming large towards the sides and angles ; angles imperfectly cut off by two vein-like lines springing from the margin on each side, obscurely united in the middle ; margin strong, remotely striate. Distance between the angles ‘0062”. (Fig. 23.) Hab. Moron deposit, Province of Seville; Rev. T. G. Stokes ; extremely rare. This fine species appears to be allied, as my kind corre- spondent Mr. Stokes remarks, to 7. areolatum of the Bar- badoes deposit, being of the same form, and having a very similar radiating cellulation ; but it differs in being a very much larger species, and in having the angles partially cut off by a pair of vein-like undulating lines given off on each side, which become faint and obscure towards the middle. The pair next the angle are less distinct than the others, and would probably be found obsolete in some specimens. The cellules are sometimes oval, and are larger and more regular as they approach the angles. The Moron deposit is remark- able for the small number of individuals of the new species which have been found in it. No one but Mr. Stokes has been so fortunate as to discover the subject of the present notice. Triceratium inelegans, nu. sp., Grev.i—Small; valve pulvi- nate, with straight sides and broadly rounded angles; | whole surface filled with irregularly radiating, somewhat remote, oblong, rather large granules, except the angles, which are minutely punctate. Distance between the angles 0025”. (Fig. 21.) Triceratium obtusum? Ehr., ‘ Mikrog” Tab. xvii, fig. 48. GREVILLE, on New Diatoms. 9 Hab. Monterey deposit ; cabinet of L. Hardman, Esq. Allied to T. tesselatum and robustum, and more nearly to T. obtusum ot Ehrenberg; but that close observer would scarcely have omitted in his figure of the latter species the crowded puncta in the angles of the Monterey diatom. Never- theless I think it right to quote it as a doubtful synonym. Triceratium dulce, n.sp., Grev.Small ; valve with slightly convex sides and subacute angles, the margin with oblong striz; surface depressed, with radiating lines of remote punctiform granules; angles raised, and filled with minute puncta. Distance between the angles 00380.” (Fig. 20.) Hab. Barbadoes deposit, Cambridge estate ; in slides com- municated by C. Johnson, Esq. ; very rare. A very elegant species, of which but few examples have occurred. It is remarkable for its depressed surface, so that when the angles are in focus the central puncta are scarcely perceptible. ‘The angles do not appear to be very prominent, but are so abruptly elevated that the vertical view of the side might be taken at first sight for a transverse line. The central puncta are minute, faint, and remote, becoming a little larger towards the margin. ‘The latter is rather broad, and -marked with elegant, oblong striz, 8 in ‘001’. Triceratium mammosum, n. sp., Grev.—Minute, with thick, produced, rounded angles, filled with minute puncta and straight sides (reckoning from the base of the angles) ; the central space hexagonal, marked with remote and scat- tered puncta. Distance between the angles 0015”. (Fig. 19.) Hab. Barbadoes deposit, Cambridge estate ; in slides com- municated by C. Johnson, Esq.; extremely rare. Very conspicuous at a glance, from the large, produced, mammeform, hemispherically rounded angles, which, being covered with puncta, appear out of all proportion to the rest of the valve. Central puncta circular, irregularly scattered. AMPHITETRAS. Amphitetras elegans, nu. sp., Grev.—Small; valve with the sides slightly concave in the middle; angles rounded, termi- nating in a small, ring-like pseudo-opening; celiulationminute, radiating from the depressed centre, somewhat smaller and more crowded within the angles. Distance between the angles ‘0025. (Fig. 24.) Hab. Monterey deposit ; L. Hardman, Esq. A most beautiful small species, elegantly radiate, with a very narrow simple margin. The pseudo-openings have the appearance of being the ends of short hyaline tubes. 10 Further Observations on the VecEeTaBLe Parasites, particularly those infesting the Human Skin. By Jasez Hoae, F.L.S., M.R.C.S., &e. (With Plates III & IV.) (Read Nov. 8, 1865.) Mr. Presrprnt,—Since you did me the honour to ask for a contribution to the ‘Transactions of the Microscopical Society’ during your term of office, [ thought I could not better engage an evening than by putting together a short account of some further observations I have been making, during the recess, on the identity of the parasitic fungi infesting the human skin. And I must request the members to receive the few remarks I am about to make as a conti- nuation of the investigations I communicated to the Society at the end of 1858, and which were published in our ‘ Trans- actions,’ January, 1859, wherein I endeavoured to show the true character of the so-called parasitic diseases of the skin, — their common origin and identity, and also the universal distribution of these parasites throughout nature. You will, I am sure, pardon a small degree of vanity, when I say that it 1s exceedingly gratifymg to me to find that the publication of the. paper just referred to seems to have been the cause of directing the attention of other observers to this very important subject. For by the labours of scientific men diseases of the skin have been gradually rescued from the hands of the empiric ; and as they are now acknowledged to be constitutional rather than local affec- tions, a simpler and more effectual method of treatment for the cure of some of the greatest ills that flesh is heir to, is distinctly pointed out, and at once resorted to. But whether future investigations will tend to confirm an opinion now gaining ground, to the effect that the poison-germs which produce the more alarming infectious diseases are likewise of a fungoid nature, I am not at all prepared to say. But of this we may be quite certain, that it is only by the aid of the microscope, in the hands of those who will patiently sit them- selves down to interrogate nature, ‘that we can ever expect to make out the character of those poisons which, generated in one body and conveyed to another, produce such terrible destruction to our race.”* For these microscopic germs, 1n- * Dr. Beale, in a highly valuable series of lectures “On the Passage of Germinal or Living Matter from one Organism to another,” published in the © ‘ Medical ‘Times and Gazette,’ 1864, enters into the question of contagion. He believes that when germinal matter has its powers of growth perverted or Hoee, on Vegetable Parasites. 3 11 visible though they be to the unaided sight, are nevertheless produced in myriads in the earth, air, and water around us, and are so diminutive that ordinary motes floating about in the atmosphere are large in comparison. And when we reflect on the very remarkable powers of life possessed by all —and the fungi in particular—which are found to resist a moist heat equal to that of boiling water, and also an in- tense frost, without at all losing their powers of germi- nation, we can no longer feel surprised that their spores are found penetrating the hairs of the head or the hair-follicles and epidermic cells of the body; nor, indeed, that they should penetrate the internal parts, even where the hard tex- tures, the bones, do not escape their destructive influence. For the very reason that these pests, botrytaceous or myco- dermatous fungi, are found both upon the external and in- ternal surfaces, it is proposed to divide them into Epiphytes and Entophytes. Although, as I have before pointed out, it is not possible that in either of these cases fungi originate disease, it is pretty certain that they frequently aggravate it, and once let the spores establish themselves on any part of the body where the secretion is not sufficiently active or healthy, and it is a difficult matter to throw off the intruder. These, then, were exactly the conclusions I had arrived at seven years ago, and since this subject has engaged the atten- tion of our countrymen, it appears that men who are deservedly . eminent on the Continent have been led to examine into the truth of these researches, and the result has been that Bazin, Hebra, and others, have considerably modified their views and reduced the number of species. It will, however, assist our investigation if I enter very degraded, it may obtain a power of indefinite multiplication, like the pus of an abscess or the secretion from purulent ophthalmia. Such pus, that is, such degraded germinal matter, he has shown to have the power of inde- pendent growth under various conditions, and to be capable of maintaining its vitality for long periods, if not completely deprived of moisture. When introduced into another animal’s body, offering favorable conditions, it in- creases and multiplies. It would appear, then, that the growth of ill-con- ditioned germinal matter may be accompanied by the development of poison in the organism that supports it; just as the growth of mould changes the quality of bread, or cheese, or other substance, on and in which it is found. He does not, however, assume the existence of spores or other bodies, whose presence he has not yet discovered, but appeals rather to the germinal matter whose existence and growth he has demonstrated ; and although he does not look for the extinction of all contagious diseases, yet he does expect that much good will be derived from keeping the body in an unsusceptible state —by living in good and pure air, by dryness and plenty of sunlight, and es- pecially by general cleanliness, as preventives of these forms of disease. 12 Hoge, on Vegetable Parasites. briefly into the early history of the parasitic diseases, and their recognised division into species. It is now more than a quarter of a century since Bassi, of Milan, discovered the vegetable character of a disease which caused great devastation among silkworms; and, about the same time, Schounlein, of Berlin, was led to the detection of certain cryptogamic vegetable formations in connection with skin diseases. ‘The observations of this distinguished man have been abundantly confirmed by Gruby, Remak, Robin, Kiichenmeister, Bennett, Jenner, and others, most of whom attempted to identify the fungus with the disease which they believed to be produced by it, and in this way separate and detach some of the most common skin diseases from the rest, and so regard them simply and almost exclu- sively as fungoid or parasitic diseases. Thus, the parasite supposed to be peculiar to, and productive of, each disease has been minutely described, and honoured with a name derived from the name of the disease which it is supposed to have originated, as appears in the following table : WILLAN. Bazin. WILson. PARASITE. | Porrigo favosa and Tinea favosa |Favus Achorion Schonleinit. lupinosa | Porrigo scutulata Tinea tonsurans/Trichosis fur-|Zricophyton tonsurans. furacea Porrigo decalvans Tinea decalvans/Alopecia Microsporon Audouini. Mentagra Tinea sycosa_ _|Sycosis Microsporon mentagra- phytes. Pityriasis versicolor |Pityriasis Chloasma |Microsporon furfur. Now, this very tempting theory involves an important principle of pathology, inasmuch as it places the parasitic fungi above described in a category by themselves, and in- vests them with characteristics entirely at variance with those of the natural history of the family of fungi, whose ' leading feature appears to me to be that of selecting diseased and decayed structure as the soil most essential to their existence; whereas this hypothesis assigns to them healthy organized matter to live and prey upon, and thereby esta- blishing specific diseases. In examining into the truth or fallacy of this theory by the light of physiology, we must bear in mind that the surface of the human body is supplied with a delicate covering, one office of which is to excrete, and another to eliminate or exude, effete matter from the Ho«e, on Vegetable Parasites. 13 blood. ‘The excretion consists chiefly of epithelial scales, and the exudation is mostly made up of fluid and gaseous matters, which sometimes become condensed and dried on the surface of the epidermis. The epithelial scales are friable and separable by very slight friction during health, and the transpired fluid makes its free escape, under ordi- nary circumstances, without any assistance from without. But want of cleanliness, deficient exercise, and much more frequently a deranged state of the health, especially a vitiated condition of the body, interfere with the natural processes of elimination ; and then the skin itself becomes diseased, and in this diseased condition may become infested by parasitic fungi, the spores and filamentous threads of which find a nidus in an abraded portion of the cuticle; or, what is more generally the case, the shafts and roots of the hairs are invaded, the hairs become brittle and stunted in growth, and at length perish and fall off. Dr. Tilbury Fox, who in 1863 published an excellent work on ‘Skin Diseases of Parasitic Origin,’ was the first to call the attention of the profession to a pomt of considerable practical value in conjunction with parasitic growths, namely, that whenever we find fungus in connection with a skin disease we must look upon it as a something superadded to the diseased condition—“ a complex condition, an eruptive disease plus a tinea” (parasite). By taking this definition as our guide, we may say without hesitation that “the pathognomonic sign of parasitic disease of the surface is the infiltration and destruction of the hairs by the spores; and the diagnosis can in nowise be considered perfect until spores or mycelia have been detected by the microscope.”’ For the future, then, we must look upon parasitic disease as non-existent without this test. I cannot, however, admit that this complex condition at all mvalidates, as Dr. Fox would seem to imply, the opinion expressed by me in my former paper, namely, that the growth of a fungus is not necessarily pathognonomic of any special form of skin disease ; nor do I quite think, with him, that the complex eruptive condition is so entirely of a secondary character simply because in tinea decalvans we sometimes find the parasite in the perished and falling hairs unaccompanied by any eruption of the skin. In the course of my experience, which appears to slightly differ from Dr. Fox, I happen to have seen in my friend Mr. Hunt’s practice cases of alopecia, sycosis, porrigo decal- vans, &c.,* with a scaly desquamation preceding the perishing and falling of the hairs, and at the same time unaccompanied * See former paper, Vol. VII, ‘Quart. Jour. Micro. Science,’ 1859. 14 Hoge, on Vegetable Parasites. by parasitic growth; therefore I still believe that an eruptive condition or an abraded secreting surface is a very necessary part of the disease, and that then the skin affords a more particularly favorable soil for the development of the fungus ; but leaving this part of the subject for the present, I shall proceed to show in an experimental and, I trust, a ‘satisfactory way that the same species of fungus often exhibits varieties of character, as well as form, at different stages of development and under varied influences ; so much so, “that neither size nor outline affords any basis for dis- tinction into species until it has been ascertained, from ex- tensive comparison of forms brought from different localities in the widest area over which the species can be traced, what are the average characters of the type, and what their range of variation.” (Bentham.) First, with regard to collecting and taking fungi, I find that the prevalence of damp or moist close weather is espe- cially favorable for the purpose; while in an opposite condition of the atmosphere—fine frosty weather—I have rarely been able to secure a supply; and, moreover, my ex- perience has proved to me that in the winter season diseases of the skin accompanied by parasitic growths disappear from among the poor who frequent our skin infirmaries. Mr. Hunt also finds that season brings with it its own peculiar type of skin disease. It appears that at particular periods of the year the atmo- sphere is, so to speak, more fully charged with microscopical atoms than it is at others. ‘The spores of the moulds, aspergilh, penicillia, and puccinia, are perhaps the most widely - distributed bodies, and towards the end of the hot weather, or about autumn time, they are very abundant. Among those who have taken them at this period of the year we must ever associate the name of one of our body, the Rev. Lord Godolpin Osborne, who, I believe, first experimented in this way during the cholera visitation of 1858. He exposed pre- pared slips of glass, slightly moistened with glycerine, over cesspools, gully-holes, &c., near the dwellings of those where the disease appeared, and caught what he named aérozoa— chiefly minute germs and spores of fungi. I was favoured with a few specimens, one of which I have placed under a microscope on the table for the purpose of comparison with the more recent specimens taken by myself two months ago ; a drawing made from this (see Plate V, fig. 4) exhibits spores almost identical with those found in the skin, &e. From the year 1858 to the present time I have amused myself by catching these floating atoms, and, so far as I can Hoe, on Vegetable Parasites. 15 judge, they are found everywhere, and in and on every con- ceivable thing, if we only look close enough for them. Even the open mouth is an excellent trap ; of this there is ample evidence, since we often find on the delicate membrane lining the mouth of the sucking, crying infant, and on the diph- theritic sore throat of the adult, the destructive plant Otdium albicans. The human or animal stomach is invaded, and in a certain deranged condition we find the Sarcina ventriculi, with its remarkable-looking quaternate spores, its torule, &c., seriously interfermg with the functions of this organ. J may mention a curious fact in connection with stomach fungus, the discovery of Lehmann, namely, if an emulsion of casein (the casein of sweet almonds) be mixed with a small quantity of amygdaline and then introduced into the stomach of the animal, it very soon ferments, and the yeast-fungus quickly changes the chemical constituents of the mass into the poisonous substance od of bitter almonds, and thus destroys the life of the animal. In specimens of the vomit from another fearful disease, the yellow fever, sent to me from Bermuda, I found a large ad- mixture of spores and torul, with altered blood-corpuscles and disintegrated epithelial scales.* Here, then, we have striking examples of the ravages committed by the fungi, but I think no one will say we are justified in attributing either fever, thrush, or diphtheria, to the presence of the Oidium found in connection with these diseases. I might go on multi- plying examples of a similar kind; but as that would incon- veniently extend my paper, I will rather proceed to give the results of experiments made with the favus fungus taken from the human body. At the time I read my former paper I was unable to show the results of any examinations, or, indeed, make more than a passing allusion to favus, although a well-known form of disease, from the circumstance of its having attracted the attention of Schonlein, who found a fungus growth always * My own observations on the presence of fungi in these vomits receive confirmation from Dr. Buchanan, who was sent by the Privy Council to make inquiries into the outbreak of yellow fever at Swansea, last September. Upon making a microscopical examination of the vomits he discovered large quantities of fungus-spores, changed blood-cells, &c. Last year IL met with fungus-spores in the chamber of the eye, a still more remarkable portion of the human body, than any above alluded to. A man fifty years of age, came to me complaining of impairment of sight. His attention was first directed to the defect by the very unusual appearance of a small “plant-like body” always before him. By a careful examination of the eye with a magnifying ophthalmoscope I was quite able to satisfy myself of the presence of a small group of puccinia spores in the vitreous humour. 16 Hoge, on Vegetable Parasites. mixed with favus crusts. The disease is one commonly known as cupped ringworm, or honeycomb scall, and is now rarely seen in this metropolis; therefore I consider myself fortunate in having been able, through the kindness of my friend Mr. Hunt, to investigate three cases, from each of which I collected scales for microscopical examination. I have here a few of the peculiar-looking crusts, and it will be ob- served that they are cupped in appearance, and of a dingy yellow colour. The crust is almost entirely composed of the Achorion, mixed with epithelial scales and broken hairs. When the fungus once establishes itself, so fearful are its ravages that in a very short space of time the whole of the cutaneous surface, with the exception of the palms of the hands and soles of the feet, becomes covered with it. I attempted to obtain a photograph of one of the patients, but cannot say very successfully ; the print gives but a faint idea of the disagreeable picture really presented to the sight. Large masses of the crusts fell off daily, each one leaving its mark behind. As the spores penetrate the hair-follicles they . destroy the sheaths of the hairs, which shrivel up and lose their colouring matter, and then break off, leaving the sur- face bald. The fact of the surface becoming so entirely denuded 1s explained in this way :—The shaft of the hair is less in cir- cumference than the bulb, and consists of hardened, shrunken epithelial cells, almost devoid of germinal matter; and the further removed from the bulb the less of vital power does it possess, and consequently, when its nutrient supply, small even at first, become interfered with and lessened by the in- creasing spores, it loses the little vitality it ever had, dies, and drops off. And in this, as in other cases, the fungus feeds upon the dead, and not the living, material. If we now take a crust and examine it more closely, it will be seen to be made up of an outer and older part, thick and dark in colour, the fungus being here in a more advanced stage, and chiefly composed of sporangia, spores, and mycelia, with fragments of several hairs imbedded in them. The under or inner and younger layer is paler in colour, and consists of spores mixed with epithelium, fatty and granular matters, and sometimes pus; and I suppose we may consider that in some cases a very large quantity of the latter ingre- dient (pus) has been mixed up with the outer. parts of the crusts. Mr. Wilson started a new theory, founded on this exceptional condition, namely, “that the favus matter is produced from the development of the nuclei of pus-cells ;” that the parasite is not a vegetable, or that, if it be, it might be Hoae, on Vegetable Parasites. : 17 looked upon as an example of the conversion of an animal into a vegetable product. It is quite possible, without a careful microscopical examination, to mistake the stroma, always present in large quantities in favus crusts, for pus. This, I think, is a mistake often committed by the more casual ob- server. We will not, however, enter into any discussion upon this theory, nor upon one still more improbable, “ the Spontaneous generation hypothesis’—of all hypotheses the most gratuitous; 1 was almost about to say absurd. I must now be permitted to add a few words upon the physical aspect of persons suffering from favus, because, as I have already stated, and not without proof, that such diseases are the embodiment, or rather the impersonification, of a weakly, unhealthy state of the body, well understood as the scrofulous habit; and associated with a dirty or neg- lected state of the skin in the majority of cases. Hebra, the great authority on skin diseases, lays much stress upon the feature of dirtiness as a cause of favus, and goes so far as to say that this accounts for its rarity among the upper classes of society. ‘The subject of one of the worst cases,” says Mr. Hunt, “ was a puny, half-starved boy of seventeen, whose appearance was that of a child of nine or ten. When he was taken from his miserable home into purer air, and well fed, the crusts died and dropped off; but when he returned to the wretched habitation of his parents, situated in one of the filthiest parts of Lambeth, and was insufficiently fed, the ve- getation grew again most rapidly—flourishing in the vitiated fluids like a vine in a mass of stercoraceous mould.” From this boy I obtained, in 1859, large supplies of the fungous crusts, and at that time, to make sure of the results of my exa- minations, I sent portions of the same to friends upon whose experiments I could rely for the confirmation of my own. Having perfectly satisfied myself, and not by one but by many trials, that the achorion (favus) produces as good a ferment, and nearly as briskly, as healthy yeast, when added to barley-wort, with only a slight difference of size and form “a difference of degree, and not of kind,” my next experi- ment was one slightly varied, for the purpose of observing the modifying influence of light over these fermentations, and at the same time ascertaining if this agent at all affected the character of the results. I was, perhaps, led to make this observation from finding that yeast requires for its more per- fect growth, not only a proper temperature, but almost occlu- sion from daylight—a fact that appears to hold good in the development and growth of most fungi. | therefore, in April last, procured a supply of fresh wort from a brewery, which VOL. XIV. b 18 Hoge, on Vegetable Parasites. I divided into three equal portions, and, for the sake of con- venience, numbered 1, 2, and 3. Into Nos. 1 and 2I put a few favus crusts; No. 1 was put carefully away in a darkened place, the temperature of which was about 70° Fahr.; Nos. 2 and 3 (the latter being simple sweetwort only) I exposed to a good light in my sitting-room window, where the tempera- ture ranges from 65° to 75° Fahr.; and each bottle was closely corked. On the second day, upon examining a portion of 1 and 2 with a }-inch power, I found fermentation had com- menced, a film spreading over the whole surface of the liquid. In No.1 were seen a fair quantity of yeast-cells, varying in form and size; shownin Pl. III, fig. 1, a. No. 2 wasina more ad- vanced stage, and some of the spores were rather larger than in No. 1. On the 4th and 5th days I took portions from all three bottles. That from No. 1 gave the best results; the spores, yeast-cells, were more numerous and spherical in form, well filled with granular matter and numerous monili- form chains of smaller spores and amorphous stroma, shown in fig. 1, 6. Compared with a small portion of fresh yeast from a beer-barrel, fig. 3, the cells and spores appeared about half the size (in the drawing, however, they are repre- sented too small). In specimen No. 2 spherical cells were fewer and smaller, with groups of ovoid spores mixed with torule, and bacterium-like bodies floating rapidly about; here and there were seen tufts of penicillium, represented in fig. 2, a. In the sweet wort No. 3 were numerous ovoid spores, without granular matter, but highly refractive, and not unlike fat-globules. On the 10th day the changes seen in specimens taken from each bottle were still more marked. From No. 1 the spores were more numerous, but certainly rather smaller, and vari- able in form, and the greater portion of them were filled with granular or nuclear matter ; there were also groups of torulz mixed with still smaller spores, fig. 1, c. This specimen when the cork was removed from the bottle, gave indica- tions of the presence of carbonic acid, and the odour was that of good fresh beer, and the greater portion of the heavy yeast had fallen to the bottom of the bottle. No. 2, on the contrary, had become quite of a dark colour, smelt sour, and the spores had much decreased in size, granular matter with bacteria being by far the more numerous; represented in fig. 2,6. The wort in No. 3 was still sweet—of a some- what vinous sweetness—and the top was thickly covered over by a whitish, flocculent, filamentous-looking mass of mould. A fortnight or rather more elapsed, and then another exa- mination gave somewhat similar results. No.1 was still per- Hoge, on Vegetable Parasites. 19 fectly sweet, while No. 2 was more sour, and ofa dark red colour ; the filamentous masses were broken up, and had fallen to the bottom of the fiuid, and the surface was slightly covered with amould. No. 3, although smelling somewhat like bad wine, was not much altered in colour, but on its surface the aspergillus was growing. Six months later No. 1 was per- fectly sweet, exhibiting well-marked spores and torule; No. 2 was rather more decomposed than 1t was on the former examination; and No. 3 remained the same. Now, upon comparing the fermentation of the achorion fungus with that of good healthy yeast, it will be seen to be almost identical. In the first place, it is as actively carried on by the former as by the latter. There is, however, just a slight difference in the size of the spores or cells already mentioned, those from yeast being the larger and more nearly spherical, with a greater number of reproductive spores, that is, cells with a single, clear, nucleated cell in their interior, while others are filled with a darker granular matter, and having only a slight tendency to coalesce or become fila- mentous, while the achorion are for the most part ovoid and very prone to coalesce and produce elongated cells or torule. Now, with reference to the slight difference in size, we must look upon this as a matter of very little importance; for to the presence of light in the one case, and its almost total exclusion in the other, this difference, I have no doubt, is almost entirely due. It would be more trustworthy if comparisons of this kind could be made at the same stage of development; for be it remembered that yeast obtained from a brewery is in a more favorable state, inasmuch as it is stopped at a certain stage of growth or de- velopment, and then set to begin its fermentation over again in fresh supplies of a new pabulum, which gives increased health and vigour to the plant; while, on the other hand, the achorion, or favus fungus, is obtained and used in an ex- hausted state from an already ill-nourished or starved-out soil. Neither can we attach much importance to differences of size and form of the spores, for even this occurs in yeast ferment; and although the ovoid is most frequently seen in achorion, it is equally common to yeast when exhausted. This is strikingly exhibited in Pl. IV, fig. 2, a drawing made from a drop of exhausted yeast taken from porter; here we have the oval and elongated cell with torule. ‘To ensure success in these and similar experiments, the fungus or yeast should be left floating on the surface of liquids; the process is either carried on very slowly or is entirely arrested by submersion. Turpin and others, in their experiments on yeast, noticed 20 Hoge, on Vegetable Parasites. that the cells become oval and bud out in about an hour after being added to the wort; but this change depends as much upon temperature and density.of the solution as upon the quality of the yeast. It is a well-ascertained fact that when yeast is added to distillery wash, which is worked at a higher temperature than brewers’ wort, fermentation com- mences earlier, and the yeast-cell grows to a much larger size. It is, mdeed, forced in this way much as a plant in a hothouse is, and then obtains to greater perfection in a shorter time. It will, however, be seen that it sooner be- comes exhausted ; and now, if we take a portion of this yeast, and add it to barley-wort, and at the same time keep it in a temperature of from 60° to 65° Fahr., it ferments languidly, and small yeast-cells are the produce. If the yeast is allowed to stand in a warm place for a few days it partially recovers its activity, but never quite. With such a yeast there is always a good deal of torule mixed with the degenerated cells, and sometimes a filamentous mass, which falls to the bottom of the vessel; from this stage it readily passes to that of must and mildew, and then becomes a wasteful feeder or destroyer. . With yeast passing to the stage of exhaustion I have see a crop of yeast fungus produced in the head of a strumous boy, seven years of age, who was much out of health, and had suffered from eczema of the eyelids, with impetigo. The disease had obstinately persisted in spite of well-directed efforts to remove it. The scabs were frequently examined, but no fungus found. The mother, by the recommendation of a friend, washed the boy’s head every morning for a week with stale beer. I saw the child a few days after these wash- ings were discontinued, and warm water only used to soak the scabs off. On placing portions of the broken hairs on a — glass slip, and moistening with a drop of liquor potasse, spores and torule were seen in abundance. Represented in PI. ITI, fig. 4. I have made frequent microscopical examinations since, with the same results. Two years have passed, and the disease remains, although parasiticidical washings have had a fair trial. A change to country air and good diet always does more good than medicine in this case. I do not look upon this single experiment as at all sufficient to prove the pro- duction of the yeast fungus by transplantation into the human skin, although it is not very unlike the achorion fungus, or that of tinea tonsurans (tricophyton) ; but, taken with many negative trials that I made, to introduce both yeast and achorion into perfectly healthy skins, without any abrasion of Hoae, on Vegetable Parasites. 21 surface, I think it has an important bearing on the sub- ject of my paper. At all events it is a fair illustration of change of type,* for when Mr. Hunt saw the boy, after the disease had persisted for at least twelve months, he at once pronounced it to be pityriasis rubra or versicolor. Wad the fungus played any part in bringing about this change in the character of the disease ? In another experiment I took portions of some penicillia and aspergilli moulds, and upon adding these to sweet wort I obtained results confirmatory of Dr. Lowe’s,t which were pretty much as follows. Having placed small quantities of spores in the wort, I stood them by in a warm room. On the second day in one of the solutions, and on the third in the other, fermentation had fairly set in; the surface of the solution was covered with a film, which proved to be well developed ovoid spores, filled with smaller granular spores (conidia) (fig. 5, Pl. IV). Onthesixth day the cells changed in form, and were more spherical. Again removing these to another supply of fresh wort, the results obtained were quite characteristic of exhausted yeast ferment. * The Rev. Mr. Berkeley, in his ‘Outlines of British Fungology,’ writes : —“Itis not possible that in these cases fungi originate disease, though it is pretty certain that they frequently aggravate it.” Nevertheless, after this clearly expressed and positive statement, we find, a few pages further on, the following contradictory assertion :—‘ That a few spores rubbed into the skin or inserted in it will soon produce the disease known as porrigo lupinosa”’ (favosa ?). And he cites Dr. Lowe as his authority for this statement ; but on looking over this gentleman’s writings, what do we find? Why, that in the course of a somewhat extended inquiry into the causes of diseases of the skin he only met with two cases in brewers’ draymen, and one in a dirty cellarman, of parasitic growths, with sycosis and favus, and which, he tells us, commenced with a sore. 1 would ask any one conversant with these diseases if this at all justifies the above assertion, or proves that the parasite can be communicated to, and grown upon, the Aealtiy human skin. For my own part, so thoroughly satisfied am I of the utter fallacy of such a statement, that I should have no hesitation in submitting my own skin to be experi- mented upon to test the truth of what I have stated. + It is only right to say that I did not follow Dr. Lowe, as some writers have stated, in this field of inquiry. My observations on skin diseases were commenced at the suggestion of my friend Mr. Hunt, in 1856, and continued for three years before my first paper appeared in print. At that time, 1859, neither Mr. Hunt nor myself had heard of Dr. Lowe’s researches, which, it appears, were communicated to a local society, and published in the ‘Hdinburgh Botanical Society’s Transactions,’ 1857. t Directions for preparing and mounting— The mode of preparing specimens of fungi for the microscope.—After having removed a small portion of the crust or a hair from the affected part, place it on a glass slip, and gently separate the mass with needle-points, and add a drop of liquor potasse, which will render it transparent; then cover with a piece of thin glass and remove any superfluous fluid with a small piece of blotting-paper. 22 Hoee, on Vegetable Parasites. From these experiments I believe that it matters little whether, we take yeast, achorion, or penicillium spores, the resultant is the same, and depends much more on the food or nourishment supplied whether the pabulum contains more or less of a saccharine, albuminous, or nitrogenous material, lactic acid, &c., together with light and temperature ; whether we have a mould (green or blue), an achorion or yeast fun- gus produced. Diversity of form in the cells, as well as quality and quantity of their material contents, is certainly due to, and in a manner regulated and controlled by, the beau- tiful law of diffusion, which admits, separates, sifts, and refines the coarser from the finer, the lighter from the denser particles, through the porous structure of the cell-wall. In conclusion, I trust I have satisfactorily shown that— Ist. There exists but one essential organism, a fungus whose spores find a soil common alike to the surface and the more secluded parts of the human or animal body. 2nd. That variations in skin diseases associated with para- sitic growth are due to differences in the constitution of the person affected; to the moisture, exudation, soil, and tem- perature, under which the development of the fungus takes place. Consequently it is neither correct nor desirable to separate and classify them as “ parasitic diseases of the skin.” 3rd. The parasitic growths vary but little in any case, and that only in degree, not in kind, some soils appearing to be better suited than others for their development, that fur- nished by the eruptive or secreting surface beimg in every way the most congenial; while diversity of form, in all cases, arise from growth taking place either upon a sickly plant, a saccharine solution, or an animal tissue. Should there be fatty matter mixed up with the specimen, it will be neces- sary toremove the cover and add a drop of ether; then wash it with dis- tilled water. Other reagents will, from time to time, be found requisite, and enable us to avoid errors in interpretation ; as, for instance, on the addition of a drop of hydrochloric or acetic acid all earthy particles are dissolved out. Ether, chloroform, or alcohol, readily remove fatty matters. A solution of potash or soda will dissolve out pus, epithelium, &c., and more quickly so if the specimen be slightly heated, while fungus-spores are not affected thereby, but, on the contrary, are better seen. In some chronic cases of skin disease we find the epithelium-scales involved ina kind of fatty degeneration, minute fat-globules, which at first sight bear a very strong resemblance to spores; these must be got rid of by soaking in ether, and then washing with strong liquor potasse. Like other vegetable cells, spores sometimes require the addition of a drop of iodine, which renders them dis- tinctly visible. View all specimens, first, with monochromat light, and after- wards with polarized light. The latter shows up the starch-granules, if present, and distinguishes the granular particles of earthy matters. For mounting and preserving the specimen, use glycerine jelly, or glycerine diluted with one third of camphor water. H. Ray Lanxuster, on the Gregarinida. 23 4th. That fungi generally excite chemical decomposition in the soils on which they feed, and that it is the exclusive province of a certain class, when spread on the surface of an albuminoid, saccharine or alcoholic, or slightly acid liquid, to develope and grow, and during growth to give rise to either the alcoholic, acetic, or putrefactive fermentation. Nores on the GREGARINIDA. By H. Ray Lanxester. (With Plate V. (Read Dec. 13th, 1865.) THoucsH the minute organisms known as Gregarinida are remarkable for the great range of their distribution, appear- Ing in various animals, both terrestrial and aquatic—from the Turbellarian worms up to the Brachyourous Crustacea and Mollusca, and even in Vertebrata—very little indeed has been added to our knowledge of their structure, de- velopment, or habitats, during the last few years. This is a matter not only for surprise, but also for regret, inasmuch as there are some important points in the history of these parasites still to be examined, and doubtless many new and interesting forms to be discovered. There is nothing to be recorded as having been ascertained with regard to Grega- rinida since the short article which I published nearly three years ago in the ‘ Quart. Journ. Mic. Sci.’ The researches of Lieberktthn* are generally accepted, and the great dif_i- culty now is to discover the true sexual reproduction of these animals. Probable sexual reproduction.—The encystation of a single or of two Gregarinida, and their gradual resolution into a number of minute cells, at first circular, and afterwards, in the ease of Monocystis Lumbrici, at least, assuming a navicula- like form, are well known. The pseudo-navicule issue from the sac, and become free organisms. They have been formed by a process analogous to gemmation in the cyst ; and it 1s in their history, I believe, that the sewual reproduction of Gregarinida must be sought. It was formerly considered that the pseudo-navicule individually developed into Grega- rine by a single process of growth ; Lieberkuhnt} showed that they undergo certain changes, their contents becoming con- * Since writing the above I have seen a short paper by Lieberkihn, in ‘Muller’s Archiv’ for the last quarter of 1865. An abstract of it will be found in the “ Chronicle.” + ‘Mém. de l’Acad. Roy. de Bruxelles,’ 1854. 24, KE. Ray Lanxester, on the Gregarinida. centrated towards the centre, after which the envelopes of the pseudo-navicells become flaccid, and allow their contents to escape, which grow into Gregarine, passing through an amcebiform stage. As far as Lieberktihn ascertained, the whole process was simply one of gemmiparous reproduction, or analogous to it. The pseudo-navicule were produced by gemmation, and the young amceboid Gregarine were pro- duced from the pseudo-navicule also by gemmation. The pseudo-navicule of the Gregarinz of the earthworm, which are the only species readily attainable for study, are so minute that there is great difficulty in defining their contents, even with a powerful objective, and it is impossible at present to ascertain satisfactorily the structure of those contents. I have, however, observed that many pseudo-navicule have, when they have passed some time in the free state, an apparently viscid substance occupying the greater part of the cavity enclosed by their thick enveloping membrane, while the finely granular substance (which is aggregated near the centre in most pseudo-navicule) is deficient. The gradual formation of this nucleus of protein matter is described by M. Lieber- kthn, but he does not seem to have observed that im many cases it 1s absent, and that there appear to be two forms of these bodies. Is it not probable that the contents of these two forms of pseudo-navicule respectively play the parts of male and female elements? It appears that im no other phase of the existence of the Gregarina is there a possi- bility of sexual reproduction taking place. The large parent Gregarinze have been so carefully watched, and the process of encystation so attentively observed, that it may be confi- dently stated that under these aspects ‘the Gregarina presents no phenomena comparable to those of true sexual reproduc- tion, and hence some observers have been led to suppose that the pseudo-navicule pass from the “ bearer” in which they are produced and attain a sexual form in some other habitat. Lieberkiihn’s observations, however, which I have confirmed, seem to indicate that in the case of Monocystis Lumbrici the changes in the pseudo-navicule which he has recorded are the only ones which take place, and that these occur without the intervention of a fresh. host. If this view of the case should be true the Gregarina which is developed from the amoeboid young might be considered as the parent-stock, the pseudo-naviculz as sexual zooids, and we should thus have a case very easily classed with the other instances of alternation of generations. I would, however, merely wish to offer this as a suggestion, since at present we have not, nor, I believe, can we have, proof that the contents of the pseudo-naviculz are to be regarded as male and female elements. BK. Ray Lanxester, on the Gregarinida. 25 Large size of some species.—It appears that the Monocystis Lumbrict has an almost indefinite power of growth, limited only by the cessation of the supply of nutrient material. In Pl. V, fig. 1, is drawn a specimen from the posterior portion of the perivisceral cavity of the earthworm, which was found floating there with two others, being of unusually large size. One of the specimens was the {,th of an inch in diameter, the contained vesicle of proportionate size, and the granules also much more conspicuous than is ordinarily the case. In the same worm the seminal vesicles and testicular sacs were found to be occupied by several individuals of Monocystis of enormous size, the whole of the cavities appeared to be filled by them, and the nourishment diverted to their use which should have been employed in the development of the seminal secretion. One of the largest of these Monocystes was 1th of an inch in length, being of a linear form (fig. 2). When it is remembered that the ordinary length of a Monocystis Lumbrict is =+,th of an inch or less, the strangeness of this large growth will be admitted. It appears that, when free to develop equally in all directions, the Gregarina assumes a more or less spheroidal form, as in the first instance, but that when growing in a confined space in company with other in- dividuals a linear increase is induced. The granules in the elongated form were much fewer than in the spheroidal one, and poured freely about in the interior. A considerable amount of activity was shown by this speci- men, and the tunic or enveloping membrane was thick, and occasionally showed striations, while in that from the peri- visceral cavity the membrane appeared much thinner and there was no movement. As arule, it seems that the gra- nules are developed in the Gregarinze at the expense of the investing tunic, and that the larger the bulk of the granules the less is the activity of the Gregarina. Structure and function of the investing tunic.——I was in- duced some time since to believe, with Dr. Leidy, that the investing membrane of the Gregarinida is double, inasmuch as an appearance tending to prove that such was the case was witnessed both by him and myselfin the Gregarina Blatte. I have now, however, reason to believe that the striations visible in the posterior sac of that species are produced merely by the contraction of a portion of the viscid material which fills it; in fact, the investing membrane must merely be regarded as a dense layer of the same sarcodic material which forms the whole creature. The membrane which invests the whole Gregarina appears to be excessively thin and ill-defined, and more or less continuous with the viscid substance contained by it, which is denser nearer the exterior, and, in fact, seems 26 E. Ray Lanxester, on the Gregarinida. to form a layer beneath the investing tunic, intermediate in density as well as position, which in one or two cases be- comes considerably developed. This occurs in the Mono- cystis of the annelid Nereis (figs. 4, 5), where the granules occupy a smaller portion of the sac than is usual, and the sar- codic substance in which they are imbedded becomes very remarkably differentiated, so that there is a broad fleshy pro- longation of the sac at one extremity, exceedingly mobile, -which indicates the direction in which progression is always made. Distinct striations, giving the appearance of fibrilla- tion, may be detected in the substance of this prolongation. It seems that here that portion of the viscid material filling the sac which is nearest to the enclosing membrane is denser than is usual, and has much of the character of sarcode, while the granules, which are excessively fine, float closely packed together in the inner portion of the same viscous material, which is less dense. ‘This species of Monocystis, it should be remarked, is very active. This, again, would tend to show that the development of granules is in opposition to the activity of the animal, which is further borne out by the fact that young Gregarine, in which there are but very few gra- nules, are always by far the most active. The striations on the investing membrane, which are noticeable in many species, such as M. Serpule, M. Sabelle, &c., are similar to those occurring on the tunics of many Infusoria. In some species they occur in immature specimens only, and are not traceable in fully grown individuals. This is the case in M. Terebelle, and in an undescribed form abundant in Cirratulus borealis (figs. 8, 9), while in certain stages of the development of /. Lumbrici a series of filamentous processes, or sometimes of small conical bodies, appear to be developed from the exterior of the investing membrane and afterwards cast off.* The prolongation of part of the sac into a proboscis provided with hooks or a broad flattened extremity, as in G. Steboldw and G. Heerii, also shows the plasticity of this portion of the saccule constituting a Gregarina. The movements of a Gregarina do not depend on the mere elasticity of the envelope, but on the contractions of the dense portion of the viscid sar- codic substance contained by it, which is continuous with it, and the development of which is opposed to the development of the granules. Specific distinctions.—It is a matter of very great difficulty to decide on specific differences in higher animals possessing many more points of character than can be found among Gre- garinida, and, indeed, among these latter it becomes almost * These filamentous bodies do not form part of the Gregarina, but are sperm-cells of the Zumbricus, in M. Lieberkihn’s opinions. EH. Ray Lanxeste|r, on the Gregarinida. 27 impossible to speak of a species with that definite meaning which zoologists attribute to the word. oy “ ae ? sXi- Na : aoa yi nt hs 8 ae . ( re . ee ie: dele ‘a AN Crt Paste’ ef ae “ wid a. ata ce ene Hat? - i i fe sey We tit ig figs sree hain ama pret nit sollte 4 coe point of a ‘A vida t ee Et Ne “i TRANSACTIONS OF THE MICROSCOPICAL SOCIETY OF LONDON. A New Apsustasty DiapHracm. By Stoney B. Kincaip, Hsq., .R.A.S: (Communicated by F. H. Wunuam, lsq.) (Read March 14th, 1866.) Tue desirability of possessing a means of adjusting the illumination of transparent objects under the compound microscope within closer limits than those allowed by the ordinary wheel of diaphragms placed beneath the stage, has been patent to microscopists almost ever since the study of the more minute forms of nature under high magnifying power has claimed to rank as a science. But although practical opticians have proposed various aperture-limiting shutters for attaining that object, no contrivance, as far as I am aware, has hitherto been described which fulfils the condition of affording an easily adjustable aperture, which constantly prescrves its centricity, and approximates more nearly to a circular figure than a square or diamond. When I turned my attention to the subject a short time since it appeared to me that the adaptation of the Iris diaphragm (which was designed some years ago to be ap- plied to the astronomical telescope for the purpose of observ- ing variable stars) beneath the stage of the microscope would at once furnish the wished-for desideratum ; and the experi- ment has proved so satisfactory that, in the hope that 1t may be of service to others engaged in microscopic pursuits, [ would beg leave to lay a description of it before the Micro- scopical Society. The arrangement, of which a sectional view is shown in Fig. 1, consists of a brass tube, A, screwing beneath the stage of the microscope at B, and within which a second tube, C, of less length, works friction tight; this latter is sprung and furnished at one end with a milled edge, D, projecting beyond the outer tube, and affording the means of rotating the inner one. ‘To the opposite extremities of these 1s attached VOL Xs cf 76 Kincaip, on a New Adjustable Diaphragm. by brass rings, E, fixed with small screws, a tube of vulcanized india-rubber, F, equal in length to A, but rather less in diameter than the interior of C. By turning the milled edge while A remains fixed, the rubber is made to extend inwards, and when half a rotation is accomplished, it com- pletely closes the aperture, which remains constantly central, and nearly circular, being, indeed, a polygon of a great Fig. 2. SN A Ae meee wm es a mw mee we me MA WS RA SSS SSS xy » SSW G 74 Y Bi A Z g Oa Gt B Be SS SESSA SS SS (a eee own om arm me ae erate a NO al (2 renee eee ee ne en ee number of sides. The principle of the contrivance will, perhaps, be more readily understood by a reference to Fig. 2 ; for if two rings, A and B, be supposed similarly divided in any number of points, and those points connected by parallel lines forming a skeleton cylinder, it will be seen at once that if one of the rings be turned half way round, every line will pass through the centre, C, of such cylinder, the general figure resembling an hour-glass. The india-rubber tube must evidently be considered as composed of an infinite number of such threads. In Fig. 2 is given a sketch of the appearance presented by the rubber when the opening is nearly closed, only six folds, however, being taken for the purpose of illustration. In conclusion, I would remark the necessity of making the tube C sufficiently long in proportion to its diameter, to allow of the rubber quite closing the aperture. The cement com- monly used by opticians in the construction of electrical apparatus seems well suited for fixing the rubber to brass, and a solution of caoutchouc in mineral naphtha may be used to join the surfaces of rubber. Cd. Descriptions of New and Rare Disroms. SeRins SX —K7K By R. K. Grevitiz, LL.D., F.R.S.E., &c. (Communicated by F. C. S. Ropur, F.L.S., &ic.) (Read March 14th, 1866.) PLAGIOGRAMMA. Plagiogramma orientale, nu. sp., Grev.—Minute; valve panduriform, with central costz and shortly produced apices ; puncta very minute, pees decussating lines. Length, “ome” (Pl. VILE, fig. 1.) Hab. Ganzibar ; Professor Hamilton. L. Smith. Almost as minute as P. atomus, and resembles it in form, only not so deeply constricted. The chief difference, how- ever, lies in the absence of costz at the ends. GEPHYRIA. Gephyria constricta, n. sp., Grev.— Valve with obtuse, cre- nate ends, and deeply constricted in the middle; coste 5—6 in ‘001”. Length, :0055” to 0072”. (Fig. 2.) Hab. Monterey deposit; L. Hardman, Esq. A noble species, of which, through the kindness of Mr. Hardman, I have seen a numberof examples. The constric- tion is so remarkable that, while the widest part of the frustule is nearly 0020”, it is often only ‘0007” across the middle. The relative proportion, however, of the two parts varies to some extent. Between the cost the valve has a minutely punctate appearance; but on a careful examination this seems to arise from a subjacent very minute cellulation. In Mr. Hardman’s cabinet is the front view of a lower valve of a gigantic Gephyria, nearly ‘0120” in length; in which the base of the valve is punctato-striate. MELOSIRA. Melosira costata, n. sp., Grev.—Pale; jomts cylindrical, uninterrupted, longitudinaliy costate. Breadth of filament, 0003” to 0007”. (Figs. 3—6.) Melosira 2—Small form with longitudinal markings, Nor- man, in ‘ Annals of Nat. Hist.,’ vol. xx. 2nd Series, p. 159. (1857.)* * ‘Notes on Diatomacese from the Stomach of Ascidex.’ By George Norman, Esq. 78 GREVILLE, on New Diatoms. Hab. North Sea, off the coast of Yorkshire, in the sto- machs of Ascidians; George Norman,.Esq. Hongkong; J. Linton Palmer, Esq. The diatom above indicated by my friend Mr. Norman I find, on examination, to be identical wilh the specimens kindly communicated to me by Mr. Palmer from Hongkong, where it appears to be abundant. The remarkable longitu- dinal coste, seven or eight of which are sometimes visible at once, constitute an admirable character. Undera high power the cost are seen to be dilated at their apices, and attached to those of the adjoining frustule. CRESSWELLIA. Cresswellia rudis, u. sp., Grev.— Valves convex, depressed at the apex, minutely cellulate, with a circle of numerous, short, obtuse spines towards the margin, and a row of similar smaller ones round the depressed apex. Diameter, ‘0035’ to. "0040". (Fig. 7.) | Hab. Monterey deposit ; L. Hardman, Esq.; R. K. G. Distinguished chiefly by the numerous, short, clumsy spines, which are nearly of the same thickness from their base to their apex, which is often encumbered with fragments apparently torn from the spines of the valve to which they have been attached. The outer circle is situated at some dis- tance from the margin; then come a few very small, scattered spines, which are probably sometimes wholly absent; lastly, the inner circle crowning the flattened apex. The substance is somewhat thick, and the cellules nine in ‘001”. Neither Mr. Hardman nor myself have been so fortunate as to find entire frustules; but this is of little consequence, as the valves in this genus are simply repetitions of each other. CoscINODISCUS. Coscinodiscus Lewisianus, n. sp., Grev.—Disc oval or ob- long; granules conspicuous, forming an irregular central cluster, from which afew nearly straight, wide lines radi- ate to each end, and some very short ones to each side; margin striated, with an interior narrow band of minute puncta. Length, 0024” to 0045”. (Figs. 8—10.) Hab. Rappahannock deposit, United States ; E. W. Dallas, Esq.; R. K. G. I have not been able to find any description of this well- marked and beautiful species. The form renders it at once GREVILLE, on New Diatoms. 79 conspicuous, for it does not appear to be ever circular or even to approach towards it, but ranges between a true oval and elliptic-oblong. There isno umbilicus, but a loose irregular cluster of large, round granules, radiating in either slightly curved or straight lines to each end, diminishing gradually in size ; the lines are so wide apart that four to seven fill up the space, and leave but little room for the few very short lines which radiate to the sides. Just within the striated margin Is a very narrow belt of minute puncta. CRASPEDODISCUS. Craspedodiscus umbonatus, n. sp.—Disc hexagonally cellu- late, the border nearly equal to half the radius, the centre rather sharply umbonate. Diameter, 0035”. (Fig. 15.) flab. Barbadoes deposit, Cambridge estate; in slides com- municated by C. Johnson, Esq. Distinguished at once by its umbonate centre, Cellules near the margin of the border 8 in :001”. COSMIODISCUS, ”. gen. Frustules simple discoid; dise radiato-punctate or cellu- late, with linear, blank radiating spaces extending from the margin inwards (no processes nor internal septa). Whether the three diatoms I have here brought together are really generically allied I will not, in the present state of our knowledge regarding them, take upon myself to say. As, however, they agree in the most prominent character, a provisional union will be, at least, convenient. The genus is constructed specially for the disc first described, which for many years has perplexed me when called upon to examine the Monterey deposit. All these discs appear to be allied to Aulacodiscus, in having blank lines or channels radiating through more or less of their surface towards the margin ; but being destitute of lateral processes they must be arranged among the Coscinodiscee. Cosmiodiscus elegans, n. sp., Grev.—Disc with a broad, smooth margin, and numerous very narrow radiating blank lines; intervening compartments filled with very minute puncta passing into striz next the margin. Diameter, -0035”. (Fig. 13.) Hab. Monterey deposit; L. Hardman, Hsq.; R. K. G. Dise with an irregular, blank umbilicus; granules minute, somewhat scattered and irregularly arranged for some dis- 80 GREVILLE, on New Diatoms. tance round the umbilicus, gradually becoming crowded and more minute, and ultimately passing into fine close striz as they reach the circumference. Radiating lines numerous (24 in the example figured), commencing indefinitely, generally at about a third of the radius from the centre, so narrow as fre- quently to resemble dark strie, but, on careful examination, are perceived to be exceedingly narrow blank spaces ; margin or border pale, smooth, and somewhat broad. Cosmiodiscus Barbadensis, nu. sp., Grev.—Dise convex, with numerous linear blank lines, extending about one third of the radius from the margin; the portion of the disc so occupied forming a sort of broad, less convex border. Diameter ‘0034’. (Fig. 12.) Hab. Barbadoes deposit, Cambridge estate; in slides com- municated by C. Johnson, Esq. ; exceedingly. rare. Disc convex for about two thirds of the radius from the centre, then becoming somewhat flattened ; umbilicus a small, circular, blank space; granules equal, minute, distinct radi- ating in straight lines to the boundary of the convex centre, then becoming larger, and diminishing gradually in size to the margin. In the flattened circumference are situated about fourteen blank, linear, radiating spaces, not produced by divergence in the lines of granules, but commencing and terminating abruptly. Cosmiodiscus Normanianus, un. sp., Grev.— Radiating blank lines numerous, extending about half way from the margin to the centre, the intervening compartments filled with radi- ating lines of minute puncta; centre with scattered and much larger puncta. Diameter 0024”. (Fig. 11.) Hab. Barbadoes deposit ; cabinet of George Norman, Esq.; exceedingly rare. The central portion occupying as much as half the radius, containing large, remotely scattered puncta, and presenting a sudden contrast to the minute puncta between the blank, radiating lines, give‘a remarkable aspect to this disc, and may possibly lead to its separation when we come to be better z ac- quainted with it. EuPpopiscus. Eupodiscus Hardmanianus, n. sp., Grev.—Large ; disc with four circular marginal processes, hexagonally cellulate, with a broad, raised, remotely striate margin, and circle of teeth. Diameter -0055”. (Fig. 14.) Hab, Shell-cleanings from South America; L. Hardman, Esq: GREVILLE, on New Diatoms. 8] A splendid and well-defined species, with four circular, not very prominent processes, placed just within the broad mar- ein, which is furnished with a circle of numerous obtuse teeth. Within this margin or border is a narrow, irregular, some- what dark line, apparently indicating a sudden depression of the surface between it and the marginal border. Hexagonal cellules 6 in ‘001’. BIDDULPHIA. Biddulphia Chinensis, n. sp., Grev.—Large; frustules quadrangular; valves with the angles terminating in short, slender, obtuse, curved processes, and with a long stout spine springing from the swollen base of each process. (Pl. IX, fig. 16.) flab. Harbour of Hongkong; J. Linton Palmer, Esq. A very fine diatom, with the colour, structure, and fragility of Biddulphia Mobiliensis (B. Baileyi, Sm.). At first sight the general resemblance is so striking that the observer might be excused for at once pronouncing it to be a large state of that species; and, considering the notoriously variable cha- racter of the valve in some Biddulphie, it would require very decided differences to separate 1t. Iam, indeed, bound to confess that I have been deceived for a time by variations from normal forms in this genus, and, for example, that I am now convinced that my B. Roperiana is nothing more than one of the endless varieties of B. aurita. Nevertheless, in the case now under consideration, I venture to assume that really good diagnostic characters exist. Of B. Mobiliensis Mr. Ralfs remarks (Pritch. ‘ Infusor.,’ p. 851, 1861): “ There is no central projection of the valves, but two slight eleva- tions, furnished with one or more bristles, and dividing the margin into three nearly equal portions. The elevations appear to be situated between the processes, but are really placed on opposite sides.” This description is well illustrated in Smith’s ‘ Synopsis,’ vol. u, pl. Ixu, fig. 322 (front view) ; and in Roper’s excellent article “On the Genus Biddulphia and its Affinities,” in ‘Trans. Mic. Soc.,’ vol. vu, Pl. I, figs. 8, 9 (side views of valve). Now, in B. Chinensis this relative position of the bristles or spines with the processes is com- pletely changed. ‘The former do not divide the margin into three nearly equal portions, nor, indeed, divide it at all, nor are they situated on the margin. They arise from the swollen base of the processes themselves, on the inner side; so that, instead of bemg margined, they may be said to be actually on the median line (an imaginary one drawn between the 82 GREVILLE, on New Diatoms. processes). If these remarkable differences are not consi- dered of value, I do not see how any-character derived from the position of spines in any of the other species can be de- pended on. No approach towards an intermediate condition has been observed. It may also be remarked that the pro- cesses seem to be influenced by the position of the spines in B. Chinensis, for they are covered outwards, and are not straight, as figured by Smith and Roper in B. Modilhensis. Biddulphia ? podagrosa, nu. sp., Grev.—Frustules quad- rangular; valves with the angles prolonged into very thick processes, which are swollen and punctate near the base, then contracted, and again dilated into broadly capitate trun- cate, punctate apices; median space, with a hemispherical or subcapitate elevation. Length of perfect frustule *0035”. (Fig. 17.) . Hab. Barbadoes deposit, Cambridge estate; in slides com- municated by C. Johnson, Esq. One of the extraordinary forms of the Biddulphia family only to be met with in the Barbadoes deposit. It is obviously allied to my Hemiaulus ? capitatus (‘ Trans. Mic. Soc.,’ vol. xi, pl. 6, fig. 24), which would have been more appropriately ‘registered as a doubtful Biddulphia. The present diatom has a most whimsical appearance. The horn-like processes seem as if they had become proliferous; as if a second series had grown out of the first. The summits are large, inflated, almost cyathiform. The central projection is punctate like the processes, and in one specimen is so prolonged as to be almost capitate. The whole surface, with the exception of the punctate portions, is smooth and somewhat glassy. The processes are ‘0020” in length. TRICERATIUM. Triceratium lautum, n. sp., Grevy.—Large; valve with straight sides, rounded angles, and large pseudo-nodules (processes) ; margin with a somewhat pectinate row of large cellules; granules rather remote, radiating from a central cluster, and increasing in size towards the margin. Distance between the angles ‘0050’. (Fig. 20.) Hab. Barhadoes deposit, Cambridge estate; C. Johnson, Esq. This species bears a great general resemblance to T. pro- minens, but differs in the marginal cellules, in the angles being arched off and filled up with much larger processes, and in the absence of any central inflation. GREVILLE, on New Diatoms. 83 Triceratium repletum, n. sp., Grev.—Small; valve with nearly straight or slightly convex sides and obtuse angles, and large ovate, minutely punctate pseudo-nodules (pro- cesses) ; surface entirely filled with small roundish granules, which become gradually smaller towards the margin, which is striate. Distance between the angles ‘00380”. (Mig. 18.) Hab. Barbadoes deposit, Cambridge estate ; in slides com- municated by C. Johnson, Esq. Conspicuous for the very large processes which fill up the almost rounded angles, and extend over more than a third of the space between the angles and centre. Cellules near the eentre, about 10 in ‘001”. Triceratium quinquelobatum, nu. sp., Grev.—Valve with five obtuse lobes, the sides concave; cellules small, radiating from the centre, hexagonal, becoming less towards the margin. Distance between the angles :0024”. (Tig. 21.) Hab. Moron deposit, Province of Seville; Rev. T. G. Stokes. This differs from the hexagonally-lobed T. reticulatum, not only in having only five angles (which might not prove of sufficient importance), but in the much smaller and more regularly hexagonal cellulation, which at the angles passes into very crowded, minute puncta. ‘The lobes are also much less rounded. Triceratium picturatum, n. sp., Grev.—Valve with slightly concave sides and obtuse angles containing a few minute puncta in the extreme apices; margin giving off a number of very short veinlets, and in the middle of each side a roundish impression reaching nearly to the centre. Distance between the angles 0082”. (Fig. 19.) Hab. Barbadoes deposit, Cambridge estate ; im slides com- municated by C. Johnson, Esq. ; extremely rare. A species somewhat akin to 7. denticulatum, but differing essentially in the three middle impressions. The general surface has remote, scattered puncta, with smaller and more numerous ones between the marginal veinlets and on the impressions, SYRINGIDIUM. Syringidium demon, n. sp.. Grev.— Frustules smooth, central portion quadrangular; one of the valves contracted into an elongated conical process, the other globose, with two truncate, spine-bearing horns and an intermediate spine. (Figs. 22—28.) Hab. Harbour of Hongkong; J. Linton Palmer, Esq. 84 GREVILLE, on New Diatoms. In general aspect, this whimsical-looking diatom comes nearest to S. Americanum, but is more minute, has a smooth surface, and the capitate valve is furnished with a spine or bristle between the processes. The frustule is subject to con- siderable variations, which may probably be accounted for by its progress toward the period of self-division. In its early stage the diatom is filamentous, specimens in my possession showing three frustules in situ (Fig. 22); and it will be per- ceived that the capitate ends of the frustules are opposed to each other within the tube, the horns meeting, and the terminal spines overlapping each other, as in the genus Hemiaulus. It appears that the frustules become fully developed within the tubes before they escape, for although, in the figure just referred to, the conical process is not yet visible, it is mature, or nearly so, in Fig. 24. When perfect, the frustule may he described as comprised of two valves, rather sharply quadrangular (as viewed in the microscope) ; the one suddenly contracted and passing into a long conical process terminating in a minute spine; the other contracted into a short, thick neck, supporting a spherical head furnished with two short, conical, truncate horns, each tipped with a spine at its inner angle, while a slender, short spine is also situated in the intermediate space. ‘The relative proportion of the two valves varies greatly, as will be seen by consulting the figures; but this seems to be of no momemt in a diagnostic point of view. A very remarkable deviation from the typical structure of the genus occurs in S. simplex, Bail.* A very minute species, in which the valves are described as “ nearly symmetrical,” and “ both gradually tapering into pyramidal cones.” It is to Mr. Palmer that we are indebted for specimens in so perfect a state as to indicate distinctly their affinity with Hemiaulus. Nevertheless, we cannot but agree with Mr. Ralfs in his observation, that, “although it is not diffi- cult to point out differences between the Chetoceree and other groups, yet, on account of the variety in their forms, we con- fess our inability, in the present state of our knowledge, to give a concise definition which shall include its own members and exclude all others.’’+ NaviIcuLa. Navicula spectalissima, n. sp., Grev.—Hlongated, deeply * « Notes on new species of microscopical organisms, chiefly from the Para River, South America.” By Loring W. Bailey. ‘ Boston Journal of Natural History,’ vol. vii, p. 343, fig. 65. + Pritchard, ‘ History of Infusoria,’ 4th edition, p. 860. 4 : 4 GREVILLE, on New Diatoms. 85 constricted, with ovate-cuneate lobes, minutely punctate ; margin composed of a single series of large, linear-oblong cellules, which, as well as the puncta, disappear opposite the central nodule. Length 0050”. (Fig. 29. Hab. Zanzibar ; Professor Hamilton. UL. Smith. One of the most exquisite diatoms which have ever come under my observatio.:, and for which I am indebted to the kindness of my excellent correspondent, Professor H. L. Smith, Gambier, Ohio, who is prosecuting original and im- portant investigations into the structure and development of the diatom frustule. The present new species belongs to the extensive group of Navicule, in which the valves are more or less constricted at the middle, constituting the exploded genus Diploneis of Khrenberg. Its nearest ally appears to be N. marginata, of Lewis,* in which there is also a minute inner structure, and a single row of large marginal cellules. In WN. spectahssima, however, this contrast of structure is carried much farther, for the puncta next the median line are more minute, and the marginal cellules form a band nearly as broad as the punctate portion itself. These cellules are 7 in 001”, and at the widest part of the valve are ‘0004 in length, and so regular as to give the margin a pectinate and crenate character. They gradually diminish in length, and disappear near the apex, and opposite the central nodule. STAURONEIS. Stauroneis rotundata, n. sp., Grev.—Small; valve linear, or very slightly dilated in the middle, rounded at the ends ; stauros broad, linear, reaching to the margin ; striz parallel, exceedingly fine, not quite reaching to the median line. Length -0033”. (Figs. 30, 31.) St. rotundata; Grev. MS.; Dr. L. Lindsay. ‘Journ. Linn. Soc.,’ vol. ix, p. 184 (name only). Hab. Otago, in New Zealand, in fresh water; Dr. Lauder Lindsay. This seems a well-marked species, with its parallel sides (sometimes slightly dilated at the middle) and very rounded ends, where the margin is broader than at the sides. Stauroneis scaphuleformis, n. sp., Grev.— Small; valve linear ; lanceolate somewhat contracted and produced at the sub-acute ends, which are arched over by the thickened * «Notes on new and rarer species of Diatomacex of the United States’ seaboard.’ By I. W. Lewis, M.D., 1861, p. 6, pl. 11, fig. 1. 86 Bastian, on the so-called Pacchionian Bodies. margin; stauros broad, dilated, reaching to the margin. Length :0036”. (Fig. 32.) St. scaphuleformis, Grev. MS.; Dr. L. Lindsay. ‘ Journ. Linn. Soc.,’ vol. ix, p. 134 (name only). Hab. Otago, New Zealand, in fresh water; Dr. Lauder Lindsay. Very similar in general appearance to the diatom figured by my friend Dr. Lewis,* as a variety of St. Legumen, of Ehrenberg; but it differs in having a very broad, dilated stauros, instead of a very narrow, simple one; and in the con- traction of the valve below the apices. On the so-called PaccHIoNIAN BopIieEs. By H. Cuariron Bastian, M.A., M.B. Lond., F.L.S. (Communicated by W. H. Incz, F.L.S.) (Read March 14th, 1866.) Certain granulations or minute polypoid excrescences in connection with the membranes of the human brain, now familiar to so many anatomists and pathologists, were first described in 1705 by Antonius Pacchionius,t and regarded by him as rounded glands, secreting a clear pellucid fluid, from which lymphatics proceeded to the pia mater. Succeeding anatomists, for a time sharing in this opinion, spoke of them as ‘ Pacchionian glands,’ and by this name they were known till a comparatively recent period, when a growing doubt as to their nature gradually resolved itself into a pretty firm conviction that they had no real claims to be included in the category of glandular structures. Now almost all anatomists prefer to speak of them as ‘ Pacchionian bodies.’ Although these growths have received a very fair share of attention since the date of their first discovery, still many of the statements made concerning them are quite conflicting, and the accounts to be found in English text-books more especially are meagre and inexact as to their real nature and mode of origin. Seeing that they are found in several situa- * “On extreme and exceptional variations of Diatomacee in some White. Mountain localities,’ &c. By F. W. Lewis, M.D. ‘Proceedings of the Academy of Natural Sciences of Philadelphia,’ Jan., 1865, pl. 2, fig. 14. + Dissert. Epistolaris de Gland. conglobatis dure meningis Humane, indeque ortis Lymphaticis ad Piam meningem productis. Reprinted also at p. 103 of his ‘ Dissert. Physico-Anatom, de dura meninga Humana,’ 1721. Bastian, on the so-called Pacchionian Bodies. 87 tions in connection with the skull and membranes of the brain—occasionally in great numbers as well as much en- larged—it is a matter of some interest to knowin what situa- tions they may be found, how they come to occupy these positions, what is their precise histological structure, whether they are normal or abnormal growths, and, if the latter, what is their pathological significance. In text-books they are principally referred to as existing on the surface of the dura mater, on one or both sides of the middle line and subjacent longitudinal sinus, and causing more or less marked depressions in the corresponding region of the skull. It is also generally stated, however, that their presence is uncertain, that they are most frequently met with in persons dying at an advanced age, and that they are occa- sionally seen in the longitudinal sinus as well as on the arachnoid along the edges of the great longitudinal fissure separating the cerebral hemispheres; whilst, if anything at all is said concerning their seat of origin, this is represented to be in the pia mater beneath the arachnoid. Such a view as to their origin was held by Cruvelhier,* Andral,+ and the late Dr. Todd,} and seems to have been adopted by other English anatomists, notwithstanding the observations of Luschka,$ who in 1852 clearly pointed out that they invariably arose from, and were direct continuations of the arachnoid mem- brane. But even other situations have been indicated in which these growths may be met with; thus Dr. Todd wrote :— “‘ Bodies somewhat similar are also found occasionally on the choroid plexuses of the lateral ventricles. Very frequently we meet with granulations of a like kind in the fringe-like processes of pia mater which descend from the velum inter- positum to surround the pineal gland, and also upon the little processes of that membrane which go under the name of choroid plexuses of the fourth ventricle.” Kolliker also states|| that they are found in connection with the choroid plexuses of the ventricles. J have myself always failed to detect them in these situations, and on several occasions having cut off little opaque bodies from these vascular fringes, looking to the naked eye somewhat like Pacchionian bodies, have in- variably found them to be, after inspection with the micro- * ¢ Anatom Descript.,’ t. iv, p. 587. + ‘Clinique Médical.’ Translated by Dr. Spillan, 1836, p. 48. + ‘Cyclop. of Anat. and Physiol,’ vol. in, art. Vervous System, p. 645. \ ‘Uber das Wesen der Paccionishen Drusen.’ Miller’s ‘ Archiv,’ NSo2, p. LOL: | ‘Manual of Human Micros. Anat.,’ 1860, p. 243. 88 Bastian, on the so-called Pacchionian Bodies. scope, altered portions of the plexus only, rendered more opaque by the deposition in their interior of calcareous matter, in the form of ‘ brain sand.’ Cruvelhier, moreover, altogether denies the similarity of the opaque granulations occasionally found on the choroid plexuses to Pacchionian bodies. Agreeing with Rokitansky* and Luschka as to the fact of these bodies being invariably growths from the arachnoid, though differing from the latter observer as to the fact of their ever springing from its parietal layer, I will first speak of them as they may be observed on the visceral portion of this membrane. When the dura mater is reflected we frequently see in more or less abundance a number of small, opaque, almost milk- white looking granulations, varying much in size, but seldom exceeding that of a rice-grain, situated on each side on the arachnoid along the median contiguous edges of the cerebral hemispheres. They exist most abundantly over the middle and commencement of the posterior third of the hemispheres, where the largest veins enter the longitudinal sinus, and are found principally at the angle and over the upper surface of the brain immediately contiguous to it, but are not met with on the vertical surface entering into the great median fissure. Occasionally, however, alittlepatch of these bodies may be seen over the upper surface of the hemisphere at a distance of an inch or more from the median line, and distinctly separated from those in this situation. The portion of arachnoid from which the Pacchionian bodies arise is invariably opalescent or opaque, and more or less thickened, and they are generally most numerous on the membrane over and covering the large veins as they leave the pia mater to enter the longitudinal sinus. They vary extremely in form, as may be seen by reference to Pl. X, fig. 1, which represents some of the shapes most frequently met with. Some are simple, others compound in-various degrees, with ternary or even quaternary buds from the primary growth. Some are sessile and attached by a broad base to the arachnoid, whilst others are fixed only by comparatively long and attenuated pedicles, or may present all intermediate conditions between these two extremes. Luschka figures a compound growth resembling a small bunch of grapes, and so far as I have seen, this distinct pediculation, whether simple or compound, is most frequent in the early stages of these growths before they become very apparent to the naked eye. Pacchionius also described bodies of a similar kind existing in large numbers in the longitudinal sinus, now well known * *Patholog, Anat,’ (Syd. Soc.), vol, iii, p, 829. Bastian, on the so-called Pacchionian Bodies. 89 _as a very common locality in which these growths may be seen, when the sinus is slit open. The bodies projecting in this situation push before them the lining membrane of the sinus, instead of perforating it, and this was the covering probably alluded to by Pacchionius when he spoke of the assumed glands in the sinus as, “propria et tenuissima membrana, veluti in saculo concluse.”? Concerning them in this situation also Dr. Todd wrote :—“ It has been supposed that these bodies are natural structures, destined to perform a mechanical office somewhat on the principle of a ball valve, but they are frequently absent altogether, and when present they have no constant relation to the venosus orifices.’’ Accord- ing to Cruvelhier,* Haller has found growths of this kind at the anterior extremity of the straight sinus, whilst he himself once met with ‘une petite masse pédiculée”’ of a similar nature in the horizontal portion of the lateral smus. I have occasionally found them pretty plentiful in this latter situation. In most cases where the Pacchionian bodies exist in any quantity it is found somewhat difficult to reflect the dura mater, on account of the adhesions between it and the arachnoid on each side of the median fissure, without tearing away portions of the latter with the upper membrane. Where this occurs, when the under surface of this reflected dura mater is examined, there is no difficulty in detecting the torn portions of arachnoid adherent to it, and if the edge of one of such portions be held with a forceps, and carefully pulled, it will be readily seen as the two membranes separate, that the adhesion is entirely due to an interlocking, by means of the Pacchionian bodies, which (still springing from the cere- bral arachnoid) have pressed against the inner layer of the dura mater, destroyed its epithelial lining, and imsinuated themselves into its substance by separating the interlacing fibrous bundles of which it is composed. Instead of its ordi- nary smooth appearance, also, the under surface of the dura mater in these parts will be found to have an open reticulated or cribriform aspect, owing to the separation of its fibres by. the growths just dislodged from between them. After lodg-— ing themselves in the substance of the dura mater, these growths still increase in size, and are developed into the little pear-shaped bodies, which can then only be pulled backwards through its meshes by exerting a considerable amount of traction. Some few of these bodies which have thus lodged themselves take on a further increase of growth, and soon exceed in dimensions any of those to be found un- attached on the surface of the arachnoid. When the skull * Toe. cit., t. iv, p. 597. 90 Bastian, on the so-called Pacchionian Bodies. cap is removed in such cases we see slight bulgings on the surface of the dura mater on either side of the middle line; at later stages these prominences would be more manifest, and at last the outer layer of the dura mater having he- come thinned and then eroded, portions of the growths protrude, differing, however, in appearance from that which they present when smaller and seen on the surface of the arachnoid.* They have now a less opaque and more pel- lucid aspect, and instead of being white in colour are seen to have a faintly reddish or even yellowish tinge. Sometimes several of these bodies, small in size and situated together in a little patch, may be seen on the surface at a slight distance from the middle line, the outer layer of the dura mater being absent over the area occupied by them. It seems a more probable supposition to imagine that this has been caused to disappear by pressure and erosion, than to account for its absence by a congenital defect, as some have suggested, seeing that this hypothesis is inadequate to explain why it should be that in preference growths should spring up on an inde- pendent subjacent membrane, precisely opposite those very parts where there is a deficient development in the one above it. Certain of the little tumours generally situated pretty close to the middle line, and mostly solitary in position, attain a morec onsiderable size still. They produce, as they increase in bulk, at first a mere depression in the corresponding region of the inner table of the skull, and at last an actual erosion of this, and even of the outer table, if their growth still con- tinues. I have several times seen the outer table of the skull reduced to a plate of extreme tenuity, though never actually perforated. Dr. Ogle,t+ however, has lately described and figured cranial bones which have been perforated by these bodies, and mentions also that Mr. Turner, of Edin- burgh, has once seen an actual perforation of the right parietal bone, in which the aperture in the outer table was large enough to give passage to an ordinary pea, whilst, as is frequently the case, the inner table was worn away over a * This difference in appearance led me at one time to imagine that they might be structures of a different nature. In fact, knowing nothing very definite about them, I looked upon the little growths found on the dura mater as Pacchionian bodies, and in earlier autopsies was in the habit of looking upon the opaque granulations of the arachnoid as something quite distinct. This, however, I soon found to be erroneous. I now suspect that the opaque white appearance of the bodies seen on the surface of the arack- noid is partly a post-mortem effect due to the absorption of serum, since those found on the surface of the dura mater assume the same appearance after a short immersion in water. + ‘Brit, and For. Rev.,’ Oct. 1865, pp. 502—4, figs, 21—93. BastIANn, 07 the so-called Pacchionian Bodies. 91 much greater area. In cases in which there has been lodge- ment only, but no perforation, by the Pacchionian bodies, the aperture through the inner table is often sharp and clearly defined. Such being the appearances and positions occupied by these bodies, and arising in all cases as they do from the arachnoid membrane, it comes to be a matter almost of accident whether they are found on the surface of this membrane, on the ex- ternal surface of the dura mater, or projecting into the longi- tudinal sinus. Those springing up on a portion of the surface of the arachnoid not in very intimate contact with the dura mater, have room and are enabled to grow without contracting adhesions; whilst those commencing on a portion closely in contact with the upper membrane (over the top of a convolution, for instance, instead of over a sulcus) penetrate between its fibres in the manner before stated, and if the portion of dura mater against which they impinge chances to be the wall of the sinus, they project into it instead of appear- ing on the outer surface of the dura. These latter in their growth push aside the reticulated fibrous bundles of the dura mater till they come in contact with the firm elastic mem- brane constituting the inner wall of the sinus. This they are unable to perforate, and instead, it slowly gives way before them, so that at last they come to project into the sinus in much the same way as an organ does into a serous sac. I have fully satisfied myself as to the nature of this covering over those bodies projecting into the sinuses, not only by recognising its microscopical similarity of structure to that which can be dissected off from other parts of the sinus, but also from the fact that I have frequently succeeded, by exert- ing considerable traction with a forceps upon a portion of adherent arachnoid outside the sinus, in pulling some of these bodies out, and leaving the little membranous caps with which they were surrounded—constituting the “propria et tenuissima membrana,” in which Pacchionius described them as being enclosed. The bodies projecting into the horizontal portions of the lateral sinuses, which are much less frequently — met with than those in the longitudinal, would appear to rise from the arachnoid covering the posterior border of the cere- bellum, and not from that on the lower surface of the posterior extremities of the cerebral hemispheres, since I have found them situated only along the lower angle of the base of the sinus.* * Since this was written I have twice detected small Pacchionian bodies on the arachnoid over the posterior border of the cerebellum, as above suggested. VOL. XIV. g 92 Bastian, on the so-called Pacchioman Bodies. The description here given of the Pacchionian bodies differs to a certain extent from that advanced by Luschka, whose views also seem to have been received by Wedl* and Forster,+ since, according to him, all the most important of these growths, pathologically speaking, namely, those which insinuate themselves into the dura mater, appear on its external surface, or project into the longitudinal sinus, take origin from the parietal arachnoid. But quite indepen- dently of the fact, that the only representative of this mem- brane now believed to exist by Kélliker and other leading histologists is a layer of epithelium,{ I have fully satisfied myself, after the most careful examination, that so far as can be ascertained, all these growths which imbed themselves in the dura mater or project into the sinuses, as well as those which remain free, seem to spring from the cerebral arach- noid.§ This is an arrangement easily demonstrated when, as is so often the case, portions of arachnoid corresponding to growths imbedded in the dura mater are found adherent to the under surface of this membrane, having been torn off during its reflection, since, on pulling the two membranes asunder, as before stated, many of the growths still firmly attached to this fragment of the visceral arachnoid, emerge uninjured from between the fibres of the dura mater, whilst the more slender pedicles of others are ruptured. The same thing, of course, occurs m the original turning back of the dura mater—certain of the pedicles give way, instead of the ararchnoid in all cases tearing, in order to permit of the separation of the adherent membranes. In such cases, where rupture has taken place, whether the Pacchionian body be situated in one of the sinuses or on the surface of the dura mater, if we pass the point of a fine needle through the mem- brane as nearly as possible in the direction of its pedicle, we shall always find it emerge on its under surface at a point where the fibres of the dura mater have the characteristic open cribriform arrangement, and in most cases be able to discover the broken extremity of the fleshy-looking little pedicle. Continuous as these bodies are with the arachnoid, so are their histological elements precisely the same. I have not been more successful than other observers in recognising * “Rudiments of Path. Histol.’ (Syd. Soc.), 1855, p. 350. { ‘Lehrbuch der Patholog. Anatom.’ ~ See concluding note. , § Virchow and many of the other German anatomists have now almost ceased to use the word arachnoid at all, believing that no distinct membrane exists to which this name can be applied. They regard the so-called ‘parietal arachnoid’ simply as the epithelial lining of the dura mater, and the ‘ visceral’ layer as only the condensed superficial layer of the pia mater. Bastian, on the so-called Pacchionian Bodies. 93 either vessels or nerves in them. Some of the statements at present in vogue concerning the histology of the Pacchionian bodies are very lax: thus, by Todd and Bowman* they are stated to be “‘ whitish granules composed of an albuminous material found amongst the vessels of the pia mater,” which in their increase push the arachnoid before them; whilst in another placet each of these bodies is said by Dr. Todd “to consist of a mass of minute granules enclosed in a mem- branous sac.” Luschka is, I believe, the only writer who mentions the existence of epithelium upon the surface of these bodies; he describes it, however, as scanty, and met with only in isolated patches. It is often not easily recognised without the aid of reagents, but when small growths of this kind, or portions of larger ones, are mounted in equal parts of water and acetic acid for microscopical examination, the structures swell and become more transparent, whilst a pretty uniform covering of roundish or elliptical cells can generally be dis- covered on the surface, lying close together, though not in contact (fig. 2). The use of the same reagent renders visible bodies precisely simiiar on the surface of the arachnoid itself, though they are somewhat difficult of detection when por- tions of it are immersed in water alone previous to examina- tion. The examination of other serous membranes, such as the peritoneum, pleura, and pericardium, showed bodies of a similar nature on their surface, and it was after careful scrutiny of them that I convinced myself that these appa- rently distinct, elliptical, nucleated cells were in reality only the nucleolated nuclei of a pavement epithelium, just such as has heen described by Henle, and similar to what I have represented in fig. 3. The containing cell on the arachnoid and its outgrowths must be extremely delicate and fragile, since, though scrapings with a knife from their surface yield crowds of nuclei, separate as well as aggregated, yet I have never succeeded in detecting the same tesselated arrange- ment of their containing cells as I have seen elsewhere, though I have occasionally seen isolated nuclei contained in a delicate and almost invisible cell (fig. 4), and all analogy would lead us to believe that the nature of the epithelium was the same on the arachnoid as on other serous mem- branes, more especially when bodies precisely similar to what are undoubtedly the nuclei of these are found on the former. The epithelium is generally best seen on the younger growths, or else on those older ones which have * *Physiolog. Anat. of Man,’ vol. i, p. 255. t ‘Cycel. of Anat. and Physiol.,’ doc. cit. 94 Bastian, on the so-called Pacchionian Bodies. inserted themselves into depressions in the cranial bones. In bodies picked out from this last situation (where, perhaps, they are more protected from friction, as well as supplied with more nutriment from the cranial diploe) I have found a large quantity of epithelium, evidently in multiple layers, accumulated on their surface. A tendency to this is some- times seen also on the arachnoid itself, since cells may be recognised in different places lying over one another as though a double or even treble layer existed. In addition to this epithelial covering, the Pacchionian bodies are composed of fibrous tissue, which may be seen in all stages of develop- ment, either in the same or different growths. Everything I have observed during the examination of this tissue in these bodies tends to confirm the opinions of Henle and Virchow* —who are so far agreed as to the fact that the undulating fibres composing the bulk of its substance are derived from the direct fibrillation of a homogeneous, hyaline, and gelatinous-looking material—and lends no support to those of Schwann or even Reichert. In great part this homogeneous material seems to grow in the Pacchionian bodies in the form of a branched network, reticulating in all directions so as to produce a pretty compact sponge-like structure. A portion of these interlacing, structureless bundles, which was scraped from the surface of one of these bodies, together with epithelium,t} is represented in fig. 5. In many parts of the interior of the growths an areolated arrangement of bundles may also be seen, apparently at a later stage of development, since their texture seems firmer, their outline more sharply defined, and in many of them, by a proper adjustment of light, faint linear markings can’be recognised, which may be the first traces of fibrillation (fig. 6). A thin, transverse section of one of the more opaque bodies on the surface of the arachnoid reveals the full maturity of the tissue (fig. 7), and instead of a network of a homogeneous or faintly fibrillated aspect, we get one composed of ordinary areolar or fibrous tissue, the bundles of which present the same re- ticulated arrangement. Occasionally I have seen a spiral fibre of elastic tissue of the kind mentioned by Luschka twisted around a still homogeneous bundle (fig. 5a), and in portions of the surface fibrous tissue of these bodies which * *Cell. Pathology.’ Translation by Chance (1859), pp. 41—45. + The minute buds so frequently found projecting from the surface of a still growing Pacchionian body, and which are the origin of the various secondary and tertiary outgrowihs, are small projections of a tissue of this kind, which gradually undergo differentiation and development as they increase in size. Bastian, on the so-called Pacchionian Bodies. 95 frequently does not show the manifest reticulated arrange- ment of the fibrous bundles, elongating cells or nuclei may be seen of the ordinary kind (fig. 8). The elastic tissue in the Pacchionian bodies is represented by fine fibres, and is not very abundant, though I have not had time further to make out its mode of development and arrangement. As is the case with the arachnoid membrane itself, these Pacchionian outgrowths, especially in old people, very fre- quently contain deposits of brain sand. Sometimes it exists in the form of the usual bright, highly refractive, and irregularly rounded nodules of various sizes, situated in the midst of the fibrous tissue, with no special envelope of any kind; whilst in others a deposition of the calcareous matter seems to occur in small separate granules, and a concentric arrangement of cellular tissue, in the form of lamelle, appears to take place around them (fig. 9), which in some eases is very distinct. Occasionally a large calcareous nodule is seen, apparently simple and of the kind first mentioned, but which, on alteration of the focus, seems to be made up of concentric lamelle, or at all events it presents a series of concentric markings. This appearance may perhaps be due to the subsequent calcareous infiltration of a concentrically arranged fibrous envelope developed around a primary saline deposit. All the forms seem to be intimately connected with one another, and according to Kélliker,* brain sand generally, “‘after the extraction of the salts, completely retains the form of the concretion, and appears as a concentrically stratified pale mass.” Kollker also speaks of corpora amy- lucea aS sometimes existing in the Pacchionian bodies; these J have never met with, unless some of the earthy nodules may be bodies of this kind which have undergone calcifi- cation. Now we come to the question, are the Pacchionian bodies to be considered as normal structures, or as the results of pathological change? ‘The investigations of the brothers Wenzel,+ and even more, the later ones of Luschka, supply us with important data for the solution of this question. As yet these growths have been found only in the human subject, notwithstanding the diligent search made for them by the above-named observers in many of the lower animals. With regard to the ages at which they are found in man the brothers Wenzel came to the following conclusions :—“ In children, from birth to the third year, these bodies, if they ever occur, must be very few. From the seventh to the * Woes cit, wo 245.0" + De penitori hom. et brut. cerebri structura. Tubinge, 1812. 96 Bastian, on the so-called Pacchionian Bodies. twentieth year they sometimes are numerous. From the latter period to the fortieth year the number is considerable, and the nearer we approach the fortieth year the greater does it become. Lastly, from the fortieth to the one hundredth year these bodies are found in great numbers.” Luschka, however, says he has never failed to find a certain number of these bodies on the arachnoid, at the borders of the great longitudinal fissure, at any period of life. Even in the new- born infants he has detected very minute outgrowths, which he considers as the rudiments of future Pacchionian bodies, though in them, as well as in other children dying during the first few years of life, their existence is easily overlooked, and they can only be detected by the most careful examina- tion, since they are then minute pellucid structures of the same colour as the unaltered arachnoid. In individuals be- tween sixteen and twenty years of age they are easily detected on account of their increased size and whiteness; and though at later periods of life they generally become more numerous and much larger, still there is a very great difference in this respect in different individuals, and in some persons dying even at middle age or beyond none of these bodies can be detected by the naked eye, though they may be seen by float- ing portions of the arachnoid in water, and then examining it witha lens. Luschka looks upon these growths as normal structures,* having a definite aim, which may be considered to be in a mature condition in individuals between the ages of twelve and twenty years, and to become pathological only by reason of their hypertrophy at later periods of life; and he accordingly names them ‘ arachnoidal vill.’ But the old name seems to me a more desirable one, since it involves no implication as to their nature; and the possibility of any function performed by these bodies seems so doubtful that it appears more desirable to look upon them, with Rokitansky, merely as hypertrophic vegetations, or polypoid excrescences from the arachnoid, notwithstanding the fact that the rudiments of them are to be met with even at the earliest periods of life. Bearing upon this question, too, it is interesting to consider how far a pathological condition (assuming it to be such) so constant as the existence of these bodies in middle and advanced life, may, in the course of ge- nerations, through the influence of hereditary transmission, have at last tended to their rudimentary production, inde- pendently of the special causes at first potential in giving rise * Andral and Dr. Todd regarded them as decided pathological products, whilst Cruvelhier, though in doubt as to their nature, was disposed to look upon them as of too frequent occurrence to be considered morbid growths. a, eS ee ee en Lani Bastian, on the so-called Pacchionian Bodies. 97 to them in the original progenitors of the race. Or are we to suppose that the conditions instrumental in bringing about their increase of size in after life have already been in opera- tion, during the intra-uterine period, to a sufficient extent to produce the early rudiments of these structures, ascertained by Luschka to exist in the new-born infant? At all events, it does not appear that these bodies can be looked upon as isolated structures of an exceptional nature, in the face of what we know as to the existence of similar hypertrophic ex- crescences from other serous as well as synovial membranes. According to Wedl,* “papillary new formations,” with a covering of epithelium, have been found by Heschl on the pleura, and especially on that portion over the lower border of the inferior lobes of both lungs; whilst it is a well-known fact that in many cases the “white patches” of the visceral pericardium have a shaggy appearance when floated in water, from the presence of minute outgrowths, which would, in all probability, present, on microscopic examination, a fibrous structure, similar to that known to be presented by the opaque patch itself. On the other hand, the bodies developed from the synovial membranes of the larger joints, in cases of chronic inflammation, so well known to pathologists—often stalked and compound in form, but occasionally simple, smooth, ovate, compressed, and compared to melon seeds by Mayo—-also present a fibrous structure, and may fairly be considered as having a close pathological relationship to the Pacchionian bodies.t Two causes seem influential in bringing about a fibroid thickening and opacity of serous membranes : undue amount of friction, on the one hand, which, as Dr. Jenner and other pathologists maintain, seems to be by far the most frequent cause of the ‘white patches’ of the peri- cardium ; and hyperzemia on the other, whether from chronic inflammation or oft-repeated congestions, to which this con- dition of the arachnoid and synovial membranes seems most attributable. Repeated congestions alone are looked upon by Rokitansky and others as capable of producing opacity and thickening of the arachnoid, independently of any inflam- matory process. Some amount of it is generally met with after the middle periods of life; and the same may be said as to the increase in number and size of the Pacchionian bodies; * Loe: eit.,p.\ 357. + In a more recent work (‘ Die Halbgelenke,’ 1858, p. 46) than his com- munication before referred to, Luschka has shown that the central part of ~ each intervertebral disc is a synovial sac, the membrane of which is developed into processes almost precisely resembling the Pacchionian bodies. (Vote added June 19th.) 98 Bastian, on the so-called Pacchionian Bodies. and at any period of life their number and size seem to be in direct proportion to the frequency with which the brain and its membranes have been subjected to congestions ; thus, even in youths or young adults, considerable enlargement of them is generally met with in those subject to frequent epileptic attacks, and less notably so in habitual drunkards. Startling exceptions occasionally exist, however, to this rule; for in- stance, I lately examined the brain of a man fifty-six years of age, who was known to have led an intemperate life, and who had in addition been insane, and perfectly incoherent in his conversation, for more than twelve months, and yet there was only the faintest opalescence of a small portion of the arachnoid, and no Pacchionian bodies to be seen with the naked eye. Such cases are, however, very exceptional; so that, leaving age out of the question, we may still look upon cerebral congestion and excitement as the causes most instrumental in bringing about the production or increased growth of these structures. This was also the opinion of Dr. Todd, who said: “ In persons addicted to the excessive use of spirituous liquors, in those of irritable temperament, and who were frequently a prey to violent and exciting passions, they are almost uniformly highly developed.” Are these enlarged Pacchionian bodies of much pathological significance? It has been thought that they may give rise to dangerous symptoms by their pressure upon the brain, and by the impediment they may offer to the circulation of the blood through the great veins entering the longitudinal sinus as well as through the sinus itself. I know of no cases on record bearing out this assumption, and am disposed to think their effects are not often very serious in the first place, because, owing to the slowness of their growth, impediment to the flow of blood through any particular vein, if it should take place, would, without difficulty, right itself by an in- creased flow through the contiguous channels; and in the next, from the fact that no growths large enough to produce any appreciable pressure upon the brain are ever found be- tween the membranes attached to the arachnoid only. Those so situated, being non-vascular themselves, receive plasma for their further increase only by absorption through the non- vascular arachnoid itself, and with which, oftentimes, they are only connected by means of a narrow pedicle, so that the conditions are by no means favorable to their attaining any notable size. Those, on the other hand, which have become imbedded between the fibres of the dura mater are enabled to absorb more nutritive pabulum directly from this more vascular membrane, with which to build up their structure, Bastian, on the so-called Pacchionian Bodies. 99 and they undergo a corresponding increase in size. Still their growth is slow, and the pressure exerted upon the cerebrum can only be insignificant, seeing also that the direc- tion is outwards towards more vascular parts, causing them to press upon the inner table of the skull, and finally produce more or less deep erosions in the vault of the cranium. Here, indeed, is a source of danger, owing to the weakening of the bony case in which the brain is lodged, rendering it less able to resist the effects of blows or external violence of any kind. But the projection of these growths into the sinuses, and their increase in this situation, seem to be the course most likely to be attended with deleterious results, since, as foreign bodies, they may lead to a blocking up of the sinus, either from the deposition of fibrinous coagula upon them in certain states of the system, or from an actual increase in their own number and size. This latter effect would doubtless be of no very unfrequent occurrence were it not for the conserva- tive influence of the tough, elastic lmimg membrane of the sinus, which, in all probability, impedes the growth of these bodies, partly by its strength and pressure, and partly because it does not give a sufficiently ready passage to the flowing pabulum afforded by the serum of the blood, in which these structures are immersed, and which, could it be assimilated more easily by the Pacchionian bodies, might cause them to grow so as almost invariably to block up the sinus, and hence lead to the most serious results.* * Since this paper was written I have seen a communication on the Pacchionian bodies by Ludwig Meyer (‘ Virch. Archiv.,’ vol. xix, p. 171 and p. 288), in which he not only insists upon the fact that these growths are invariably developments from the visceral arachnoid, but also has antici- pated me in the recognition of the completeness of their epithelial covering. Dr. Cleland, however, I have also found, in spite of Meyer’s statements, re- affirms that some of these bodies do arise, in the manner described by Luschka, from the internal surface of the dura mater (parietal arachnoid), in a paper in the ‘Glasgow Med. Journal,’ 1863, p. 148. (Wote appended June 19, 1866.) 100 On a form of Lrar-HoLtpER for the Microscorgr, and a REVOLVING SLIDE-HOLDER With SrLenite Stace. By James Smitu, F.L.S. (Read May 9th, 1866.) On a Leaf-holder for the Microscope. THE instrument to which I would this evening venture to draw the attention of the Society, and which I have called a leaf-holder, as indicating the class of objects for which it was designed and is best adapted, is intended to supply a want I have often felt in the examination of leaves, feathers, wings of moths, and other similar large flat objects which frequently require to be placed in a particular position, both as regards the microscope and the source of illumination. I have also found, in observing aphides or minute fungi upon the surfaces of leaves, very great difficulty in getting the object into a good position for examination, the ordinary stage forceps being in some cases almost useless for the pur- pose. In the above set of drawings, a, shows the double ring form- ing the clip, made of a thin elastic yellow metal ; B, the foun- dation ring, upon which the others work; c, the complete instrument with leaf inserted; and p, the small holder for such minute objects as could not be well held by the rings alone. The ring B, which forms the foundation upon which the others rotate, may be made of somewhat stouter metal, the piece projecting at the side forming the socket to attach it to the stem, as shown inc. In 4, the double ring forming the Situ, on a Slide-holder for the Mocroscope. 101 holder, the lower one (a) has three small projections on its inner margin, which being doubled over the inner edge of ring B (as indicated by the dotted points) form at once the means of attachment and rotation. The second or upper ring (c) is brought into its proper place, over, and lightly touching the first by bending the middle piece (6), which makes a sort of spring hinge, keeping the rings together, and retaining by its pressure the object in its place between them ; p, the secondary holder for very small objects, consists of a flat piece of metal of sufficient length to be conveniently held by the rings forming the clip; in the centre of this flat piece a small watch spring jomt (4) is fixed, the object being secured between this point and the projecting portion in the centre of the piece itself. When a leaf or other such large object is to be examined it is placed between the rings, which by their tendency to come together hold it with sufficient firmness, and at the same time without injuring the specimen; and it can then be rotated upon its own centre by pushing the projecting portion forming the spring hinge, or the two small pieces (d d). The other rotation is of course effected by turning the milled head at the end of the stem; bringing the leaf examination at any desired angle with respect to the object-glass, while a half turn brings the underside into view without the necessity of disturbing the object itself; this facility of examination, which is given by the ring-like form of the instrument, will be found of some little value. With respect to the size of the rings forming the clip, I may say that although in my own instrument they are about one inch in diameter, yet I think they might with advantage be made somewhat smaller; but as this is very much a matter of convenience, no precise size need be given. On a Revolving Slide-holder for the Microscope, combined | with Selenite Stage. The accompanying diagrams show a very simple addition to the accessory apparatus of the microscope, which I would term a revolving slide-holder, and which will, I think, be found of use with some of the simple forms of microscopes. Tt consists (as will be seen in the drawings) of an upper plate, a, about 3 in. by 1, with two clips for holding the slide, a secondary one upon which the top plate revolves, an inter- mediate space (B a), and a lower plate somewhat larger and 102 Smitu, on a Slide-holder for the Microscope. heavier forming the stage plate; further description seems scarcely needed. With many objects it is absolutely necessary to have them in a certain position with respect to the light to see them at all, and with many more a slight change in position renders them far more distinct, and I am led to think that in such cases this slide-holder will be found both con- venient and useful from the ease with which a slide placed upon it can be completely rotated; it might also be found useful in some cases of examining transparent objects by oblique light, and the hole in the lower plate might be made oblong, so as not to interfere with the oblique rays from the mirror. A second and more general use to which this slide-holder might be applied is that of a selenite-holder for use with the polarizing prisms. In the ‘ Microscopical Journal’ for July, 1860, pp. 203-4, I described a simple form of selenite stage having for its object a means of removing and replacing again the various selenites without disturbing the slide under exami- nation or requiring to alter the focus of the microscope. In the revolving stage plate I now bring under the notice of the Society, it will I think be seen that by means of the in- tervening space between the lower and secondary plates, as shown in a, drawing B, the selenite plates can be slipped in and out without disturbing the object; and in the case of this holder there is the additional advantage obtained of having the object itself revolvable, while the polarizing prisms and the selenites remain in a fixed position with regard to each other —an arrangement which brings out some remarkable effects. It will also be apparent that when this secondary stage is used with a microscope that has a revolving stage plate of its own, the selenite plate and object under examination may be made to rotate in the same or in an opposite direction to one another; while the polarizing prisms remain fixed. 103 On a Binocutar Microscope ror Hicu Powers. By F. H. Wenuam. (Read May 9th, 1866.) THE common binocular microscope performs satisfactorily up to the 1, but for powers above this a special arrangement is needed for the prism, which must be set close behind the posterior lens of the 1th, ~,th, and upwards, in order to obtain an entire field of view in each eye. ‘This it is found to accomplish perfectly when in that position; but still for very delicate test objects requiring the utmost extent of aperture for their definition, it will not resolve them as clearly as with the single body, from the fact that the aperture is divided and half only effective in each eye. It has therefore long been thought desirable to obtain the whole aperture in each tube. This has recently been effected by Messrs. Powell and Lealand by means of an inclined disc of glass with parallel sides; the partial reflection from the under surface is again reflected into the second eye by means of a rectangular prism. Assum- ing this surface to be placed at an angle of 45°, the amount of reflected light will be only 53°66 out of 1000 of the incident rays, or nearly th part. To collect half the hght the reflector would have to be set at 821°, but this would cause the glass plate to extend to such a length as to render the adaptation nearly impracticable, but even with the above- named enormous difference in the relative quantity of lght, the arrangement as turned out by the hands of these clever mechanicians has surprised us with the fact that a good effect may be obtained by such means, and haying thus started the principle it remains to be seen what improvements can be made with the view to increasing the quantity of reflected light, and if possible obtaining a more equal result in each eye. By slightly modifying the existing arrangement of Messrs. Powell and Lealand, light otherwise lost may be utilised. In order to prevent the image from the second surface of the reflecting disc from appearing at the eye, and overlapping and confusing the first, Messrs. Powell and Lealand make it of considerable thickness. The secondary image is thus so far separated as to be thrown beyond the reach of the rectangular prism, and practically this light is totally lost. As the disc is made thinner, so do the images approximate and the distance between them diminish. Therefore if the glass is made as thin as practicable, and a very slight angle given to 104 Wenuam, on a Binocular Microscope. the two sides, these may be so arranged that both images are ultimately combined at the eye-piece. There would be no difficulty in working the glass to a mean thickness of ,th of an inch. In this form the angle between the sides would be so exceedingly small that the chromatic effect considered as a prism would be inappreciable in the direct eye-tube. Another idea was to dispense with the rectangular prism and employ a wedge-shaped piece of glass, with the back silvered as shown by fig. 1, making use of the front and back surfaces for the two reflections and separation of the images. The wedge should be achromatic, and com- posed of angles of flint and crown as shown. But this could only be em- ployed singly in such microscopes as have the object-glass set at right angles with the body. This plan might be of use for viewing sun-spots in a telescope where a diagonal eye-piece is seldom objectionable. In a microscope the in- crease of light obtained by removing the reflecting prism would not probably be very appreciable. If two reflecting and transmitting surfaces be placed in close contact, both images will be combined at the same point. On this princple the following arrangement was tried: aa, fig. 2, are two similar right-angied prisms, with their \ ‘ \ \ + Te ' 162°. 5% 6: a ; 6 'B diagonals in contact : these are to be sufficiently tilted out of the plane of the microscope to throw the first reflecting sur- face out of the range of total reflection, and allow direct rays to be transmitted. The rays, 6 0, reflected from both the diagonal planes, after leaving the side of the prism a, were thrown into the second body of the microscope by means of another right-angled prism, c, while the transmitted rays Wenuam, on a Binocular Microscope. 105 passed through straight into the direct tube. The perform- ance of this arrangement was very satisfactory, an equal amount of light being apparently obtained in each eye. ~The next plan is to be preferred, shown in the diagram four times the full size. aa, fig. 3, im outline, resembles the now well-known form of “ Wenham prism,” but in order to transmit light the first reflecting angle, 4, must be within the a ald ~ Reais pees eos =f ro range of total reflection. This for crown glass is when the ray makes with the surface an angle of 48° 11’, and allowing due margin for difference of density, the incident angle should not be less than 50° with the plane, consequently the angle, 6, should be inclined 40°. The back angle, c, must be arranged in accordance with the inclination given to the bodies of the microscope, but as a rule the difference be- tween the angles of the front and back surfaces is half the angle of deviation of the ray from the perpendicular. In the microscope for which this prism was made, the bodies are set relatively at 15°; the back of the prism is, therefore, shown in the diagram 471°. This also falling within the range of total reflection must have its surface silvered. On the first inclined surface of the main prism is adjusted the prism d, with two polished surfaces making an angle of 40°. With each other this brings the top of the supplementary prism parallel with the base. The rays from the object-glass are transmitted without any displacement into the direct tube. A portion of the same rays are reflected from both contiguous surfaces, and thence from the silvered back into the slanting body. The two prisms are fitted into a small drawer of the usual size which slides into the opening of the ordinary binocular microscope. The two prisms need not be pressed into contact—if so, Newton rings are formed ; they may be set a visible distance asunder, but great care is 106 Wewnuam, on a Binocular Microscope. needed in adjusting the small prism so as to get both reflec- tions combined, otherwise a blurred image will be seen in the slanting body. As to the performance of this arrangement the introduc- tion of the prisms do not perceptibly interfere with the definition in the direct tube—delicate markings may be seen quite as well with the prism in place as out, and with proper workmanship the result is equally good in the other; and having the privilege of using both eyes, the observer is enabled to view diatoms and other minute objects more agreeably, and with a better idea of their structure, than with single vision. The great defect is a want of stereoscopic effect arising from the near similarity of the images. In this respect it falls far short of the common prism in the qualification of giving a perspective view with the lower powers. In most arrangements constructed on the principle here described it is immaterial at what distance behind the object- glass the prism and reflecting surfaces are situated; the definition will be equally good, and the field entire, if fixed close to the eye-pieces. The rectangular prisms arranged with their diagonals in contact may be otherwise made serviceable for the micro- scope. With some plan of modifying the light it may be used for a camera lucida and also for an illuminator in place of the glass disc employed where the object-glass acts as its own condenser for opaque objects. On this principle of illumination the right system appears to be to obtain a very intense parallel ray of light, of as small a diameter as possible, thrown through a portion only of the object-glass. With these prisms it is possible to obtain totally reflected light for the illumination, at the same time that the image of the object is transmitted. The hght for the illumination must in this case be sent through the object-glass somewhat obliquely, and to reduce the diameter of the ray down to the small size required a stop of tinfoil may be atached to the lateral surface of the prism. ihe Microscopical Society. 107 Consritution and Laws of the Microscoricat Sociuiy of Lonpon. (Revised May 9th, 1866.) Presidents of the Society. Richard Owen, F.R.S., &e. . : : . : 1840 John Uindley, Ph.D. F.R.S., &e.-- ; ‘ : 1842 Thomas Bell, F.R.S., &e. — - 4 : 1844. James Scott Bowerbank, LL.D., F. ES cee. 1846 Georse busk, FR.S,, Sc. : ; : ; ; 1848 Arthur Farre, M.D., F.RB.S., &e. . : ‘ : 1850 George Jackson, F. R. Cs. 1852 William Benjamin Carpenter, M.D., F. R. Sos Se ; 1854: George Shadbolt . : : ; 1856 Kdwin Lankester, M.D., le p., F. Te S, .» &C. : 1858 John Quekett, ERS. ce he : : : 1860 Robert James Farrants, F.R.C.S. . i ¢ : 1861 Charles Brooke, M.A., F.R.S., &c. : : : 1863 James Glaisher, F.R.S., &c. . : : : : 1865 Objecis of the Society. Tue Mricroscoricat Society or Lonpon is constituted for the promotion and diffusion of improvements im the optical and mechanical construction, and in the mode of application, of the Microscope :— For the communication and discussion of observations and. discoveries tending to such improvements, or relating to sub- jects of Microscopical observation :— For the exhibition of new or interesting Muicrescopical objects and preparations, and for the formation of an arranged collection of such objects :— For affording the opportunity and means of submitting difficult and obscure Microscopical phenomena to the test of instruments of different powers and constructions :— For the establishment of a Library of standard Micro- graphical Works. VOL. XIV. h 108 Constitution and Laws of Constitution and Government of the Society. The Microscopical Society of London shall consist of Ordinary and Honorary Members, and of Associates. The Ordinary Members shall elect, out of their own body, a President, four Vice-Presidents, Treasurer, Secretaries, and Council, in accordance with the following Laws; to whom, subject only to the restrictions imposed by the Laws, all business relating to the Society shall be entrusted. I.—Of the Members. 1.—The Society shall consist of Ordinary and Honorary Members, and of Associates; the number of the Honorary Members shall be limited to twenty. 2.—Everv candidate for admission as an Ordinary Member of the Se.icty must be proposed by three or more members, who mst sign a certificate in recommendation of him, which mus. set forth the names, description, place of residence, and caalifications of the candidate, and state that he is desirous of becoming a member; and the proposer, whose name stands first upon the certificate, must have personal knowledge of the candidate. The certificate shall be read aloud by one of the Secretaries at the first Ordinary or Annual General Meeting of the Members next ensuing, and shall then be suspended in a conspicuous place appropriated for that pur- pose in one of the rooms of the Society. The method of voting for the election of Members shall be by ballot. 3.—The ballot shall take place at the Ordinary or Annual Meeting at which the certificate shall have been read the second time, and immediately after such reading. No such ballot shall be valid unless twelve or more members ballot ; and when two thirds or more of the members balloting shall be in favour of the candidate, such candidate shall be declared to be duly elected. 4.—The Secretaries shall address, or cause to be addressed, to every person elected a member, a letter to inform. him thereof, on the day following his election, together with a copy of the Laws of the Society, a List of Members, and a eard announcing the days on which the Society will hold its meetings during the season. 5.—Hach Ordinary Member on his admission shall pay an entrance fee of one guinea, and an annual subscription of one guinea for the current year, which subscription shall be con- sidered as due on the Ist of January in every subsequent year. Members who shall be elected, however, in the months. the Microscopical Society. 109 of October, November, or December, shall not be called upon for a subscription for the current year. 6.—-Any member may on his election compound for his future annual contributions by a payment of ten guineas, in addition to his entrance fee of one guinea; or he may at any time afterwards (all sums then due being first paid) com- pound for his annual contributions by the like payment of ten guineas. Every such composition shall be invested in Government Securities, in the names of Trustees. 7.—No person elected a member shall be entitled to exercise any privilege as such, nor shall his name be printed in any list of the Society, until he shall have paid his admission fee and first annual subscription or composition ; and unless these be paid within two months from the day of his election, or within such further time as the Council may grant, the election of such member shall be void. 8.—Associates shall be elected in the same manner as Ordinary Members, but the admission fee and annual sub- scription shall be remitted. -9.—The Ordinary Members shall have the right to be present and to vote at all Ordinary or Annual Mectings, and to propose candidates for admission to the Society. They shall also be entitled to the use of the instruments, books, and mounted microscopic objects in the Society’s collection, under such restrictions as the Council shall deem necessary. They shall have the privilege of personally admitting one visitor to the Ordinary and Annual Meetings of the Society, whose name shall be entered in a book kept for that pur- pose, together with the name of the member admitting such visitor. 10.—No member shall have the privilege of voting on any occasion, or be entitled to receive the publications of the Society, if his subscription be twelve months in arrear. 11.—Honorary Members and Associates shall possess all the privileges of Ordinary Members, excepting those of pro- posing candidates, of voting, of imtroducing visitors, and - receiving the Publications of the Society. 12.—The payment of the admission fee shall be considered as distinctly implying the acquiescence of every member elected into the Society, in all the Laws, regulations, and by-laws thereof. 18.—Any member who may be absent from the United Kingdom durimg the space of one year, shall, upon pre- viously giving to one of the Secretaries notice im writing of his intention, be exempt from the payment of his annual contribution during such absence. 110 Constitution and Laws of 11.—Honorary Members. 14.—Every person eminent in Microscopical Science shall be eligible as an Honorary Member. 15.—LEvery such person proposed for admission as an Honorary Member must be recommended by three or more Members, all of whom must certify in writing that he is a person eminent in Microscopical Science, and that they have a personal knowledge of him, or are acquainted with his works. 16.—The mode of proposing and balloting for Honorary Members shall be the same as that prescribed for Ordinary Members; but no person shall be balloted for as an Hono- rary Member unless the Council shall have previously approved of him. | III.—Withdrawal and Removal of Members. 17.—No member shall be considered to have withdrawn from the Society until he shall have paid his arrears and given a written notice of his intention to resign to one of the Secretaries. 18.—Whenever it shall be proposed to remove any member from the Society, the same shall be done by a resolution of Council, which shall be read at three suces- sive Ordinary Meetings, and be suspended in the intervals in the Society’s room of Meeting; and at the last of the said meetings the proposition shall be balloted for, and if two- thirds of the members balloting shall vote for such member’s removal, he shall be removed from the Society accordingly. 19.—The names of all members who shall be in arrear of their annual subscription for more than two years shall be publicly suspended in the Society’s ordinary room of meeting, with the amount of subscriptions due from each; and unless the same shall be paid within three months after such suspension, their names shall be liable to be removed from the list of the members. IV.—Annual Meeting and Election of Officers. 20.—An Annual Meeting of the Society shall be held in the place of the Ordinary Meeting for February, for the election of officers for the year ensuing, and for receiving the report of the Council on the state of the Society, or to enact, alter, or repeal Laws. the Microscopical Society. lll 21.—Notice of the Annual Meeting shall be given from the Chair, at the preceding Ordinary Meeting of the Society in January, and also upon the cards of the Ordinary Meet- ings. 22.—The Council, at the Ordinary Meeting in December, shall declare the names of the four members whom they recommend to retire, and propose to the Society the names of four other members to supply their places in the Council ; they shall also declare the names of the other Officers whom they recommend for election. 23.—At the Annual Meeting the officers and four members of Council, to replace those who retire, shall be elected. The mode of election shall be by ballot. 24.—In the event of any member of the Society being desirous of proposing other names than those recommended by the Council, a written list of the same shall be delivered to one of the Secretaries, on or before the Ordinary Meeting in January, and the same shall be read from the Chair, and publicly suspended in the Society’s rooms, with the list recommended by the Council; and no member shall be eligible for election into the Council unless he has been pro- posed in the manner and form above specified. 25.—The President or other member in the Chair shall appoint two Scrutineers from among the members present, _ to superintend the ballot during its progress, and to report the result to the meeting. 26.—If in the interval between the two Annual Meetings the office of President, Vice-President, Treasurer, or Secre- tary, may become vacant, either by death, resignation, or otherwise, the Council shall have power to appoint one of their own members to fill such office until the next Annual Meeting. V.—Ordinary Meetings of the Society. 27.—The rooms shall be open to members at the hour of 7 o’clock, for microscopical investigation. The Chair shall be taken at 8 o’clock precisely. 28.—The ordinary course of business shall be as follows:— Ist. The names of the visitors, and of the members by whom they are introduced, shall be announced from the Chair. Qnd. The minutes of the proceedings of the previous meeting shall be read, and submitted for con- firmation: 112 Constitution and Laws of 3rd. The lists of candidates for election and for sus- pension shall be read,. and the ballot for the election of members shall take place. Ath. Scientific communications shall be read and dis- cussed. et 29,.—The Chair shall be vacated at 9 o’clock, or as soon after as may be convenient; and the Society shall resolve itself into a Conversazione. 30.—At the Ordinary Meetings nothing relating to the Laws, or, to the enactment of new Laws, shall be introduced or discussed. VI.—The Auditors. 31.—Two Auditors shall be appointed by the Society at the Ordinary Meeting in January. : 32.—They shall audit the Treasurer’s accounts, and pro- duce their report to the Annual Meeting of the Society, to be held in February. They shall have the power of calling for all necessary accounts and vouchers. 33.—No member of the Council shall be eligible as an Auditor. VIl.—Council. 34,.—The business of the Society shall be conducted by © the President, four Vice-Presidents, Treasurer, and two Secretaries, who, with twelve other members, together with the past Presidents elected previous to the year 1866, shall constitute the Council; and at all meetings of the Council five shall be a quorum. - 85.—Four of the twelve members of the Council shall retire annually, and four new members’ shall be elected in their places. . 86.—The Council shall hold their Ordinary Meetings on the day of the Ordinary Meetings of the Society. 37.—Extraordinary Meetings may be held at the discretion of the President, who shall direct the Secretaries to issue ‘especial summonses for the occasion. | 38.—The ordinary mode of decision on questions before the Council shall be by show of hands, unless a ballot shall hé demanded. 49.<-Any member who shall be personally interested in the Microscopical Society. 113 the question before the Council, shall retire during the con- sideration and discussion of the same. 40.—The Council shall present, and cause to be read to >the Annual Meeting, a report on the general concerns of the Society for the preceding year; and such report, or the sub- stance thereof, shall be printed under the direction of the Council, for distribution among the members. VIII.—The President and Vice-Presidents. 41.—The President shall be in virtue of his office Chairman of the Council, and shall take the Chair at all Ordinary, Annual, or Extraordinary Meetings of the Society; he shall regulate the order of proceedings, and shall, ex officio, be a member of all Committees appointed by the Council. 42.—In the absence of the President, one of the Vice- Presidents, or in their absence the Treasurer or one of the members of Council, shall take the Chair and conduct the business of the Meeting; and in the case of the absence of all those officers, the Meeting may elect any other member present to take the Chair. 43.—No member shall be eligible as President or Vice- President of the Society for more than two years in succes- sion; and two of the Vice-Presidents shall retire annually. LX.—The Treasurer. 44.—It shall be the duty of the Treasurer to receive all sums of money due to the Society, and to pay therefrom only such amounts as may be ordered by the Council. 45.—He shall keep an account of such receipts and pay- ments, and shall produce the same at all Meetings of the Council. 46.—The Treasurer shall pay all moneys received by him into the hands of the Society’s banker, retaining a sum not exceeding £30 for the payment of current expenses. X.—The Secretaries. 47.—It shall be the duty of the Secretaries to attend all Meetings of the Society and Council. 48.—They shall take, or cause to be taken by the Assistant Secretary, minutes of the proceedings, and prodiice and read 114 Constitution and Laws. them at the ensuing Mecting; read the scientific papers pre- sented to the Council, if requested by the authors; and con- duct the correspondence of the Society. 49.—The Council shall be empowered to appoint an Assis-« tant Secretary, and to assign to him such portion of the duties of Secretary as it may think desirable, at such remu- neration as the Council may deem proper. XI.—Scientific Papers. 50.—All scientific papers shall be submitted to, and ap- proved by, the Council, previously to their being read at the Ordinary Meetings of the Society. 51.—They shall be read in the order in which they have been received, unless the Council shall otherwise direct; and the discussion of the subject of each paper shall immediately follow the reading thereof; but it shall be left to the discre- tion of the Chairman to take the discussion on two or more papers, on similar subjects, together. 52.—The papers and illustrative drawings to be considered the property of the Society, unless the authors shall stipulate to the contrary. 53.—Authors shall be at liberty to read their own papers. XI1.—Publications. 54.—The Transactions of the Society shall be published at such intervals, and on such conditions, as the Council shall think fit. 55.—They shall consist of a selection from the papers which shall have been read at the Ordinary Meetings of the Society ; such selection to be made by the Council. 56.—The authors of such papers as may be published by the Society shall be entitled to twelve copies, free of expense. XU.— Library. 57.—The books in the possession of the Society shall be allowed to circulate among the members, under such regula- tions as the Council may deem necessary, but they shall be returned to the library on or before the next Ordinary Meeting following that on which they may have been taken out. Owen, on the Surface-fauna of Mid-ocean. 115 XIV.—WMicroscopes and collection of Objects. 58.—The microscopes and microscopic objects in the pos- session of the Society may be employed by the members during the period of the Ordinary Meetings, but shall not be taken out of the Society’s rooms without the permission of the Council. XV.—Trustees. 59.—The Council shall appomt three members of the Society to act as T'rustees of the property of the Society, of whom the Treasurer shall be one; and may appoint others in their place, on any vacancy occurring by resignation or otherwise. 60.—The Council shall decide on the mode of investing the property of the Society, which investment shall be in the names of the Trustees for the time being. XVI.—Of altering the Laws. 61.—No permanent alteration in the Laws of the Society shall be made, except at the Annual Meeting, or at a special General Meeting to be convened for the purpose by the President, with the sanction of the Council; and notice of any proposed change must be given on or before the preceding Ordinary Meeting. On the Surracn-Fauna of Mip-ocean. By Masor Samvuen R. 1. Owen, F.L.S., F.A.S.L., Member of the Micro- scopical Society, and Associate of King’s College, London. (Read June 13th, 1866.) No. 3.—The Towing-net.* Tuer time is now coming when we shall be distributed far and wide for the summer’s vacation, and many will have the opportunity of using the towing-net, by beimg near the sea or upon its waters. I wish to say a few words on the subject of its use, and what may be expected from its assistance. Towing-nets for short distances, and only in calm, fine 3 Nos. 1 and 2, on the Surface-fauna of Mid-ocean, “ Recent Polycys- dina” and “ Foraminifera,’ were read before the Linnean Society, and will be found in their publications: 116 Owen, on the Surface-fauna of Mid-ocean. weather, is not all that is required. Nets should be made that will tow from even a steam-vessel, and thus be made to sweep the ocean-surface for several degrees at atime. By this course a satisfactory account may be given of our own and the neighbouring seas; and to such as take long sea voyages they will open out a vast field of interesting research. I will begin by describing a simple form of net, such as may be rigged out at a few hours’ notice. A grummet should be made for the mouth, to which three cords may be attached to connect it with the towing-line; that line should be a good stout piece of stuff, and capable of bearing a great strain. To the grummet should be attached, first, a bag, the upper part of which may be made of a thin canvas, the lower part of strong jean, ending in a piece of close calico or linen; the bottom must be left open, and tied round with a tape when used: this will be found convenient for taking out the con- tents; and by leaving it open and towing it so for a short time, it can be thoroughly washed. Over the whole an outer covering of the strongest sail-cloth should be put, the upper part, in like manner, attached to the grummet, the lower part left open, and a portion for a foot or eighteen inches of the seam left to be coarsely laced up with a piece of cord, the same being done for the bottom itself. If necessary, a third covering may be put between these of any strong but rather porous material; but this, in its turn, should be left open at the bottom, and only tied when required for use. Its length should be so adjusted, when tied, that the inner lining of calico may rest against it, and be relieved from the strain. The outer sail-cloth should, in like manner, be laced up to receive and support the whole. For a net to be used when the vessel is under steam, or m heavy weather, the grummet may be three inches diameter in the clear. Any young nautical friend will explain how a grummet is made; and the whole of the apparatus may be sown down from a foot below the mouth to near the bottom with two seams, making it into three tubes. This will be found to answer in every respect all that can be required of a net, even in the roughest weather. A piece of strong fine net may be arranged at the mouth; this will prevent larger things from going to the bottom; they can be at once taken out on getting the net on board. For the removal of the finer contents, it will be necessary to unloose the outer cover, untie and turn up the second, then the calico bag, containing what is wanted, can be untied, turned inside out, and care- fully washed into a bowl of salt water, where the material maybe passed through a sieve of coarse muslin, The larger Owen, on the Surface-fauna of Mid-ocean. 117 will thus be separated from the finer portions; by decanting each part so obtained the heavier will be separated from the lighter ; thus, four divisions well adapted for examination will be in separate vessels. Hach haul being thus treated, a re- gister may be kept in bottles and on glasses of every portion of the ocean passed over. Weak spirit, or a solution of bay salt and arsenic, will pre- serve things in a wet state; others may be allowed to dry on the glass slides. Larger nets may be made on a similar principle for quiet sailing and finer weather. Nets with large openings, a yard wide, may be used in calms, and from boats. A bent cane and a straight deal lath make a very good mouth. The material nearest the opening should be of fine net; below this muslin should be used, and at the bottom the fine close calico bag, made open, and tied when used. A bag of coarse net should be attached to the mouth, penetrating it a yard or so, to in- tercept the larger things that may get into it. To use these nets conveniently, a spar or bamboo should be rigged out on the quarter or side of the vessel, having a guy or two to support and steady it; a pulley or small block should be fastened at the outer end, through which the towing- line may pass and come in board some distance forward of the place from which the spar is projecting; this will relieve the spar, in a great measure, from the strain. It would be found difficult to haul in such a net when the vessel is going ten knots an hour, but this difficulty is entirely removed by having a second thinner line attached to the side of the mouth of the net; by hauling on this the strain of the water is at once taken off and the net brought in board with the greatest ease, and, moreover, should the tow-line break the net 1s saved by the second line from bemg lost. Tt will be found that the length of the towing-line must be regulated in some degree by the size of the net and the rate of sailing; if too short, the net will only touch and dance upon its surface without taking up the water ; if too long, it may be carried under water, and so increase the strain as to endanger the line or spar. The length should be sufficient to allow the mouth to keep dipping in and taking up water when the vessel 1s going at great speed; but when a slower rate is to be adjusted for, then the mouth should keep at the surface, the grummet being generaliy nearly under water, but the waves of the sea will interfere with any great nicety in this respect. The hne should be strong cnongh for any sudden jerk that might occur, 118 Owen, on the Surface-fauna of Mid-ocean. I need not here go deeply into the various interesting objects that may be met with by the use of such an arrange- ment. The Polycystina, with their interesting allies the Acanthometra; the Thalassicolla, &c. &c., about which so little is really at present known, might be found. I am persuaded that the genera Pulvinulina and Globigerina, of the family Colymbite of the Foraminifera, will be found on the surface of the ocean near home. Dr. Wallich found them in great numbers in the sediment forming the bed of the Atlantic. From 70 to 98 per cent. of this deposit m the deep seas is often composed of these Rhizopods. ‘These two genera, together with the Orbulina of Dr. Carpenter, but which I have now proved to be a sub-genus of Globigerina, have been found to be surface-forms on every part of the ocean that I have sailed over. Different classes of creatures will be found on the surface during the night to those found in the day time; from sunset till daylight the Polycystina, Foraminifera, Acanthometra, Entomostraca, small Pteropods, and shelled Molusca, must be looked for; during the day the Crusta- ceans, Thalassicolla, Creseis, &c., will repay our endeavours. I hope enough has been said to induce some to try the ex- periment on a scale that will bring great results. When at sea I had not the chance of entering upon a field of observation that promises to be very fruitful and interest- ing. I had no spectrascope with me to examine into the nature of the light given off by the various phosphorescent forms that are at times met with in such profusion on the sea-surface. I would now make an appeal in their behalf. We shall look forward with interest to receive papers on this subject when we meet again at the close of the year. I hope that some of our correspondents abroad will take it up, and send us the spectra of the fire-fly, lantern-fly, and a host of other luminous creatures. At home the glowworm and phosphorescent sea-surface forms might all be attended to. Those who visit the Mediterranean and more southern parts of the ocean this summer might add the spectrascope to their scientific instruments for this purpose. I take much interest in this subject, but, as I am not likely to have an early opportunity of prosecuting the investigation, I have brought it forward for the benefit of others who may be more fortunate. These spectra must be compared with those we shall get from such sources of phosphorescent illumination as phos- phorus, heated fluor spar, and many others that I might name. I have the pleasure to present to the Society a slide con- Owen, on the Surface-fauna of Mid-ocean. 119 taining the most brilliant phosphorescent Entomostraca that I have met with. (See figs. 1,2, 3.) When these were taken the sea was alive with them. When swallowed by or entangled with other creatures they in their turn appear to be also luminous. They also give lumi- nosity to the water itself as it flows over them. When they are at rest they gradually cease to give out light; but as soon as they are disturbed or in motion, or the vessel containing them is shaken, they again become bright, even after many hours’ confinement. Kach of these specimens I picked out while phosphorescent, that there might be no mistake about the giver of light. The nearest of the Hntomostraca that I have been able to compare with these is the species Gibbosa, genus Cypridina, of the order Astrucoda, named and figured by Dana. He reports having found his specimens in the Pacific, in lat. 15° 20’ south, ieee: Fig. 3. and long. 148° west. He notes them as “ very brillant.” My specimens from which these drawings are taken were caught in the month of November, in the Bay of Bengal, in lat. 8° north, and long. 90° east. There is no reason why such things should not have a wide range. It may, there- 120 Owen, on the Surface-fauna of Mid-ocean. fore, be the same species.* It will be satisfactory to have more specimens of this from the Pacific, as we all know how an error might creep in, in labelling each specimen, when the collector passed over so many oceans during the same voyage. I have seen the ship’s decks running with liquid fire when the net containing this species has been taken on board. I must again express my regret that I had no spectrascope with me on my last voyage. J am therefore unable to lay before you the drawings of the spectra of the luminous Entomostraca that are on the table. I shall conclude by hoping that some of my zealous fellow-workers will take up the subject, and at an early day make up for my want of opportunity. It will end in more than a few interesting ex- periments. I look for results that may not only add to our chemical knowledge, but to such as may afford us some hints on matters that are at least the nearest akin to the nature of organic life. * The difference in the form of the beak has since made me think it may be found entitled to be considered a distinct species.—S. R. I. O. ERRATUM IN CAPTAIN MITCHELL’S PAPER ON THE SCREW MICROMETER. Page 71, line 3 from bottom. Vor—“ With my micrometer a negative eye-piece (one by Powell and Lealand), with four filaments, amounts to the divisions of the micrometer head.” Read—“ In my micrometer a negative eye-piece (one by Powell and Lealand), the thickness of one filament is equal to two divisions of the micrometer head.” TRANSACTIONS OF THE MICROSCOPICAL SOCIETY OF LONDON. Descriptions of New and Rare Diatoms. Serizs XX. By R. K. GrevittE, LL.D., F.R.S.E., &c. (Communicated by F.C. 8. Ropsrr, F.L.S.. &c.) (Read May 9th, 1866.) (Plates XI and XII.) PLAGIOGRAMMA. Plagiogramma elongatum, nu. sp., Grev.—Frustules elon- gated, with two central cost ; valve linear, narrower towards the rounded apices, generally very slightly contracted in the middle; strize composed of rows of large, distinct, subquad- rate granules. Length -0074”. (PI. XI, figs. 1, 2.) Hab. In cleanings of shells from South America; Laurence Hardman, Esq. In the character of the markings this noble species is allied to P. tessellatum, but,it is twice the size, and the valve is of a different form, linear instead of elliptical, rounded at the ends, near which it becomes narrower and more strictly linear. It is the finest species of the genus hitherto dis- covered. Plagiogramma? angulatum, n. sp., Grev.—F rustule in front view linear, with parallel sides, central and terminal costee ; the space between the terminal costz and the apex oblique; strice forming a very narrow band. «Fig. 3.) Hab. Barbadoes deposit, Cambridge estate; m slides com- municated by C. Johnson, Esq. ; extremely rare. All the specimens I have met with present the front view ; and as the ends are distinguished from those of all the other species in being, as it were, sharply bevelled off on each side, some slight doubt may exist as to its generic position. The VOL. XIV. a 122 GREVILLE, on New Diatoms. strie are 16 in ‘001”, and form a narrow marginal band. There is a remarkable angularity and squareness in the whole aspect of this diatom. Length about -0040”. GEPHYRIA. Gephyria gigantea, u. sp., Grev.—Valves much elongated, broadly cuneate and obtuse at the ends; costze about 34 in ‘001” (Figs. 7, 8.) Hab. Monterey deposit, California; Laurence Hardman, Esq. i truly magnificent species. A lower valve now before me measures ‘0120’ in length! A smaller example is °0100”, in which the breadth is ‘0017’ in the middle. Towards the ends the valve dilates a little, and then becomes broadly cuneate or elliptic-cuneate. Compared with this species, all those previously described are as dwarfs. In the largest of oie (G. incurvata) the coste of the valve are about 7 in ‘001”, i the one now described they are only 34 in ‘001’. OMPHALOPELTA. Omphalopelta Moronensis, n. sp., Grev.—Small; dise with six compartments, filled with decussating striz variously arranged, causing a play of colour; three of them pale, with a deltoid impression, the others darker, with a sort of trira- diating nucleus and a marginal spinous process. Diameter 0030”. (Fig. 14.) Hab. Moron deposit, Province of Seville; Laurence Hardman, Esq.; extremely rare. An exquisite little diatom, the markings of which cannot be satisfactorily reproduced by: the artist, as they depend for effect upon the slightest change of focus. I have endeavoured to delineate what. may be regarded as the most peculiar aspect. The play of colour is somewhat similar to that seen in O. versicolor, only uot so brilliant. This effect seems to arise, not alone from the outer pellicle, the striz of which are uniformly decussate, but partly from the undulation of the surface, and possibly from the subjacent structure. The marginal processes do not occur in all the compartments in accordancewith the generic character, but onlyin thealternate darker ones. At the same time the diatom is too closely allied to O. versicolor to admit of its beg removed. The presence or absence of spines, in many cases, at least, does not appear to be of much importance. GREVILLE, on New Diatoms. 123 AULACODISCUS. Aulacodiscus sparsus, n. sp., Grev.—Small; dise with 4 linear-oblong, submarginal processes; granules minute, coloured, so remote as not to be conspicuously radiate ; umbilicus a subcircular blank space; furrows becoming gradually wider as they approach the processes; margin with a row of puncta. Diameter ‘0030’. (Fig. 6.) Hab. Barbadoes deposit, Cambridge estate; in slides com- municated by C. Johnson, Esq.; extremely rare. The only species with which the present very beautiful diatom can be compared is A. Kilhkellyanus, which it re- sembles in the disc, having a general appearance of being sparsely filled with granules, while it is not much inferior in size. But in that species the lines of granules are conspicu- ously radiate, the sparse appearance depending upon the distance between the lines, the granules themselves being arranged in a pretty close series. The number also of pro- cesses in the same species is constantly three. In our new species the sparse character arises from the distance between the individual granules in the lines, which is so great that the radiation of the lines does not strike the eye at once, while the granules get disposed into half-concentric wavy lines, which have a beautiful effect. The number of processes is four. CESTODISCUS. Cestodiscus pulchellus, n. sp., Grev.—Disc circular, very convex, with minute, remote, radiating puncta, becoming irregularly crowded, and slightly less in size towards the margin; processes numerous; margin, as well as the space between it and the granules, striated. Diameter ‘0030”. (Fig. 5.) Hab. Nankaurie deposit, Nicobar Islands; in a slide_ kindly communicated by George Norman Hsq. ; very rare. Distinguished by the remote punctation, which consider- ably neutralizes the effect of the radiating character. In the centre the granules are somewhat loosely disposed. Towards the margin the radiating granules pass abruptly into a band of others, crowded and irregularly arranged, from the outer edge of which band the processes arise, sixteen or more in number. Margin strongly defined and conspicuously striate. . Cestodiscus Stokesianus, n. sp., Grev.—Dise circular, with 124 GREVILLE, on New Diatoms. lines of very minute puncta, closely radiating from the very centre, and terminating towards the margin in a belt of still smaller irregularly crowded puncta; processessmall,6; margin striated. Diameter 0030”. (Fig. 4.) Hab. Moron deposit, Province of Seville; Rev. T. G. Stokes. This species differs from C. pulchellus, with which it agrees in form and size, in the crowded character of the radiating lines which fill the disc, and in the very much smaller number of processes. The latter are somewhat inconspicuous. The puncta which form the band between ‘the radiating lines and the striated margin are smaller than the others, and irregularly crowded. I am obliged to my indefatigable friend Mr. Stokes for having brought this addition to the genus under my notice. ; Rourivaria (char. amended). Frustules very compressed, cohering into a short filament ; valves slightly elevated at the angles, with a central glistening nodule prolonged into two short, linear, obtuse processes ; the margin pectinate-ciliate. The fortunate discovery of perfect frustules in situ enables me to determine the true position of this very interesting and curious genus, three species of which were published in the ‘Quart. Journ. of Mic. Sci.” Vol. III, New Series. At that time nothing more was known of them than what was afforded by a side view of the valve, which, however, was sufficient of itself to separate them from all known diatoms. The genus is unquestionably allied, as my friend Mr. T. G. Rylands suggests, to the Biddulphiee. The angles, of the valves are not prolonged into horns, but are only slightly elevated, and consequently the valves of opposite frustules, as seen in the front view, are brought so near together that the marginal ciliz;of.each nearly cross the intervening space. The best view of the structure, showing its affinity with the Biddulphiee, is to be obtained from the valve when so placed as to present both the front and lateral surfaces. (Fig. 10.) The genus, in fact, passes into Biddulphia through B. jfim- briata, and especially through B. spinosa. Mr. Rylands, who with his usual kindness aud acuteness examined, at my request, R. elliptica very critically, satisfied himself that of the two central processes one was straight and the other curved, as in the flexure of the forefinger; and that the pro- cesses of the opposing valves were interlocked, the straight process of the one passing mutually through the curved pro- GREVILLE, on New Diatoms. 125 cess of the other. Such an arrangement exhibits a remark- able analogy with that which exists in Syndetocystis, a MS. genus, to be described by Mr. Ralfs in his forthcoming supplement to the Diatomacee of Pritchard’s ‘ History of Infusoria.” It was discovered in the Barbadoes deposit, and also belongs to the Biddulphiafamily. In that most wonderful genus the valves are nearly circular, fringed with ciliz, and furnished with two intra-marginal rounded processes, and in the centre with another solitary process, erect, cylindrical, and elongated, and terminated by a laterally projecting ring. Looking at frustules in situ, in the front view, it is perceived that the stalk of the process of one valve passes through the ring of the process of the opposing valve, and, as this is the mutual position, the two frustules move freely as on pistons, and can he pulled asunder until the respective rings are brought into contact, but, of course, no further. Nothing but force can separate them. In the cabinet of my friend Mr. George Norman is a chain of four frustules so united. Ruiilaria elliptica, Grev.—Valve narrow-elliptical, raised at the angles into two short conical elevations. (Figs. 9, 10.) Rutilaria elluptica, Grev.—‘ Journ. of Mic. Sci.,’ Vol. IIT, New Series, p. 229, Pl. IX, fig. 3 (valve). The figures which I am now able to offer will, it is hoped, render the structure quite intelligible. The front view ex- hibits four valves in situ, with the intermediate zone. The figure of the valve I formerly published was simply a side view. I now give the valve as seen under the most favorable circumstances for illustrating its relation to Beddulphia, viz., a partially front view. Rutilaria superba, n. sp., Grev.—lLarge ; valve elongated, oblong in the middle, gradually contracting towards each end into a narrow neck, which again dilates, and then suddenly terminates in a broadly elliptical, subacute apex. Length 0065”. (Figs. 11, 12.) Hab. Barbadoes deposit, Cambridge estate ; in slides com- municated by C. Johnson, Esq. A fine species, with frustules almost as long as R. epsilon, _ but with a totally different diagnosis. ‘The species to which it comes nearest is R. ventricosa ; but it differs (so far as we know at present) in its far more elongated form and in the dilated ends of the valve. J have seen many specimens of R. ventricosa, none of which exhibit the last-named character; on the contrary, the prolonged extremities of the valve are sometimes more slender and attenuated than they appear in my figure (Mic. Journ.,’ Vol. III, N. S., Pl. IX, 126 GreviL_e, on New Diatoms. fig. 2). Nevertheless, these two diatoms may be ultimately found to be extreme forms of one.and the same species. Fig. 11 exhibits a front view of two frustules in situ. CocconEIS. Cocconeis armata, n. sp., Grev.—Small ; dise broadly oval, with rather large, subremote, decussating granules, and distant marginal tubercles; median line straight, with a parallel row of very minute close puncta on each side. Length -0021”. (Fig. 13.) Hab. Barbadoes deposit, Cambridge estate ; in slides com- municated by C. Johnson, Esq.; extremely rare. A brilliant and well- marked little diatom. The median line very slender. The granules arranged in intersecting curves, 8 in ‘001’. Marginal tubercles, about 8 on each side. NAVICULA. Navicula strangulata, n. sp., Grev.—Valve elongated, deeply constricted at the middle, and composed of two ovato- cuneate subacute lobes, very minutely punctato-striate, with a narrow border of larger, more remote striz (or cellules). Length :0042”. (Fig. 24.) Hab. In marine dredgings, Nassau, West Indies. Among the multitude of described Navicule I can find no trace of this or the following well-marked species. The present diatom is evidently allied to N. marginata of Lewis, not only in form, but in the contrast between the minutely punctate striz of the general surface and the row of larger cellules which constitute the margin. In the diatom before us these cellules are relatively much smaller than in WN. mar- ginata, but they are, nevertheless, evident. The general strie are almost parallel, becoming slightly oblique only towards the ends. These striz, taken near the median line, are 20 in: ‘001”, while those at ‘the margin (cellules) are 10 in (GOL. Navicula Jamaicensis, n. sp.. Grev.—Elongated, with a deep constriction, dividing the valve into two oblong-elliptical lobes, somewhat produced and obtuse at the ends; structure minutely punctate, the puncta (cellules) arranged quincun- cially, with a row of still smaller puncta along the margin. Length :0040”. (Fig. 238.) Hab. Jamaica; obtained by washing seaweeds. dé tke lil GREVILLE, on New Diaioms. 127 This diatom has no immediate affinity with the preceding. There is no edging of larger cellules, but, on the contrary, a row of smaller puncta. ‘The general structure, too, is unlike what is usually seen in the genus, the punctz, which increase in size towards the margin, being not primarily so arranged as to produce the effect of striz, but im guincunx fashion. Near the margin they are 15 in *001”. Navicula Egyptiaca, n. sp., Grev.—Elongated, narrow, convex, with elliptical subacute ends, and very gradually and slightly constricted at the middle; a lmear lanceolate band of short broad coste midway between the margin and median line, interrupted opposite the nodule, and a partial view of a second band of coste at the margin. Length 0050” to :0065”. (Figs. 16, 17.) Hab. Stomachs of Holothuriz; in slides kindly com- municated by W. J. Baker, Hsq., and George Norman, Esc. My friend Mr. Ralfs has justly remarked in his observa- tions on the genera Navicula and Pinnularia, that, “ were the costze always plainly developed as in Pinnularia nobilis and its allies, no difficulty could occur in determining the genera; but in many of the more minute species it is often very diffi- cult to distinguish between striz and costz;’ and he adds very truly, “that it is impossible to say to which genus a large number of Ehrenberg’s species should be referred. He resolves the difficulty by merging for the present, at least, Pinnularia in Navicula. The very elegant diatom now under consideration would be, according to the late Professor Smith, an unquestionable Pinnularia, and it is too well marked to be mistaken for any other species. Coste about 10 in -001”. This Holothurian material is rich in many species, and there can be no doubt that collections from the stomachs of the Holothuriade generally, especially in the warmer parts of the world, would amply reward the diatom hunter. Navicula permagna (Bail.), Ralfs.—Large, lanceolate or turgid-lanceolate, with somewhat obtuse apices; stric fine, close, an intramarginal line, and a second shadowy line between the margin and the median line, and generally a rather broad, longitudinal, median blank space. Length °0060” to -0108”. (Figs. 18—21.) Navicula permagna, Ralfs, in Pritch. ‘Tnfus.’ (1861), p. 907. —Lewis, ‘Notes on Diatom. of U. 8. Seaboard,’ p. 12, pl.u, fig. 11 (var.). Pinnularia permagna, Bail., ‘Mic. Obs.,’ p. 40, pl._u, figs. 28, 38. 3 Hab. Abundant in the Hudson River at West Point, and 128 GREVILLE, on New Diatoms. occurs of a smaller size in Lake Monroe, at Enterprise, Florida; Bailey. In most of our large Atlantic rivers and brackish marshes ; at Cape May, saltmarsh near Cold Springs, abundant; Dr. Lewis. Mouth of the River Berbice, West Indies, at half tide; Dr. Abercrombie. Having had occasion some years ago to notice that this species exhibited a remarkable range of variation, I have endeavoured to ascertain to what extent it may be traced. In taking the original figures of the late Professor Bailey as our starting-point, we find the longitudinal median space so large that the strie are regarded as forming a mere marginal band, constituting, in fact, the salient feature in the specific character of Bailey, and subsequently of Ralfs. In the smaller of the two figures given by the former the median space is equal to half the entire breadth of the valve. The next American authority is my friend Dr. Lewis, of Phila- delphia, who publishes a figure of a singular variety, which, he says, is more common on the Delaware River and its tributaries than that represented by Bailey, and which, he thinks, may be the Navicula Esox of Kutzing. (Fig. 21.) In this variety the breadth of the median blank space is diminished nearly one half. In my two larger figures (18, 19), drawn from Berbice specimens, the breadth of the same part is again considerably reduced; and in the small figure (20), from the same locality, the blank space has become a mere line. Thus, although the extremes present an extraordinary difference, we have the discrepancy recon- ciled by intermediate conditions. In a dry state the valve of the Berbice examples exhibits very gorgeous colouring, the general hue being fine blue, while a broad, bright, crimson streak extends down each side midway between the median line and the margin, passing into orange-yellow towards the ends. It is to be regretted that there should be no reference to this in the American notices of the species. Another character which is prominent in the Berbice specimens is not mentioned by Bailey or Lewis. I refer to the shadowy lines, one of which passes down the whole length of the valve on each side between the margin and the median line; the other, close to the margin itself, is indistinctly given in Dr. Lewis’s figure. The former seems to be uncertain{as to its position, being much nearer the median in my figure 20 than in figures 18 and 19. These lines appear to be caused by superficial ridges, the intermediate spaces being generally concave ; and if so, the character is an important one. With regard to the striation in some large valves, I have counted 16 in ‘001’. In some small varietes 25, or even more, in GREVILLE, 0n New Diatoms. 129 001”. They are generally less close opposite the nodule, being 15 in one specimen, while in other parts of the same valve they are 20 in :001”. The fact is, however, that no dependence can be placed on characters of this description. Besides the examples already referred to, I have some from Long Island agreeing with the intermediate form of the species, and a slide containing a large series from a salt marsh at Cold Springs, Cape May, U.S., all the specimens being small and intermediate. Ina drawing copied by my friend Mr. Roper from a specimen obtained by Professor Bailey from drift ice on the -Hudson River the leading characters are very prominent, especially the longitudinal ridge-like line; and the median space is nearly as broad as in Professor Bailey’s figures. Navicula Zanzibarica, n. sp., Grev.—Large ; valve ellip- tical, with the apices obtuse, somewhat produced; strize minutely moniliform, divided by a blank line into two series, the one linear, very narrow, parallel with and next the median line, the other containing a sort of irregular spot opposite the nodule. Length ‘0074’. (Fig. 22.) Hab. Zanzibar; in slides kindly communicated by Professor H. L. Smith, of Kenyon College, Gambier, Ohio. A noble diatom, and, beyond dispute, an excellent species. The striz are obviously moniliform, slightly oblique, inter- rupted by a narrow blank line, not contracted opposite the nodule, gradually attenuated towards the ends, and disappear- ing before reaching the apex. On each side the median line, and parallel with it, is a narrow line or band of strie; and these two bands, along with the median line itself, as they approach the ends become somewhat elevated and produced, and terminate in what may be regarded as a broad keel. Opposite the nodule, and midway between the margin and median line, is a curious spot composed of an irregular cluster of puncte, puckered, as it were, in the middle, while the surrounding striz are for a small space thrown into con- fusion. The first specimen which I found conveyed the impression that this singular appearance was the result of - some accidental malformation ; but all the valves which have been subsequently discovered present the same character. The striz are 17 in -001”. Navicula rimosa, un. sp., Grev.—Elliptic or elliptic-oblong, with a band of fine striz less than a third of the semi-diame- ter in width, a second very narrow band close to the median line, and a third narrow one between the two and not extend- ing to the ends; the intermediate spaces obscurely punctate (cellulate). Length 0035” to ‘0060”. (Fig. 25.) VOL. XIV. 130 GREVILLE, on New Diatoms. Hab. Red Sea; cabinet of Laurence Hardman, Esq. The intermediate linear band of striz serves to distinguish this species at a glance. It has at first sight the appearance of a cleft in the valve, for the striz, being very fine, are not at once perceived. It extends generally to about two thirds of the length of the valve. Sometimes it follows the curve of the valve, but in others (as in the figure) it is straight or very nearly so. Navicula excavata, n. sp., Grev.—Elliptic, with an external band of fine striz, less than half the semi-diameter of the valve in breadth, and a very narrow series next the median line; intermediate space obscurely cellulate, with a large sudden indentation opposite the nodule. Length about ‘0030”. (Fig. 15.) Hab. Red Sea; cabinet of Laurence Hardman, Esq. A species having much of the contour of N. Hennedyi, but differing from it in the much finer strize (about 35 im -001”) and in the large remarkable notch or excavation in the inter- mediate space opposite the nodule into which the marginal striz extend. $4, 1 HM‘ Farlane, Lith? Edin® VAXVNS Mor Sees AVWNMD. BH WCE a auhe We BX. Greville, del EN TEE oh Tums Mor Go VAI MSPLM Ws? 4 * “Vuyfy we ‘ 6 eNt hh Hb Vas cls é ae Z (ae ph A HW Wks Ray OC EE eed zi \ St a i 7 J y A a ‘ PH, Greville aelt - on stone by ¥. Huth, 5 "WHME Fallane, Lith? Bain DESCRIPTION OF PLATES I & II, Illustrating Dr. Greville’s paper on New Diatoms. Series XVIII. Fig. 1.—Plagiogramma decussatum, front view. 2.— Bs ie side view. 3. 5 Barbadense. 4.—Mastogonia Actinoptychus. 5.—Xanthiopyxis ? umbonatus. 6.—Coscimodiscus elegans. 1.— ee pulchellus. 8.— robustus. 9,10.— 7s oblongus. 11.—Brightwellia Johusoni. 12.—Actinoptychus minutus. 13.—Hupodiscus minutus. 14.—Biddulphia Johnsoniana, front view. 15.— 5 valve. 16.— F manmosa, front view of valve. 17.—Auliscus Hardmanianus. 18.—Hehopelta nitida. 19.—Triceratium mammosum. 20.— Ps dulce. 21.— . imelegans. 22.— ns Robertsianum. 93.— Bs Stokesianum. 24,—Amphitetras elegans. All the figures are x 400 diameters. TRANSACTIONS OF MICROSCOPICAL SOCIETY. DESCRIPTION OF PLATES III & IV, Illustrating Mr. Jabez Hogg’s paper on Vegetable Parasites. PLATE III. Fig. 1, a.—Second day, specimen from No. 1. Favus-ferment in barley- wort, set aside in a darkened room. Yeast-cells, chiefly ovoid in form, with spores and a few epithelium-scales. 1, 6.—Fifth day, specimen from No. 1. The yeast-cells more circular in form and larger in size. Spores and torule, with bacterium-like bodies in an active state. 1,¢—Tenth day, specimen from No. 1. Yeast-cells slightly degene- rating, becoming more ovoid ; torulz and bacteria. 2,a.—Fifth day, specimen from No. 2, freely exposed to light. Small growth of yeast-cells, with spores and tufts of mycelia, penicillium, and a few large epithelium-scales; bacterium-like bodies not drawn. 2, 6.—Tenth day, specimen from No. 2. Yeast-cells degenerating and disappearing; spores of mould, mycelia, and bacteria increasing. 3. —Healthy yeast-cells fresh from a porter brewery, drawn rather smaller than they measured. 4. —Portion of a scab taken from a boy suffering from eczema of eye- lids and impetigo of scalp, showing spores, moniliform chains, torulz mycelium, and epithelium-scales. PLATE IV. 1.—Fresh yeast transferred to a saccharine solution, and showing on the second day a tendency to degenerate. 2.—Degenerated or exhausted yeast taken from the bottom of a porter- vat; cells nearly: all void, and torule abundant. 3.—Favus-fungus grown in a pure saccharine solution. 4.—Aérozoa. Spores with mycelium, &c., taken in the atmosphere during the cholera visitation of 1858. 5.—Penicillium-spores. Mould growing in saccharine solution. 6.—Aspergillus-spores growing in saccharine solution. 7.—Puccinia-spores growing in saccharine solution. . Magnified 400 diameters. rand Mor fe Vo LIV NS. MIL ae 1é o AN A Jabex Hogs del. Taffen West so. eS ; W West imp Trond Nor Foo Vib XH NS FUL. WWest amp Jabez Hogs del. Tuffen’ West sc. - eee NSE ewe, és E Ray Lankester del. Tuffen Westsc. tad lt Raia ba TRANSACTIONS OF MICROSCOPICAL SOCIETY. DESCRIPTION OF PLATE V, Illustrating EH. Ray Lankester’s paper on the Gregarinida. ig. ae unusually large Monocystis Lumbricorum of the circular form, from the posterior extremity of the visceral cavity of LZ. terrestris, ss th inch in diameter. 2.—An unusually large MW. Lumbricorum of the elongated or linear form, from the seminal vesicle of a specimen of ZL. ¢errestris, in which all the - genitalia were occupied by such forms, !th of an inch in length. 3.—Nucleus or vesicle of the individual drawn in fig. 1. 4, 5.—Monocystis pellucida, Kolliker, adult specimens, which are not pellucid, showing the extensive development and apparent fibrillation of the sarcodic envelope. 6, 7.—Forms of Monocystis (IZ. Nemertis, Koll.?) met with abundantly in Ommatoplea and Convoluta and once in Aphrodita hystrix. 8.—Monocystis Cirrhatuli, n. sp., a large form abundant in the perivisceral eavity of C. Lorealis. 9.—Young individual of M. Cirrhatult. 10.—Monocystis Hunice, u.sp., from intestine of #. Harassii. 11.—WMonocystis Terebelig, Kolliker, from Terebella nebulosa. 12.—Monocystis Phyllodoce, a form differing considerably from that described. by Claparéde. 13.—Somatic granules from WM. Lumbricorum., wea is + ag a 7 f ae nd aa VI Or J TV NS oUt, Nair S, HC Srv W.West aap. TRANSACTIONS OF MICROSCOPICAL SOCIETY. DESCRIPTION OF PLATE VI. Illustrating Mr. Richard Beck’s paper on an Acarus and its Agamic Reproduction. In the lower part of the plate is shown the position usually taken by this Acarus after arriving at maturity, viz., that of standing over and guard- ing a large number of eggs. The shells of those eggs already hatched refract a most brilliant blue, and the presence of the parent is often detected by the eye catching this colour. In the upper part of the plate are shown the falces, with their fangs and combs, and between them the piercers and sucking apparatus of the mouth. The two small diagrams at the side represent the extremities of two feet, each provided with two claws, two rows of tenent hairs, and one of them having an unusually long terminal hair. The figure at the very top represents the anus. a cals PP c ve ry * 3 ead = er trans Mécr ve VA RIV NS SL VIE ey eS y WEES Ko By uentey & TRANSACTIONS OF MICROSCOPICAL SOCIETY. DESCRIPTION OF PLATE VII. Ilustrating Mr. Tuffen West’s paper on the Egg of Scato- phaga and on the Cast Skin of an Ephemeron. Figs. 1 to 7 represent the structure of the Egg of Scatophaga. Fig. 1.—Ventral aspect. 2.—Lateral aspect. 3.—The opening on side view; p, the delicate pellicle investing the young larva. 4.—Portion of the egg-case, about the middle, showing its reticulate and elevato-punctate structure. 5 —Part of tip of one of the divergent appendages, to show the minute punctation on its surface. 6.—Part of the dark portion of the cover, with its 4-5 angular reticulation and translucent spots. Figs. 8 to 11 illustrate the Notes on Cast Skin of an Ephemeron. 8.—Cast skin entire, except the ends of the tails; p. z., pro-thorax m. 8., mesothorax; m.¢., metathorax; a. p., alar pellicle, &c. 9,.—Hxuvie of head, under surface; aa, antenne; ee, pe, pe, eyes tr, tr, trachee. 10.—Profile view of head of an allied species; this is added as explanatory of the preceding figure; similar letters apply to it, with the addition of 0, one of the ocelli. The grotesque appearance imparted by the upper pair of eyes, borne aloft on stout columns, is well seen. 11.—End of foot, consisting of a recurved, sharply-pointed claw, attached to the side of a pedicellate oval pulvillus. The cast skin figured, when placed on a square of thin covering-glass, adhered sufficiently to bear removal upside down from the spot where it was obtained to a distant apartment. “4. 7 i ner ag Aras of tal 0 PT We ay 4 sheen ee a u ae Soc UAdW NS FLV a WH MS Farlane, Lift! Edin® ‘ a jit he Vy 4 W)18.. NM / / t by F Huth. eA one i : iva aire Ketan a Mh) “ey ie] i. | AM NS Pl, oo Pe. WHM° Farlane, Lith Bein’ J ot, fe} ie) ° oO ° ) Mir Soe fe) on 88 Sp Po 900 o> e e, yee RAL We : Wi Wie ) of i dy My ey, iy, Oy Oi) a, aK Ye) Y, My df xy 41 Pkt rtstiet °°) 3 ou t bq 3 ° ee TRANSACTIONS OF MICROSCOPICAL SOCIETY. DESCRIPTION OF PLATES VIII & IX, Illustrating Dr. Greville’s paper on New Diatoms. Series XIX. Fig. 1.—Playiogramma orientale. 2.—Gephyria constricta, valve. 3—6.—Melosira castata. 7.—Cresswellia rudis. 8—10.—Coscinodiscus Lewisianus. 1ll.— * Normanianus. 12.— . Barbadensis. 13.— 55 elegans. 14.—Hupodiscus Hardmanianus. _ 15.—Crodispedodiscus umbonatus. 16.—Biddulphia Chinensis. Vere, podagrosi. 18.—TZriceratium repletum. 19.— H pieluratum. 20.— 5 lantum. 21.— 5p quinguelobatun. 22—28.—Syringidium Demon. 29.—Navicula spectatissima. 30, 81.—Stanroneis rotundata. - 32.— ¥ scaphulaforms. All the figures xX 400 diameters, except fig. 16, which is x 200. TRANSACTIONS OF MICROSCOPICAL SOCIETY. DESCRIPTION OF PLATE X, Illustrating Dr. Bastian’s paper on Pacchionian Bodies. Fig. 1.—Different forms of Pacchionian bodies seen on surface of arachnoid. 2.—Appearance of epithelial covering of Pacchionian body. 3.—Tesselated epithelial cells from surface of pericardium. 4.—Solitary cells of same kind from Pacchionian body. 5.—Homogeneous, structureless network of tissue from surface of same body. a. Spiral elastic tissue. 6. More highly developed tissue of same kind, presenting slight traces of fibrillation. 7. Interlacing bundles of fibrous tissue fully developed from more mature Pacchionian body. 8. Ordinary fibrous tissue from surface of mature body. 9. Different forms of caleareous deposit. a. Granules with concentrically arranged tissue developing around them. b. Body of same kind, only larger and more mature. c. Simple, highly refractive, calcareous nodules. 4d. A much larger one, showing concentric markings, Oe Ne ae ee ™ oo Trans Mic Soc. VANS WK. W.West amp. ic Tuffen West sc. » . ee, wy ak | | | Bungee Hm Hea fenthentbe 1} Ee ee SL IW NSP i 5 ee, Wy ei wie Ty ooo @%60 6 0° Hnahdne ste OE EELS SEEN PEELE EEN Gs Aree trees Do are ray ath Mn hee ANAS AASE SPIN GHEE EEE Let RV QUES ENE [HIT _ PIT ae ——TR RR f alate ef ue lolelalelels {ete ; ~ ‘ gos0gddn000000000 ooooca 0090000000dg0090990000003 > ‘ a8o° C Jeanangeq9q9999900 999090000 paneteeinen tte eee reece nN S30 8 209899990 Q 9999999999 mn $209 a aaAAAAASARSS 2 plete ischetetekt tite ces eco RSC ee e ose. ea 1a 5 5o % ba Oe be AAAQMANAADAAAANANANNAAA yADAAAANAAAARAANAARDANADD, y* WNS PAD if 7 Sel Uoled Tran. Mau of da peooouetttniinittttensmemanttttt tite. SS (00RDoror, s2e2tv000N0000NdNNNNNNINY AT shh) TN innit in rt iy ul “nn . - cd AN ANY l Wi) Wee R 8 . RAN i . UT Ml WL Wij i i : ot . | AMMAN HOLE im eet amen ST nn a an es i i i TT oe e iii = SEDAN NN NNN NNN vm ATTN NW : CHAT AA fy: Lae a 2 LC) Hi i) HN i AN \\ \ acc UR fe: TOPS SUSSIAMELHUAULOSAUTESRESUARRESESTEDSSSeU boot bes USIT ESSN PPSSEIAATLA TASS O23 BEREO =~ ~-—_- ARGTSSHTELETSATEARALES UTTER AES TEER an FTE ARYL ASAONG IERIE SYSEIEEESETERIIE EST ar an as \\ A ah AN RUA pa aa \\ ne ANY Tres ff eA AI AN AN Sy) WS) COT seas Het ce *s e®e@ &s ——_ 7980000090000000000000009%°" "990099 Aww WD mn WHM Fatlane, Lith? E y¥F Huth. 6 DY tr n : 4 RE. Greville del! TRANSACTIONS OF MICROSCOPICAL SOCIETY. DESCRIPTION OF PLATES XI & XII, Illustrating Dr. Greville’s paper on New Diatoms. Series XX. Fig. 1.—Plagiogramma elongatum, front view. 2.— 55 a valve. 3.— M angulatum, front view. 4..—Cestodiscus Stokesianus. 5.— es pulchellus. 6.—Aulacodiscus sparsus. 1.—Gephyria gigantea, \ower valve, frout view. 8— ,, 3 valve, side view. 9.—Rutilaria elliptica, front view. WO 5 ae valve. 1l.— 5, superba, front view. 12.— a » valve, side view. 13.—Cocconeis armata. 14.—Omphalopelta Moronensis. 15.—WNavicula excavata. 16.— ,, Egyptiaca, front view. MY iy i side view. 18,19.— ,, permagna, very large, from Berbice. 20.— ,, 55 small var., from Berbice. 21— ,, :: var. from Delaware River, U.S. (out- line of Dr. Lewis’s figure). I=" 4, Zanzibarica. 93.— ,, Jamaicensis. I— strangulata. 95.— 4, rimosa. All the figures are x 400 diameters. ¥ : gp ¥ ie INDEX TO TRANSACTIONS. — VOLUME XIV. A. Acarus, description of an, and its agamic reproduction, by Richard Beck, 30. Actinoptychus minutus, 5. Amplitetras elegans, 9. Auditors’ report, 43. Aulacodiscus sparsus, 123. Auliscus Hardmanianus, 6. B. Bastian, H. Charlton, M.A., M.B. Lond., F.L.8., on the so-called Pacchionian Bodies, 86. Beck, Richard, on the object-glass its own condenser, or a new kind of illumination for opaque objects under high powers, 37. » Richard, on an improved grow- ing cell, 34. » Richard, on a short description of an acarus and its agamic repro- duction, 30. Biddulphia Chinensis, 81. a Johusoniana, 6. 59 2? mammosa, 7. » ? podagrosa, 82. Binocular microscope for high powers, on a, by F. H. Wenham, 103. Brass slide clip, notes ona, by R. L. _ Maddox, M.D., 65. Brightwellia Johnsonia, 4. C. Cell, an improved growing, by Richard Beck, 34. Cestodiscus pulchellus, 123. Stokestanus, 123. VOL. XIV. Cobweb micrometer, by Captain J. Mitchell, 71. Cocconeis armata, 126. Coscinodiscus Barbadensis, 80. ie elegans, 3. ee Lewisianus, 78. a Normanianus, 80. a oblongus, 4, a pulchellus, 3. 3 robustus, 3. ; elegans, 79. Craspedodiscus umbonatus, 79. Cresswellia rudis, 78. D. Diaphragm, a new adjustable, by Sid- ney B. Kincaid, Esq., F.R.A.S., 75. Diatoms, description of new and rare, by R. K. Greville, LL.D., F.R.S.E., &c., Series XVIII, 1. i Series XIX, 77. . Series XX, 121. E. Hphemeron, description of the ski cast by an, in its ‘“ Pseudo-imago”’ condition, by Tuffen West, F.L.S., &e., 69. Eupodiscus Hardmanianus, 80. G minutus, 5. G. Gephyria constricta, 77. » gigantea, 122. Gregarinida, notes on the, by H. Ray Lankester, 23. l 134 Greville, R. K., LL.D., F.R.S.E., &., on new and rare diatoms, Series XVIII, 1. » Series XIX, 77. » series XX, 121. H. Heliopelta nitida, 5. Hogg, Jabez, F.L.S., M.R.C.S., on vegetable parasites infesting the human skin, 10. ; IL Illumination of objects with high powers, by E. G. Lobb, Hsq., 39. K. Kincaid, Sydney B., Esq., F.R.A.S., ou a new adjustable diaphragm, 75. L. Lankester, E. Ray, notes on the Gre- garinida, 23 Leaf-holder, on a form of, for the Microscope, by James Smith, F.L.S., - 100 Lobb, E. G., Esq., note on the illumi- ir of objects with high powers, 39. M. Maddox, R. L., M.D., notes on a brass slide clip, 65. Mastogonia Actinoptychus, 2. Melosira costatu, 77. Microscopical Society, meeting of, 41. Microscopical Society of London, laws of, 107. Mitchell, Capt. J., on the cobweb- micrometer, 71. Monocystis Cirratuh, 27. a Lunice, 28. vs Nemertis, 28. » . pellucida, 28. Pe Plhyllodoca, 28. Mounting, on a method of dry, by James Smith, Esq., F.L.5., 29. anniversary INDEX TO TRANSACTIONS. N. Navicula spectalissima, 85. » excavata, 130 » rimosa, 129. » strangulata, 126. » Zamzibarica, 129. O. Object-glass, the, its own condenser ; or a new kind of illumination for opaque objects under high powers, by Richard Beck, 36. Omphalopelta Moronensis, 122. Owen, Major Samuel R. L., F.L.S., on the surface-fauna of mid-ocean, 116. Pp, Pacchionian bodies, on the so-called, by H. Charlton Bastian, M.A., M.B. Lond., F.L.S., 86. Parasites, vegetable, infesting the human skin, by Jabez Hogg, ¥'.L.S., M.R.C.S., 10. Plagiogramma Barbadense, 1. =. decussatum, 1. 3 orientale, 77. oo elongatum, 121. President’s address, by James Glaisher, F.R.S., 45. R. Rutilaria superba, 125. S. Scatophaga, structure of the ege in, by Tuffen West, F.L.S., &c., 67. Smith, James, Esq., F.L.8., on a method of dry mounting, 29. ry 99 on a form of leaf-holder for the micro- scope, 100. 99 ” on a revolving slide-holder, for the mi- croscope, 101 Slide-holder, on a revolving, for the Crone by James Smith, F.L.S., INDEX TO TRANSACTIONS. 135 Stauroneis rotundata, 85. Triceratium picturatum, 83. a scaphuleformis, 85. 4 quinquelobatum, 83. Surface-fauna of mid-ocean, on the, “A repletum, 83. by Major Samuel R.1.Owen, F.L.S., 115. W. Tt Wenham, F. H., on a binocular mi- Triceratium grande? 7. croscope for high powers, 103. ey Roberisianum, 7. West, Tuffen, F.L.S., &c., description ‘ inelegans, 8. of the skin cast by an ephemeron, in 3 obtusum, 8. its pseud-imago condition, 69, 5 Stokesianum, 8. Be = on the ws dulce, 9. structure of the egg in Scatophaga, 3 mammosum, 9. : re lautum, 82. 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