QUA G204 | Atex: Apassiz. Hibrary of the Mluseum OF COMPARATIVE ZOOLOGY, AT HARVARD COLLEGE, CAMBRIDGE, MASS. Founded by private subscription, in 1861. | LIVI Deposited by ALEX. AGASSIZ. e mee 79 AGA soir New Series, No. LXXIV. (7 Price 6s. APRIL, 1879. THE QUARTERLY JOURNAL OF MICROSCOPICAL SCIENCE. a z i @& ~ Ne zN LONDON: J. & A. CHURCHILL, NEW BURLINGTON STREET. MDCCCLXXIX. J, -B,-Adlard.} LONDON: J. & A. CHURCHILL, NEW BURLINGTON STREET. 1879, [Bartholomew Close. CONTENTS OF No. LXXIV.—New Series. MEMOIRS: PAGE QUARTERLY JOURNAL OF MICROSCOPICAL SCIENCE: EDITED BY EK. RAY LANKESTER, M.A., F.R.S., F.LS., Fellow of Exeter College, Oxford, and Professor of Zoology and Comparative Anatomy in University College, London ; WITH THE CO-OPERATION OF WILLIAM ARCHER, F-.R.S., M.R.I.A., Dublin. F. M. BALFOUR, M.A., F.R.S., F.L.S., Fellow and Lecturer of Trinity College, Cambridge. AND BS GDEIN, M.D. E.R:S., Lecturer on Histology in St. Bartholomew's Hospital Medical School, London, VOLUME XIX.—New Szrzzs. With Allustrations on Wood and Stone. LONDON: J. & A, CHURCHILL, NEW BURLINGTON STREET. 1879. cuto el cat AON 0 URE Go ee | — - ¥ m GAN Te ih 3 12 Sok sy Lb ie ys eo ty i 4 Mat - a 4% : ’ CONTENTS. CONTENTS OF No. LXXIII, N.S., JANUARY, 1879. MEMOIRS: On the Existence of a Head-Kidney in the Embryo Chick, and on Certain Points in the Development of the Miillerian Duct. By F, M. Batrour, M.A., Fellow of Trinity College, Cambridge ; and ApAM Sepewick, B.A., Scholar of Trinity canee Cam- bridge. (With Plates I aad II) Notes on some of the Reticularian Rhizopoda of the cones Expedition. By Henry B. aoe F.R.S. (With Plates III, IV, and V) : Researches on the Flagellate Infusoria and Allied Organisms. By O. Butscu1t, Professor of Zoology in the sig Sa of Heidel- berg. (With Plate VI) ; _ The Morphology and Systematic Position of the Spongida. By F. M. Batrour, M.A., Fellow of Trinity College, Cambridge * Flagellated Organisms in the Blood of a Rats. is TimMoTHy Ricuarps Lewis, M.B. 5 . NOTES AND MEMORANDA: Observation on the Capitellide by Dr. Huco E1sie Bacteria as the Cause of the Ropy change of Beet-root Sugar STEIN’s ‘ Organismus der Infusionsthiere ’ PROCEEDINGS OF SOCIETIES: Dublin Microscopical Club Titty, Contents, and Inprx to Vol. XVIII. b PAGE 20 63 103 109 115 116 118 120 hy CONTENTS. CONTENTS OF- No. LXXIV; N.S., APRIL, 1879. MEMOIRS : * Observations on the Structure of Cells and Nuclei. By H. KiEty, M.D.,, F.R.S. (With Plate VII) On the Apical and Oral Systems of the Echinodermata. By P. HERBERTCARPENTER, M.A., Assistant Master at Eton College. Part II. The Development of the Harth-worm, Lumbricus Trapezoides, Dugés. By Nixonas KunrnenBere. (With Plates IX, X, XI) PAGE 125 176 206 The Nematoid Hematozoa of Man. By Timotny Ricuarps Lewis, M.B. (With Plate XII) CONTENTS OF No. LXXV, N.S., JULY, 1879. MEMOIRS : Notes on Some of the Reticularian Rhizopoda of the ‘ Chal- _ lenger” Expedition. By Hzwry B. Brapy, F.R.S. (With Plate VIII) ; The Morphology of the Vertebrate Olfactory Organ. By A. Mitnes Marsuatt, M.A., D.Se., Fellow of St. John’s College, Cambridge. (With Plates XIII, XIV) On the Brain of the Cockroach, Blatta Orientalis. By E. T. Newrton, H. M. Geological Survey. (With Plates XV, XVI) The Microphytes which have been found in the Blood, and their Relation to Disease. By Trmorny Ricnarps Lewis, M.B., Surgeon Army Medical Department; Fellow of the Calcutta University. (With Plate XVII) ~ Observations on the Glandular Epithelium and Division of Nuclei in the Skin of the Newt. By E. Kirin, M.D.,F.R.S. (With Plate XVIII) : , : : On the Early Development of the Lacertilia, together with some Observations on the Nature and Relations of the Primitive Streak. By F. M. Barrour, M.A., E.RS., Fellow of aie College, Cambridge. (With Plate XIX) : On Certain Points in the Anatomy of Peripatus Capensis. By F. M. Batrour, M.A., F.R.S. ; : : 245 261 300 340 356 404 421 431 CONTENTS, Vv PAGE NOTES AND MEMORANDA: Chlorophyll in Turbellarian Worms and other Animals . . 434 A New Genus of Protista ; : ; 5 . 437 PROCEEDINGS OF SOCIETIES: Dublin Microscopical Club ’ = - - . 438 CONTENTS OF No. LXXVI, N.S., OCTOBER, 1879. MEMOIRS: On Some Points in the Early Development of the Common Newt. By W.B.Scort, B.A., Fellow of the College of New Jersey, Princeton, and Henry F. Oszory, B.A., Princeton. (With Plates XX and XXI) . : ; 5 . 449 The Structure of Haliphysema Tumanowiczii. By E. Ray LaNnkKESTER, F.R.S, (With Plate XXII) . ; . 473 Lithameba Discus, nov. gen. et sp., one of the Gymnomyxa. By HE, Ray Lanxester, F.R.S. (With Plate XXIII) . . 484 On the Structure of the Vertebrate Spermatozoon. By HENEAGE Grpses, M.B. (With Plate XXIV) ; . 487 NOTES AND MEMORANDA: New Record of Zoological Literature . : 492 Mr. Bolton’s Agency for the Supply of Maecoreanic Grsaniania: 492 TITLE, CoNTENTS, AND INDEx. : Baye: eee ECP Lh SEES sim. Uh APY { 7 ana ws if . fi aim i = WAM Wh posts") oe . ee - * ‘ De eA Fd é | PED Wnt” mahi Ni) 29) ee A ok ee ee : oy i iciaH) 3) aaliginie ry age, ; - FPR Sc: re — ee JOS para - - 7 , rehearse at Ff MEMOIRS. On the Existence of a Heapv-Kipney 7” the Empryo Carcx, and on CERTAIN Potnts iz the DuveLopment of the MULLE- rniaAN Ducr. By F. M. Baxrour, M.A., Fellow of Trinity College, Cambridge; and Apam Szpewicx, B.A., Scholar of Trinity College, Cambridge. (With Plates I and II). Tue following paper is divided into three sections. The first of these records the existence of certain structures in the embryo chick, which eventually become in part the abdominal opening of the Miillerian duct, and which, we believe, correspond with the head-kidney, or ‘‘ Vorniere” of German authors. The second deals with the growth and development of the Miillerian duct. With reference to this we have come to the conclusion that the Miillerian duct does not develop entirely independently of the Wolffian duct. The third section of our paper is of a more general character, and contains a discussion of the rectifications in the views of the homologies of the parts of the excretory system in Aves, necessitated by the results of our investigations. We have, as far as possible, avoided entering into the ex- tended literature of the excretory system, since this has been very fully given in three general papers which have recently appeared by Semper,! Fiirbringer,” and by one of us.? All recent observers, includmg Braun‘ for Reptilia, and Egli® for Mammalia, have stated that the Miillerian duct develops as a groove in the peritoneal epithelium, which is continued back- ward as a primitively solid rod in the space between the Wolffian duct and peritoneal epithelium. ! “Das Urogenital System der Plagiostomen.’”’ ‘Arbeiten a. d. Zool.- Zoot. Institut. Wurzburg.’ 2 “Zur Vergl. Anat. u. Entwick. d. Excretionsorgane d. Vertebraten.” * Morphologisches Jahrbuch,’ vol. iv. 3 “On the Origin and History of the Urino-genital Organs of Verte- brates.” ‘Journal of Anat. and Phys.,’ vol. x. 4 © Arbeiten a. d. zool.-zoot. Institut. Wurzburg,’ vol. iv. 5 * Beitr. zur Anat. u. Entwick. d. Geschlechtsorgane,’ Inaug. Diss., Zurich, 1876. VOL. XIX.—NEW SER. A 2 F. M. BALFOUR. In our preliminary account we stated,) in accordance with the general view, that the Miillerian duct was formed as a groove, or elongated involution of the peritoneal epithelium adjoin- ing the Wolffian duct. We have now reason to believe that this is not the case. In the earliest condition of the Miillerian duct which we have been able to observe, it consists of three suc- cessive open involutions of the peritoneal epithelium, connected together by more or less well-defined ridge-like thickenings of the epithelium. We believe, on grounds hereafter to be stated, that the whole of this formation is equivalent to the head-kidney of the Icthyopsida. The head-kidney, as we shall continue to call it, takes its origin from the layer of thickened epithelium situated near the dorsal angle of the body cavity, close to the Wolffian duct, which has been known since the publication of Waldeyer’s im- portant researches as the germinal epithelium. The anterior of the three open involutions or grooves is situated some little distance behind the front end of the Wolffian duct. It is simply a shallow groove in the thickest part of the germinal epithelium, and forms a corresponding projection into the adjacent stroma. In front the projection is separated by a considerable interval from the Wolffian duct; but near its hindermost part it almost comes into contact with the Wolffian duct. The groove extends in all for about five of our sections, and then terminates by its walls becoming gradually continued into a slight ridge- like thickening of the germinal epithelium. The groove arises as a simple depression in a linear area of thickened germinal epithelium. The linear area is, however, continued very con- siderably further forward than the groove, and sometimes exhibits a slight central depression, which might be regarded as a forward continuation of the groove. The passage from the groove to the ridge may best be conceived by supposing the groove to be suddenly filled up, so as to form a solid ridge pointing inwards towards the Wolffian duct. The ridge succeeding the first groove is continued for about six sections, and is considerably more promintnt at its posterior extremity than in front. It is replaced by groove number two, which appears as if formed by the reverse process to that by which the ridge arose, viz., by a hollowing out of the ridge on the side towards the body cavity. The wall of the second groove is, after a few sections, continued into a second ridge or thickening of the germinal epithelium, which, however, is so faintly marked as to be hardly visible in its middle part. In its turn this ridge is replaced by the third and last groove. This vanishes after one or two sections, and behind the point of its disappearance we have failed to find any further traces of the 1 ¢ Proceedings of Royal Society, 1878.’ EXISTENCE OF HEAD-KIDNEY IN THE EMBRYO CHICK. 3 head-kidney. The whole formation extends through about twenty-four of our sections and one and a half segments (muscle- plates) . We have represented (Plate I, Series a, Nos. 1—10) a fairly complete series of sections through part of the head-kidney of an embryo slightly older than that last described, containing the second and third grooves and accessory parts. The connection between the grooves and the ridges is very well illustrated in Nos. 3, 4, and 5, of this series. In No.3 we havea pro- minent ridge, in the interior of which there appears in No. 4 a groove, which becomes gradually wider in Nos. 5 and 6. Both the grooves and ridges are better marked in this than in the younger stage; but the chief difference between the two stages consists in the third groove no longer forming the hin- dermost limit of the head-kidney. Instead of this, the last groove (No. 7) terminates by the upper part of its walls becoming constricted off as a separate rod, which appears at first to contain a lumen continuous with the open groove. This rod (Nos. 7, 8, 9, 10) situated between the germinal epithelium and Wolffian duct is continued backward for some sections. It finally termi- nates by a pointed extremity, composed of not more than two cells abreast (Nos. 8—10). Our third stage, sections of which are represented in series B (Plate I), is considerably advanced beyond that last described. The most important change which has been effected concerns the ridges connecting the successive grooves. A lumen has appeared in each of these, which seems to open at both ends into the adjacent grooves. At the same time the cells, which previously constituted the ridge, have become (except where they are continuous with the walls of the grooves) partially con- stricted off from the germinal epithelium. The ridges, in fact, now form ducts situated in the stroma of the ovarian ridge, in the space between the Wolffian duct and the germinal epithe- lium. The duct continuous with the last groove is somewhat longer than before. In a general way, the head-kidney may now be described as a duct opening into the body cavity by three groove-like apertures, and continuous behind with the rudiment of the true Miillerian duct. Although the general constitution of the head-kidney at this stage is fairly simple, there are a few features in our sections which we do not fully understand, and a few points about the organ which deserve a rather fuller description than we have given in this general sketch. — The anterior groove (No. 1—3, series B, Pl. I) is at first somewhat separated from the Wolffian duct, but approaches close to it in No. 3. In Nos. 2 and 8 there appears a rod-like body on the outer side of the walls of the groove. In No. 2 4 F, M. BALFOUR, this body is disconnected with the walls of the groove, and even appears as if formed by a second invagination of the germinal epithelium. In No. 3 this body becomes partially continuous with the walls of the groove, and finally in No. 4 it becomes completely continuous with the walls of the groove, and its lumen communicates freely with the groove.’ The last trace of this body is seen on the upper wall of the groove in No. 5. We believe that the body (7,) represents the ridge between the first and second grooves of the earlier stage ; so that in passing from No. 3 to No. 5 we pass from the first to the second groove. The meaning of the features of the body 7, in No. 2 we do not fully understand, but cannot regard them as purely accidental, since we have met with more or less similar features in other series of sections. ‘The second groove becomes gradually narrower, and finally is continued into the second ndge (No. 8). The ridge contains a lumen, and is only connected with the germinal epithelium by a narrow wall of cells. A narrow passage from the body cavity leads into that wall for a short distance in No. 8, but it is probably merely the hinder end of the groove of No 7. The third groove appears in No. 11, and opens into the lumen of the second ridge (7,) in No. 12. In No. 18 the groove is closed, and there is present in its place a duct (r,) connected with the germinal epithelium by a wall of cells. This duct is the further development of the third ridge of the last. stage; its lumen opens into the body cavity through the third and last groove (gr,). In the next section this duct (7) is entirely separated from the germinal epithelium, and it may be traced backwards through several sections until it terminates by a solid point, very much as in the last stage. In the figures of this series (B) there may be noticed on the outer side of the Miillerian duct a fold of the germinal epithelium () forming a second groove. It is especially conspicuous in the first six sections of the series. This fold sometimes becomes much deeper, and then forms a groove, the upper end of which is close to the grooves of the head-kidney. It is very often much deeper than these are, and without careful study might easily be mistaken for one of these grooves. Fig. o, taken from a series slightly younger than B, shows this groove (w) inits most exaggerated form. The stage we have just described is that of the fullest develop- ment of the head-kidney. In it, as in all the previous stages, there appear to be only three main openings into the body-cavity ; but we have met in some of our sections with indications of the possible presence of one or two extra rudimentary grooves. 1 A deep focus of the rather thick section represented in No. 3 shewed the body much more nearly in the position it occupies in No. 4. EXISTENCE OF HEAD-KIDNEY IN THE EMBRYO CHICK. 5 In an embryo not very much older than the one last described the atrophy of the head-kidney is nearly completed, and there is present but a single groove opening into the body cavity. In series p (PI. IJ) are represented a number of sections from an embryo at this stage. Nos. 1 and 2 are sections through the hind end of the single groove now present. Its walls are widely separated from the Wolffian duct in front, but approach close to it at the hinder termination of the groove (No. 2). The features of the single groove present at this stage agree closely with those of the anterior groove of the previous stages. The groove is continued into a duct—the Miillerian duct (as it may now be called, but in a previous stage the hollow ridge connecting the first and second grooves of the head-kidney)—which, after becoming nearly separated from the germinal epithelium, is again connected to it by a mass of cells at two points (Nos. 5, 6, and 8). The germinal epithelium is slightly grooved and is much reduced in thickness at these points of contact ( gv, and gr), and we believe that they are the remnants of the posterior grooves of the head-kidney present at an earlier stage. The Miillerian duct has by this stage grown much further backwards, but the peculiarities of this part of it are treated in a subsequent section. We consider that, taking into account the rudiments we have just described, as well as the fact that the features of the single groove at this stage correspond with those of the anterior groove at an earlier stage, we are fully justified in concluding that the permanent abdominal opening-of the Miullerian duct corresponds with the anterior of our three grooves. Although we have, on account of their indefiniteness, avoided giving the ages of the chicks in which the successive changes of the head-kidney may be observed, we may, perhaps, state that all the changes we have described are usually completed between the 90th and 120th hour of incubation. The Glomerulus of the Head-Kidney. In connection with the head-kidney in Amphibians there is present, as is well known, a peculiar vascular body usually de- scribed as the glomerulus of the head-kidney. We have found in the chick a body so completely answering to this glomerulus that we have hardly any hesitation in identifying it as such. In the chick the glomerulus is paired, and consists of a vascular outgrowth or ridge projecting into the body cavity on each side at the root of the mesentery. It extends from the anterior end of the Wolffian body to the point where the foremost opening of the head-kidney commences. We have found it at a period slightly earlier than that of the first development of the head- 6 F, M. BALFOUR. kidney. It is represented in figs. » and F, Pl. II g/, and is seen to form a somewhat irregular projection into the body cavity, covered by a continuation of the peritoneal epithelium, and attached by a narrow stalk to the insertion of the embryonic mesentery (me). In the interior of this body is seen a stroma with numerous vascular channels and blood corpuscles, and a vascular connec- tion is apparently becoming established, if it is not so already, between the glomerulus and the aorta. We have reason to think that the corpuscles and vascular channels in the glomerulus are developed iu situ. The stalk connecting the glomerulus with the attachment of the mesentery varies in thickness in different sections, but we believe that the glomerulus is continued un- broken throughout the very considerable region through which it extends. This point is, however, difficult to make sure of owing to the facility with which the glomerulus breaks away. At the stage we are describing, no true Malpighian bodies are present in the part of the Wolffian body on the same level with the anterior end of the glomerulus, but the Wolffian body merely consists of the Wolffian duct. At the level of the pos- terior part of the glomerulus this is no longer the case, but here a regular series of primary Malpighian bodies is present (using the term “primary” to denote the Malpighian bodies developed directly out of part of the primary segmental tubes), and the glomerulus of the head-kidney may frequently be seen in the same section as a Malpighian body. In most sections the two bodies appear quite disconnected, but in those sections im which the glomerulus of the Malpighian body comes into view it is seen to be derived from the same formation as the glomerulus of the head-kidney (Plate II, fig. ¥). It would seem, in fact, that the vascular tissue of the glomerulus of the head-kidney grows into the concavity of the Malpighian bodies. Owing to the stage we are now describing, in which we have found the glomerulus most fully developed, being prior to that in which the head-kidney appears, it is not possible to determine with certainty the position of the glomerulus in relation to the head-kidney. After the develop- ment of the head-kidney it is found, however, as we have already stated, that the glomerulus terminates at a point just in front of the anterior opening of the head-kidney. It is less developed than before, but is still present up to the period of the atrophy of the head-kidney. It does not apparently alter in constitu- tion, and we have not thought it worth while giving any further representations of it during the later stages of its existence. ‘Summary of the development of the head-kidney and glomerulus. —tThe first rudiment of the head-kidney arises as three successive grooves in the thickened germinal epithelium, connected by ridges, EXISTENCE OF HEAD-KIDNEY IN THE EMBRYO CHICK. 7 and situated some way behind the front end of the Wolffian duct. In the next stage the three ridges connecting the grooves have become more marked, and in each of them a lumen has appeared, opening at both extremities into the adjoining grooves. Still later the ridges become more or less completely detached from the peritoneal epithelium, and the whole head-kidney then consists of a slightly convoluted duct, with, at the least, three peritoneal openings, which is posteriorly continued into the Miillerian duct. Still later the head-kidney atrophies, its two posterior openings vanishing, and its anterior opening remaining as the permanent opening of the Miillerian duct. The glomerulus arises as a vascular prominence at the root of the mesentery, slightly prior in point of time to the head-kidney, and slightly more forward than it in position. We have not traced its atrophy, We stated in our preliminary paper that the peculiar struc- tures we had interpreted as the head-kidney had completely escaped the attention of previous observers, though we called attention to a well-known figure of Waldeyer’s (copied in the ‘ Elements of Embryology,’ fig. 51). In this figure a connec- tion between the germinal epithelium and the Miillerian duct is drawn, which is probably part of the head-kidney, and may be compared with our figures (Series B, No. 8, and Series p, No. 4). Since we made the above statement, Dr. Gasser has called our attention to a passage in his valuable memoir on ‘ The Develop- ment of the Allantois,”! in which certain structures are described which are, perhaps, identical with our head-kidney. The fol- lowing is a translation of the passage :— “In the upper region of Miiller’s duct I have often observed small canals, especially in the later stages of development, which appear as a kind of doubling of the duct, and run for a short distance close to Miiller’s duct and in the same direction, open- ing, however, into the body cavity posterior to the main duct. Further, one may often observe diverticula from the extreme anterior end of the oviduct of the bird, which form blind pouches and give one the impression of being receptacula seminis. Both these appearances can quite well be accounted for on the supposi- tion that an abnormal communication is effected between the germinal epithelium and Miiller’s duct at unusual places; or else that an attempt at such a communication is made, resulting, however, only in the formation of a diverticulum of the wall of the oviduct.” The statement that these accessory canals are late in developing, prevents us from feeling quite confident that they really cor- respond with our head-kidney. 1 ‘Beitrage zur Entwick lungsgeschichte d. Allantois der Miller’schen Gange u. des Afters.’ Frankfurt, 1874. 8 F, M. BALFOUR. Before passing on to the other parts of this paper it is necessary to say a few words in justification of the comparison we have made between the modified abdominal extremity of the Miillerian duct in the chick and the head-kidney of the Icthyopsida. For the fullest statement of what is known with reference to the anatomy and development of the head-kidney in the lower types we may refer to Spengel and Fiirbringer.! We propose ourselves merely giving a sufficient account of the head-kidney in Amphibia (which appears to be the type in which the head-kidney can be most advantageously compared with that in the bird) to bring out the grounds for our determination of the homologies. The development of the head-kidney in Amphibia has been fully elucidated by the researches of W. Miiller,? Gotte,? and Firbringer,* while to the latter we are indebted for a knowledge of the development of the Miillerian duct in Amphibians. The first part of the urino-genital system to develop is the segmental duct (Vornieregang of Fiirbringer), which is formed by a groove- like invagination of the peritoneal epithelium. It becomes con- stricted into a duct first of all in the middle, but soon in the pos- terior part also. It then forms a duct, ending in front by a groove in free communication with the body cavity, and terminating blindly behind. The open groove in front at first deepens, and then becomes partially constricted into a duct, which elongates and becomes convoluted, but remaias in communication with the body cavity by from two to four (according to the species) separate openings. The manner in which the primitive single opening is related to the secondary openings is not fully under- stood. By these changes there is formed out of the primitive groove an anterior glandular body, communicating with the body cavity by several apertures, aud a posterior duct, which carries off the secretion of the gland, and which, though blind at first, eventually opens into the cloaca. In addition to these parts there is also formed on each side of the mesentery, opposite the peri- toneal openings, a very vascular projection into this part of the body cavity, which is known as the glomerulus of the head- kidney, and which very closely resembles in structure and posi- tion the body to which we have assigned the same name in the chick. The primitive’ segmental duct is at first only the duct for the head-kidney, but on the formation of the posterior parts of a kidney (Wolffian body, &c.) it becomes the duct for these also. 1 Loc. cit. ? «Jenaische Zeitschrift,’ vol. ix, 1875. * ‘ Entwickelungsgeschichte d. Unke.’ * Loc. cit. EXISTENCE OF HEAD-KIDNEY IN THE EMBRYO CHICK, 9 After the Wolffian bodies have attained to a considerable deve- lopment, the head-kidney undergoes atrophy, and its peritoneal openings become successively closed from before backwards. At this period the formation of the Miillerian duct takes place. It is a solid constriction of the ventral or lateral wall of the segmental duct, which subsequently becomes hollow, and acquires an opening into the body cavity quite independent of the openings of the head-kidney. The similarity in development and structure between the head-kidney in Amphibia and the body we have identified as such in Aves, is to our minds too striking to be denied. Both consist of two parts—(1) a somewhat convoluted longitudinal canal, with a certain number of peritoneal openings; (2) a vascular prominence at the root of the mesentery, which forms a glo- merulus. As to the identity in position of the two organs we hope to deal with that more fully in speaking of the general structure of the excretory system, but may say that one of us! has already, on other grounds, attempted to show that the ab- dominal opening of the Miillerian duct in the bird is the homo- logue of the abdominal opening of the segmental duct inAmphibia, Elasmobranchil, &c., and that we believe that this homology will be admitted by most anatomists. If this homology is admitted, the identity in position of this organ in Aves and Amphibia necessarily follows. The most striking difference between Aves and Amphibia in relation to these structures is the fact that in Aves the anterior pore of the head-kidney remains as the permanent opening of the Miillerian duct, while in Amphibia, the pores of the head-kidney atrophy, and an entirely fresh abdominal opening is formed for the Miillerian duct. if. The Growth of the Miillerian Duct. Although a great variety of views have been expressed by different observers on the growth of the Miullerian duct, it is now fairly generally admitted that it grows in the space between a portion of the thickened germinal epithelium and the Wolffian duct, but quite independently of both of them. Both Braun and Hgli, who have specially directed their attention to this point, have for Reptilia and Mammalia fully confirmed the views of previous observers. We were, nevertheless, induced, partly on account ofthe @ priori difficulties of this view, and partly by certain peculiar appearances which we observed, to undertake the re-examination of this point, and have found ourselves unable altogether to accept the general account. We propose first 1 Balfour, “ Origin and History of Urinogenital Organs of Vertebrates.” ae of Anat, and Phys.,’ vol. x, and ‘‘ Monograph on Elasmobranch ishes,”’ 10 F. M. BALFOUR. describing, in as matter-of-fact a way as possible, the actual observations we have made, and then stating what conclusions we think may be drawn from these observations. We have found it necessary to distinguish three stages in the growth of the Miillerian duct. Our first stage embraces the period prior to the disappearance of the head-kidney. At this stage the structure we have already spoken of as the rudiment of the Miillerian duct consists of a solid rod of cells, continu- ous with the third groove of the head-kidney. It extends through a very few sections, and terminates bya fine point of about two cells, wedged in between the Wolffian duct and germinal epithelium (described above, No. 7—10, series a, Plate I). In an embryo slightly older than the above, such as that from which series B was taken, but still belonging to our first stage, a definite lumen appears in the anterior part of the Miillerian duct, which vanishes after a few sections. The duct terminates in a point which lies in a concavity of the wall of the Wolitfian duct (Plate I, Nos. 1 and 2, series e@). The limits of the Wolffian wall and the pointed termination of the Miiller- ian duct are in many instances quite distinct; but the outline of the Wolffian duct appears to be carried round the Miillerian duct, and in some instances the terminal point of the Miillerian duct seems almost to form an integral part of the wall of the Wolffian duct. The second of our stages corresponds with that in which the atrophy of the head-kidney is nearly complete (series pD and H, Plate IT). The Millerian duct has by this stage made a very marked progress in its growth towards the cloaca, and, in contradistinction to the earlier stage, a lumen is now continued close up to the terminal point of the duct. In the two or three sections before it ends it appears as a distinct oval mass of cells (No. 10, series p,and No. 1, series H), without a lumen, lying between and touching the external wall of the Wolffian duct on the one hand, and the germinal epithelium on the other. It may either lie on the ventral side of the Wolffian duct (series D), or on the outer side (series H), but in either case is opposite the maximum thickening of that part of the germinal epithelium which always accompanies the Millerian duct in its backward growth. In the last section in which any trace of the Miillerian duct can be made out (series p, No. 11, and series u, No. 2), it has no longer an oval, well-defined contour, but appears to have completely fused with the wall of the Wolffian duct, which is accordingly very thick, and occupies the space which in the previous section was filled by its own wall and the Miillerian duct. In the following section the thickening in the wall of the EXISTENCE OF HEAD-KIDNEY IN THE EMBRYO CHICK, 11 Wolffian duct has disappeared (Plate II, series u, No. 3), and every trace of the Miillerian duct has vanished from view. The Wolffian duct is on one side in contact with the germinal epithelium. The stage during which the condition above described lasts is not of long duration, but is soon succeeded by our third stage, in which a fresh mode of termination of the Miillerian duct is found. (Plate II, series 1). This last stage remains up to about the close of the sixth day, beyond which our investi- gations do not extend. A typical series of sections through the terminal part of the Millerian duct at this stage presents the following features : A few sections before its termination the Miillerian duct appears as a well-defined oval duct lying in contact with the wall of the Wolffian duct on the one hand and the germinal epithelium on the other (series 1, No. 1). Gradually, however, as we pass backwards, the Millerian duct dilates; the external wall of the Wolffian duct adjoining it becomes greatly thickened and pushed in in its middle part, so as almost to touch the opposite wall of the duct, and so form a bay in which the Millerian duct lies (Plate II, series 1, Nos. 2 and 3). As soon as the Miillerian duct has come to lie in this bay its walls lose their previous distinctness of outline, and the cells composing them assume a curious vacuolated appearance. No well-defined line of separation can any longer be traced between the walls of the Wolffian duct and those of the Miillerian, but between the two is a narrow clear space traversed by an irregular network of fibres, in some of the meshes of which nuclei are present. The Miillerian duct may be traced in this condition for a con- siderable number of sections, the peculiar features above de- scribed becoming more and more marked as its termination is approached. It continues to dilate and attains a maximum size in the section or so before it disappears. A lumen may be observed in it up to its very end, but is usually irregular in outline and frequently traversed by strands of protoplasm. The Miillerian duct finally terminates quite suddenly (Plate II, series 1, No. 4), and in the section immediately behind its ter- mination the Wolffian duct assumes its normal appearance, and the part of its outer wall on the level of the Miillerian duct comes into contact with the germinal epithelium (Plate II, series I, No. 5). We have traced the growing point of the Miillerian duct with the above features till not far from the cloaca, but we have not followed the last phases of its growth and its final opening into the cloaca. 12 F. M, BALFOUR, In some of our embryos we have noticed certain rather pecu- liar structures, an example of which is represented at y in fig. k, taken from an embryo of 123 hours, in which all traces of the head-kidney had disappeared. It consists of a cord of cells, connecting the Wolffian duct and the hind end of the abdominal opening of the Miillerian duct. At the least one similar cord was met with in the same embryo, situated just behind the ab- dominal opening of the Miillerian duct. We have found similar structures in other embryos of about the same age, though never so well marked as in the embryo from which fig. k is taken. We have quite failed to make out the meaning, if any, of them. Our interpretation of the appearances we have described in connection with the growth of the Miillerian duct can be stated in avery few words. Our second stage, where the solid point of the Miillerian duct terminates by fusing with the walls of the Wolffian duct, we interpret as meaning that the Miillerian is growing backwards as a solid rod of cells, split off from the outer wall of the Wolffian duct ; in the same manner, in fact, as in Amphibia and Elasmobranchii. The condition of the terminal part of the Miillerian duct during our third stage cannot, we think, be interpreted in the same way, but the peculiarities of the cells of both Miillerian and Wolffian ducts, and the indistinctness of the outlines between them, appear to indicate that the Miillerian duct grows by cells passing from the Wolffian duct to it. In fact, although in a certain sense the growth of the two ducts is independent, yet the actual cells which assist in the growth of the Miillerian duct are, we believe, derived from the walls of the Wolffian duct. III. General Considerations. The excretory system of a typical Vertebrate consists of the following parts :— 1. A head-kidney with the characters already described. 2, A duct for the head-kidney-—the segmental duct. 3. A posterior kidney—(Wolffian body, permanent kidney, &c. The nature and relation of these parts we leave out of consi- deration, as they have no bearing upon our present investigations.) The primitive duct for the Wolffian body is the segmental duct. 4, The segmental duct may become split into (a) a dorsal or inner duct, which serves as ureter (in the widest sense of the word) ; and (4) a ventral or outer duct, which has an opening into the body cavity, and serves as the generative duct for the female, or for both sexes. These parts exhibit considerable variations both in their struc- EXISTENCE OF HEAD-KIDNEY IN THE EMBRYO CHICK. 13 ture and development, into some of which it is necessary for us to enter. The head-kidney! attains to its highest development in the Marsipobranchi (Myxine, Bdellostoma). It consists of a !on- gitudinal canal, from the ventral side of which numerous tubules pass. These tubules, after considerable subdivision, open by a large number of apertures into the pericardial cavity. From the longitudinal canal a few dorsal diverticula, provided with glomeruli, are given off. In the young the longitudinal canal is continued into the segmental duct ; but this connection becomes lost in the adult. The head-kidney remains, however, through life. In Teleostei and Ganoidei (?) the head-kidney is generally believed to remain through life, as the dilated cephalic portion of the kidneys when such is present. In Petromyzon and Amphi- bia the head-kidney atrophies. In Elasmobranchii the head- kidney, so far as is known, is absent. The development of the segmental duct and head-kidney (when present)is still more important for our purpose than their adult structure. In Myxine the development of these structures is not known. In Amphibia and Teleostei it takes place upon the same type, viz., by the conversion of a groove-like invagination of the peri- toneal epithelium into a canal open in front. The head- -kidney is developed from the anterior end of this canal, the opening of which remains in Teleostei single and closes early in embryonic life, but becomes in Amphibia divided into two, three, or four openings. In Elasmobranchu the development is very different. “The first trace of the urinary system makes its appearance as a knob springing from the intermediate cell-mass opposite the fifth proto-vertebra. This knob is the rudiment of the abdominal opening of the segmental duct, and from it there grows backwards to the level of the anus a solid column of cells, which constitutes the rudiment of the segmental duct itself. The knob projects towards the epiblast, and the column connected with it lies between the mesoblast and epiblast. The knob and column do not long remain solid, but the former acquires an opening into 1 T am inclined to give up the view I formerly expressed with reference to the head-kidney and segmental duct, viz, “that they were to be regarded as the most anterior segmental tube, the peritoneal opening of which had become divided, and which had become prolonged backwards so as to serve as the duct for the posterior segmental tubes,” and provisionally to accept the Gegenbaur-Firbringer view which has been fully worked out and ably argued for by Fiirbringer (loc. cit. p.96). According to this view the head- kidney and its duct are to be looked on as the primitive and unsegmented part of the excretory system, more or less similar to the excretory system of many Trematodes and unsegmented Vermes. ‘The segmental tubes I re- gard as a truly segmental part of the excretory system acquired subse- quently. —F. M. B. 14 F, M. BALFOUR. the body-cavity continuous with a lumen, which makes its appear- ance in the latter.” The difference in the development of the segmental duct in the two types) Amphibia and Elasmobranchii) is very important. In the one case a continuous groove of the peritoneal epithelium becomes constricted into a canal, in the other a solid knob of cells is continued into a rod, at first solid, which grows backwards without any apparent relation to the peritoneal epithelium The abdominalaperture of the segmental duct in Elasmobranchii, in that it becomes the permanent abdominal opening of the ovi- duct, corresponds physiologically rather with the abdominal open- ing of the Millerian duct than with that of the segmental duct of Amphibia, which, after becoming divided up to form the pores of the head-kidney, undergoes atrophy. Morphologically, however, it appears to correspond with the opening of the segmental duct in Amphibia. We shall allude to this point more than once again, and give our grounds for the above view on p. 19. The development of the segmental duct in Elasmobranchii as a solid rod is, we hope to show, of special importance for the elucidation of the excretory system of Aves. The development of these parts Petromyzon is not fully known, but from W. Miiller’s account (‘Jenaische Zeitschrift,’ 1875) it would seem that an anterior invagination of the peri- toneal epithelium is continued backwards as a duct (segmental duct), and that the anterior opening subsequently becomes divided up into the various apertures of the head-kidney. If this account 1 In a uote on p. 50 of his memoir Firbringer criticises my description of the mode of growth of the segmental duct. The following is a free trans- lation of what he says: “ In Balfour’s, as in other descriptions, an account is given of a backward growth, which easily leads to the supposition of a structure formed anteriorly forcing its way through the tissues behind. This is, however, not the case, since, to my knowledge, no author has ever detected a sharp boundary between the growing point of the segmental duct (or Miillerian duct) and the surrounding tissues.” He goes on to say that “the growth in these cases really takes place by a differentiation of tissue along a line in the region of the peritoneal cavity.” Although I fully admit that it would be far easier to homologise the development of the segmental duct in Amphibia and Elasmobranchii according to this view, I must nevertheless vindicate the accuracy of my original aecount. I have looked over my specimens again, since the appearance of Dr. Firbringer’s paper, and can find no evidence of the end of the duct becoming continuous with the adjoining mesoblastic tissues. In the section, before its dis- appearance, the segmental duct may, so far as I can make out, be seen as a very small but distinct rod, which is much more closely connected with the epi- blast than with any other layer. From Gasser’s observations on the Wolffian duct in the bird, Iam led to conclude that it behaves in the same way as the segmental duct in the Elasmobranchii. I will not deny that it is possible that the growth of the duct takes place by wandering cells, but on this point I have no evidence, aud must therefore leave the question an open one.—F. M. B. EXISTENCE OF HEAD-KIDNEY IN THE EMBRYO CHICK. 15 is correct, Petromyzon presents a type intermediate between Amphibia and Elasmobranchii. In certain types, viz., Marsipo- branchu and Teleostei, the segmental duct becomes the duct for the posterior kidney (segmental tubes), but otherwise undergoes no further differentiation. In the majority of types, however, the case is different. In Amphibia,! as has already been mentioned, a solid rod of cells is split off from its ventral wall, which after- wards becomes hollow, acquires an opening into the body cavity, and forms the Miillerian duct. In Elasmobranchii the segmental duct undergoes a more or less similar division. ‘‘It becomes longitudinally split into two complete ducts in the female, and one complete duct and parts of a second in the male. ‘The resulting ducts are the (1) Wolffian duct dorsally, which remains continuous with the excretory tubules of the kidney, and ventrally (2) the oviduct or Miillerian duct in the female, and the rudiments of this duct in the male. In the female the formation of these ducts takes place by a nearly solid rod of cells, being gradually split off from the ventral side of all but the foremost part of the original segmental duct, with the short undivided anterior part of which duct it is continuous in front. Into it a very small portion of the lumen of the original segmental duct is perhaps continued. The remainder of the segmental duct (after the loss of its anterior section and the part split off from its ventral side) forms the Wolffian duct The process of formation of the ducts in the male chiefly differs from that in the female, in the fact of the anterior undivided part of the segmental duct, which forms the front end of the Miillerian duct, being shorter, and in the column of cells with which it is continuous being from the first incomplete.” It will be seen from the above that the Miillerian duct consists of two distinct parts—an anterior part with the abdominal open- ing, and a posterior part split off from the segmental duct. This double constitution of the Miillerian duct is of great importance for a proper understanding of what takes place in the Bird. The Mullerian duct appears therefore to develop in nearly the same manner in the Amphibian and Elasmobranch type, as a solid or nearly solid rod split off from the ventral wall of the segmental duct. But there is one important difference concern- mg the abdominal opening of the duct. In Amphibia this is a new formation, but in Hlasmobranchii it is the original open- ing of the segmental duct. Although we admit that in a large number of points, including the presence of a head-kidney, the urino-genital organs of Amphibia are formed on a lower type than those of the Elasmobranchii, yet it appears to us that this does not hold good for the development of the Miillerian duct. 1 Firbringer, loc. cit. 16 F, M. BALFOUR:; The above description will, we trust, be sufficient to render clear our views upon the development of the excretory system in Aves. In the bird the excretory system consists of the following parts (using the ordinary nomenclature) which are developed in the order below. 1. Wolffian duct. 2. Wolffian body. 3. Head-kidney. 4. Millerian duct. 5. Permanent kidney and ureter. About 2 and 5 we shall have nothing to say in the sequel. We have already inthe early part of the paper given an account of the head-kidney and Miillerian duct, but it will be necessary for us to say a few words about the development of the Wolffian duct (so called). Without entering into the somewhat extended litera- ture on the subject, we may state that we consider that the recent paper of Dr. Gasser! supplies us with the best extant account of the development of the Wolffian duct. The first trace of it, which he finds, is visible in an embryo with eight proto-vertebre as a slight projection from the intermediate cell mass towards the epiblast in the region of the three “hinder- most proto-vertebre. In the next stage, with eleven proto-verte- bree, the solid rudiment of the duct extends from the fifth to the eleventh proto-vertebra, from the eighth to the eleventh proto- vertebra it lies between the epiblast and mesoblast, and is quite distinct from both, and. Dr. Gasser distinctly states that in its growth backwards from the eighth proto-vertebra the Wolffian duct never comes into continuity with the adjacent layers. In the region of the fifth proto-vertebra, where the duct was originally continuous with the mesoblast, it has now become free, but is still attached in the region of the sixth and to the eighth proto-vertebra. In an embryo with fourteen proto-vertebrz the duct extends from the fourth to the fourteenth proto-vertebra, and is now free between epiblast and mesoblast for its whole extent. Itis still for the most part solid though perhaps a small lumen is present in its middle part. In the suceceding stages the lumen of the duct gradually extends backwards and forwards, the duct itself also passes inwards till it acquires its final position close to the peritoneal epithelium; at the same time its hind end elongates till it comes into connection with the cloacal section of the hind-gut. It should be noted that the duct in its backward growth does not appear to come into continuity with the subjacent mesoblast, but behaves in this respect exactly as does the segmental duct in Elasmobranchii (vide note on p. 14). The question which we propose to ourselves is the following :— What are the homologies of the parts of the Avian urinogenital system above enumerated? The Wolffian duct appears to us mor- * © Arch, fiir Mic. Anat.,’ vol. xiv. EXISTENCE OF HEAD-KIDNEY IN THE EMBRYO CHICK. 17 phologically to correspond iz part to the segmental duct,! or what Fiirbringer would call the duct of the head-kidney. This may seem a paradox, since in birds it never comes into relation with the head-kidney. Nevertheless we consider that this homclogy is morphologically established, for the following reasons :— (1) That the Wolffian duct gives rise (wide supra, p. 12) to the Miillerian duct as well as to the duct of the Wolffian body. In this respect it behaves precisely as does the segmental duct of Elasmobranchii and Amphibia. That it serves as the duct for the Wolffian body, before the Miillerian duct originates from it, is also in accordance with what takes place in other types. (2) That it develops in a strikingly similar manner to the segmental duct of Hlasmobranchii. We stated expressly that the Wolffian duct corresponded only in part to the segmental duct. It does not, in fact, in our Opinion, correspond to the whole segmental duct, but to the segmental duct minus the anterior abdominal opening in Hlasmobranchii, which becomes the head-kidney in other types. In fact, we suppose that the segmental duct and_head- kidney, which in the Ichthyopsida develop as a single formation, develop in the Bird as two distinct structures—one of these known as the Wolffian duct, and the other the head-kidney. If our view about the head-kidney is accepted the above position will hardly require to be disputed, but we may point out that the only feature in which the Wolffian duct of the Bird differs in deve- lopment from the segmental duct of Elasmobranchii is in the ab- sence of the knob, which forms the commencement of the segmental duct, and in which the abdominal opening is formed; so that the comparison of the development of the duct in the two types confirms the view arrived at from other considerations. The head-kidney and Miillerian duct in the Bird must be con- sidered together. The parts which they eventually give rise to after the atrophy of the head-kidney have almost universally been regarded as equivalent to the Millerian duct of the Ichthyopsida. By Braun, however, who from his researches on the Lizard satisfied himself of the entire independence of the Miillerian and Wolffian ducts in the Amniota, the Miillerian duct of these forms is re- garded as a completely new structure with no genetic relations to 1 The views here expressed about the Wolffian duct are nearly though not exactly those which one of us previously put forward (‘ Urinogenital Organs of Vertebrates,’ &c., p. 45-46), and with which Furbinger appears exactly to agree. Possibly Dr. Firbinger would alter his view on this point were he to accept the facts we believe ourselves to have discovered. Semper’s view also differs from ours, in that he believes the Wolffian duct to correspond in its entirety with the segmental duct. 2“ Urogenital System d. Reptilien.” ‘Arb. aus d. zool.-zoot. Inst.’ Wiirzburg, vol. iv. VOL. XIX. —NEW S8ER. B 18 F, M, BALFOUR, the Miillerian duct of the Ichthyopsida. Semper', on the other hand, though he accepts the homology of the Miillerian duct in the Ichthyopsida and Amniota, is of opinion that the anterior part of the Miillerian duct in the Amniota is really derived from the Wolffian duct, though he apparently admits the independent growth of the posterior part of the Miillerian duct. We have been led by our observations, as well as by our theoretical de- ductions, to adopt a view exactly the reverse of that of Professor Semper. We believe that the anterior part of the Miullerian duct of Aves, which is at first the head-kidney, and subsequently becomes the abdominal opening of the duct, is developed from the peritoneal epithelium independently of all other parts of the excretory system; but that the posterior part of the duct is more or less completely derived from the walls of the Wolffian duct. This view is clearly in accordance with our account of the facts of development in Aves, and it fits in very well with the develop- ment of the Millerian duct in Elasmobranchii. We have already pointed out that in Elasmobranchii the Millerian duct is formed of two factors—(1) of the whole anterior extremity of the seg- mental duct, including its abdominal opening ; (2) of a rod split off from the ventral side of the segmental duct. In Birds the anterior part (corresponding to factor No. 1) of the Miillerian duct has a different origin from the remainder; so that if the development of the posterior part of the duct (factor No. 2) were to proceed in the same manner in Birds and Elasmo- branchii, it ought to be formed at the expense of the Wolffian (2. e. segmental) duct, though in connection anteriorly with the head-kidney. And this is what actually appears to take placo. So far the homologies of the avian excretory system are fairly clear ; but there are still some points which have to be dealt with in connection with the permanent opening of the Miillerian duct, and the relatively posterior position of the head-kidney. With reference to the first of these points the facts of the case are the following :— In Amphibia the permanent opening of the Miillerian duct is formed as an independent opening after the atrophy of the head-kidney. In Elasmobranchii the original opening of the segmental duct forms the permanent opening of the Miillerian duct and no head- kidney appears to be formed. In Birds the anterior of the three openings of the head- Sod remains as the permanent opening of the Miillerian uct. With reference to the difficulties involved in there being apparently three different modes in which the permanent opening ' Loe. cit. EXISTENCE OF HEAD-KIDNEY IN THE EMBRYO CHICK. 19 of the Miillerian duct is formed, we would suggest the following considerations : The history of the development of the excretory system teaches us that primitively the segmental duct must have served as efferent duct both for the generative products and kidney secre- tion (just as the Wolffian duct still does for the testicular pro- ducts and secretion of the Wolffian body in Hlasmobranchii and Amphibia) ; and further, that at first the generative products entered the segmental duct from the abdominal cavity by one or more of the abdominal openings of the kidney (almost cer- tainly of the head-kidney). That the generative products did not enter the segmental duct at first by an opening specially developed for them appears to us to follow from Dohrn’s principle of the transmutation of function (Functionswechsel). As a consequence (by a process of natural selection) of the seg- mental duct having both a generative and a urinary function, a further differentiation took place, by which that duct became split into two—a ventral Miillerian duct and dorsal Wolffian duct. The Miillerian duct without doubt was continuous with the head-kidney, and so with the abdominal opening or openings of the head-kidney which served as generative pores. At first the segmental duct was probably split longitudinally into two equal portions, but the generative function of the Miillerian duct gra- dually impressed itself more and more upon the embryonic deve- lopment, so that, in the course of time, the Miillerian duct developed less and less at the expense of the Wolffian duct. This process appears partly to have taken place in Elasmobranchi, and~stili more in Amphibia; the Amphibia offering in this respect a less primitive condition than Elasmobranchii ; while in Aves it has been carried even further. ‘The abdominal opening no doubt also became specialised. At first it is quite possible that more than one abdominal pore may have served for the generative products; one of which, no doubt, eventually came to functionalone. In Amphibia the specialisation of the opening appears to have gone so far that it no longer has any relation to the head-kidney, and even develops after the atrophy of the head-kidney. In Elasmobranchu, on the other hand, the functional opening appears at a period when we should expect the head-kidney to develop. This state is very possibly the result of a differentiation (along a different line to that in Am- phibia) by which the head-kidney gradually ceased to become developed, but by which the primitive opening (which in the development of the head-kidney used to be divided into several pores leading into the body cavity) remained undivided and served as the abdominal aperture of the Miillerian duct. Aves, finally, appear to have become differentiated along a third line; 20 HENRY B. BRADY. since in their ancestors the anterior pore of the head-kidney appears to have become specialised as the permanent opening of the Miillerian duct. With reference to the posterior position of the head-kidney in Aves we have only to remark, that a change in position of the head-kidney might easily take place after it acquired an inde- pendent development. ‘The fact that it is slightly behind the glomerulus would seem to indicate, on the one hand, that it has already ceased to be of any functional importance; and, on the other, that the shifting has been due to its having a connection with the Miillerian duct. We have made a few observations on the development of the Miillerian duct in Lacerta muralis, which have unfortunately led us to no decided conclusions. Jn a fairly young stage in the development of the Miillerian duct (the youngest we have met with), no trace of a head-kidney could be observed, but the cha- racter of the abdominal opening of the Miillerian duct was very similar to that figured by Braun.! As to the backward growth of the Miillerian duct, we can only state that the solid point of the duct in the young stages is in contact with the wall of the Wolffian duct, and the relation between the two is rather hke that figured by Fiirbinger (Pl. I, figs. 14-15) in Amphibia. Norss on some of the Revicutartan Ruizopopa of the ‘‘ CHALLENGER” Exprepition. By Henry B. Brapy, ERS.) With: Plates! 1M: LV 5.V. I.—On new or little known Arenaceous types. Tue quantity of material, obtained by dredge and tow-net, brought home by the scientific staff of the ‘‘ Challenger” Expedition is so vast, and the conditions under which it was collected are so varied, that much time must elapse before any detailed account of the results of its examination can be made public. So far as the microzoa are concerned the mere wash- ing, sorting, and examining under the microscope of so large a number of samples of the sea-bottom, to say nothing of the surface-gatherings, has been a long and tedious process ; but the time required for their complete investigation and for the preparation of the plates necessary for the illustration of each group of organisms is likely to be an even more considerable source of delay. To no section of the work does this apply 1 Loe. cit. NOTES ON RETICULARIAN RHIZOPODA. 21 with greater force than to the Rhizopoda, and it seems desir- able, therefore, that some of the more interesting facts and in- ferences which have been already acquired should be made the subject of a preliminary notice. I propose in the present, and perhaps in one or two sub- sequent papers, to give a brief, and in some respects a pro- visional description of certain new or little understood types of Rhizopoda, indicating the lines in which additions to our knowledge of the group are furnished by the ‘‘ Challenger” collections, rather than to attempt anything in the way of systematic history, which can only be rightly done when the results come to be treated collectively and in detail. I shall confine myself to the consideration of types actually obtained in this Expedition, except in one or two instances in which specimens from other sources seem to supply missing links, or otherwise assist in the elucidation of morphological pecu- larities. The list of observing stations drawn up and printed for the use of those engaged in working out the natural history of the Expedition extends to 354 localities. ‘Some of these are represented by mere soundings, of which only a small reference sample of the bottom was preserved, whilst a few include several dredgings made on the same or successive days within a restricted area. Not unfrequently a number of consecutive dredgings in mid-ocean at similar depths are practically identical in their organic constituents, and again, the physical characters of a certain number of the samples are not sufficiently promising to warrant the expenditure of much time over them, so that it has been necessary to make a selection from the series. About fifty dredgings, represent- ing conditions as diverse as possible, were taken in the first place for complete examination, and by the light of the results obtained from these, further selections were made from time to time, until altogether about 140 have been exhaustively worked out. By ‘‘ exhaustively” I mean that the sand or mud was washed, to begin with, ona sieve of the finest wire gauze (that known as No. 120), the meshes of which were something less than ~1,th of an inch in diameter. Practically it was found that what passed through this sieve was for the most part veritable mud, composed either of fine inorganic particles, or of the impalpable débris of calcareous tests of one sort or other. Cocoliths were usually present in this finest material, occasionally also the frustules of Diato- mace, and more commonly the siliceous skeletons of the minute species of Radiolaria, but for the Reticularian Rhi- zopoda it was of little value; not because it did not 22 HENRY B. BRADY. contain numberless specimens, but because they belonged invariably to species represented plentifully in the coarser siftings. When there was anything to be gained by doing so it was examined either in water or dry, and balsam mountings were made from it. The material thus washed was sorted by successive siftings, and worked over little by little under a power of about twenty diameters. It is not with the very minute forms that we are concerned in the present paper, but rather with some of the larger types, par- ticularly those which build for themselves composite tests, consisting of sand or other foreign bodies, more or less embed- ded in calcareous cement or adherent to a chitinous envelope. Until comparatively recent years but little was known of the larger arenaceous Rhizopoda. The discovery of Astro- rhiza limicola by Sandahl in 1857 remained unnoticed until attention was drawn to it by the late M. Sars, and before that time probably Zitwola Soldanit was the largest known living member of the group, whilst amongst fossils the Creta- ceous Lituola (Haplophragmium) irregulare held a similar position. In 1867 the elder Sars discovered Rhabdammina and Sac- cammina in deep water off the coast of Norway, and though neither of them were described or figured in his memoir,! the kindness of his son, Professor G. O. Sars, in distributing specimens, has left no difficulty as to their identification. The cruise of the ‘‘ Lightning” in 1868 and of the “ Porcu- pine” in 1869 and the succeeding years, brought to light a considerable series of types not previously known. Some account of these may be found in Dr. Carpenter’s ‘ Micro- scope and its Revelations’ (fifth ed., pp. 530—4588), and in a pamphlet? prepared fora soirée of the Royal Microscopical Society of London by the same author, and again in a short paper on the Genus Astrorhiza,’ published some time ago in this Journal. The most prominent of the new genera so described are Pilulina and Botellina, together with a fusiform type assigned to Williamson’s genus Proteonina,* and a “ Nautiloid Lituola,” since named by myself Cyclammina. In » “Fortsatte Bemerkuinger over det dyriske Livs Udbredning i Havets Dybder,” ‘ Vidensk.-Selsk. Forhandlinger,’ for 1868. : * * Descriptive Catalogue of Objects from Deep-sea Dredgings, exhibited at the Soirée of the Royal Microscopical Society, King’s College, April 20th, 1870, by Dr. Carpenter, F.R.S., &e.’ > “On the Genus Astrorhiza of Sandahl, lately described as Haecke- lina by Dr. Bessels,” by W. B. Carpenter, M.D., C.B., F.R.S., ‘Quart. Journ. Mic. Sci.,’ N. 8., vol. xvi, pp. 221—224, pl. xix. “ Since separated from that genus on good grounds by the Rev. A. M. Norman, who has given it the name of Marsipella. NOTES ON RETICULARIAN RHIZOPODA. 23 his work on the Microscope, before alluded to, Dr. Carpenter describes and figures many other forms under such names as ‘ Orbuline Lituola,” ‘“‘ Globigerine Lituola,” ‘ Orthoce- rine Lituola,” and the like. It is much to be regretted that many of these which represent important genera, have never been adequately illustrated, so that they are but little known, except to the few who possess verified speci- mens. Some of them might very properly have been treated in the present paper, for with one or two exceptions they all have been found in the ‘‘ Challenger’ material, but the limited space available for figures is already crowded with forms for the most part even less known than they are. After all, it is only a few out of a large number of new species that can be alluded to in a brief notice of this sort, and the object has been to select salient types, and leave the intermediate forms for the more extended memoir which will be furnished in the official account of the “ Challenger” cruise. The ‘Introduction to the Study of the Foraminifera,’ by Dr. Carpenter and Messrs. Parker and Rupert Jones, may be accepted as the epitome of our knowledge of the Order, so far at least as it depends on the minute structure of their tests, at the time of its publication in 1862. In this work the arenaceous types constitute the family Lrrvonipa, and are distributed under three generic heads—Lituola, Trochammina, and Valvulina. Lituola is characterised as having a test rough and sandy on the exterior, the interior of the chambers being either simple and undivided or laby- tinthic. Trochammina is distinguished by the finer mate- rials selected for the construction of the test and the larger proportion of calcareous or ferruginous cement used in their incorporation. The shell-structure in Valvulina is described as more open to variation, usually rough and sandy as to its exterior, but sometimes revealing a perforate, calcareous, shelly basis beneath, and the triserial arrangementof the cham- bers is accepted as the most noteworthy character of the genus. Professor Reuss, writing about the same time, whilst ad- mitting the difficulties of the position, proposes to divide the somewhat unwieldy group included in the genus Lituola of English systematists; and, as a matter of convenience, there was even then, no doubt, much to be said in favour of his view. In his latest work,! published after his death, he divides the family Lrrvotrp#a of his classification, which is scarcely coextensive with the genus Litwola of the “Introduc- tion,’ into four genera—Polyphragma, Haplophragmium, 1 “Das Elbthalgeberge in Sachsen,’ 2ter Theil, p. 119, 1874. 24 HENRY B. BRADY. Lituola (proper), and Haplostiche. These will be considered at a later stage when the Lituoline forms are spoken of more in detail. It will, however, become manifest as we proceed that neither of these schemes are any longer applicable to the purpose for which they were devised, and the more recent sug- gestions of Prof. Zittel' and Prof. T. Rupert Jones? scarcely satisfy the exigencies of the present position. How far the cha- racters on which these and other previous classifications are based, may be of service for the rearrangement of the group, with its enlarged boundaries, will be determined as we go on. It is not altogether satisfactory to have tu depend solely upon the structure and conformation of the external skeleton or test for distinctive charaeters. There can scarcely be a doubt that the sarcode bodies of animals varying so much in their external features must have important dif- ferences. The researches of R. Hertwig, on the animal of Miliola and Rotalia,? and those of F. E. Schulze* on Poly- stomella and Lagena, permit no longer the belief that the Reticularian Rhizopoda consist of mere masses of undifferen- tiated protoplasm, and a wide field of investigation is thereby opened, in which the employment of chemical reagents, in conjunction with the higher powers of the microscope, may be expected to yield a harvest of hitherto unnoted facts. But, for these methods of research the fresh, if not the living animals, can alone be used; material long preserved in alcohol, as the ‘“‘Challenger”’ dredgings have necessarily been, furnishes only the knowledge derivable from the harder tissues and the portions rendered permanent by inorganic constituents. There is one question to which attention must for a moment be directed before entering upon more strictly morphological considerations, namely, the chemical composition of these arenaceous tests. It is not often that specimens of any single species of recent Foraminifera can be obtained in suf- ficient quantity for reliable analysis, but amongst a few of the larger arenaceous forms this can. occasionally be done. The dredged material from the ‘ Challenger” Station No. 122 (off Pernambuco), contains Hyperammina elongata in considerable abundance, and in No. 24 (off Culebra Island, West Indies) Cyclammina cancellata, is one of the most prominent Rhizopods. No better examples than 1 «Handbuch der Palaontologie,’ 1 Band, 1 Lieferung, 1876. 2 «Monthly Micro. Journ.’ (Feb., 1876), No. 86, p. 89. 3“ Bemerkungen zur Organisation und systematischen Stellung der Foraminiferen,” ‘Jenaische Zeitschr. fir Naturwiss.,’ vol. x, p. 42, pl. 2, 1876. 4 ¢ Archiv fiir mikr. Anat.,’ vol. xiii, 1876. NOTES ON RETICULARIAN RHIZOPODA. 25 these could have been chosen for chemical investigation, for the one represents a very sandy non-labyrinthic type, usually but little coloured, the other a finely cemented form with smooth exterior, having its chamber-cavities filled with can- cellated shelly growths of deep brown colour. Both species are of considerable size, and about a gramme by weight of each was with some littie trouble collected for analysis. I have had the advantage of the assistance of my friend Mr. J.T. Dunn, B. Sc., Demonstrator in the Chemical Laboratory of the College of Physical Science in Newcastle, in this por- tion of my work. The specimens were thoroughly washed, in the first place, to free them from soluble saline matter, after which the analysis of Hyperammina elongata, gave the following result: Loss on ignition (organic matter and CO,) 279 Silica. : : ‘ : : : : 92°5 Peroxide of iron with a little alumina 2-0 Lime and magnesia : : ° : ; 2°2 9°6 Treated in the same way the tests of Cyclammina can- cellata yielded as follows: Loss on ignition (organic matter and CO,) 74 Silica. : : : : : : p 80°5 Peroxide of iron with a little alumina 8:9 Lime 2-9 Perhaps the most noteworthy fact conveyed by these figures is the large proportion of ferric oxide the tests of both species, but especially of Cyclammina, contain. The iron is present as peroxide, not as silicate or phosphate, and the red colour of the shells is retained or even brightened after ignition. Hyperammina gave no phosphoric reaction whatever, and in Cyclammina the trace of phosphates was inappreciable. It has been a matter of debate what the red- brown tint of the tests of the arenaceous Rhizopoda is determined by, but so far as these two species are concerned there can be nolonger any doubt. At the same time it must not be regarded as proved that iron invariably furnishes the colouring matter of the investment of Foraminifera. I am at present inclined to believe with Dr. Wallich that, in some thin-shelled, calcareous and chitinous forms at least, the brown stain is of organic origin. 26 HENRY B. BRADY. The precise way in which the siliceous sand-grains are held together and the nature of the cement, if there be any true inorganic cement, are points not easy to determine ; different genera probably differ widely in these particulars. The very small percentage of calcareous matter in proportion to the silica, in both of the above analyses, is a remarkable fact, and one that scarcely accords with the idea that the siliceous material is incorporated by carbonate of lime, as generally set forth. The smooth tests of the various species of Trochammina have been supposed to contain the largest amount of calca- reous matter in proportion to siliceous or other embedded constituents of any of the arenaceous Foraminifera ; but at great depths, for example at 3000 to 4000 fathoms in the North Pacific, specimens of Zrochammina (Ammodiscus) in- certa are found, the most delicate of which will bear treat- ment with nitric acid without material change. Nor is this an isolated fact. I have before me some specimens of Litewola (Reophax) nodulosa, obtained near the Antarctic Circle (Station 156,—1975 fathoms), of large size, that is to say, ranging from half an inch to an inch or even more in length, and stout in proportion. One of these has been digested for a considerable time in nitric acid with the assistance of heat, until everything soluble was removed, yet it still re- tains its form unimpaired, and has sufficient solidity to bear handling ; indeed, the only change apparent to the naked eye is the alteration of colour from dark brown to dirty white. It is clear that in this case the cement was neither calcareous nor ferruginous. In a later paper I shall be able to show that, under certain conditions, true Miliole are to be met with in which the test is thin, homogeneous, and purely siliceous—so completely siliceous that no effervescence can be detected when the shells are placed in acid under the micro- scope. It was long since demonstrated that the tests of Trochammine, living in brackish water, are non-calcareous, though they retain to a great extent their normal sandy exterior, and that one of the J@lole under similar conditions has a thin, brown, sandy investment. In both these cases the sand-grains are embedded in a chitinous envelope and do not depend on any mineral cement. From such facts it becomes evident that carbonate of lime and peroxide of iron, though secreted to a greater or less extent by many arena- ceous Rhizopods, are by no means necessarily the cementing material ;—that a chitinous envelope or external layer of altered protoplasm may be the basis to which the sand-grains are adherent orin which they are more or less embedded ;— NOTES ON RETICULARIAN RHIZOPODA. 27 and lastly, as it can be shown that Foraminifera have the power of secreting silica even to the extent of forming a continuous shelly investment, the easiest explanation of the fact that so many composite tests are not disintegrated by the action of acids, lies in the supposition that secreted silica enters more or less into their composition. At the same time it is quite clear that the precise nature of the investment of many normally arenaceous types is a matter depending largely on external or accidental circumstances. The fuller consideration of these and kindred matters will arise naturally in the description of the organisms in which they form characteristic features, so that without further preface we may proceed to a review of the more interesting forms belonging to this particular group of Rhizopods. PsaMMospH#RA Fusca, F. HE. Schulze. PI. 1V, figs. 1, 2. Psammosphera fusca, F, 4. Schulze, 1874. II. Jahresberichte d. Komm. Untersuch. d. deutsch. Meere in Kiel, p. 113, pl. li, fig. 8, a—/f. This is one of the simplest of the arenaceous Foraminifera, andalthough small specimens are not uncommon in deep water, it remained undescribed until the publication of Professor Schulze’s memoir in the North Sea researches above quoted. Ten or twelve years ago I found it in considerable abundance in one of the “ Bulldog” soundings obtained by Dr. Wallich, but the specimens were all very small, and it was then difficult to decide whether they were Foraminifera or not. It has been the custom to consider that the tests of the arenaceous Rhizo- poda are of necessity imperforate ; in other words, that except the single conspicuous pseudopodial orifice the investment is non-porous, and the fact of these specimens having no general aperture seemed to throw doubt upon their nature. But it is now evident that the term ‘imperforate ” is only applica- ble to a limited number of genera, and that some at least of the sandy forms have more or less porous tests, though, owing to the irregularities of the surface and their rough texture, the orifices are traced with difficulty. Schulze’s description of the species is quite accurate as applied to large specimens. They are spheroidal bodies, from two to four millim. (4; to 4 inch) in diameter, without any perforations visible to the naked eye, commonly free, but occa- sionally adherent to small stones. The test itself is from *25 to ‘dO millim. thick, and is composed of coarse sand-grains, united by a cement of fine texture and of characteristic grey-brown colour. Whilst the exterior is more or less rough, owing to 28 HENRY B. BRADY. projecting sand-grains or fragments of stone, the interior is throughout even and smooth. The tendency of the animal to attach itself to foreign bodies is revealed in many different ways ; sometimes a frag- ment but little smaller than the remainder of the test, is built into the wall; in other cases the shell is erected, tent-like, upon a stone. In one of the “Challenger” dredgings (Station 122— 350 fathoms, off the coast of Brazil) minute specimens are very common, and in a large proportion of them the test is built upon or around a sponge-spicule. One of these, with the side partially ground to show the interior, is represented in: Pl. Il, fig. 2. It is somewhat remarkable that, notwithstanding the thick- ness of the test and its rough composite texture, these sandy spheres are quite translucent when fresh, and they retain their character for a long period if preserved in glycerine or diluted alcohol. The specimens described by Professor Schulze were found in mud, from depths of 100 to 200 fathoms, in the North Sea, but the species is of not unfrequent occurrence in the “‘ Challenger ” material from stations both in the North and South Atlantic and in the North Pacific, at depths varying from 250 to 2740 fathoms, In the deeper dredgings the examples are invariably small. Psammosphera fusca may also be added to the list of British species, as it occurs in sands dredged in Loch Scavaig (Skye) from 45 to 60 fathoms. Genus—SOROSPH ERA, nov. (swpdc, heap; oatpa, a sphere.) SorosPHHRA CONFUSA, 7.sp. PI. IV, figs. 18, 19. Characters.—Test free, irregular ; consisting of a number of convex or spheroidal chambers, either discrete or more or less embracing, irregularly crowded together. Walls thin, loosely arenaceous in texture. General aperture, none. Long diameter of large specimens, 7 inch (4'5 millim.). There is, so far as I am aware, no recognised genus “in which the large irregular polythalamous Rhizopods, with characters somewhat roughly indicated in the foregoing de- scription, can be properly placed. One of their most striking features is the absence of any general aperture. In none of the specimens I have met with can any definite general pseudopodial orifice be detected. One or two of them have a sort of crack or fissure in the depression between two of NOTES ON RETICULARIAN RHIZOPODA. 29 the segments, but it appears to be the result of accident, and the specimens are not otherwise complete. If this be the normal condition of the test, and it may be assumed that it is, it would suggest a near affinity to the genus Psammo- sphera. That the comparatively thick and well-cemented test of Psammosphera affords free passage for the sarcode in the form of pseudopodia, without any general aperture, is a well-ascertained fact, and there can be no difficulty, therefore, in supposing that Sorosphera with its thinner shell of open granular texture does the same; in point of fact, these two genera are in very similar position to some of the hyaline calcareous Foraminifera, such as Ordulina, which depend on minute foramina rather than on a large central orifice for the meaus of extending their sarcode beyond the limits of the chamber-cavities. I have long been convinced that the use of the words ‘‘ Perforate ” and ‘‘ Imperforate,”’ as a class distinction amongst the Foraminifera, is an untenable one, and these types are sufficient evidence that the arenaceous forms at any rate are not necessarily imperforate. In some genera of Foraminifera, Cristellaria, for example, specimens may be found in which the stoloniferous tubes uniting the chamber-cavities are distinct from the radiate orifices that have in succession served as the general aper- ture; but such case are rare and, as a rule, the general aperture of the terminal chamber forms the passage connect- ing it with the cavity of the segment next formed. It follows, therefore, that in a polythalamous test like Soro- sphera, in which there is no external general aperture, the sarcode segments cannot be connected by stolons, and unless the pores of the contiguous chamber-walls serve the purpose of stoloniferous passages, the individual chambers must have a separate rather than a corporate existence. We know, however that the sarcode of perforate Foraminifera spreads itself freely over the surface of the shell before extending itself in pseudopodial filaments, and there can be little doubt that the interstices amongst the sand-grains of the contiguous chamber-walls are sufficient to afford free communication between the segments. The absence of any general aperture may be held to account for the irregular growth of the test and the want of order amongst the segments, for it is clear that if the proto- plasm exudes at all points of the surface, a fresh chamber may be formed whenever sufficient has collected at one spot to segregate itself into a mass of the requisite size. The specimen figured (Pl. IV, fig. 18) is the largest, and on the whole the best, that has inthesto been found. In one 30 HENRY B. BRADY, of the “ Challenger ” dredgings the species is by no means uncommon, but owing to the loose crumbling character of the test, nearly every specimen is more or less broken and much in the condition of that represented in fig. 19 of the same plate. A number of individuals, apparently belonging to the same species, have been met with, bearing only three or four segments. These are generally of smaller size, and are com- posed of finer sand-grains; the segments have the normal globular shape, but they are more symmetrically arranged. The distribution of Sorosphera confusa appears to be somewhat local, but in areas wide apart. It occurs amongst the ‘‘Challenger” gatherings at one station in the North Atlantic (off the Azores, 900 fathoms), at one in the South Atlantic (off Buenos Ayres, 1900 fathoms), and at two points near together in the North Pacifie (2050 and 2900 fathoms respectively), and I have also met with it in one of the “« Porcupine ” soundings in the North Atlantic. Genus—PELOSINA, nov. (nAde, mud.) General Characters.—Test free, one- or many-chambered, with walls composed of a thick Jayer of mud, terminating in an elongate chitinous neck. PELOSINA VARIABILIS, 7. sp. Pl. III, figs. 1, 2, 3. Characters.—Test consisting of a single chamber, or of several independent (?) chambers irregularly associated. Segments unsymmetrical, variable in shape, generally rounded, elongate and tapering. Walls thick, composed of fine mud deposited on a chitinous (?) basis, which is usually extended beyond the body of the test as a sort of neck. Aperture terminal. Size of the individual segments variable, sometimes } inch (8 millim.) or more in length. It is not easy to determine with any certainty the affinities of the shapeless or irregularly shaped muddy organisms which have been placed together under the generic name Pelosina. That they are inhabited by sarcode animals is known, but what common characters they may have, suff- ciently permanent and distinctive to serve as the basis of a zoological group—generic or even specific—is not so manifest. Of the larger Rhizopoda, perhaps Astrorhiza limicola pre- sents the nearest parallel in the employment of indiscrimi- nate mud as the material for the construction of its invest- ment, and the same species presents an example of the com- NOTES ON RETICULARIAN RHIZOPODA. on parative absence of any kind of cement or other incorporating medium for the extraneous matters which are used in forming its walls. Hence the test is soft and crumbling and the requisite strength is obtained by increased thickness, and it is never compact. enough in texture to be spoken of as a “ shell.” What the precise nature of the membranous tubular prolongations of the test may be, whether they are part of a definite chitinous envelope or merely the superficial portion of the sarcode in a somewhat altered condition, has not been satisfactorily determined. The genus Astrorhiza again furnishes us with the nearest parallel. The specimen of A, cornuta(P1.1V, fig. 15) has tubular membranous extensions from the ends of the branches, not always simple, as in Pelosina, but usually bifurcating ; and in a large undescribed species of the former genus of which I have a specimen, dredged by Mr. F. M. Balfour in the North Sea, a con- siderable portion of the body of the animal has a membranous investment, only slightly sprinkled with sand-grains or mud. These facts tend to indicate that Pelosina should have a place very near to Astrorhiza in the zoological series. The best specimens of Pelosina variabilis amongst the “ Challenger” deep-sea spoils are from a sounding on the east side of New Zealand, in 1100 fathoms, but single specimens have been met with in several other localities. PELOSINA ROTUNDATA, 7. sp. Pl. III, figs. 4, 5. Characters.—Test consisting of a single fiask-shaped or pyriform chamber, with produced membranous neck. Walls thick composed of muddy Gilobigerina-ooze. Diameter, ~th inch, (2 millim.),. This species differs from P. variabilis, in that it consists uniformly of a single subglobular or pyriform chamber, and that it is usually of smaller dimensions. The walls are rela- tively very thick, and are composed of soft, greyish-white, muddy material, with scarcely any incorporating cement. It naturally follows that the central cavity occupies but a very small proportion of the entire bulk of the test. Pelosina rotundata appears to be essentially a North Atlantic species. Amongst the “Challenger” dredgings I have only found it from one station, namely, off the Azores, in 1675 fathoms, but it occurs in one of the ‘ Porcupine” soundings in much shallower water, 109 fathoms. o2 HENRY B. BRADY. Genus—H YPERAMMINA, Brady. General characters.—Test free or adherent, elongate, tubular; primordial end closed and rounded; opposite extremity open and unconstricted, forming the general aper- ture. ‘Texture arenaceous, interior smooth. HypERAMMINA ELONGATA, Brady. Hyperammina elongata, 1878. ‘ Annals and Mag. Nat. Hist.,’ Ser. 5, vol. i, p. 433, pl. 20, fig. 2 a, h. Characters.—Test free, in the form of a straight, or nearly straight, unbranched, tapering tube ; the wide end closed and rounded, the narrow end constituting the general aperture. Exterior either loosely sandy or compact and smooth, rarely polished. Length up to $ an inch or more (10 or 16 millim.). Amongst the dredged sands brought home by Capt. Feilden from the recent North Polar Expedition were one or two specimens of this somewhat striking type. Compared with examples from less boreal latitudes they are very small and not such as can be regarded as average representatives of the species, and for this reason the drawings which accompany the description of them, though quite accurate, must be accepted with some allowance until a series of more charac- teristic figures can be furnished. ‘The type was by no means unknown previously, inasmuch as fine specimens had been found in dredgings made by the staff of the ‘ Porcupine” in the North Atlantic, and in material obtained by the “‘ Chal- lenger” at various stations both in the North and South Atlantic and in the North and South Pacific. The texture of the test in Hyperammuina elongata is some- what variable. In large specimens it is usually loose and sandy, but the sand-grains being fine and of nearly even size, the exterior is, notwithstanding, tolerably smooth. Small individuals are generally much longer in proportion to their diameter than the larger ones ; they are often darker coloured, and their exterior is usually quite smooth or even polished. The interior in all cases is smooth and often stained brown, either by animal secretion or by the adherent remains of dark coloured sarcode. This colouration is quite distinct from the general yellowish hue of the test, which is determined by the presence of small quantities of per- oxide of iron. As has been before stated, the geographical distribution of Hyperammina elongata is very wide, and this is equally true of its bathymetrical range, but though the species has been met with at depths up to 2600 fathoms, the NOTES ON RETICULARIAN RHIZOPODA, 33 largest specimens have been found in dredgings from 300 to 500 fathoms. HyPERAMMINA RAMOSA, %. sp. Pl. III, figs. 14, 15. Characters.—Test free; consisting of a subglobular pri- mordial chamber with a tubular extension. Tubular por- tion branched; relatively wide at its commencement, but narrowing as it becomes divided. Texture usually loosely arenaceous ; exterior rough, often beset with sponge-spicules. Length indefinite. This organism, though manifestly allied to the typical form last described, differs from it in several important particulars. The test never attains the same dimensions as the larger examples of Hyperammina elongata. The texture is gene- rally coarse, and the surface is commonly rough, or even hispid,with the sand-grains and partially incorporated sponge- spicules used as building material. Instead of tapering uniformly from the rounded end, the test is constricted near its commencement, so as to form a more or less bulbous pri- mordial chamber. ‘The tubular limb issuing from this is branched instead of simple, wide at first, but narrowing as it becomes more and more divided. The finer ramifications are exceedingly thin and fragile, and it is impossible to say what length they may attain. The distribution, both geographical and bathymetrical, of Hyperammina ramosa is very similar to that of H. elongata already described. The two species are very often, though by no means invariably, found in the same batches of dredged material. Fragments of delicate branching arenaceous tubes belonging to this or some analogous form are exceedingly common in deep-sea material, though they often cannot be identified with certainty. HYPERAMMINA VAGANS, 7. sp. Pl. V, fig. 3. Characters.—Test more or less adherent ; consisting of a spherical primordial chamber opening into a long, usually unbranched tube, of nearly even diameter, sometimes par- tially free, but commonly spreading in irregular tortuous lines over the surface of shells, stones, or other foreign bodies, the open unconstricted end of the tube serving as the general aperture. Walls thin; texture finely arenaceous; surface smooth but not polished. Colour brown, the primordial chamber usually of darker hue than the tube. Length indefinite. In some areas the fine arenaceous tubes of this or other similar Rhizopod are found to a greater or less extent on VOL. XIX.—NEW SER. c 34 HENRY B, BRADY. almost every fragment of shell or stone presenting a surface favorable to their growth. It is rarely, however, that the tests are even approximately complete or perfect, and the pri- mordial chamber being generally the missing portion they have hitherto been passed over, under the supposition that they were the tubes of adherent annelids. This imperfection arises from the fact that the primordial chamber is seldom completely attached to the body on which the remainder of the test is adherent. The tubular portion of the test is of indefinite length and always seeks some solid basis to spread itself upon, in the absence of which it is occasionally found in little masses formed of irregular coils adherent to each other. The bulbous end is often quite free, projecting above the remainder of the test, from which it does not otherwise differ in external characters, except that it is of a darker reddish-brown colour. Hyperammina vagans differs from both H. elongata and HZ, ramosa in its parasitic habit ; from the former also in the great length and tortuous course of the tubular portion, and from the latter in the simple unbranched contour of its extensions. There is only one Foraminifer, so far as I know, with which it is at all likely to be confounded, namely, Webbina clavata, P. and J., but the primordial chamber in that species is a simple, adherent, tent-like, shelly dome, and the tube a semi-cylindrical covering, neither of which has any floor proper to itself. There is a fossil organism, occasionally met with in paleeozoic limestones, of considerable interest in connection with this species. It consists of rounded masses of finely arenaceous tubes folded irregularly backwards and forwards, or otherwise coiled, so as to form little bundles. My friends, Prof. H. A. Nicholson, and Mr. R. Etheridge, jun., have re- cently called my attention to some of these, which exist in large numbers in the Silurian rocks of Girvan in Ayrshire, and they will, I believe, be described in their forthcoming ‘Monograph of Girvan Fossils,’ under the provisional generic term Girvanella. When the time comes for treating the ‘* Challenger’ Rhizopoda in detail, I shall be able to give drawings of specimens of Hyperammina vagans, which scarcely differ from the palzeozoic fossil except in their some- what larger size. For the most part H. vagans is a deep-sea species, the finest specimens being from two dredgings in about 2000 fathoms, one in the North Pacific, the other in the South Atlantic, but it occurs also at smaller depths, especially in th North Atlantic. pths, especially in the NOTES ON RETICULARIAN RHIZOPODA, 35 Genus—JACULELLA, nov. JACULELLA AcuTA, 2. sp. Pl. III, figs. 12, 13. Characters.—Test elongate, straight or nearly so, closed and pointed at one extremity, gradually increasing in width towards the other, which, slightly constricted and rounded, but otherwise open, forms the general aperture. Texture arenaceous, very compact, and hard; exterior surface rough, interior also rough, but in a less degree. Colour rich brown in the earlier portion of the test, becoming gradually lighter towards the wide end. Length } inch (8°5 millim.). It is often an exceedingly difficult matter to determine whether the tubular, non-septate, arenaceous tests, so fre- quently met with in certain localities and in such diverse forms, have belonged to sarcode animals or to annelids, and there is unfortunately no character short of those pertaining to the live inhabitant that can be regarded as certain evi- dence. Annelid tubes of the commoner species are easily recognised, and so also are the cylindrical tests of Rhizopoda when they are either septate or labyrinthic, or show a dis- tinct primordial chamber; but many of the specimens alluded to, both arenaceous and porcellanous, present none of these features, and the decision rests on probabilities rather than positive indications. These remarks apply with some force to the species now under consideration. ‘The specimens were selected from a number of doubtful organisms, as probably of Rhizopod origin, on the strength of two or three characters which, taken together, were thought to have considerable weight. The first of these was the firmly arenaceous texture of the test, then the distribution of colouring matter which, as in Hyperammina vagans and several other species, is of deep brown red in the early portions and gradually becomes lighter, and, lastly, a fact of negative value, namely, that the rough interior appeared ill-adapted for the organisation and life conditions of an annelid. Not trusting my own opinion on the matter, I submitted some of the tests to Dr. McIntosh, the recognised British authority on the Annelida, who after examining them, expressed avery decided belief that they did not belong to animals of that group. On the other hand, there is no other non-septate type of Rhizopoda with a test increasing so rapidly in diameter, and with an aperture relatively so large; and, again, almost every specimen, if not every one, has a minute orifice at the narrow end. The 36 HENRY B. BRADY. first of these objections is of little real weight, and the second may depend on accidental breakage, a not improbable occur- rence under the circumstances. Whilst still hesitating about my specimens the Rev. A. M. Norman had obtained the same species in his dredgings from the coast of Norway," and, without knowing that I had been working upon it, had assigned it in his own mind to the Foraminifera. He sug- gested the name Jaculella as applicable to the genus, and I am very glad to adopt it. The form and general appearance of Jaculella acuta is shown in Pl. III, fig. 12; and fig. 13 represents a specimen ground down to show the interior. As has been said, it is exceedingly rare to find a large individual with the thinner extremity perfect, and the test is so hard and brittle that it breaks away still more in process of grinding. The largest specimens of this species which have been met with in the “ Challenger’ material are from Station 122 (off the coast of Brazil, 350 fathoms), and some of these are a third of an inch or more in length. Its range of distribu- tion can hardly at present be satisfactorily laid down. Genus.—MARSIPELLA, Norman. MARSIPELLA GRANULOSA, 2. sp. PI. IIT, figs. 8, 9. Characters.—Test free, fusiform, tapering nearly equally towards both ends ; composed of fine grey sand, with very little calcareous cement. Cavity nearly uniform in diameter ; walls thickest in the middle of the test. Exterior granular, interior nearly smooth. Apertures simple, one at each end of the test often tinged brown. Length + inch or more (5 or 6 millim.). Amongst the Rhizopoda of the “‘ Porcupine” Expedition is a very striking species, common in certain areas, having an elongate, fusiform test, often curved and twisted, especially near the extremities, and usually tapering more rapidly at one end than at the other. The test is formed of sand- grains neatly fitted together, or, especially near the ends, of acicular sponge-spicules, laid side by side and united by just sufficient calcareous cement to produce a firm investment. The extremities are both open, and serve as pseudopodial apertures. Dr, Carpenter assigns this form to Williamson’s 1 Mr. Norman also tells me that he dredged Juculel/a in St. Magnus’ Bay, Shetland, in about 60 fathoms, in 1867, and it thus becomes an addition to the British Fauna. NOTES ON RETICULARIAN RHIZOPODA, ov genus Proteonina.! The Rev. A. M. Norman, in his in- teresting paper on Haliphysema and forms apparently allied to it? has thrown much light on the group to which the “ Porcupine”’ species probably belongs, and discarding the supposed affinity to the so-called Proteonina, which is a feeble Lituoline form of the Haplophragmium series, has given it the new generic name, Marszpella. In this course I entirely concur. As the occurrence of Marsipella elongata, Norman, is pretty much confined to areas in the Atlantic, further north than any point in the line of the “ Challenger’’ cruise, its history need not be dwelt upon here, but a form which appears more nearly allied to it than to any other described type is occasionally met with in southern latitudes. This I propose to call Marsipella granulosa. It agrees with M. elongata in its fusiform contour, and in having an aperture at each extremity of the test, and these perhaps may be regarded as the essential characters of the genus. On the other hand, the test is composed entirely of fine sand, and it is much less compactly built than that of M. elongata, the walls being thick in the middle and thinning away towards the ends. A specimen, laid open, is shown in PI. III, fig. 9, but portions of the slender extremities have crumbled away in the process of grinding. Figure 8, of the same plate, repre- sents a nearly perfect individual. The material selected for the construction of the test, in the absence of sponge spicules, is an even-grained, light-coloured, very fine sand, and as the amount of cement (whatever it may be) secreted by the animal is very small, the requisite solidity appears to be attained by the thickening of the walls, and this takes place to such an extent that the central cavity is little more than a tube of nearly even diameter. The interior is smooth and stained reddish brown to a greater or less degree, and the same colouration is also apparent externally at the extremities of the test around the orifices. The best specimens of Marsipella granulosa have been found in a dredging off the Azores, at a depth of 1000 fathoms. Genus—RHABDAMMINA, m™. Sars. RHABDAMMINA LINEARIS, 2. sp. PI. III, figs. 10, 11. Characters.—Test free, linear; straight or curved ; con- ? Carpenter, ‘The Microscope,’ fifth ed., 1875, p. 533, fig. 273, d. e. f :—Willliamson, ‘ Rec. For. Gt. Br.,’ p. 1, pl. 1, figs. 1—8. 2 “Annals and Mag, Nat. Hist.,’ ser. 5, vol. i, p. 281, pl, 16, fig, 7, 38 HENRY B. BRADY. sisting of a cylindrical arenaceous tube, with swollen centra chamber. Tubular portion often irregular in outline, taper- ing towards the ends; shell-wall of the central chamber thinner than that of the two arms. Length i inch (4:5 millim.). Amongst the types of arenaceous Rhizopoda enumerated by the lamented Scandinavian naturalist, Michael Sars, in the short paper summarising the results of his deep-sea researches,! is a fine large species, which he names Rhabdam- mina abyssorum. In the absence of any description from the pen of the discoverer it may be characterised as having a radiate test, consisting of three to five long arenaceous tubes, diverging from the central point like the spokes of a wheel. In specimens from some localities there is a small central chamber, and in these cases the arms are broad at the point of insertion and somewhat tapering, but more frequently the arms are of nearly even diameter, and there is little or no swelling at the point of union. Generally speaking, the tubular portions radiate on one plane and the test is com- planate, but sometimes this order is not observed, and they diverge irregularly. Specimens of Rhabdammina abyssorum from the southern hemisphere do not differ in any important particular from those obtained by Sars from a depth of 450 fathoms off the Norwegian coast. Under favorable conditions the species attains a considerable size, but owing to the tenuity and brittleness of the rays it is seldom, probably, that specimens are quite perfect ; examples, however, are not uncommon that must, when complete, have measured an inch from point to point. In three or four of the ‘‘ Challenger” dredgings there is found a much smaller form referable to the same genus, but with sufficiently distinctive characters of its own, and this I propose to name Rhabdammina linearis. It may be regarded as a two-rayed modification of the type, with a central in- flated cavity. The two arms are seldom of the same dia- meter, nor are they usually set on so as to form a right line. In texture the test is more loosely built, and the sand-grains less completely incorporated, than in the typical species. In light-coloured specimens the extremities are sometimes stained reddish brown. The mere fact of possessing but two arms instead of three, four, or five, would not by itself constitute a valid reason for distinguishing a variety by name, especially if it were found in company with the radiate form ; but, taken in conjunction 1 inch (1:25 mm). The first examples of this beautiful little shell that came under my notice were in the Rev. A. M. Norman’s mountings from the “ Valorous”’ dredgings in Davis’ Straits, but the ** Challenger” material has yielded a supply of specimens from a number of localities. Zrochammina trullissata is easily distinguished from any other species by its perfectly regular, nautiloid, or Nonionine contour, the number of chambers in each whorl, their sigmoid sutural lines, and its polished brown exterior. It is not unlike the very large nautiloid type, Cyclammina, in its general conformation, but differs widely from it in point of size and internal struc- ture. The inner surface of the test of Zr. trullissata some- times exhibits a slightly raised reticulation, but this in no case, so far as my observation goes, is more than a mere superficial marking, and never comes to anything re- sembling the cancellated shelly growths that often nearly fill the chambers of Cyclammina. The distribution of the species is wide, but it is by no means abundant in any locality. The best ‘“‘ Challenger ” specimens are from twostations in the North Atlantic and two in the South Atlantic, the depth of water varying from 390 to 2200 fathoms. TROCHAMMINA RINGENS, n. sp.!_ PI. V, fig. 12, a, 5. Characters.—Test nautiloid, oblong, compressed, biconvex; composed of few convolutions, of which the last entirely en- closes the previous ones. Peripheral margin acute-angular, or slightly rounded, lobulate; septal lines curved, somewhat excavated. Segments large, about five in each convolution, embracing. Colour brown, surface usually polished. Aper- ture an arcuate slit, overhung by a slight swelling or pro- minence on the face of the terminal chamber, and near the margin of the previous convolution. Longer diameter =!, inch (1:25 mm.). ‘ This form was recorded by Mr. Norman, in the “ Valorous” Report (‘ Proc. Royal Soc.,’ xxv, 1876, p. 218), as “very near to, if not identical with, Globigerina arenaria, Karrer,” but he has subsequently received types of that species from Dr. Karrer, and is now satisfied of their entire dis- tinctness. 58 HENRY B. BRADY. Trochammina ringens is nearly allied to the species last described ; the points of distinction, are nevertheless suffi- ciently apparent. Compared with 77. trullissata, it has only about half the number of segments in each convolution, and the final whorl completely encloses the previous ones, instead of leaving the penultimate coil partly exposed at the centre. The general contour of the test is biconvex rather than depressed in the umbilical region, and the terminal segment is conspicuously large. In colour, texture, and minute struc- ture, the two forms are alike, but Zr. ringens has none of the reticulation of the inner surface of the shell that has been ascribed to Zr. trullissata. It appears to be a very rare species. I have only notes of its occurrence in three of the “ Challenger ” dredgings, one of them from the North Atlantic, off Siera Leone (1750 fathoms), one from the South Atlantic, off Buenos Ayres (1900 fathoms), and the other from the North Pacific (1850 fathoms). Since the above description was written I find that the Rev. A. M. Norman has this form also in his collection from the “ Valorous” dredgings at the entrance of Davis’ Strait, in 1750 fathoms. TROCHAMMINA PAUCILOCULATA, 2. sp. PI. V, figs. 13, 14. Characters.—Test ovoid, slightly compressed, obscurely spiral ; composed of about two convolutions, the latter of which almost entirely conceals the earlier one. Segments few, usually three in each convolution, inflated; sutures slightly constricted. Test thin, finely arenaceous, brown ; exterior smooth, often polished ; interior smooth. Aperture a curved slit on the superior surface, at the inner margin of the last segment. Length, ;4 inch (0°45 millim.). Though a very minute species Troehammina pauciloculata is striking and distinct. It is isomorphous with the genus Allomorphina of Reuss, the recent specimens of which are of even smaller dimensions, but it has the shell texture characteristic of its own genus, whilst Reuss’s type is hyaline and perforate. In its general plan of growth it closely resembles the Rotalians, notwithstanding its small number of segments, and their unsymmetrical disposition. TROCHAMMINA CORONATA, 2. sp. Pl. V, fig. 15. Characters.—Test nautiloid, biconcave, composed of few convolutions ; peripheral margin lobulate and rounded. Seg- ments distinct, variable in number, inflated. Aperture NOTES ON RETICULARIAN RHIZOPODA. 59 simple, situate on the face of the terminal segment near its junction with the previous convolution. Colour buff to reddish brown ; surface smooth, not polished. Diameter =, inch (2°5 mm.). This handsome species differs from its congeners in size as well as in general contour. The larger specimens are fully one tenth of an inch in diameter, and are coronate or bicon- cave in form. The chambers are few in number, tent-like, and more or less embracing, though the successive convolu- tions do not entirely conceal those immediately preceding them. The width of the spiral band increases with each turn, and the chambers of the final whorl are very much larger than those of the earlier ones. The texture of the test is uniformly very finely arenaceous and opaque, but within certain limits, ¢.e. from a creamy white to a dark brown, the colour varies a good deal. Amongst previously described Foraminifera it is not easy to find any with cha- racters approaching those of Zrochammina coronata ; per- haps the nearest is Zr. inflata, but in that species the test is Rotaliform, in other words, all the segments are more.or less exposed in a spiral line on the superior face, whilst those of the last convolution only are visible on the inferior side, which is very different from the symmetrical, nautiloid habit of the new species. Fine specimens of Tr. coronata have been met with at the western side of both the North and South Atlantic, namely, at two stations near the West Indies (390 fathoms and 450 fathoms), and at two stations off the coast of South of America (675 fathoms and 1900 fathoms). TROCHAMMINA LITUIFORMIS, 7. sp. Pl. V, fig. 16. Characters.—Test free, crozier-shaped; consisting of an irregularly septate or pseudo-septate tube, spiral at its com- mencement, afterwards linear. Segments irregular in size, subcylindrical or ventricose; sutural lines excavated. Aperture simple, terminal. Surface smooth; colour light brown. Length +} inch (3°7 millim.). There are already known at least two crozier-shaped varieties of Trochammina, the Carboniferous Tr. centrifuga, and the Permian 77. filum, but these are alike characterised by the absence of septa both in the spiral and linear portions of the tests, and pertain rather to the Ammodiscus series than to Trochammina proper. They are also, both of them, com- paratively minutein size. The specimens now described are of fine dimensions, though somewhat irregular in genera 60 HENRY B, BRADY, contour and in septation. In colour and shell-texture they are precisely similar to Zrochammina coronata. Trochammina lituiformis has been met with in the North Atlantic (West Indies, 390 fathoms, and off the Azores, 900 fathoms), and at two stations in the South Atlantic, on the coast of South America in about the latitude of Pernambuco (350 and 675 fathoms). HorMOSINA GLOBULIFERA, 2. sp. PI. IV, figs. 4, 5. Characters.—Test composed of a single spherical chamber with a tubular neck, or of several (2 to 6) such chambers, each larger than its predecessor and more or less embracing it. Segments arranged in a straight or curved linear series, terminating in a thin tubular neck. Texture very finely arenaceous, surface smooth. Length of polythalamous specimens often + inch (3 millim.). The figures, 4 and 5 of Pl. LV, afford a very insufficient representation of this species, inasmuch as specimens are not unfrequently found possessing four, five, or even more chambers, and of correspondingly increased dimensions. In default of room for sufficient figures, the object has been to illustrate a tendency not uncommon amongst Foraminifera, which shows itself strikingly in this particular species, namely, the cessation of growth after the formation of a chamber of reiatively large size. Asa rule the specimens of Hormosina globulifera which have the largest number of segments are those with the smallest initial chambers, and, on the other hand, if a very large primordial chamber is found the test usually remains monothalamous and no further growth takes place. A comparison of the size of the Lageni- form test (fig. 4) with that of the earlier segment of fig. 5, will illustrate this fact. The rule nolds good not only of the first chamber, but in varying degree to the life-history of Foraminifera generally. It is very com- monly seen in polythalamous species that, with the forma- tion of a chamber of abnormal size, the growth, that is, the continued segmentation of sarcode, is abruptly stopped. Instances of this occur in every section of the Order. What- ever, therefore, may be the significance of monothalamous as distinct from polythalamous tests amongst the Rhizopoda of other groups, the character in this case is not of specific, still less of generic importance. There is no difficulty in distinguishing these Hormosine from their Lituoline isomorphs- by their regularity and NOTES ON RETICULARIAN RHIZOPODA, 61 symmetry of form, their thin walls, and smooth, almost homogeneous, tests. FH, globulifera is essentially a deep-water Foraminifer. Out of eight localities in which I have notes of its occurrence, six are at depths of more than 1000 fathoms, and three of these at more than 2000 fathoms. Its distribution appears to be world wide, the ‘‘ Challenger’ collections furnishing specimens from both the North and South Atlantic and the North and South Pacific Oceans. Hormosina OvicuLa, 2. sp. Pl. IV, fig. 6. Characters.—Test long and very slender, tapering ; com- posed of several fusiform segments joined end to end, without overlapping, in straight or slightly curved linear series. Walls thin, texture very finely arenaceous. Colour yellowish brown, with a band of somewhat darker hue encircling the narrowest part of the stoloniferous tubes. Length, + inch (5 millim.). A very delicate fragile little organism and one seldom found entire. Hormosina ovicula stands in much the same relation to H. globulifera that Nodosaria pyrula does to N. radicula ; that is to say, its segments are produced at the two ends and are joined by their narrow extremities, instead of the suc- cessive lobes being sessile and more or less embracing. The deepening of the brown colour in portions of the test, which has been noticed in connection with other species, shews itself in the present instance in the little ring sur- rounding the stoloniferous tubes at their narrowest point. Each of these points having been of course, in its turn, the pseudopodial aperture of the shell. Hormosina ovicula is, to even a greater degree than its congener, HH. globulifera, a deep-water species. Specimens have been met with in six of the “‘ Challenger” dredgings, which represent depths ranging from 1900 to 2600 fathoms, aud I have no note of its occurrence in shallower water. Of these, two were dredgings from the South Atlantic, two from points lying to the South of Australia, and two from the North Pacific. 62 HENRY B. BRADY. Genus—CYCLAMMINA, noo. (xixAoc, a circle; apupoc, sand.) CycLAMMINA CANCELLATA, 2. sp. Nautiloid Litwola, Carpenter, 1875. ‘ The Microscope and its Revelations,’ fifth ed., p. 536, fig. 274, a, 8, ¢. Cyclammina cancellata (Brady, M.S.), Norman, 1876. ‘ Proc. Roy. Soc. Lond.,’ vol. xxv, p. 214. Lituola canariensis, Carter, 1877. ‘Ann. and Mag. Nat. Hist.,’ ser. 4, vol. xix, p. 203, pl. 13, figs. 26—29. Characters.—Test free, nautiloid, biconvex, depressed at the umbilicus ; margin entire or slightly lobulate, angular or somewhat rounded; composed of from two to three con- volutions, each of which encloses completely, or almost com- pletely, the previous ones. Segments numerous, ten to sixteen in the last convolution ; narrow, bounded by sinuate, slightly excavated lines radiating from the umbilicus. In- terior of the chambers almost (sometimes entirely) filled with finely arenaceous tubular growths. Surface smooth and imperforate, except where abraded; colour, various shades of brown. Aperture normally a crescentic slit in the ter- minal segment, close to its union with the previous convolu- tion; but, in addition, there are often a number of large pores irregularly distributed on the face of the terminal chamber. Size variable; many specimens reach 2 inch (4 millim.) in diameter. The main structural features of this interesting type have been already treated by Dr. Carpenter (loc. cit.); but as the manuscript name appended to my specimens several years ago has been employed by at least one author to distinguish the species, it seems right that I should summarise its zoological characters. This is the more necessary because the organism has no place in the scheme which I have sug- gested for the Lituoline genera. I cannot quite agree with Dr. Carpenter in regarding it as a Lituola ; still less with Mr. Carter in assigning it to Ltuola canariensis, which is a very distinct, minute, thin-shelled, Nondonina-like species. As I believe it is one of the forms concerning which we have more to expect from Dr. Carpenter’s pen, it would be unbecoming in me to enter into minute details respecting its structure. Cyclammina cancellata is very widely distributed. In FLAGELLATE INFUSORIA AND ALLIED ORGANISMS, 63 addition to the examples from North Atlantic localities, obtained by the scientific staffs of the “‘ Porcupine” and the * Valorous,” fine specimens have been found in many of the “* Challenger” dredgings, namely, from off the Canaries and from the West Indies; from two or three stations in the South Atlantic; from the South Pacific (off New Zealand) ; and from the Eastern Achipelago. ‘The depths of these soundings range from 390 fathoms to 1900 fathoms, but the largest specimens occur on bottoms of less than 700 fathoms. A very interesting modification of the type—perhaps only a variety—occurs in deep water off the coast of South America. It is somewhat smaller than the common form, and differs from it in general contour and in colour. Its shape is nearly globular, so that it may be regarded as an isomorph of Nonionina pompilioides; it is of a beautiful grey hue, and the surface presents almost more than the normal glossiness. RESEARCHES 07 the FLAGELLATE INFUSORIA and ALLIED Oreanisms. By O. Birscuii1, Professor of Zoology in the University of Heidelberg! Proressor Birscuur points out the value of a careful study of the Flagellata, some of which appear to be more nearly allied to the vegetable than to the animal kingdom. He concludes his preface with a hope that he may be able at a future time to amplify the present record. I.—Tue True FLAGELUATA. Spumella.—Cienkowski (“Ueber Palmellaceen und einige Flagellaten,” ‘ Arch. fiir mikr. Anat.,’ Bd. vi, 1871, p- 432). Small Flagellata, which, so far as is known, are colourless. They are either free-swimming, or are temporarily attached by a threadlike prolongation of the hinder end of the body. 1 Abridged from a paper in the ‘ Zeitschrift f. Wissensch. Zoologie,’ Bd. xxx, by D’Arcy Power, B.A., Exeter Coll., Oxford. C4 PROFESSOR O. BUTSCHLI. Anteriorly is a flagellum of considerable size, near which are sometimes one or two smaller accessory flagella. Food materials are received into a vacuole formed at the base of the flagellum ; this vacuole in some forms becomes converted into a liplike prominence. A nucleus is present. Repro- duction has as yet only been seen to take place by simple division during the motile stage. According to Cienkowski a cyst is produced in the inner part of the protoplasmic body of the organism, a portion of which is consequently lost by the encystation. Spumella termo, J. Clark (‘Ann. and Magaz. Nat. Hist.,’ 4th ser., vol. i, p. 135, figs. 1—4). Monas termo, Ehrenberg (?), (‘Die Infusionsthiere als vollkommene organismen,’ Leipzig, 1838, p. 7, pl. i, fig. 2.) These Monads (Plate vi, figs. 1 and 2) were often found by Biitschli as small Flagellata widely diffused in foul water. In spite of a few minor differences they appear to be identical with the form described by Clark, and with the Monas termo of Ehrenberg. Spumella termo is a small organism with a somewhat oval and flattencd body ; the greatest thickness is 0:005—0:006 mm. in an average-sized specimen. These small Flagellata are usually more or less fixed by the hinder end of the body, which is not rounded off, although no peculiar shell-like prolongations of this end, produced from the body itself, are visible ; but occasionally, as generally happens in Spumella vulgaris (Cienk.), the posterior end is drawn out into a delicate process. Sometimes the Spumella leaves its resting place and swims about rapidly by means of its flagellum. During the resting stage the flagellum, which springs from the anterior end of the body, is seen curved in the way figured. No accessory flagellum is perceptible in this species. Near the base of the flagellum rises the lip as a corner of the somewhat sharply defined anterior edge of the body. The lip either consists of colourless protoplasm, like the true body of the organism, or it appears more transparent, because it has produced within itself a vacuole filled with fluid (fig. 1 a). This vacuole of the liplike prominence is sub- servient to the reception of food; thus, the Bacteria and Micrococci, which constitute the chief food of the organism, are driven against the liplike prominence by the lashings of the flagellum ; they either escape or are taken into the vacuole, which is now much swollen (fig. 1 b). The vacuole then passes gradually down, along the side of the body FLAGELLATE INFUSORIA AND ALLIED ORGANISMS, 65 (fig. 1 c), tothe posterior end, where it ultimately becomes so entirely surrounded that it no longer projects sac-like beyond the body. After atime such particles appear to lose the vacuole by which they were surrounded, and numbers are found lying free in the protoplasm. Occasionally, also, vacuoles containing no food materials are carried backwards. It thus seems as if the vacuoles were formed at definite intervals, and were pushed back without the ingestion of food acting as a necessary stimulus. The vacuoles may also be formed directly on the ingestion of food, although one is usually readily prepared for such an event in the liplike pro- minence. Clark supposed that there was acytostome or cell mouth between the base of the flagellum and the lip, usually kept closed, which allowed the lip to play a part in the swal- lowing of food. The process of the rejection of food remnants has been observed by Biitschli in a stalked form of moderate size; the materials to be extruded were surrounded by large irregular vacuoles formed from time to time within the body ; these vacuoles were moved to the side on which was the lip, and stood out hernial like from it, when they either emptied their contents, or, still retaining them, were pinched off from the body. A single rapidly contracting vacuole was constantly present on the side opposite the lip. A vesicular nucleus with clear border and distinct nucleoli was frequently visible in the anterior part of the body, not far behind the base of the flagellum. Of the phenomena of reproduction, Biitschli only suc- ceeded in observing the frequent divisions, which are executed in a way which seems to be general in the small proportion of Flagellata which have as yet been examined in regard to this point (Plate vi, fig. 2). In the individual which is about to divide a second flagellum makes its appearance. Thus instead of the primitively simple flagellum, two are formed. The shape of the organism, however, is not noticeably changed, except that it appears slightly more globular, and the lip prominence seems to pass away. The further process of division can be followed in fig. 2, a toe. The body of the organism is first constricted and then divided between the separated flagella. The pinched-off parts then gradually draw away from each other for a con- siderable distance, till the two daughter organisms are only united by a very delicate thread, which ultimately breaks, and the two products of the division separate from each other. The mode in which the multiplication of the flagella takes place is not determined. The entire process of division VOL. XIX.—NEW SER, E 66 PROFESSOR O. BUTSCHLI. occupies only a few minutes, but from the minuteness of the organism the behaviour of the nucleus cannot be observed. No encystation has as yet been noticed in this form. Spumella neglecta, Monas neglecta, cf. Clark (loc. cit., p- 138, pl. v, figs. 5, 6), is closely allied to the form just described. Spumella vulgaris, Cienkowski (loc. cit.). Butschli is able on the whole to confirm Cienkowski’s description. It is distinguishable from Spumella termo by its very round, and almost spherical shape, and by the absence of the liplike prominence. Spumella(?) truncata, Fresenius (“ Beitrage zur Ken- ntniss kleinster organismen,’’ ‘Abhandl. der Senkenberg. Gesselsch. zu Frankfurt-a-M.,’ Bd. ii, pl x, fig. 42), is placed provisionally with Cienkowski’s Spumella; it is a very cha- racteristic organism, and has been well figured by Fresenius, who has described it as Monas truncata in the explanation of his plate, though he has omitted all mention of it in the text. The organism (Plate vi, fig. 3) is very flat, being but thin in proportion to its length and breadth. The contour of the broad side is somewhat oval, although the end bearing the flagellum is cut off to form a sharp slope; the opposite pole, on the other hand, being either smoothly rounded off or mo- derately pointed. From the higher portion of the anterior end of the body—the sloping portion—proceed two flagella, which are of no great length. In the clear protoplasmic body, near the longer side, is a vesicular nucleus with large dark inner body, which is generally somewhat in front of the centre of the body. The contractile vacuole is on the opposite and shorter side of the body, close to the front anterior border. Immediately in front of the vacuole is a dark band, running nearly parallel to the oblique anterior border, from the shorter side almost to the base of. the flagellum. This band is composed of a substance of high refractive index, which on closer scrutiny always appears to be irregularly granular; and it is sometimes quite apparent that it is made up of a number of highly refracting granules. This band is analogous with the one found by Cienkowski in Spumella vulgaris, and should perhaps be classed with the so-called eyespots in other Flagellata. The protoplasmic body contains great numbers of per- manent vacuoles, amongst which the food vacuoles, with their enclosed particles, are so clearly distinguishable that there FLAGELLATE INFUSORIA AND ALLIED ORGANISMS. 67 is no doubt that Spwmella truncata takes solid food, although neither the kind of nutriment nor the mode of ingestion is yet ascertained, owing to the rapid and uninterrupted move- ments of the organism. Chromulina Cienkowski (“ Ueber Palmellaceen und einige Flagellaten,” ‘ Archiv. fiir Mikr. Anat.,’ Bd. vi, 1871, . 435). ; Small Flagellata with a flagellum, contractile vacuole, and coloured disc. Inside is a cyst—the entocyst. No solid food appears to be taken. ‘The presence of the nucleus is doubtful. Chromulina ochracea, Ehrenberg (‘ Die Infusionsthiere als Vollkommene organismen,’ Leipzig, 1838, p. I1, pl. i, fig. 7), Monas ochracea, Khrb.—These small organisms are placed in the genus Chromulina, Cienk., in spite of the fact that the production of a cyst within the protoplasmic body— which is the most remarkable peculiarity of the species— has not yet been observed. The identity with Monas ochracea of Ehrenberg is very doubtful. Chromulina ochracea (Plate vi, fig. 4) is a small organism measuring 0-006 to 0:008 mm. in length and breadth ; it was obtained in the lake in the Grand-ducal park at Carlsruhe, where it was present in such numbers as to tinge the water of a yellowish-brown colour. The body is much flattened (fig. 4 c, seen from the narrow side), being heart-shaped, oval, or sometimes irregular in appearance, when looked at from the flat side (fig. 4 a b). Within the colourless protoplasm composing the body, two large coloured discs of a brown or yellowish-brown colour are constantly present; these discs entirely fill up the interior of the body. In the narrower end of the body lies a deep red eyespot of elongated rod-like appearance, and close to it are usually a number of dark granules of high refractive index (fig.4a andb). About the centre of the body is a contractile vacuole, which is very conspicuous during the diastole, and which contracts tolerably slowly. ‘The very rapid flickering, as well as convulsive and tottering movement, which is only broken at intervals by short periods of rest, is due toa flagellum of two or three times the length of the body, which is very difficult to observe. It probably arises, not from one end of the body, but from one of the broad surfaces of the body (fig. 4c). No nucleus has yet been noticed. Occasionally some of the organisms which seem to have lost their flagellum, execute amceboid move- ments and put out tolerably long pseudopodia. 68 PROFESSOR O. BUTSCHLI. The author next describes a small parasitic Flagellate found in the alimentary canal of a free living Nematode Trilobus gracilis. ‘The individuals were aggregated together by their non-flagellate poles, into radiating colonies. Single individuals, which are easily isolated, are very long and spindle-shaped, so as to be almost rod-like (from about 0°011 mm. in length); they are colourless, and are provided at the blunter end of the body with a large thick flagellum, of almost twice the length of the body. A contractile vacuole lies somewhat behind the base of the tentacle, and at some distance below this, in the otherwise feebly and very finely granular protoplasm of the body, is seen a small mass of high refractive index, composed of dark granules. No nucleus is observable. The movement of the organism is tolerably slow after it has been removed from the intestine of Trilobus, at least in water, in which it dies rather quickly. Antophysa,, Bory de Vincent. Small colourless Flagellata forming racemose colonies ; the number of individuals forming a colony varies from two to fifty, according to Clark. The individuals of each racemose colony are attached without lateral connection, by a short stalk-like prolongation of the hinder end of the body to a fine terminal branch of the thick, branching, brown-coloured main stem; each individual has a large flagellum and a delicate accessory flagellum, a lip-like prolongation for the ingestion of food, and a contractile vacuole. The nucleus is doubtful. Reproduction by fission on the stalk in the colony ; whole colonies, as well as single individuals, fre- quently separate themselves and swim about, such individuals again becoming fixed, probably form the commencement of a new colony. Antophysa vegetans, O. F. Muller. Volvox vegetans, Muller (‘ Animalcula Infusoria,’ p. 22, pl. ii, figs. 22—25). Antophysis Milleri, Bory (‘ Encyclopéd. méth.,’ 1824 ; ‘Hist. Nat. des Zoophytes,’ p. 66). Epistylis vegetans ?, Ehrb. (‘ Die Infusionsthiere als voll- kommene organismen,’ Leipzig, 1838, p. 285, pl. xxvii, fig. 5). Antophysa Miilleri, Dujardin (‘ Histoire nat. des Infu- soires,’ Paris, 1841, p. 302). Antophysa Miillert, Cohn (‘ Entwickelungsgeschichte der Mikroskopischen Algen und Pilze, Nov. act. Ac. c. L.C., &c.,’ Bd. xxiv, p. 109, pl. xv, figs. 1—8). FLAGELLATE INFUSORIA AND ALLIED ORGANISMS. 69 Antophysa_Miilleri, Clap. and Lachm (Claparéde and Lachman, ‘ Etudes sur les Infusoires,’ pp. 64—66). Antophysa Milleri, Clark (‘ Ann. and Magaz. Nat. Hist.,’ Ath ser., vol. i, p. 209). Antophysa Miilleri, Archer (“ On Antophysa Mulleri,” this Journal, vol. vi, N.S., 1866, p. 182). _ Antophysa Miilleri, Fromentel (‘ Ktudes sur les Micro- zoaires,’ Paris, p. 337, pl. xxvi, fig. 5). These organisms (Plate vi, fig. 6) were discovered by -~ O. F. Miller. Kuetzing supposed that the brown stalk was a peculiar fungus—Stereonema—and distinguished six dif- ferent kinds. Lately (1861) Archer has shown that the main stem of the organism increases independently, and that the colonies at the terminal branches are to be looked upon as swarm spores, which are, from time to time, produced from the branches, so that the main stem is to be regarded as the chief organism. Dujardin, in opposition to Ehrenberg, was the first to prove adequately the flagellate nature of these organisms, which he placed near Ehrenberg’s genus Uvella. Bitschli now confirms Clark’s account in its essential features. For instance, as regards the presence of a deli- cate, small, and very rapidly-vibrating accessory flagellum, close to the base of the chief flagellum, and as to the exist- ance of a lip or beak-like prominence of similar nature with, and in the same position as, the one found in Spumella termo, Clark. Reproduction takes place within the colony by fission of the individuals, as described by Clark (lI. c.), although Biitschli states that he has seen nothing of the case or coat described by that author. Division (Family ?): Cylicomastiges. The two genera, Codosiga and Salpingeeca, are closely allied outwardly. They differ chiefly, if not solely, in the fact that: the latter are provided with peculiar shells, like Bicosceca and Dinobryon, whilst the former genus, on the contrary, is devoid of such shell. Both genera possess a remarkable peculiarity in the existence of a large collar or calyx sur- rounding the base of the single flagellum; and it appears right to make this point one of a classificatory importance. The endoderm cells of Sponges are, as Clark has shown, provided with a similar collar, and so, classify Sponges as one will, there still remains the remarkable agreement—still requiring explanation—between the flagellum-bearing cells of the Sponges and certain flagellate organisms. ‘This appears the 70 PROFESSOR O. BUTSCHLI. more noteworthy, as this peculiar condition of the flagellate cells has never been found in other organisms. Codosiga, Clark (‘Ann. and Mag. Nat. Hist.,’ 4th ser., vol. i, p. 191). Antophysis, Bory (‘Encycl. Méthod. Hist. Nat. des Zoophytes,’ 1824). Epistylis, Ehrb. (‘Die Infusionsthiere als vollkommene organismen,’ Leipzig, 1838). | ? Pycnobryon, Fromentel (‘ Htudes sur les Microzoaires,’ Paris, pp. 212 and 337). Uvella, Fromentel, op. cit., p. 338. Small, colourless, colony-forming Flagellata. The single individuals have a long flagellum anteriorly, arising within a very large collar. ‘The organisms are naked, devoid of a covering. Food is ingested into a food vacuole situated outside the collar at its base. A contractile vacuole and nucleus are present. The colonies are formed as they are in Antophysa, the individuals arising from the end of a straight and unbranched main stem, which is frequently of considerable length. Reproduction by longitudinal fission of the individuals forming the colony has been observed. Codosiga botrytis, Ehrb. Antophysis solitaria, Bory (‘ Encyc. méth.,’ p. 67). et _ (Bory), Fresenius (“Beitrage zur Kenntniss kleinster organismen,” ‘ Abhandl. der Senkenberg Gesellsh. zu Frankfurt-a-M.,’ Bd. 1, p. 233, pl. x, fig. 29, 30). Epistylis botrytis, Ehrb (p. 284, pl. xxvii, fig. 4). Codosiga pulcherrima, Clark (loc. cit., p. 139, pl. v, figs. 7—27). "? Uvella disjuncta, Fromentel (p. 338, pl. xxv, fig. 8). ? Pycnobryon socialis, Fromentel (p. 137, pl. ¥xvi, fig. 9). These very interesting, but yet common, forms (PI. vi, fig. 7) were discovered in 1858 by G. Fresenius, who with reason held that they were the same as the Epzsfylis botrytis of Ehrenberg ; whether, on the contrary, Antophysa soli- taria of Bory de Vincent, after which Fresenius named the species, is identical with the Epistyls botrytis of Ehren- berg is doubtful. The number of organisms going to make up a colony was long a matter of dispute ; usually only four or five are seen, whilst Clark has observed eight, and Khren- berg ten. Solitary individuals are frequently mounted upon short slender stalks. The pedicels of older colonies, richer FLAGELLATE INFUSORIA AND ALLIED ORGANISMS. 71 in individuals, are thicker and longer (fig. 7 a); at their attached base a flattened portion serving for attachment is seen under favorable circumstances, whilst the stem itself appears tubular, dark sides, and a clear homogeneous axis substance being distinguishable. Occasionally the usually colourless stem is tinged of a somewhat yellowish brown. The individuals forming the colony spring from the upper end of the stem, each being carried upon a delicate proto- plasmic stalk, which passes directly into the hinder end of the organism. ‘These stem-like prolongations of the hinder poles are not contractile, at least not in any noticeable degree. The flagellum springs from the centre of the obtuse anterior pole of the body. When it is at rest it frequently falls, somewhat curled in a very characteristic way. The delicate membrane-like collar surrounds the blunted anterior pole (fig. 7 a—c) ; it is usually seen in optical section as two dark diverging lines, which at first give the impression of two accessory flagella, and for these they have been occasionally mistaken. Fresenius described the collar as a delicate, blunted ap- pendage, from which a cilium causing motion (Bewegungs- faden) projected. The size and appearance of the collar are exceedingly variable; sometimes it projects only very slightly beyond the anterior end. Separate specimens have been ‘seen swimming freely, which did_not possess any trace of a collar. Generally it is of considerable height, as in fig. 7a, b, oc- casionally (fig. 7 c) it is a very noticeable object. Clark has observed that this change in the height of the collar is very rapidly executed in one and the same individual, that the funnel can be drawn in, that is, can be made to blend with the protoplasm of the body, and can be again protruded. This fact, in connection with its conduct during fission, points to the conclusion that the collar is only the protoplasm of the anterior end of the body modified in a peculiar way, and that it may be regarded in a certain sense as a further modification of the lip-like prolongation of such an organism as Bicoseeca. The collar cannot alter its shape without at the same time changing its height. Whilst the organism is in move- ment it is able to contract, and the shape becomes more rounded, whilst the free edge of the collar is so much con- tracted that it almost closes (fig. 7 d), although its usual condition is that of a more or less funnel-shaped opening. According to Clark, the cytostome or spot where the in- gestion of food takes place, is at the anterior end of the 72 PROFESSOR O, BUTSCHLI. body, near the base of the flagellum within the collar. The process of ingestion of food has not yet been fully followed out. By careful observation, however, a vacuole-like struc- ture (fig. 7 a, z) is seen to project upon one side of the body close below the base of the collar, and beyond the contour of the body. Soon this structure disappears, and after a cer- tain time another similar one appears upon the opposite side. It has also in some measure the appearance of wandering about close under the base of the collar; but it is not yet known whether this really happens, or whether different vacuoles rise and then vanish in opposite parts of the body. The whole matter, however, becomes simple, if it be assumed that the vacuole changes its position. The ingestion of food takes place into the middle of these vacuoles in the following way :—Particles of various kinds — Micrococci, Bacteria, &c.—are often driven by the movements of the flagellum on to the outer surface of the collar, to which they adhere; occasionally the entire outer face of the collar is seen to be covered by such ad- herent particles. Gradually all the particles are seen to be pushed backwards, first on to the collar, and alittle later to the base of the collar, until they touch the vacuole, by which they are taken up and engulphed as food for the body. The remnants of the food are extruded close to the base of the flagellum within the collar. The nucleus situated near the anterior end is first seen within the body, it consists in the living state of a transparent portion containing dark bodies. The nucleus becomes much more prominent after treatment with acetic acid, but there still remains the dark and somewhat granular case and the transparent exterior. The protoplasmic body is very frequently filled with a number of large non-contractile vacuoles in addition to the food vacuoles. These large vacuoles can only be distinguished from one another by their boundary walls, which are comparatively very delicate ; hence the whole organism appears to be a large alveolar vacuole. The contractile vacuoles are always double, and lie at the posterior end of the body on opposite sides, not quite in the same section, since one is generally a little in advance of the other, nearly in the centre of the body’s length. No third contractile vacuole was observed by Biitschli, although one has been described by Clark. The two vacuoles contract alternately ; their contraction is very slow. The formation of the vacuole is peculiar, and has analogies with the same process in such ciliata as Uroleptus. The mode is as follows: — A narrow-elongated space filled FLAGELLATE INFUSORIA AND ALLLED ORGANISMS, 73 with fluid makes its appearance beneath the upper surface of the body at the spot where the last vacuole disappeared (fig. 7c, v); this space, so far as can be determined, is formed by the flowing together of several smaller vacuoles. Shortly before the systole the space rounds itself into a vacuole. The author has, unfortunately, failed to find the condition of division, and so has not been in a position to confirm Clark’s interesting observations on this point, which are shortly as follows :—The division occurs longitudinally, and so is in conformity with the general rule amongst the Flagel- lata. The organisms next become globular, and the flagel- lum becomes shorter and shorter, till it is finally entirely withdrawn into the protoplasm. Then begins the peculiar division of the body of the organism in the neighbourhood of the flagellum, from which point it gradually proceeds backwards; finally, the collar is drawn into the division, and is gradually cut through from the base to the apex. In the meanwhile, a flagellum, which is at first small, but which gradually increases as the process of division proceeds, is budded out from the anterior end of each of the products of the fission. The posterior thread-like elongation of the body, which attaches the organism to the common stalk of the colony, also undergoes division, until’ finally the two products of the fission become completely separated. The author has observed forms which were surrounded by a delicate viscid case (fig. 7 b), and also others whose bodies were covered with Bacteria (fig. 7 e). The average size, not reckoning the collar, was 0012 mm. The organisms have been found very frequently upon Alge and so forth, upon the stems of Antophysa vegetans, and once upon colonies of Volvox dioicus, Cohn. They withstand a considerable degree of foulness in the water where they occur. Salpingeca, Clark (‘ Ann. and Mag. Nat. Hist.,’ 4th ser., vol, 15 :p, Lag). This genus differs from the foregoing in the fact that the animals live in transparent cups or flask-like shells ; they are solitary, and not colony-forming as far as they have yet been observed; their method of reproduction is unknown. Salpingeca gracilis, Clark? (op. cit., p. 199, pl. vi, figs. 88 and 39). This organism (Plate vi, fig. 8) resembles Codosiga, but inhabits an elongated case, which has sometimes 74 PROFESSOR 0. BUTSCHLI. the shape of a test-tube, becoming much narrower pos- teriorly. The author is unable to confirm Clark’s statement that the hinder portion terminates in a delicate prolonga- tion. The length of the broad tube is 0°027 mm., and it consists of a perfectly transparent firm mass, of a chitinous nature to all appearance, although no micro-chemical tests were applied to determine its constitution. In no case was the material of a viscid consistency, as stated by Clark. The organism itself occupies only a comparatively small (4) part of the tube, within which it is very moveable. It can stretch itself so far out that nearly the whole of the collar is extruded, or it can very rapidly retract itself to the hinder end of the tube. It is not known what causes these rapid movements of retraction, but in one case a delicate thread seemed to run from the posterior end of the body to the side wall of the tube. The co-operation of the flagellum inthis action seems very doubtful. The relations of the flagellum and collar are seen in fig. 8. The flagellum is so delicate as to be scarcely visible. The ingestion of food has not been observed. The nucleus is placed anteriorly, and is made much more visible by the use of acetic acid. A contractile vacuole of considerable size is found in the hinder third of the body. The rate of contraction is slow, and the re-forma- tion is brought about by the flowing together of several small vacuoles, which appear either shortly before or during the systole of the previous vacuole. Once it was found that after the vacuole had contracted and re-formed for some time in one place, it began instead on the opposite side of the body ; this phenomenon probably gave rise to Clark’s state- ment that there were two contractile vacuoles as in Codosiga botrytis. Salpingeca amphoridium, Clark (?), (op. cit., p. 203, pl. vi, figs. 37, 37 d). This species has been found only on a single occasion by the author; it agrees fairly with Clark’s description. The appearance of the case is characteristically flask-like (Plate vi, fig. 9); in the form described by Clark the fixed end was rounded or somewhat pointed, whilst in this it is broadly flattened; in both cases the organism almost en- tirely fills the case, which thus appears to be a cast of the animal. The collar and flagellum are seen with difficulty. Numerous vacuoles are found within the body, but only one of these is contractile, whereas in Clark’s Salpingeca amph o yidium there were two large contractile vacuoles and three smaller ones. Fvod vacuoles are seen passing backwards FLAGELLATE INFUSORIA AND ALLIED ORGANISMS, (5) through the long neck. No nucleus was found, neither was the process of food ingestion observed. Salpingeca Clarkii, new sp. This organism was frequently found on the stem of Antophysa vegetans ; it must be regarded as a_ peculiar species, closely allied to Clark’s Salpingeca marina,, from which it differs in the form of its case, as is shown in fig. 10. The shape is comparable with that of a flower vase, and it extends behind into a delicate stem-like por- tion, which, as in Salpingeca gracilis, is a hollow and narrower portion of the case, and not a solid support, as it is in Salpigeca marina. The free anterior border of the case is spread out so as to be broadly funnel-shaped, and from it project the collar and flagellum. ‘The organisms are also able to open or close the border of the calyx, and this is undoubtedly in connection with the mobility of the creatures in their cases. They are ordinarily found, like Salpingeca marina, in the front portion of their cases (fig. 10), but on being disturbed they go down to the bottom, so that the collar, which has become closed, only just projects above the rim of the calyx. In this condition it is very difficult to dis- tinguish the collar. The flagellum is readily visible, and is generally quite motionless and slightly extended. The inges- tion of food has not been followed, although there are usually a number of particles, which are undoubtedly food particles, lying in the body. The nucleus is easily seen, and lies, as in other forms, anteriorly ; its structure is the same as in Codosiga and Salpingeca gracilis. The contractile va- cuoles are present, situated on opposite sides of the body, as in Codosiga, or close to each other, as in fig. 10. The height of the calyx i is 0-019 mm. As an appendix to the genus Salpingceca a small orga- nism is here mentioned, which was pretty frequently found upon the stem of Antophysa veyetans, and of whose exact position the author is not quite certain, on account of the great diffi- culty in studying a new organism of such minuteness. These small Flagellate organisms inhabit a case fixed upon the stems of Antophysa, as seen in fig. 11, a c, which shows varying forms. ‘The walls, which are of considerable thick- ness, are of a deep brown colour, and have an irregular and rough contour. The height of the case is about 0-008 mm. The protoplasmic body generally fills the case, and may either extend beyond it to a greater or less extent, or not at all, At the anterior extremity, which extends beyond the case. 76 PROFESSOR O. BUTSCHLI, is seen the flagellum, which is sometimes vibrating (fig. 11, a). On either side of the flagellum is seen, though with great difficulty, a faint line, which resembles the optical section of the collar in Salpingeeca. Frequently neither the flagel- lum nor collar is visible (fig. 11, c), or the latter appears to be shrivelled, in which case the organism is remarkably like a rhizopod. A nucleus lies within the more or less granular protoplasm, and near it are (fig. 11, a), one, and in some cases three contractile vacuoles (v), lying at the hinder end of the body (fig. 11, c). Bicoseca, Clark (‘ Ann. and Mag. Nat. Hist.,’ 4th ser., vol. i, p. 139). : Stylobryon, Fromentel (‘ Htudes sur les Microzoaires).’ Small organisms with a single long flagellum at the anterior end, together with a large lip- or beak-like pro- minence for the ingestion of food. A contractile vacuole is present, and a nucleus doubtfully so. Each individual, like Dinobryon, inhabits a calyx-like case, into which it can retract itself with the assistance of a very elastic thread which springs from the posterior end of the body. Occasionally, as in Dinobryon, colony-building forms are observed. These organisms are found both in salt and fresh water. Bicoseca lacustris, Clark (’), (op. cit., p. 188, pl. v, figs. 33, 33 c). This species is very frequent in ponds, where it attaches itself to Algee and other water plants, and often to the main stem of Antophysa. Solitary individuals are generally observed, whose calyx is attached to a delicate stem. In the forms observed by Clark this stem reached at the most only half the height of the calyx, but in those seen by Biitschli the stem far exceeded the calyx in length (fig. 12, a). Occasionally colony-building forms have been noticed (fig. 12,a b.) The young calyces are produced from the mouths of the older forms, just as they are in Dinobryon. A dark supporting line has several times been seen to extend from the posterior end of such a young specimen to the older one (fig. 12, b), and consequently it must be asserted that the young calices are provided with stalks, which extend from the inner wall of the older ones. The shapes of the calyx are seen in the figures. The openings are either rapidly enlarged as in fig. 12, b, or as rapidly narrowed (fig. 12, c and d),and it can sometimes be clearly seen that the opening is nearly closed, when the FLAGELLATE INFUSORIA AND ALLIED ORGANISMS, Uh animal withdraws itself into its calyx, although this is by no means always the case (fig. 12, b). Clark was probabl right when he attributed this power of closing the shell to young forms. Sometimes the calyx is not circular, but is triangular. Of this, however, the author is not quite certain. The height of the calyx is, on an average, 0'014 mm. The organism is attached to the base of it by means of a thread springing from the hinder end of the body ; it is this thread which Clark rightly compares with the hinder flagellum of many heterotrich Flagellata, as, for instance, many forms of Cercomonas. The contractile vacuole is a little distance rom the point of origin of this thread of attachment. The fflagellum, of considerable length, springs from the anterior end and stands out straight from the body when it is in its usual state of rest (fig. 12, c). The extreme end alone vibrates or bends at this time, throwing the minute particles of food with considerable force against the beak-like pro- minence. When, however, the organism is retracted into its ease the flagellum is rolled up (fig. 12, b) so that it is pro- tected by the case. The lip- or beak-like prominence for the reception of food is very noticeable, and appears to resemble most nearly the one found in Antophysa. It is seen, by observing it in dif- ferent positions, to be strictly a leaf-like broadened prolonga- tion (fig. 12,c andd). A vacuole formed before the ingestion of food has never been observed, but one is produced as soon as a small particle of food has been thrown between this prominence and the base of the flagellum. The vacuole so formed takes in the food and distributes it in the body. Clark placed the mouth at this spot, although, there is no doubt, that no such orifice exists preformed for the reception of food, but only that a particular spot on the surface of the body is set aside for this purpose. Clark has observed that the food remains are extruded a little above the spot at which the food is ingested, but the author has not yet followed out the act of defeecation. Nothing is noticeable in the body proper of the organism. Clark, however, has observed in the two species of this genus which he examined, a furrow extending along the whole length of the body, beginning at the base of the flagellum, and traceable to the point of origin of the posterior thread of attachment. He believes that this groove is distinguishable by a peculiar contractility. The body itself is possessed of a certain contractility, as it has been seen to become spherical without the aid of the posterior thread. The nucleus has 78 PROFESSOR O. BUTSCHLI. not been observed by the author, although he does not doubt but that it 1s present. The process of reproduction has not been followed, but it almost certainly increases by fission, like its fellows. In the formation of a colony one of the young buds, as in the case of Dinobryon, settles upon the rim of the old calyx, and builds there a new case for itself; and in this way from a single one arise the compound trees of a great number of indi- viduals. Clark has found a second variety of this species, Bicoseca gracilis ; it is a marine form. The Stylobryon imsignis of Fromentel' forms definitely a third kind, which differs chiefly from Bicoseca lacustris in the fact that each calyx of the colony possesses its own very long stem ; this form stands somewhat in the same relation to Bicoseca lacustris as Dinobryon petiolatum Duj. to the ordinary Dinobryon sertularia. Dinobryon, Ehrbg (‘Die Infusionsthiere als vollkom- mene organismen,’ Leipzig, 1838, p. 124). Dinobryon setularia, Ehrenberg (op. cit., p. 124, pl. vii, fig. 8). Dinobryon, Dujardin (‘ Histoire Nat. des infusoires,’ Paris, 1841, p. 321, pl. i, fig. 2). Dinobryon, Perty (‘Zur Kenntniss kleinster Lebens- formen nach Bau, Function, Systematik,’ &c., p. 178). Dinobryon, Claparéde and Lachmann (‘ Etudes sur les Infusoires,’ p. 65, pl. xii, fig. 66). Dinobryon, Fromentel E. de (‘ Etudes sur les Microzoaires,’ Paris, p. 336, pl. xxvi, fig. 1). Of this beautiful form Biitschli states that he has found only free swimming colonies (Plate vi, fig. 13). The vase-like case of the individual organisms calls to mind the very similar cases in Bicosceca and Salpingeca, whilst the grouping of the individuals to form a colony is just like the arrangement in Bicoseca lacustris. The young calyces also grow from the inner side of the free edges of the old forms, generally single but occasionally double. The or- ganisms are of a yellowish-brown or green colour, the colours proceeding, as in many coloured Flagellata, from two pigment discs, which are placed side by side on the colourless proto- plasm of the body (fig. 13 a and 13 b). Of these discs one is generally the longer, and extends further forward than the other. Ehrenberg noticed thatthe smallinhabitants of the cases were very contractile ; from the anterior end springs a rather ' Op. cit., p. 336, pl. ix, figs. 12—14; pl. xxvi, fig. 8. FLAGELLATE INFUSORIA AND ALLIED ORGANISMS, 79 long flagellum of even thickness throughout; it generally moves along its whole length with a serpentine, less fre- quently with a rolling, motion. The author has noticed a small accessory flagellum close to the flagellum known to Ehrenberg. ‘The accessory flagellum is generally at rest in an extended condition. Biitschli also believes that he has seen a delicate thread arising from the posterior end of the body, and attaching it to the base of the case. The eye- spot lies close to the base of the flagellum, whilst the two contractile vacuoles are close to each other at the hinder portion of the anterior third of the body; the contraction of these vacuoles is quick and sudden. Fdécke! was the first to recognise a single contractile vacuole in these organisms, and after him Claparéde described and figured them. No nucleus was observed by Biitschli, as the little free-swimming colonies are difficult to treat with reagents. Occasionally a group of small granules. of high refractive index were ob- served in the hinder third of the body ; it cannot be decided whether the minute organisms take solid food. Fromentel has lately described a dark cytostome at the base of the flagellum ; he appears to have mistaken the eyespot in this way. e regards the formation of a colony, the following points are noticed by Butschli:—The colony is doubtless formed by fission of the organisms in their cases, but the actual fission has not yet been followed out. Calices have, however, been seen, which, in addition to an individual situated at the bottom, have a second caseless form placed at the mouth of the calyx (fig. 13 bh). It appears to be proved that these two individuals have proceeded from the fission of the previous inhabitant of the calyx, since each contains only a single pigmented disc, whilst the anterior one alone possesses an eyespot. Carter has observed a somewhat similar phenomena in the fission of his Euglena agilis in its encysted state, for the hinder product of division is in the same way devoid of an eyespot. The anterior organism, in a more advanced stage, is attached to the mouth of the calyx by its posterior pointed extremity, and then a small calyx forms round its hinder half. A large cyst (fig. 13, a,c) has been seen at the mouth of an empty calyx; it consisted most exteriorly of a coarse sheath containing a smaller excentric sheath; this in turn was filled with a protoplasmic contents and the two charac- teristic pigment discs. No eyespot was visible, but the 1 ”. The lash, however, may be considerably longer than this, as the slepe from the body-portion is very gradual, and when the eye follows it to the bounds of visibility an impression is conveyed that there may be still more of it, beyond the power of either Ross’ 54,” or Powell and Lealand’s +,” to reveal. - They are not very sensitive to the action of reagents ; a weak solution of ammonia did not affect them for some time, but a stronger solution of potash affected such of them as it came into contact with at once: others in the middle of the field continued to exhibit movements for several hours; probably they had not been touched by the potash. A weak solution of bichloride of mercury in acetate of potash and camphor water (as used for preserving preparations) did not seem to affect them materially, seeing that they maintained their activity m such a solution for eight hours. They retain their vitality longer in a weak salt- solution than in pure distilled water. A cover-glass with an aqueous solution containing them was inverted over a bottle of chloroform for several minutes, but the movements of the organisms were unaffected ; if, however, a drop of blood contain- ing them be similarly placed over chloroform they disappear, probably owing to the action of the chloroform-vapour on the blood itself. A drop of the blood was placed on a slide arranged for the 1 Two such illustrations have been reproduced by the permanent pho- tographic process of the Autotype Company, and will be issued with the complete paper in the Government of India Sanitary Report already referred to. FLAGELLATED ORGANISMS IN BLOOD OF HEALTHY Rats. 113 application of electricity to microscopic preparations, and it was found that an interrupted current of such a strength as could not be comfortably borne by an individual was tolerated by these beings for several consecutive hours. The only difference appreciable between a preparation thus dealt with and one not so treated was, that the movements ceased a few hours sooner in the former than in the latter, possibly owing tv the chemical change induced in the blood itself by the current. I have examined the blood of a great number of rats for the purpose of ascertaining what proportion of them contains these organisms in their blood, and find that of those specially ex- amined for this purpose their existence was demonstrated in 29 per cent. Sometimes, however, the number detected were very few, not more than one or two in a slide, but in the greater number of cases they were very numerous, every slide containing several hundreds. Being anxious to ascertain precisely the species of rats in which these organisms were found, I consulted an accomplished naturalist, Dr. John Anderson, Superintendent of the Indian Museum, and he was so good as to identify the specimens for me from time to time. The result has been that it has been defi- nately ascertained that these organisms may be found in two species, viz. Mus decumanus and Mus rufescens. It would appear that they are not found in mice. I have examined the blood of a large number, but never detected any organisms of the kind; nor have I seen them in any animals other than rats. It is possible that these minute organisms ought to have been described in the part of this paper devoted to the description of microphytes, as they present many features in common with motile organisms undoubtedly of vegetable origin: on the othef hand, taken as a whole they appear to approach more closely to the forms of life usually classified as Protozoa; such, for example, as several of the species of Dujardin’s genus Cercomonas. It should, however, be noted that many believe that these organisms are zoospores and not animalcules. The nearest approach to a description of these hamatozoa which I can find is in a recent paper by Biitschli,’ in which he refers to a flagellated parasite which he has often observed in the intestinal canal of a free nematode (Zrilobus gracilis). He refrains from giving it a name, owing to the uncertainty which exists with regard to organisms of this kind. He generally found them in large numbers, often forming stellate colonies owing to their being attached by their non-flagellated ends. They readily became detached, and then presented a some- * See page 68 and Plate VI, fig. 5, of the present number of this Journal. VOL, X1X.—NEW SER, H 114 TIMOTHY RICHARDS LEWIS. what spindle-shaped body, about 11in length, and with a some- what thick flagellum about double this length, so that the total length of the protozoon would be 33, something more than half the length of the flagellated organism found in the rat’s blood. Near the base of the flagellum of Bitschli’s protozoon a con- tractile vacuole could be distinguished, but I have not been able to detect any such vacuole in these rat-hamatozoa. Seeing that the blood of such a large proportion of rats con- tains these organisms, I can hardly suppose that their existence has hitherto escaped notice, unless it be that rats in HKurope do uot harbour like parasites. Davaine,! in the recent edition of his work, makes mention that M. Chaussat had found minute ne- matodes in the blood of a black rat (Mus rattus), but I have not seen any nematode in the blood of rats in this country. In the tissues, bladder, &c., of rats such parasites are very common, but their description does not come within the province of this paper. The nearest approach to the flagellated hematozoa of rats which I have seen described is to be found in a foot-note in Dr. Bastian’s ‘Beginnings of Life,’ * where it is stated that Dr. Gros had seen minute worms (vermicu/es) in the blood of a field-mouse (mwdot) which were so numerous as to cause the blood to present an animated appearance ; and that the blood of the mole was often found to be in a similar condition. They were so small as to be barely visible under a power magnifying 400 diameters. I have not been able to obtain any minute description of these vermicules, but I anticipate that it will be found that they closely resemble the flagellated protozoa found in the blood of Indian rats. With regard to the health of the rats in which these flagel- lated organisms were detected, there was nothing to suggest in any way that they were less healthy than others not so affected, and I have repeatedly kept rats for a considerable time for the purpose of observing whether any special symptoms would be inanifested suggestive of the existence of such organisms in the circulation. It should be mentioned that it frequently happened that the rats caught in a particular room would be affected, whereas the blood of rats in another part of the building would not contain them. The servants had ultimately come to recog- nize this, as, whenever they learnt that a particular rat’s blood contained the desired organisms, they diligently endeavoured to secure the rest of the family. Calcutta, August, 1878. 1¢Traité des Entozoaires,’ Edit. ii, pp. 11, 957; 1877. Leuckart’s ‘ Parasiten,’ vol. ii, p. 636. wee Vol p.da8; 1872. NOTES AND MEMORANDA. 4 Observations on the Capitellide by Dr. Hugo Eisig.—A peculiar organ connected with the alimentary tract of the Capitellide has recently been described by Dr. Hugo Hisig, under the title Nebendarm (‘‘ Nebendarm d. Capitellide,” ‘Zoologischer Anzeiger, No. 7, 1878). This organ, which has been met with in all the main families of the Capitellide, consists of a narrow tube on the neural side of the alimentary tract into which it opens in front and pro- bably also behind. The anterior opening is situated close to the posterior boundary of the esophagus. The position of the posterior opening varies somewhat, and its existence has not been so clearly established as that of the anterior open- ing. The chief interest connected with this organ is the comparison Dr. Eisig has made on the one hand between it and an embryonic organ found in the Ichthyopsida, and named subnotochordal rod, and on the other with the siphon of the Echinoid alimentary tract. The subnotochordal rod is primi- tively a canal split off from the neural side of the alimentary tract for the greater part of its length, which soon becomes solid, and occupies a position (according to Dr. Dohrn’s view of the relationship between Annelida and Vertebrata) very simi- lar to that of the Nebendarmof the Capitellide. The siphon of the Echinoids resembles the Nebendarm in communicating at both extremities with the alimentary tract. Dr. Eisig mentions that Spengel has recently detected in Bonellia an organ similar to the Nebendarm in its connections. The homologies sug- gested by Dr. Eisig for the peculiar organ he has discovered are certainly plausible, but can hardly claim to be satisfac- torily established. The segmental organs of the Capitellide have also been studied by Dr. Kisig (‘Mittheilungen a. d. Zoologischen Station zu Neapel., Bd. I, Heft I), and the conclusions he has arrived at are of some interest in relation to the possible homology between the vertebrate segmental tubes and the segmental oS NOTES AND MEMORANDA. organs of the Annelida. It is generally stated that in no case is there more than one pair of segmental organs in each annelidan segment, although the coexistence of segmental organs and generative ducts in the same segment in the Terri- colus Oligocheeta led Professor Lankester to regard two as > the typical number of pairs for each segment. Dr. Eisig has now shown that in Notomastus more than one pair of segmental organs is frequently present in a seginent, and that in Capitella capitata a plurality of these organs in each segment is the rule. Moreover, in Capitella the number in each segment in- creases from before backwards. In adult Amphibia there are usually several segmental tubes in each segment, and the actual number in each segment also increases from before backwards. This fact has been used as an argument against the comparison of the segmental organs in Vertebrata and Annelida ; but Dr. Eisig’s observations prove that on this point at any rate there is no important difference between the organs in the two types.—F. M. B. Bacteria as the Cause of the Ropy Change of Beet-root Sugar. —The so-called “ Frog-spawn” of sugar manufacturers is a gela- tinous formation, the origin of which has hitherto been explained in various ways. Professor Cienkowski has recently published at Charkow a memoir, in which he describes and figures a Bac- terium as the cause of the remarkable and economically important phenomena connected with this alteration of sugar. According to Scheibler, the “ Frog-spawn” is the protoplasm of the cells of the sugar-beet; according to Jubert and Mendes, this gummy substance is an aggregate of various organised ferments. Durin ascribes the “ Frog-spawn”’ to a peculiar fermentation, due to the action of diastase on crystalline sugar, whereby the latter is broken up into cellulose (the spawn) and glucose. Cienkowski’s researches, carried on both in a sugar factory and by means of culture experiments, prove that the view put forward by Jubert and Mendes is essentially the correct one; the “Frog-spawn” is in reality a product of the vital activity of Bacteria; it is to these organisms, and not to diastase, that we must ascribe the decomposition of the crystalline sugar discovered by Durin. The jelly of the “ Frog-spawn” shows in its structure and development the closest resemblance to the Ascococeus Billrothir of Cohn (see this Journal, vol. XVI, p. 264, and Plate XX, fig. 1, for Cohn’s description and figure of Ascococeus Billrothi). It is, perhaps, only a variety of that species, and in any case belongs 3 NOTES AND MEMORANDA. Ry to the same genus of Schizophyta, and may be named “ 4, mesenteroides.” A structure identical in every respect with the “ Frog-spawn” of sugar factories arises spontaneously on slices of cooked beet- root which are kept moist with free access of air; such culture specimens differ from those of the factories only in their smaller size and less density of the jelly. The jelly-balls of the “ Frog- spawn” consist of accumulations of jelly-masses or units, the so-called ‘‘ Gallertkerne.’’ These units are naked, without enve- lope; they are closely adpressed one to another, or are attached to one another in rows so as to form botryoidal loose or compact gut-like masses. By combination of such units spherical or irregularly-shaped lumps are produced, which again become com- pacted into larger masses. he jelly of the ultimate spheroids has a varying consistence—hard, elastic, sharply defined, or semi- fluid, with confluent outlines. It is soluble in concentrated potassic hydrate and in sulphuric acid; according to Durin, also in ammonio-cupric hydrate. Cienkowski failed to obtain this reaction, and only saw a faint blue coloration as the result of this reagent. Iodine with strong sulphuric acid produces no change in the jelly. The most important part of the ultimate spheroids are the builders of the jelly—uamely, the Bacteria embedded in it. In young examples they are present without exception; in older lumps difficult to detect. They exhibit the most varied forms, which are commonly known as Micrococcus, Torula, Bacterium- chains, Bacillus, and Vibrio. The common Bacteria pass into the Zooglea condition, developing from colourless Leptothrix-like filaments (see this Journal, October, 1878) by a process of transverse subdivision and by the production of jelly around both entire filaments and the pieces into which they subdivide, and we find that the developmental history of the “ Frog-spawn’’ is similar. Here too, as forerunners of the gelatinous growth, we find colourless filaments, which are often serpentine in form. The gelatinization of the Ascococcus-builders is easy to follow, especially when they are growing on very slimy substrata. But the “ Frog-spawn” will also originate directly around isolated Bacteria. Such gelatinous ultimate spheroids, formed indepen- dently of one another come into contact with one another by further growth, adhere together and form miniature examples of the “ Frog-spawn.” The nearly allied 4. Beddrothii develops itself spontaneously on cooked and uncooked beet-root. The jelly which envelopes the Bacteria is in this case not so copious, and less refringent, than in the former species. In cultures kept fairly dry A. Biltrothii attains an enormous size; it is easily visible with the naked eye. It forms brown or greenish heaps 118 NOTES AND MEMORANDA. composed of numerous upgrowths ; such examples differ in many respects from the forms described by Cohn and Billroth. The ultimate morphological elements into which they can be divided are, as in the former species, gelatinous spheroids with enclosed Bacteria. All the properties of the “ Frog-spawn,” and nearly all the phenomena which accompany its formation, are in harmony with the supposition that these jelly-masses of the sugar factories are produced by Bacteria. Only in the extraordinary rapidity of their production (half an hour according to Feltz), do we come upon a difficulty, the explanation of which can only be looked for when we have a fuller knowledge of the developmental history of Bacteria. As a starting-point for further researches in this direction the following facts are of value : (1) That in very viscid saccharine solutions all the Bacteria, without forming individualised Zoog]cea-masses, are embedded in a common gelatinous substance which is coagulated by alcohol. (2) The capability possessed by the Bacteria of forming balls of this substance around themselves. (3) That a mechanical movement of the nutrient fluid appears to act favorably on the formation of the ball-lke masses. A very viscid decoction of beet takes, as Cienkowski says he has often seen, a marked gelatinous consistence almost immediately when agitated. The mechanical movement of the beet-juice during the process of squeezing it out of the roots, will probably enough prove in this way to be one of the essential conditions of the rapid formation of “ Frog-spawn.”’ Cienkowski’s observations show then, that the “Frog-spawn” of the sugar-factories is no peculiar isolated phenomenon, but with- out any difficulty can be assigned a place in the category of the processes of jelly-formation so widely spread among the Algee. —IHi. Ray Lanxesrur. ) Stein's ‘Organismus der Infusionsthiere.—The first volume of the third part of this great work has just appeared, consisting of 150 pages of letterpress and 24 folio plates. The third part is devoted to the Flagellata, and in the present volume we have an exhaustive history of the discoveries and writings of previous observers, from Ehrenberg to Carter, Busk, Williamson, Hicks, and James-Clarke. The plates are accompanied by full explanations ; the systematic description of genera and species will follow. Forms allied to those described in Professor Biitschli’s paper, an abridged translation of which appears in the present number of this Journal, are figured in profusion. A most remarkable form isthe Rhipidodendron splendidum, a tube- making Flagellate, the tubes of which are aggregated in dense NOTES AND MEMORANDA, 119 flabelliform masses. The genera Volvox, Pandorina, Chlamydo- coccus, &c., as well as Huglena and Phacus, are included by the author among the animal Flagellata, and are copiously illustrated. The antherozooids of Volvox are regarded merely as a smaller generation of Flagellate individuals. The Ritter von Stein regards this as probably the most interesting and important section of his great work, and all will agree that its appearance is most opportune, ; PROCEEDINGS OF SOCIETIES. Dustin MicroscoricaLt Cus. 11th April, 1878. Peronospora infestans ravages, exhibited.—Dr. Moore showed some of the leaf-tissue of the potato permeated by the Perono- spora-pest, in order to point out the manner in which it became thereby disintegrated and killed. Dinophysis norvegica, from Melville Bay, was exhibited by Dr. Moss, R.N. Biddulphia Chinensis, from Yeddo Sea, exhibited.—Rev. E. O’Meara exhibited some specimens of Biddulphia Chinensis, Grev., collected by. Mr. Moseley, H.M.S. “Challenger,” from the surface of the Yeddow Sea, near Yokohama. ‘This in all essen- tial points agreed with Greville’s figure of the examples gathered in the harbour of Hong-Kong, but in some minor details a differ- ence was noticeable. In the figure referred to the surface of the valve seen in front view is represented as hollowed in the middle, whereas in the specimeus exhibited the boundary line is gene- rally straight, and in some cases showed a slight elevation in the middle. Moreover, the processes are more robust and longer than they are represented in Greville’s figure of the species. New Closterium from New Jersey.—Mr. Archer showed ex- amples of a Closterium found amongst some Desmidian forms in an old gathering lying in the Herbarium of Trinity College, Dubiin, and made at New Jersey, America, kindly given to Mr. Archer by Professor E. Perceval Wright. On the slide, at first glance seemingly a poor one, there were to be detected no less than forty-three species. The Closterium in question is a very robust form, considerably curved and very strongly striated; the strize very few. It most approached Olosterium costatum, common in this country. Singularly enough, a single example from New Jersey of that species was opportunely on the slide, quite agree- ing with the British and the Irish form, of which he likewise showed a Scotch specimen; and Mr. Archer took the opportunity to contrast it with the new species. This has more of the size and a good deal of the curvature, without the median inflation of Closterium moniliferum ; its strie are much coarser than those of Closterium costatum. Very opportunely, too, there occurred a Zygospore of the new species on the slide; it is large, sub- orbicular, thick-walled, and smooth, seemingly not remaining at all attached to the empty parent-cells. This species Mr. Archer would designate as Cl. crassestriatum. DUBLIN MICROSCOPICAL CLUB. 12] Section of Spine of Temnopleurus toreumaticus, exhibited.—Mr. Mackintosh exhibited a cross-section of the spine of Zemno- pleurus toreumaticus, Klein, which showed a single cycle of solid wedges of an irregular triangle-shape, intercalated between which were narrow spokes of reticulated tissue running out from the central pith. Elongate Unicellular alga, allied to the so-called Closterium obtusum, Bréb. Mr. Archer drew attention to a unicellular form seemingly, so to say, congeneric with the so-called Clos- terium obtusum (Bréb.), and with those other allied forms Mr. Archer has shown from time to time at the Club meetings, and to which possibly should be added one or two usually, but doubt- fully, referred to Spirotenia (including Spirotenia obscura). They are all elongate, like Closterium, it is true, with pale clear spaces at the ends, but no moving granules, nor do the green contents form longitudinal radiating lamine. ‘The present form was but very slightly arcuate, convex on one—the “ upper ”— margin, straight, or nearly so, on the cther—the “lower ’— margin, ends slightly tapered and bluntly rounded, the endo- chrome forming lines running towards the ends. It was thus by its tapering, not cylindrical, figure, and sides not parallel, as well as by its smaller size, distinct from Brébisson’s plant. It more resembled in form that shown at the November meeting in 1875, but it was considerably smaller, and the contents wanted the knob-like ending at either extremity, as well as the still single granule suspended in the middle of the cavity. The cell-wall showed here and there certain obvious thickenings, sometimes imparting a certain amount of waviness to the outline. Cell- division transverse, the two young cells remaining appended end to end for some time. Whether the group of forms in question should be relegated to the Desmidiez at all, and if so, as a dis- tinct and new genus, any more than Ankistrodesmus, for instance, would seem to amount to a begging of the question, inasmuch as conjugation has not been observed in any one of them, if, indeed, the brown so-called Cylindrocystis occurring in the pools on the flat moor above Lough Bray should not be really placed therewith, and which has a smooth orbicular Zy gospore. Winter state of Bryopsis plumosa.—Dr. B. Perceval Wright exhibited some living specimens and a long series of prepara- tions illustrative of a very peculiar mode of growth he had met with during the winter months in Bryopsis plumosa. In some cases the long and very tortuous and irregularly knobbed cells were the much altered pinne of the frond, which had fallen off and then vegetated in this manner ; in other cases these were outgrowths of the base of the frond. In several instances these winter growths assumed the appearance of having oogonia, as in Vaucheria, but in no one instance was a true re- production seen, and after months of careful watching the speci- mens were destroyed by an unknown parasitie algal form. It 122 PROCEEDINGS OF SOCIETIES, might be convenient to indicate these winter growths of Bryopsis as its Vaucheria-condition, the history of which has yet to’be written. May 16th, 1878. Section of Ram’s Penis, shown under a 13 inch Smith and Beck’s objective. Mr. B. Wills Richardson exhibited a carmine stained cross-section of a ram’s penis he had prepared a few previously. The portions corresponding to the human corpora cavernosa were mostly composed of dense fibrous intersecting bands, the intersections being closest at the part where the septum in the penis of man is situated. These bands passed outwards to join longitudinal bands, also of great density, which formed the outer wall of the section. An artery and a vein, the representatives of the corpora cavernosa vessels in man, passed through the centre of each half of the section. In spaces between some of the decussating bands, near the circum- ference of the section, there were portions of unstained tissue largely composed of remarkably fine fibres. Clusters of fat cells were seen in some of the spaces. There was no corpus spon- giosum, strictly so-called. In the section exhibited it was repre- sented by unstained bands which, as it were, held the urethral wall in position. These were probably cross-sections of blood channels. The urethra itself resembled the collapsed human urethra, being in the section a transverse slit having short fissures leading from it. Sections of Strongylocentrotus nudus, exhibited—Mr, Mackin- tosh exhibited a cross-section of the spine of Strongylocentrotus nudus, A. Agass., which showed a small central axis of reticular tissue, numerous well-marked cycles of solid wedges, the whole structure recalling that of Str. armiger, A. Agass. described in Club Minutes of April, 1875. The sections being made purposely rather thick, showed the brilliant purple and yellow colouration to great advantage. New Coscinodiscus.—Rev. E. O’Meara exhibited an undescribed form of Coscinodiscus found in material collected by Mr. Moseley in the harbour of Hong-Kong. This form was of considerable size, being ‘0148" in diameter ; the middle of the valve perfectly smooth, having a somewhat stellate appearance in consequence of the radiate lines of areoles being of unequal length, the ends of some approaching nearer than others to the centre. The lines of areoles are close, the areoles small throughout, distinctly iarger towards the margin. This striking form Mr. O’Meara proposed to name Coscinodiscus Sinensis from the locality in which it was found. Copal with embedded organism, exhibited.—Mr.M’ Donnell, lately from Lakes Nyassa and Nyanza, showed alarge series of polished pieces of copal, having embedded a variety of insects, leaves of plants, &c., in good preservation, and ready to be submitted to a low power of the microscope. DUBLIN MICROSCOPICAL CLUB. 123 June 19th, 1878. Gephyria Dyeriana, exhibited—Rev. E. O’Meara exhibited a specimen of Gephyria Dyeriana, a new species found by him in a gathering made by Mr. Moseley at Kerguelen’s Land, and de- scribed by him (Mr. O’Meara) in ‘ Linn. Journ. Botany,’ vol. xv, p- 59, pl. i, fig. 10. Restelia lacerata, exhibited—Mr. Pim showed the fungus Restelia lacerata found by him much diffused over a hawthorn- hedge at Woodenbridge, Co. Wicklow. Cosmarium, n. s., very minute, with finely spinous Zygospore, exhibited.—Mr. Archer showed examples of an extremely minute and rather common little Cosmarium (to give an idea of its size, scarcely so large as the well-known C. tinctum), of which, how- ever, the zygospore was not before exhibited or recorded. This little Cosmarium was characterised by a flatness of the top— a small character on which to build a species, some might say— but Mr. Archer thought one could hardly miss to know the species for all that; but further, it is the only one of the extremely minute forms with a spinous zygospore. The zygospore is globular and beset with extremely minute fine and pointed spines, lending thereto an almost hirsute appearance. This was the third occasion on which Mr. Archer had taken this form con- jugated. He would call it Cosmarium lasiosparum. Tetraspores in Polysiphonia.—Dr. E. Perceval Wright exhi- bited mounted specimens, showing the different stages in the evolution of the Tetraspores in Polysiphonia formosa. Their point of origin would seem to be always between the central cell and its surrounding cells (siphons). At the base of the central cell a small portion of protoplasm is detached, this then soon divides transversely, the lowermost morsel forms a very minute table, while the uppermost assumes an oval form ; this latter remains attached to the former by means of a little stalk of pro- toplasm, which eventually supports the cell which originates the tetraspores. These are formed by the division of the protoplasm of the cell formed out of the upper oval-shaped mass. Ié divides into four nearly equal portions ; these have no points of attach- ment to each other. But in the process of growth these four masses gradually arrange themselves after the very characteristic method of these vegetative cells. July 20th, 1878. Cylindrocystis crassa and Mesotaeniwm violascens in company from Co. Kerry, were shown by Dr. Moore. These alge are widely diffused, yet scanty, and it is hard to get a good and pure unmixed gathering. Chytridium with bacillar zoospores—Mr. Archer showed a Chytridium on Kremosphera viridis with zoospores caught during egress. The point of interest was their very elongate or cylin- drical figure, not, as seems usual, orbicular, or nearly so. With 124, PROCEEDINGS OF SOCIETIES. the bright speck at one end, they had thus a great and curious resemblance to some Bacterian forms. Cosmarium fontigenum, Nordst.—Mr. Archer showed examples of the only Cosmorium he could find in the stuff labelled Cos- marium fontigenum in Nordstedt’s and Wittrock’s “ Alge exsic- cate’’—this, if it be the form had in view by Nordstedt, is a very common one in this country and in Scotland, but it hardly agrees with the figure accompanying the material. That under view is somewhat like Oosmarium bioculatum, but differs in its truncate top, and in possessing a slight depression just beneath the obscure upper angles, thus causing the ends to appear as if somewhat produced. If this be Nordstedt’s C. fontigenum, it would be the first time that author would have so far exaggerated the characteristics of any of the many species brought forward by him as to render the least doubt of the identity, for they are always most truthful and charmingly accurate in all details. It is possible, however, the true fourm may have yet to be en- countered. Triceratium problematic, shown.—Rev. EK. O’Meara exhibited a form of Triceratium found by him in Mr. Moseley’s collection at Kerguelan’s Land, but only one example of which was met with, and that not quite perfect. It was very large, and the areolation distinct ; he could not as yet identify it with any form of this genus as yet described. Pithophora Kewensis, State of, exhibited.—Dr. E. Perceval Wright exhibited a series of mounted specimens of Pitho- phora Kewensis, and some living specimens, for which he was indebted to the goodness of Sir Joseph Hooker, C.B. This species, described by Dr. Wittrock from specimens found in the Tropical Aquarium at Kew, was in general appearance somewhat like a Cladophora. But it was remarkable to find in the specimens exhibited, which seemed to represent the winter stage of the plant, almost the same branchless, tortuous, and irregularly knobbed filaments as he had shown at the May meeting in Plumosa. The resemblance was, of course, only a very geveral one, for in the one plant we had an unicellular, in the other a multi-cellu'ar algal form; still this stage of Pithophora was well worthy of being very attentively studied. oer ee) UW. Agrees) | New Series, No. LXXIII. B... 6s. JANUARY, 1879. THE QUARTERLY JOURNAL LONDON: J. & A. CHURCHILL, NEW BURLINGTON STREET. MDCCCLXXIX. J.-£, Adlard.] : ; _ . [Bartholomew Close. -pivar Lospects. The objects which I examined are the following : 1. The epithelial cells of the mucous membrane of the intes- tine, including the cells lining the crypts of Lieberkiihn. 2. The ciliated epithelial cells lining the tubes of the epididymis. 3. The gland cells of the submaxillary gland of dog and man. 4, The gland cells of mucous glands. 5. The epithelial cells of the glands of stomach and of Brunner’s glands. 6. The gland cells of liver. 7. The cells of laminated pavement epithelium, including those of the rete Malpighii of the epidermis. This Journal, vol. xviii (New Ser.), July, 1878, p. 315. VOL. X1X.—-NEW SER, I a eee — = CONTENTS OF No. LXXIII.—New Series. NOTES AND MEMORANDA: Observation on the Capitellide by Dr. Huco Eisic 2AM. Rottoun 115 Bacteria as the Cause of the Ropy change of Beet-root Sugar ER Landrosterl 16 Loc. cit., p. 187. * Loe. cit., p. 189: 180 P, HERBERT CARPENTER. tion! that many Paleocrinide and Cystidea have remained permanently in this condition appears to me to be an ex- ceedingly happy one, as far as the former group is concerned, Fic. XIII.—Seation through a Pentacrinoid, with a closed tentacular ves- tibule, the mouth not having yet broken through to the exterior. (After Gotte.)? ae. Ambulacral epithelium. al, Alimentary canal. an. Rudiment of anus, marking the position of the blasto- pore. tp. Posterior division of the left peritoneal sac, from which the subtentacular canals are derived. /p’. Its anterior division, forming the tentacular vestibule. m. mouth. mt. Mesentery, separating the cavities of the right and left peritoneal sacs. fi Roof of the teatacular vestibule = vault of Palzocrinoidea. rp. Right peritoneal sac, giving rise to the greater part of the body cavity. rp’, Its posterior extension into the developing stem. t. Tentacles. wr. Watervascular ring. though I do not think it applicable to the Cystids with grooves on the “vault.” It gives us a complete explanation of their subtegminal mouth, the presence of which has been so successfully demonstrated by Wachsmuth,’ in accordance with Schultze’s suggestion.* Thus, in many Paleozoic genera the mouth is permanently subtegminal, while in the more modern forms it is only temporarily so during the 1 Loe. cit., p. 687. ? See Plate xxvi, fig. 19, of Gotte’s paper. 3 Loe. cit., pp. 116, 120. * Loe, cit., p. 7 (119). ORAL AND APICAL SYSTEMS OF THE ECHINODERMS, 18] Pentacrinoid stage of development, and ultimately opens directly to the exterior. Wachsmuth’s descriptions of some natural casts of the structures below the vault of the Actinocrinide correspond in a most striking manner with what Gotte has shown to be the condition of the young Pentacrinoid. He describes the centre of radiation for the concealed ambulacra as a variously shaped space or plane, surrounded by a furrow. The middle of this space is frequently occupied by a small opening, or by a little cone indicating an aper- ture leading to the inner cavity. This little central opening, situated at the upper end of the vertical axis below the vault, occupies, as Wachsmuth points out, the same position as the mouth of Antedon occupies in the peristome (fig. X11T, m). Now, this lip or peristome is nothing more than the floor of the tentacular vestibule, which is closed till late in the Pentacrinoid stage (fig. x111, r), but ultimately opens to the exterior ; while the corresponding space in Actinocrinus remains permanently closed and covered in by the system of actinal plates, namely, the single central one with the six (=5) orals around it. Gotte’s suggestion also helps us to understand why there is no central actinal plate developed inside the oral circlet of Comatula. For it would be situated precisely at the point where the rupture of the peristome occurs that placesthe tenta- cular vestibule, into which the true mouth opens,in communi- cation with the exterior. Were it developed it would only be in the way, and have to undergo resorption to a greater or less extent, just as the central abactinal plate of many Urchins is more or less completely resorbed after the appearance of the anus. We find, then, that the oral system of the Palgocrinoidea consists of a central actinal plate, around which six (= five) oral plates are disposed. The resemblance between this arrangement and that of the central abactinal plate, with the five basals disposed interradially around it, strikes one at once, and we thus find a complete correspondence between the primitive conditions of the skeletal elements developed around the two peritoneal sacs of the Crinoid larva. On the actinal as well as on the abactinal side there is a single central plate surrounded by five others, which are inter- radial in position. There is, however, no known Crinoid in which we find this primitive condition persisting, even as an embryonic feature. For the central actinal plate is limited to the Palgocrinoidea, while in all but Holopus (so far as is known) the rudiments of the stem make their appearance at 182 P, HERBERT CARPENTER, a very early stage of development, simultaneously with those of the other plates of the skeleton, and (as I believe) carry away the central abactinal plate from the neighbourhood of the basals. A suggestion essentially similar to the one just made has already been put forward by Wachsmuth,' who regards the central abactinal plate as the basis, a view which, as I have already endeavoured to show, is no longer tenable.2 Wachsmuth also compares the interradial peri- ABACTINAL SYSTEM. Actinat System. Wachsmuth. | P. H. Carpenter. Central Basis. Central Plate at Central Plate. Plate. end of stem. Peripheral Parabasals Basals. Orals. Plates. or Interradial. Subradials. | pheral plates (orals) of the actinal surface to the so-called parabasals or subradials of the abactinal system, which ‘were undoubtedly the first developed parts of the dorsal side, and the parts which are the most highly developed in the Cystideans.” It will be noted how this passage strengthens the arguments which I have already brought forward in favour of the view that the so-called subradials are the true basals of those Crinoids in which they occur. The diameter of the visceral mass of the Pentacrinoid is so slight that the orals are sufficient to cover it in com- pletely on the ventral side. But in the Palzocrinoidea it is not only absolutely, but also relatively, much larger, so that the oral or “apical” system alone is insufficient to cover it. Accordingly we find that the “ apical’ plates do not make up the whole of the vault of the Palzocrinoidea, but “ there are other summit plates following a radial direction, which are either attached to the apical pieces or separated from them by a belt of small polygonal plates,” while the inter- mediate spaces between these radial areas are occupied by the interradial plates of the vault. The number and arrange- ment of these plates vary greatly in different species, accord- 1 Loe. cit., p. 189. 2 Part I, this Journal, Vol. XVIII, pp. 360, 370, 371, ORAL AND APICAL SYSTEMS OF THE ECHINODERMS, 183 ing to the number of primary arms that spring out directly from the body. As a general rule, according to Wachsmuth,}! “the summit plates increase in proportion to the number of primary arms of a species, in the same manner and on the same principle as the plates of the dorsal side.” We find then, that in the Palwocrinoidea there is an almost complete correspondence in the skeletal developments on the actinal and abactinal surfaces of the body.2 The centre is occupied in each case by a single plate, surrounded by five others, which are situated interradially. But the first and second radials of the abactinal pole appear to be unrepre- sented on the actinal surface. Peripherally, however, there is again a very close correspondence in the arrangement of the plates on the two surfaces. The vault of the Palgocrinoidea appears to be something sui generis, and altogether unrepresented in our more modern forms. According to Wachsmuth,? with whom I entirely agree, ‘‘it cannot in the remotest degree be homologised with the ventral peristome ” of the recent Crinoids. ‘It forms a continuation of the radial and interradial series of the dorsal side, and serves merely as a covering and protection for the organs underneath.” There is every reason to believe that these were of essentially the same character as in the recent Crinoids, namely, ambulacral grooves with the radial water- vessels underlying them. The ambulacra of a Comatula or Pentacrinus are continued from the arms on to the disc, where they converge towards the peristome; while in the Paleocrinoidea they enter the cavity of the vault by aper- tures at the base of each arm, and continue their centripetal direction as subtegminal channels along the inner surface of the vault. These channels were first discovered in Actino- crinus by Huxley and Billings,* and are “ floored by a series of plates which form an elongated arch under them.” Alternating with the upper edges of these plates there are found, in good specimens, two rows of minute quadrangular interlocking plates, longitudinally arranged so as to cover the tubes. Hence, under the vault these canals must have been “‘ formed of two rows or nieces below (subambulacral) and two above (swperambulacral), all alternately arranged.” By Wachsmuth, as by Meek and Worthen,® they are 1 Loe. cit., p. 187. * See Addenda, No. 3, on p. 204. 3 Loc. cit., p. 190. * «On the Cystidee of the Lower Silurian Rocks of Canada,’’ ‘ Geo- graphical Survey of Canada,’ decade iii, p. 27. »* © Notes on some points in the Structure and Habits of the Palsxozoic Crinoidea,” ‘The Canadian Naturalist,’ 1869, pp. 443, 444. 184 P. HERBERT CARPENTER, regarded as continuations of the ambulacral grooves of the arms. In these Actinocrinide the structure of the arms is not yet known; but in Cyathocrinus the brachial ambulacra are bordered by a row of interlocking triangular plates, which Wachsmuth! compares to the “‘ marginal plates ” in recent Crinoids. They rest on an outer row of plates longitudinally arranged and attached to the arm-joints. This double series of alternating plates extends beneath the vault of Cyatho- erinus, but the subambulacral plates appear to be absent from the grooves of both vault and arms. We thus find that the ambulacra of the Crinoids may be surrounded by three sets of plates—(1) An upper series, present in both Cyatho- crinus and Actinocrinus. (2) An under series present in Actinocrinus only. (3) A lateral series, present in Cyatho- erinus only (so far as we yet know). Wachsmuth has already pointed out the homology of the upper series (1) with the marginal plates in recent Crinoids (fig. xiv sup), but he has overlooked the fact that both the other series (2, 3) are also represented, at any rate in the disc of Pentacrinus caput-meduse. According to Muller’— “An den Armen und Pinnulae beschrauken sich die kalkigen Bildungen auf der Ventralseite bloss auf die Saumplattchen der Ambulakralrinnen. Am Kelch dagegen sind die Ambulakralrinnen noch ausser den Saumplattchen durch kalkigen Bildungen unterstiitzt. Diejenigen Plattchen welche den Rand der Ambulakralrinnen bilden, haben eine wallartige Erhohung und dienen den Ambulacra Sowohl fur Hinfassung als fur Stiitze der aufger- ichteten Saumplattchen; man kann sie Seitenplatten der Ambulacra MEDNEN. Fes. hacia ess Unter der weichen Auskleidung der Rinne liegen auch noch Tafelchen.” This last set of plates (fig. xrv sub) was termed subambu- lacral by Miller, and there can, I think, be little doubt that Fic. XIV.—Diagram of the plates surrounding the ambulacra on the dise of Pentacrinus. Slightly altered from J. Miller. ad. Adambu- lacral (3). az. Anambulacral. = sw. Subambulacral (2). Sup. Superambulacral = marginal plates or “ Saumplattchen (1). wo. Water vessel. it represents the double row forming the floor of the subteg- minal galleries of Actenocrinus. ' Loc. cit., p. 122. 2 © Bau der Echinodermen,” loc, cit., p. 57. ORAL AND APICAL SYSTEMS OF THE ECHINODERMS. 185 These galleries enclosed between the super- and sub- ambulacral plates lodged, I believe, not only the ambulacral grooves but also the water vessels. In the recent Crinoids and Starfishes these two are separated in each arm by a membranous partition containing several structures, which need not be considered here. Around the mouth the grooves expand into a peristomial area, beneath which is the water- vascular ring. The subtegminal galleries of Actinocrinus open into what Wachsmuth! calls an “‘ annular vessel,” com- posed of minute interlocking plates, and resting on the convoluted digestive organ. This ring has five small open- ings leading into the subtegminal galleries, and alternating with these on the lower side of the ring there are five other small openings, which Wachsmuth supposes to have been ‘in connection with organs of the interradial system (com- municating perhaps with a circulatory system).”’ This “annular vessel” represents, I believe, both the peristomial area of our recent Crinoids and the subjacent water-vascular ring, which is only separated from it by mem- brane. It is easy to understand the nature of the inter- radial openings on its floor. I imagine them to be the openings of the small tubes which, in the recent Crinoids, depend from the water-vascular ring into the body cavity. According to Ludwig,” they open freely into it, and are to be regarded as afferent vessels serving for the introduction of water into the ambulacral system, and therefore as collec- tively representing the sand canals of the other Echino- derms. In the Ophiurids, however, there is not only a sand canal extending from the madreporite to the water vascular ring, but depending from this ring into the body cavity there are a number of apparently cecal diverticula, the vasa ambulacrala cavi of Simroth.2 The resemblance between these and the so-called “ Steincanale ” of the Cri- noids is very close, as pointed out by Huxley* and the two sets of tubes appear to me to be truly homologous. Like Greeff,> I am not altogether satisfied (pace Ludwig) that they actually open into the celom in Comatula, while Simroth believes them to be blind in. Ophiactis. Hence I cannot quite agree with Ludwig’s view of their character. 1 Loe. cit., p. 118. 2 « Crinoideen,” loc. cit., p. 48. * “ Anatomie und Schizogonie der Ophiactis virens, Sars.,” Zeitsch. f. wiss. Zool.,’ xxviii, p. 456. * «The Anatomy of Invertebrated Animals,’ p. 586. * “Ueber den Bau der Crinoideen,” ‘Marburg Sitzungsberichte,’ No. 1, 1876, p. 22. 186 P. HERBERT CARPENTER, For if they do functionally represent the sand canals of the other Echinoderms,’why do they coexist with the sand canal in the Ophiurids? Whatever their nature, however, they were present in Actinocrinus, but greatly reduced in number. In both Antedon and Actinometra they are extensively deve- loped ; but Ludwig has found that in Rhizocrinus! there is but one in each interradius, and I imagine that this was also the case in Actinocrinus. From what has been said above, it will be evident that I entirely accept Schultze’s hypothesis of a subtegminal mouth in the Paleocrinoidea, which has been attacked by Billings,” but ably defended by Wyville Thomson,’ Liitken,* Meek and Worthen,’ and lastly, by Wachsmuth.® The last mentioned observer says that ‘‘ The little central aperture located at the upper end of the vertical axis, occupied on the casts, and hence below the vault of these Crinoids, exactly the same position that the internal mouth of Antedon, occupies at the peristome, while the position of the string-like ridges (in case they represent passages, as I can hardly doubt) is analogous with that of the open food grooves of recent Crinoids.” I cannot but believe that Wachsmuth’s explanation of these ridges is the true one, though it is by no means necessary that they should repre- sent closed passages. In many recent Comatule it is ex- ceedingly common for the ambulacral grooves of the disc to be considerably raised above the interambulacral areas, so as to present an appearance of “ elevated rounded ridges almost like strings overlying the surface,” just as Wach- smuth describes in his casts. Billings’ objections to the theory of a subtegminal mouth in the Palzocrinoidea, appear to me to be the result of a confusion of terms, and of a want of acquaintance with the anatomy of recent Crinoids. In the first place he described two quite distinct and separate structures under the single name of ‘‘ambulacral groove.” On p. 20 of the Decade, he used this term in the sense in which it was used by Miiller, namely, to denote the furrows radiating outwards from the Yeluoc..cit., p. 118. * “Notes on the Structure of the Crinoida, Cystidea, and Blastoida,” ‘Canadian Naturalist,’ 1869, pp. 277—283, and 1870, pp. 191—198. 3 “On the Structure of the Palzozoic Crinoids,’ ‘ Nature,’ vol. iv, pp. 496—497. * “Notes on Loven’s Articles on Leskia mirabilis and on Hypouome aa ” Canadian Naturalist,’ 1868, pp. 489—441, and 1869, pp. 267— 269. 5 Loe. cit., pp. 441—446. 6 Loc, cit., pp. 116—120. ORAL AND APICAL SYSTEMS OF THE ECHINODERMS. 187 mouth over the ventral perisome of the disc and arms. These grooves are altogether outside and above the radial trunks of the water-vascular, blood-vascular, and generative systems, which are covered in by the ventral perisome bearing the grooves. Billings, however, supposed that ‘‘ the grooves of the arms are occupied” by these tubes, and spoke of them as continued into the interior of the vault by notches in the first radial piates. Here he confounded the supra- tegminal ambulacra with what I have elsewhere described as the “ ventral radial furrow,” occupying the middle line of the skeleton. All the soft parts of the arm are situated above, this skeletal groove, but beneath the ambulacral groove, which Miiller was accustomed to call the “ Ten- takelrinne,’ in distinction to the skeletal one which he termed the Armrinne “ worin Weichtheile gelegen sind.”? Billings, however, confounded the two, and because the vas- cular and generative tubes which lie above the armgroove (being partially contained in it) do not communicate with the stomach, he supposed it to have been impossible for food particles to gain access to the interior of the animal from the arms of a Paleocrinoid, which, as far as we know, resembled in these points the arms of a Comatula or Penta- crinus. Here he quite overlooked the fact that the ventral perisome covering the arm of a recent Crinoid bears the true ambulacral groove, along which, and therefore above the vascular trunks, the food particles travel towards the mouth. The remains of these brachial ambulacra are found in the Paleocrinoidea, and they undoubtedly entered the vault by the ambulacral openings at the bases of the arms, which Billings himself discovered, together with and above the vascular trunks. Billings? supposes that the ambulacra of the Crinoids and Asterids contain the vascular, nervous, and generative trunks, “which are situated on the outside of the animal, and communicate with the interior through the mouth.” Consequently he regarded this aperture as having three functions, being (1) the oral, (2) the ovarian, and (3) the ambulacral opening, and he therefore ‘compared it with respect to the last two, to the openings at the arm bases of the Paleocrinoidea. ‘These were undoubtedly both ovarian and ambulacral, as the generative organs and the water- vessels passed through them to reach their respective cir- cumoral centres. The ambulacra of the arms also entered here and converged towards a subtegminal mouth. Billings refused to admit the oral nature of this opening, which he ' « Pentacrinus,” loc. cit., p. 35. ? Decade iii, loc. cit., p. 19. 188 P. HERBERT CARPENTER. appeared to regard as a central ambulacral orifice, and con- sequently supposed that on Schultze’s theory, ‘* Caryocrinus ornatus was a polystome animal, and drew in its food through its six ovarian apertures.” To me, as it did to Billings,’ this certainly does appear ‘‘ utterly incredible.” Wyville Thomson,” Agassiz,> and Liitken have laid great stress on the fact that in all the recent Echinoderms the mouth is in the centre of the radial system, and that, there- fore, the valvular orifice of the Paleocrinoidea, which is situated at the point in the vault behind the radial centre of the ambulacra, cannot possibly be the mouth, but is probably the anus. Billings admitted the universal connection of the mouth and radial centre in the recent Echinoderms, but, being firmly convinced that the valvular orifice was oro-anal in function, he asserted* that “in at least a large proportion of the paleozoic Crinoids the mouth was altogether discon- nected from the radial system,” this being evident from ‘‘simple inspection.”” He did not, however, make it clear how “simple inspection” can demonstrate the oral nature of the valvular orifice. He supposed the same to have been the case in the Cystids, in which, like De Koninck® and Gray,® he regarded the “‘ ovarian pyramid” of Von Buch as oral in function; while the small opening near the centre of the upper part of the body, from which the ambulacra radiate, was called by him an ambulacral orifice,’ through which “the vessels of the aquiferous system and of the organs of reproduction which were situated in the grooves of the arms communicated with the interior.”” Loven’ has entirely adopted Billings’ views, but Agassiz, like Liitken and Wyville Thom- son, has opposed them strongly, and reaffirms the views of Volborth and Miller, that the mouth is at the radial centre of the ambulacra, and is, in fact, the minute ambulacral orifice of Billings. It appears to me that there can be no doubt about this so 1 «Canadian Naturalist,’ 1870, p. 197. * “On a New Palxozoic Group of Echinodermata,” ‘Edinburgh New Philosophical Journal,’ vol. xiii, p. 106. ° “Note on Lovén’s Article on Leskia mirabilis,’ ‘ Annals of the Ly- ceum of Natural History,’ vol. ix, pp. 243—245. 4 «Canadian Naturalist,’ 1869, p. 279. > Loe. cit., pp. 53 ef. seq. ® ‘Catalogue of the Recent Hchinide or Sea Eggs in the Collection of the British Museum,’ 1855, p. 63, t. 4, f. 4. 7 Decade iii, p. 15. ° “Om Leskia mirabilis,’ Gray, ‘Ofversigt af Kongl. Vetenskaps- akademiens Forhandlingar,’ 1867, No. 5, pp. 436—440, ORAL AND APICAL SYSTEMS OF THE ECHINODERMS, 189 far as Spheronites is concerned, this being the type taken by Lovén for comparison with the other Echinoderms. Wyville Thomson, indeed, regards these forms as “ Crinoids, or a parallel group ;” and 1 imagine their ventral surface to be in every respect homologous with that of our modern Crinoids, more especially of Actinometra. In this genus the ambulacra form an open horseshoe-shaped curve, very much as in Spheronites. The mouth is placed in the middle of this curve, but it is often extremely small and inconspicuous, being merely a short and narrow slit in the peristomial area. I have often experienced great difficulty in finding it even in spirit specimens, in which the perisome was quite bare ; while in dry specimens of such species as Act. solaris, in which the anambulacral plating is often very completely de- veloped, I should, like Miiller,! have altogether failed to find it, had I not known with tolerable certainty, from other considerations, where to look for it. I imagine the Cystids with calycine ambulacra to have resembled, in this respect, such recent Crinoids as Hyocrinus, in which there is an ex- tensive anambulacral plating on the disc and minute plates in the marginal leaflets at the sides of the ambulacra. We find precisely the same condition in the so-called recent Cystid, Hyponome Sarsi, in which the ambulacra are fringed and overlapped by marginal scales, while the remainder of the ventral surface ‘‘is clothed with rather small, thickset, irregular scales ;”? and it appears to me that Wyville Thom- son® is right in regarding Hyponome as a true Crinoid. According to Loven’ the “absence of any indication of a calyx” tells strongly against this view, but I believe that Hyponome is merely the disc of a Crinoid, which has fallen out of its calyx, and that indications of its attachment to a skeleton are seen in the “ five broad dichotomous rays on the dorsal surface.’”* Thus then I regard the vault of the Cystids (at any rate of those with open ambulacra), as quite distinct from the vault of the Palgocrinoids, but as homologous with the ventral perisome of our recent Crinoids. This is frequently covered with an extensive anambulacral plating, which is perforated by the small water-pores. In Pentacrinus most of the anambulacral plates are perforated in this way, the 1 “Ueber die Gattung Comatula, Lam. und ihre Arten,’” ‘ Abhandl. der Berlin Akad.,’ 1847, p. 245. 2 * Nature,’ loc. cit., p. 497. 3 3 On Hyponome Sarsii, a recent Cystidean,” ‘Canadian Naturalist,’ 1869, p. 266. * See Addenda, No. 4, on p. 205. 190 P, HERBERT CARPENTER. water-pores being very numerous, and in Caryocrinus! the pores are also numerous, but ‘‘ nehmen den antiambulacralen Theil des Kelches hinter den Armen bis zur Basis ein.” On the other hand, Ludwig? has shown that in Rhizocrinus there is but one water-pore in each interradial area of the disc, although the plating of the perisome may be very exten- sive. Water-pores are found in most Cystids, being variously arranged into poriferous or tubular structures, but the distri- bution of these is very different in different genera. They are usually antiambulacral, as in Caryocrinus, but in Protocrinus and Glyptospherites they occur between the ambulacra of the ventral surface as in Pentacrinus. Billings® has at- tempted to show “ the gradual passage or conversion of the respiratory organs of the Cystidea, Blastoidea, and Palao- crinotdea into the ambulacral canal system of the recent Echinoderms.” I cannot, however, regard his attempt as successful. This is not the place for a critical examination of his arguments, but I may remark that the pectinated rhombs of the Cystids and the hydrospires of the Blastoids are all interradial, while the water-vascular trunks of the recent Echinoderms are radial in their origin. Further, Miiller has pointed out that the homologues of the former in the recent Crinoids are the water-pores of the disc, the exist- ence of which appears to have been quite unknown to Billings; and Ludwig* has recently shown the very close resemblance between the structure of the so-called genital clefts of the Ophiurids and the hydrospires of Pentatremites, so that there is no occasion to seek for the homologues of the latter in the water-vascular system of the Crinoids or Ophiurids as Billings has done. The skeleton of a modern Crinoid then, may be regarded as composed of three distinct systems of plates, viz. the abactinal or apical, the actinal or oral, and the intermediate, which is both ambulacral and inter- or anambulacral. These may be developed in very different degrees of complexity, especially in the older forms. Their mutual relations are presented as simply as possible in the modern Hyocrinus, while in genera like Eucalyptocrinus and Rhodocrinus, one or more of these systems is extremely complicated by the extensive subdivision of its primary elements and the de- velopment of secondary ones. Lastly, in Comatula the oral Bau der Echinodermen,’ p. 64. 2 Loc. cit., p. 118. 3 “Canad. Nat.,’ 1869, p. 426. 4 “ Beitrage zur Anatomie der Ophiuren,” ‘ Zeitschr, fiir wiss. Zool.,’ Bd. XXXl, pp. 282-285. ORAL AND APICAL SYSTEMS OF THE ECHINODERMS. 19] and the apical systems, although extremely well developed in the larva, undergo very extensive changes which result in the total disappearance of the oral system, and a consider- able modification of the basal element in the calyx. In some tropical species the anambulacral system may reach a high stage of development, but in the British species it is very imperfect even in the larva, and shares the fate of the oral plates by undergoing complete resorption.! I have already endeavoured to determine the homologies of the Crinoidal calyx in the other Echinoderms. Let us now attempt to solve a similar problem with regard to the other elements of their skeleton. The oral system of a Crinoid consists essentially of five plates or series of plates, disposed interradially around the mouth. I have already stated that I have entirely failed to find any traces of these plates in any of Agassiz’ figures of Asterid larve, and that as far as can be judged from Metschnikoff’s figures their pre- sence in the Ophiurids is very uncertain.” In the Holothu- rians, however, the oral plates of the Crinoids are very well represented. Kowalewsky® figures five large triangular plates around the mouth of the young Psolinus brevis, without any trace of a commencing skeleton in any other part of the body. He makes no reference to them whatever, but they seem to persist through life; if not in Psolinus, at any rate in Psolus ephippifer in which, according to Wyville Thomson, a slightly elevated pyramid of five very accurately fitting calcareous valves closes over the oral aperture and the ring of oral tentacles. Again, Krohn‘ describes a Holothurian larva in which the border of the blunt and rounded anterior end is “durch 5 vorspringende durchlocherte Kalkscheibchen in eben so viele Lappen getheilt.” Besides these, the whole perisome con- tains a number of overlapping reticulated plates. These also occur in the Cucumaria larva figured by Selenka,’ but there is no trace of orals,and the plates are smaller than in Krohn’s larva, and not in contact. With regard to the Hchini, it might seem at first sight rather a hopeless task to attempt to determine the elements of an oral system among the large number of plates which 1 W. B. Carpenter, ‘ Phil. Trans.,’ loc. cit., p. 471. 2 See Addenda, No. 5, p. 205 3 ** Beitrage zur Entwickelungs-geschichte der Holthurien,” ‘ St. Peters- burg Memoirs,’ tome xi, No. 6, fig. 13. 4 “ Beobachtungen aus der Entwickelung der Holothurien und Seeigel,”’ ‘ Miiller’s Archiv.,’ 1851, p, 347. * “Zur Entwickelung der Holothurien,” ‘Zeitschr. fiir Wiss. Zool.,’ Band. xxvii, taf. xiii, fig. 28. 192 P. HERBERT CARPENTER, cover the buccal membrane of an ordinary Urchin. But in the remarkable form Leshkia (Palzostoma) mirabilis, there are only five plates on the buccal membrane. These are large, triangular, and interradial in position, as they alter- nate with the bases of the ambulacra. Here I believe we have the key to the problem, one which both Gray and Lovén have attempted to use, and in two different ways, neither of which seems correct when viewed by the light of our present knowledge. In 1851, Gray! wrote as follows, respecting Leskia: ‘In the form of the mouth and vent it has con- siderable affinity with the fossil Cyst:dea of Von Buch, as especially the genus Echinospharites.” Some years later, when Billings and others had attempted to show that the so-called “ ovarian pyramid” was really the mouth or mouth- anus, Lovén® compared its five valves to those surrounding the mouth of Leskzia, a point which seemed to give con- siderable support to Billings’ views. On the whole, however, it seems most probable that Agassiz, Liitken, and Wyville Thomson, are right in regarding the ovarian pyramid as anal in function. Agassiz? compares its five valves to the five plates which cover the anal opening in many young Echini, during a considerable period of their growth, but which ulti- mately undergo much modification. Leaving the Cystids for the present and returning to the simpler and more comprehensible recent Crinoids, I think there can be little doubt as to the homology of the oral plates of Hyocrinus and of the Pentacrinoid larva of Antedon, with the similar and similarly situated plates in the actinostome of Leskia. We have seen that the Crinoid skeleton may be regarded as composed of three distinct systems of plates, the apical, the oral, and the intermediate. The latter is developed in an equatorial zone, occupying the larger or smaller area of perisome which gradually appears between the oral and apical systems of the larva. A general homology (irrespective of details) between the apical systems of Crinoids and Eehini is now universally admitted ; and if, as I have endeavoured to show, the five oral valves on the actinal membrane of Leskia are homologous with the oral circlet of a Crinoid, then the coronal plates of the Urchin must represent those developed in the equatorial zone of the Crinoid. A still closer resemblance in matters of detail will be pointed out further on. In some young spatangoids (Brissopsis) the actinostome is 1 Loe. cit., p. 63. > © Om Leskia mirabilis,” loc. cit., pp. 4836—440. 3 Note on Lovén’s article on Leskia mirabilis, loc. cit., p. 243. ORAL AND APICAL SYSTEMS OF THE ECHINODERMS, 193 pentagonal, while in others there is a smaller number of actinal plates than usual, but Palzostoma is the only genus in which a regular radiate arrangement is perceptible. The actinal membrane of all Desmostecha, whether it be regularly imbricated or not, bears ten large prominent interradial plates, which are pierced by the ten large buccal tentacles.’ They appear to develop from the continuous plating of lime- stone cells which extends over from the abactinal side so as to cover the whole actinal surface of the young Urchin. They are found in all young Echini, being the first plates to appear of all those on the actinal membrane,” while in many genera they always retain a ‘greater preponderance.” Agassiz regards them as homologous with the five actinal plates of Zeskia, and they would therefore represent the five oral plates of the Crinoids. This view is strengthened by the fact that they are pierced by the ten large buccal tentacles, much in the same way as the ocular plates (=radials) are said to be pierced by the odd terminal tentacles of the ambulacra, while the orals of the young Crinoid are also opposite to five pairs of short tubular tentacles placed interradially, though not perforated by them. These orals alternate with five large azygos tentacles, the homologues of which in the Urchins separate each pair of buceal shields, and ultimately become the odd terminal tentacles. I am by no means sure that Agassiz is right in comparing these buccal plates of the Desmosticha to the oral valves of Leskia. In the first place they are paired and perforate, while the latter are single and imperforate. ‘This, however, is a comparatively unimportant difference. The one on which I would lay most stress is the mode of origin of the buccal shields, which is very different from that of the oral plates of Crinoids. Agassiz himself describes them as formed by an extension of the limestone plating from the abactinal over on to the actinal surface. It can, of course, be urged that this be also the origin of the oral valves of Leskia. If so, they cannot be homologous with the oral plates of the Crinoids; but, as far as mere appearance goes, they resemble these far more than they do the ten perforate buccal shields of the Desmosticha. Lovén,* however, gives an entirely different interpretation of these buccal shields. . aoe of the Hchini,’ p. 699, plates ix, figs. 2 and 4, and x, "2 ‘Revision,’ p. 735. 3 © Revision,’ p. 583. * Loe, cit., pp. 27—29, 194. P, HERBERT CARPENTER. He regards them as the “rudiments of the first primary plates of the ambulacra,” which are arrested in their extension towards the peristome by the resistance of the auricles that are attached to the internal surfaces of the ambulacral plates, and serve as supports to the lantern. For between every two pairs of these, nearer the periphery, he finds smaller triangular plates intercalated, which he regards as the first traces of the interradial areas. In the Cidaridez, however, the bases of the auricles are interradial, and they therefore offer no resistance to an extension of the ambulacra towards the margin of the corona. As the plates successively reach this margin, their sutures are opened and they undergo considerable changes, so as to give rise to the imbricated plates of the actinal membrane, which are therefore merely metamorphosed ambulacral plates. In many Urchins (Echinus, Temnechinus, Strongylocentrotus) the actinal membrane is quite bare, with the exception of the ten perforated buccal shields. ‘These are formed very early near the edge of the test, but gradually approach the bases of the teeth during development. In certain genera (Porocidaris) small imbricating plates are formed between them and the teeth, while the remaining peripheral part of the membrane is left bare. More commonly, however, this is covered by imbricating plates in greater or smaller number. Thus, in Hemipedina the ten buccal plates are large and occupy nearly the whole membrane, which bears eight or ten very much smaller ones between them and the test. But in Salenia and Tozxopneustes the membrane is chiefly covered by a number of imbricating plates closely packed together, though the ten perforated buccal plates remain distinct. In TZrigonocidaris they are but slightly more prominent than the others, and in the Diadematide and Cidaride all trace of them is lost, at any rate in the adult, as seems also to be the case among the irregular Urchins. In LEchinothriz and in the Kchinothuride the actinal membrane is covered, as in the Cidaride, by a number of movable imbricating plates, which perform the part of ambulacral and interambulacral plates, like those of the test ofan ordinary Urchin. For the imbricated plates continuing the ambulacral system on to the actinal membrane are pierced for suckers identical with those of the rest of the ambulacral zone, extending unbroken to the actinostome as far as the buccal tentacles, which are not different in size from the other ambulacral tentacles. These imbricating buccal plates which Lovén regards merely as metamorphosed ambulacral plates, form a much ORAL AND APICAL SYSTEMS OF THE ECHINODERMS 195 larger proportion of the test of the C:daride than the plates on the actinalmembrane do in the other Urchins. For the number of coronal plates is small, especially in young specimens, the test of which seems to consist almost entirely of an actinal and abactinal system, separated by a narrow band of coronal plates. Further, these imbricated buccal plates are arranged radially in rows made up of more than two plates, with the plates lapping in opposite directions in the ambulacra and interambulacra. These peculiarities are also found in the plates not only of the buccal membrane, but also of the corona of the Hchinothu- ride, and they are characteristic of the Palechinide. Hence, Agassiz! has suggested that the test of these last was made up of plates homologous with the buccal plates of Cidaris. Were the narrow band of coronal plates in a young Cidaris to disappear entirely, and the buccal plates to take a correspondingly great development, we should have a spherical Urehin agreeing in every respect with the typical Palzchinus. The test would be reduced to the actinal and abactinal systems, and be entirely made up of small ambulacral and interambulacral plates consisting of several rows, and homologous with those of Asthenosoma and Crdaris. Instead of regarding the test of a Palechinus as consisting only of an abactinal, together with an enlarged actinal system, Agassiz? has pointed out that the latter may be also considered as a corona, reaching almost to the jaws, the actinal membrane being reduced to an insignificant member, as in the Clypeastroids. This view is essentially similar to that put forward by Lovén. It appears to me that it is the more correct of the two, and I imagine that the Palechinide exhibit to us a condition of the Echinoderm skeleton, closely similar to, and yet different from that which is found in many Crinoids. It is worth notice that there are many Holothurians, the condition of which is in some measure comparable to that of the Palechinide and Echinothuride. Thus, in Psolus, Ocrus, Colochirus, and Echinocucumis, there is a flexible test, 7.e. a thick leathery membrane, in which large cal- careous plates are imbedded, and in Colochirus they are pierced for the tubular feet. The homology of these plates with the test of Hehint has been already pointed out by Semper.? In Psolus there is also an oral system, but no distinct apical system has been traced, while in the Perisso 1 « Revision,’ pp. 257, 646. 2'* Revision,’ p. 646. ’ ** Reisen im Archipel der Philippinen,” ii, 1. ‘ Holothurien,’ p. 58. 196 P, HERBERT CARPENTER. echinide the reverse is the case. In the irregularity of the plating the Holothurians resemble the Crinoids, but even in the latter there are traces of a radiate arrangement in the plating of the disc, which resembles the alternation of the ambulacra and interambulacra in the test of an Urchin. Thus, in Pentacrinus,! there are rows of small marginal plates at the sides of the ambulacra, and in the interradial and interbrachial areas between them are the perforated anambulacral plates. These marginal plates at the sides of the ambulacra also occur on the disc and arms of Rhizocrinus, and on the arms of Pentacrinus, Hyocrinus, Bathycrinus, and of the young Antedon, in which they ultimately undergo resorption. Wachsmuth? has found them also in the arms of Cyathocrinus and of other Paleozoic Crinoids, in which they are borne upon small quadrangular plates situated on the outside of each groove, and interlock with one another over the middle line of the groove so as apparently to close it completely. Wachsmuth believes that they were movable, and only closed over the furrow when the arms were folded up. Miiller found an outer row of plates sup- porting the delicate marginal plates of the ambulacra of Pentacrinus of the same nature as those described by Wach- smuth in Cyathocrinus, and he seems to have called them adambulacral (fig. xiv, ad), and to have regarded them as homologous with the similarly named plates in the Asterids and Ophiurids.? In this I entirely concur, and I would go still further and compare the double row of marginal plates covering the ambulacral grooves (fig. XIV, sup.) to the ordinary swuperambulacral plates in the test of the Urchins, and in the Ophiurids. In most Ophiurids these plates are arranged in a single row, but they are primitively double, as in the young Aste- rids, in which they ultimately become resorbed. In the Urchins this is not the case, and the ambulacral areas consist of two rows of plates, but they differ from the marginal] plates of Pentacrinus and most other Crinozds in being perforated by pores, through which the tubular feet reach the exterior. In Cyathocrinus, however, Wachsmuth has found the apices of these marginal plates to be perforated, so that the course of the ambulacra is marked out by double rows of small pores, very much as in the Urchins. Another striking resemblance between the elements of the 1 Miller, “ Pentacrinus,” loc. cit., p. 49. 2 Loc. cit., pp. 120—124. * See Huxley’s “ Lectures on General Natural History,” ‘Medical Times and Gazette, Dec. 13, 1856, p. 587. ORAL AND APICAL SYSTEMS OF THE ECHINODERMS, 197 ambulacral skeleton of the Crinoids and of the other Echino- dern:s has already been mentioned. Underlying the ambu- lacra on the dise of Pentacrinus, Miiller' found a series of median azygos plates, which he termed subambulacral, and he compared them to similar plates found by Roemer beneath the ambulacra of the Biastoids. I pointed out above that they are also represented in the Paleocrinoidea. Miller rightly regarded them as corresponding in their position with respect to the water vessel with the radial ossicles of the oral calca- reous ring in the Holothurians, and with the rotule in the lantern of Echini. Simroth? has shown that there are good reasons for regarding the rotule (together with the radii) and the auricles as respectively representing the first and second vertebral ossicles of the Starfish arms. Had Miller continued to hold his original views, which are now generally accepted,as to the homology of the radial pieces of the oral ring in the Holothurians with the auricles of the Echinz, and with the vertebree of the Starfish arms, he would, no doubt, have also described these last as subambulacral.®? The principal component of the Crinoid skeleton being anti-ambulacral (or abactinal) is, of course, not to be found in the Urchins, and is only imperfectly represented in the Starfishes. It is merely an extensive development in a radial direction of the primitive abactinal or apical system, situated at the dorsal pole of the larva, which is of extreme importance in Kchinoderm morphology, for, as shown by Agassiz,‘ it is the foundation of the whole skeleton, whether anti-, sub-, or super-ambulacral. ‘In fact, the external limestone plates forming the test of a Sea-urchin, the reticulated network of the actinal and abactinal surface of a Starfish, together with the ambulacral and interambulacral plates and the plates forming the disc of an Ophiuran, the upper, lower, and side arm-plates, as well as internal skeleton, are all directly derived from the simple system of limestone plates of the abactinal surface of the Kchinoderm embryo.” In the Crinoids the abactinal or antiambulacral system remains most nearly in its primitive condition, extending but very slightly towards the actinal side. But in the other Echinoderms the radial plates of the abactinal system, situated round the dorsal pole of the embryo, gradually extend towards the edge of and down on to the actinal side, so ' Pentacrinus, loc. cit., p. 49, and ‘ Bau der Echinodermen,’ pp. 57, 58. * “ Anatomie und Schizogonie der Ophiactis Virens,” Sars., Zweiter Theil, « Zeitschr. fiir Wiss. Zool.,’ xxviii, pp. 511, 512. 3 See Addenda, No. 6, p. 205. * ‘North American Starfishes,’ pp. 91—93. 198 P. HERBERT CARPENTER. as to enclose the water-system. The Ophiurids and Urchins remain permanently in this condition, but in the Asterids the superambulacral plating is resorbed along the central line, its edges sending out small spurs to form the vertebral ossi- cles or subambulacral system, which makes up the principal element in the Starfish skeleton. In the Crinoids, however, no extensive changes of this kind take place, and in this respect, as well as in the condition of their actinal skeleton, they are in a far more embryonic condition than are the other Echi- noderms, so that we have another strong piece of evidence in favour of the view that they are phylogenetically the oldest members of the group. It will have been gathered from the foregoing pages that the general views which I hold respecting Echinoderm mor- phology are essentially those of Johannes Miiller, as modified and extended by A. Agassiz. Gdtte,! however, has recently put forward some considerations which have led him to adopt precisely the opposite of Miller’s views, namely, that the apex of a Starfish represents the whole convex part of an Kchinid shell, instead of the apex of the Urchin corre- sponding to the whole antiambulacral surface of the Starfish. Further, Gotte considers the arms of the Crinoids to be homologous with the oral tentacles of the Holothurians. A view similar to this was put forward some time ago by Wyville Thomson,’ and also later by Huxley,? who seems to have subsequently abandoned it, as there is no mention of it in his ‘ Anatomy of the Invertebrata.’ Gotte regards the Echinoderm skeleton as, so to speak, the result of a combination in varying degrees of two modes of radiation which are essentially opposed to one another. One of these systems corresponds in position with the water- vascular trunks, and is thus radzal as regards the general symmetry of the Echinoderm type. In the brachiate orders (Starfishes and Crinoids) it forms the skeleton of the arm bases. The other skeletal system, as seen in the Crinoid, is that of the first formed part of the calyx, viz. the basis, on the abactinal surface of the body, together with the oral system of the actinal surface. ‘This system alternates in position with the tentacle-bearing arm bases, and is, there- fore, interradial. It is the more prominent of the two in the young Comatula, in which the basals and orals attain a considerable size before the appearance of the radials. 1 Loc. cit.,’ pp. 627—630. 2 *Kdinburgh New Phil. Journal,’ loc. cit., p. 115. 3 “Notes on the Invertebrata,” ‘Medical ‘Times and Gazette,’ Aug. 14, 1875, pp. 178, 174. ORAL AND APICAL SYSTEMS OF THE ECHINODERMs. 199 Later on, however, they undergo a considerable regressive metamorphosis, while the abactinal skeleton of the arms develops very rapidly, as the water-vascular stems extend outwards from the disc, bearing with them the odd terminal tentacle. This mode of growth, with some slight modifica- tions, is common to the Asterids and Ophiurids, the arms of which, as of the Crinoids, may be regarded as an extreme development of the primary tentacular ceeca borne upon the water-vascular ring of the larva, which becomes much en- larged and acquires a calcareous skeleton. The water- vascular ring of the Holothurian embryo also bears five tenta- cular ceca, but the water-vascular trunks indicating the five antimera, are not formed (when present) by these ceca being carried outwards away from the ring, as is the case in. the Starfishes ; for they appear separately as five other diver- ticula from the water-vascular ring, alternating with the tentacular rudiments. Gotte assumes that these ceca are of primary importance, and occupy a similar position in all Echinoderms. He is consequently led to regard the Starfish arms, with their ptimitive terminal tentacles, as homologous with the branching tentacles of the Holothurians. In the same way he compares the intertentacular antimers of the Holothu- rians to the interradial antimers of the Crinoids ; for these which contain the basal and oral plates, alternate with the tentacle-bearing arm rudiments, that ultimately attain so great a development and obliterate or obscure the primary interradial skeleton. I regret that I am unable to accept Gotte’s views. He brings forward no argument in their favour, except, of course, one of time, namely, that the five ceeca which first appear as outgrowths of the water-vascular ring, develop in the Holothurians into the branched oral tentacles, and in the Starfishes into the large terminal tentacles at the ends of the arms. Further, if Gotte’s views are correct, the con- clusions which naturally follow from them are completely at variance with many facts of Echinoderm morphology. He regards the condition of the Echini as essentially similar to that of the Holothurians, though the ambulacral areas are not completely homologous in the two groups, owing to the presence of interambulacra in the Urchins, and to slight differences in the mode of origin of the water-vascular trunks. In the Urchins the “ urspriinglichen Tentakelanlagen werden nicht in Arme fortgesetzt, deren Entwickelung eine beson- dere aborale Strahlgliederung unterdriickte und die damit alternirende orale Gliederung zur ausschliesslich herrschen- 200 P, HERBERT CARPENTER. den machte ; indem also Fortsetzungen der ersten Tentakel- gefasse in den aboralen Korpertheil hineinwachsen, bezeich- nen die von ihnen gebildeten Ambulacralfelder nicht die einzigen Strahlsegmente, sondern wechseln regelmassig mit den Interambulacralfeldern ab, welche gewissermassen ein Strahlsystem fiir sich bilden, da auch ihre ersten Skelet- anlagen gleichzeitig mit den ambulacralen aber unabhangig von denselben und nicht paarig gerade so wie die radiaren Riickenplatten der Seesterne entstehen.” I must confess that I cannot agree with these conclusions of Gétte’s. On his own showing, the water-vascular stems in the embryo Urchin do not alternate with the primary tentacular ceeca as in the Holothurians, and yet the anti- mera they indicate are supposed by him to be homologous in the two cases. If the relative positions of the primary tentacular ceeca and of the water-vascular stems are mor- phologically as important as Gotte supposes, surely he is somewhat inconsistent in completely disregarding them, as in the case just quoted. Krohn! states that the five primary tentacles of the young Urchin disappear, instead of persisting and branching as in the Holothurians; but according to Agassiz? and Lovén® the mode of growth of the new tentacles is the same as in the Starfishes. They are formed in successive pairs at the bases of the large primary tentacles, which are thus carried away from the water vascular ring as the test enlarges and the radial stems elongate. Agassiz* states positively that they pierce the ocular plates, but Perrier’ altogether denies this. Whether they are present in the adult or not, the fact that they ter- minate the growing water-vascular trunks, as in the Star- fishes, is a sufficient argument against Gotte’s views, which are based upon the hypothesis that the arms of the Starfishes are not homologous with the ambulacral areas of the Urchins and Holothurians, but with the buccal tentacles of the latter. Upon this hypothesis the ambulacra of the Urchins are supposed to be developed altogether from the right antimer, like the apex of the Starfishes and the basis of the Crinouds. Gotte therefore regards the aboral portions of the Starnsh body as equivalent, not merely to the apex, but to tne whole convex portion of the Echinid shell, the ventral side of which 1 Miiller’s ‘ Archiv,’ 1851, p. 351. 2 ¢ Revision,’ p. 725. 3 ‘Loc. cit., p. 28. 4 ¢ Revision,’ p. 682. ® “Recherches sur |’Appareil Circulatoire des Oursins,” ‘ Archives de Zoologie Expérimentale et Générale,’ vol. iv, p. 622. ORAL AND APICAL SYSTEMS OF THE ECHINODERMS, 201 represents the peristomial area of the Starfish ; while the arms of the latter are structures peculiar to it, and therefore not ~ comparable to any parts of an Urchin. This is of course a complete reversal of Miiller’s idea that the apex of the Urchins represents the whole antiambulacral dorsum of the Starfish. So far as the actual origin of the ambulacral plates is concerned, there is some ground for this hypothesis of Gotte’s ; for Agassiz has shown that the external limestone plates forming the test of a Sea-urchin are all directly derived from the simple system of limestone plates on the abactinal surface of the embryo. But he has also shown that the reticulated network of the actinal and abactinal surface of a Starfish, together with the ambulacral and inter- ambulacral plates, have the same origin, which tells strongly against the truth of Gotte’s hypothesis. Other considerations too, demonstrate the general correct- ness of Miiller’s views. The corona of the Urchins is the result of an extreme vertical elongation of that portion of the equatorial zone of the larva that lies between the peris- tome and the radials (=oculars), which last remain in close contact with the basals (=genitals). It may, therefore, be termed extra-radial. In the Crinoids the radials also remain in close proximity to the basals, as in the Urchins, but the equatorial zone is very much extended horizontally. It is supported by a dorsal skeleton, which is built up gradually upon the radial circlet, and is also therefore extra-radial, or better,swpra-radial. In the Starfishes, on the other hand, there is a similar lateral extension of the equatorial zone which forms the ventral surface of the arms, but their dorsal surface is altogether unrepresented in the other Echino- derms, and may be called intra-radial. For it is the result of a separation of the radials from the rest of the calyx by a constant formation of new spines at the base of each ray, so that instead of their resting directly on the basals there is a long interval between the two rings of plates. The dorsal surface of a Starfish is therefore strictly compara- ble to the apex of an Urchin or the calyx of a Crinoid (as far as the first radials), as was supposed by Miller. But be- tween the arms of a Starfish or Crinoid and the ambulacra of an Urchin, there is only a general homology, not one which can be followed in much detail.! The views advanced above may perhaps be better under- stood by the help of the accompanying simple diagrams. If the basal, radial, and oral circlets of the young Crinoid be 1 Compare Agassiz, ‘ Revision,’ pp. 758—760, and ‘North American Starfishes,’ pp. 87, 88. 202 P, HERBERT CARPENTER. represented by the letters B, R, and O respectively, their relative positions just after the appearance of the radials are represented in fig. 15. The line separating RR and O in- dicates the position of the above-mentioned equatorial zone separating the oral system developed around the left perito- neal sac, from the calyx which is formed around that of the Fic. XV.—Diagram showing the relative positions of the basals, orals, and radials, in an early stage of the development of a Crinoid. : Basal. . Oral. R. Radial. £q. Line indicating the position of the equatorial zone which separates the oral and apical systems. right side (compare figs. 1, vi1I, 1X in Part I). Fig. xv1 shows the mode in which the supra-radial antiambulacral skeleton 2 R22 R 3 Fie. XVI.—Diagram showing the relations of the apical and oral systems in an adult Crinoid. BOR. as in Fig. XV. R, R;. Second and third radials. of the arms of a Crinoid is formed in support of a lateral ex- tension of the equatorial zone. In the Urchins and Holo- Frc, XVII.—Diagram showing the relative positions of the basals, orals, and radials in Leskia mirabilis. Lettering as in Fig. XV thurians, however, the extension of the equatorial zone is in a vertical direction (fig. xv11), and in the former it becomes covered by a superambulacral plating, which extends over on to it from the abactinal side. In the Starfishes (fig. xv111) the radials are carried out from ORAL AND APICAL SYSTEMS OF THE ECHINODERMS, 208 the calyx by the constant formation of new spines at the base of each ray, which are supported by a long narrow limestone plate, extending distinctly from the basal plate almost to the terminal radial. This plate, according to Agassiz, is also derived from the primitive abactinal system, as are the superambulacral plate on the actinal surface with the subambulacral spurs formed from its edges. It is com- parable to the antiambulacral arm skeleton of a Crinoid, except that it is ztra- instead of extra-radial. The super- Fic. XVIII.—Showing how the radials r of the young Starfish are carried away from the basals (= genitals) B, and form the ocular plates at the ends of the arms. ambulacral plate is absorbed in the Asterids, but persists in the Ophiurids as the ventral plating of the arm. The plating of the grooves on the ventral surface of the Crinoids, although occupying a superambulacral position, does not seem to have the same origin as the corresponding plating in the Starfishes. The precise homologies of the ambulacral grooves of the Crinoids in the other Echinoderms have yet to be worked out, but I am inclined to think that Greeff’s suggestions! are right in their general principle. Agassiz’s observations support them as far as the Urchins and Star- fishes are concerned, while those of Gotte, on the other hand, demonstrate that the ambulacral grooves of the Crinoids are a peripheral extension of the tentacular vestibule of the larva, the floor of which forms the peristomial area whence the groove-trunks radiate. This vestibule. (fig. x111, Jp’) is derived from the left or oral division of the enteroccel, so that the ambulacral epithelium (fig. x11, ae) covering its floor and the so-called “ambulacral nerve”’ beneath it must be hypoblastic in their origin. Further, in many Actinome- tre these structures are altogether absent from several of the posterior arms, as if the growing vestibule had been un- able to extend itself so far from the oral ring, which in this genus is excentric or even marginal. We have yet to learn that the ambulacral or nerve-epithe- lium of the other Echinoderms is a hypoblastic organ, and that the grooves of the Starfish arms are derivatives of the * “Ueber den Bau der Echinodermen,” ‘Dritte Mittheilung. Marburg Sitzungsberichte,’ No, 11, 1872, pp. 165169. 204 P, HERBERT CARPENTER. enteroccel, as must be the case if these structures are homo- logous with the similar and similarly placed parts in the Crinoids. POSTSCRIPT. 1. Figs. 11 and vii in Part I are described as “after Lovén.”? I much regret that, owing to an inadvertence on my part, the madreporite was omitted from Fig. 11 (Apical system of Salenia). Its proper position would be in the genital (3) at the south-west corner of the figure. It should also have been stated that both Figs. 11 and vit are inverted with respect to the positions in which they are given by Lovén. ‘This was done in order to bring them into positions corresponding to those in which the Crinoids are usually figured, viz. with a radius due south (Figs. 111—v1). The anus in Lovén’s own figure of Salenia (Kitudes, pl. xx1, fig. 177) is south-east, and the madreporite north-east. I am anxious to rectify these omissions, as it has been represented to me that my diagrams of Lovén’s figures would give to the reader an incorrect idea of his views of the whole Echinoid body, for which I should be exceedingly sorry. 2. In the note to pp. 369—70 of Part I, I have commented upon Agassiz’ not mentioning Dr. Carpenter’s descriptions of the young Comatula in the second issue of the ‘ Embryo- logy of the Starfish.’ I fear, however, that I did not make it sufficiently clear that Agassiz’ memoir remained sub- stantially as it was written thirteen (now nearly fifteen) years ago; and that the notes “on the points where additions have been made by subsequent investigations” were added merely “for the sake of calling attention to the present condition of the subject.’ In one of these notes, however, Agassiz implies his entire acceptance of Lovén’s opinions respecting certain homologies (from which I am, unfortu- nately, obliged to differ), although he was presumably acquainted with Dr. Carpenter’s observations, which do not altogether accord with the opinions in question. It there- fore seemed to me that Agassiz was taking rather a one- sided view of the present condition of the subject in speaking of Lovén as having *‘ most thoroughly proved” these homo- logies, despite Dr. Carpenter’s observations to the contrary, and in not mentioning these last at all. IfI have in any way been unfair to Agassiz, for whose Echinoderm-work I have naturally the very greatest admiration, I here tender him my apologies. 3. It will be understood, I hope, that the presence of a ORAL AND APICAL SYSTEMS OF THE ECHINODERMS. 205 single central abactinal plate in the Palzocrinoids (or, at any rate, in the larval stages), which my views suppose, is merely an inference from the presence of such a plate in the stalked larva of Comatula (See Part I, pp. 374, 379, 382). It is almost needless to point out that its existence is scarcely susceptible of proof. 4, Since the above essay was written (July, 1878) I find that the opinions expressed by Sir Wyville Thomson and myself regarding Hyponome have been verified by an examination of the “Challenger” dredgings in Torres Strait. Sir Wyville Thomson determined on the spot that Hyponome is merely a Comatula minus its calyx and arm-skeleton. The ‘ Challenger” collection of Comatule contains many specimens from Torres Strait, as well as from other localities, which exhibit the Hyponome-condition more or less perfectly. Some of these are Antedons, and the others Actinometre. In the latter the anambulacral plating is very extensively developed, and the resemblance to Spheronites (first pointed out by A. Agassiz) very complete. d. It is possible that the mouth-shields or “ first inter- mediate interambulacral pieces” of the Ophiurids are really oral plates which appear late, and ultimately assume a somewhat abnormal position. Similar plates occur in Brisinga (Sars and Ludwig), and Miller mentions the existence of unpaired interambulacral plates round the actinostome of other Asterids, but he did not regard them as comparable to the mouth-shields of Ophiurids. 6. Ludwig (‘ Ophiuren,’ p. 251) makes an alteration in Miller’s terminology which is, I think, unsuitable, as it will only lead to needless confusion. In the Crinoids in which the ventral side is upwards, the plates beneath the water-ves- sel were termed subambulacral by Miiller; and as mentioned above, he extended this name to similarly situated plates in the other Echinoderms, while he spoke of the ventral plating of the Ophiurid arms as superambulacral. Ludwig, however, considers this inconvenient, as the Ophiurids, unlike the Crinoids, have their ventral side downwards, so that the ventral plating is s¢rctly subambulacral. It would be interesting to learn how Ludwig would name the coronal plates of an Urchin. According to his reasoning, these are superambulacral round the apex, but subambulacral round the mouth, while neither name is applicable to those round the equator of the test. Surely if Miller himself did not think it inconvenient to call the ventral plating of the Ophiurids superambulacral, it hardly beseems us to cavil at his nomenclature, especially when the proposed change VOL, XIX,—~NEW SER. fe) 206 NIKOLAS KLEINENBERG. cannot but result in a dire confusion of terms. Thus, the subambulacral plates of the Ophiurids would represent the superambulacral ones of the Crinoids and Urchins, and vice versd! On page 267 Ludwig takes Simroth to task in the following words for doing very much the same that he has done himself—“ Verwirrung aber wird durch Simroth dadurch angerichtet, dass er die fiir diese Skeletstiicke von Joh. Miiller eingefiihrte Bezeichnung auf andere Sticke iibertragt.” Substitute my friend Ludwig’s name for Simroth’s in the above sentence, and his own words become applicable to himself! The DEVELOPMENT of the EARTH-WORM, LUMBRICUS TRAPE- zo1DES, Ducks. By Nixotas KLEInENBERG. (With Plates EX SX, XD) w Ischia, as in the neighbourhood of Naples, the most common of the Lumbricide is Lumbricus trapezoides (Dugés); it is abundant in gardens and in the muck-heaps of farms. Associated with this, but rarer, and prefering sandy soil and the neighbourhood of water, is another species, probably Lumbricus teres (Dugés). The reproduction of Lumbricus trapezoides, like that of L. teres, is most active during the whole of the cold and temperate season, that is to say, from October to June, when the hot and dry weather begins, but never ceases altogether, since even in July and August capsules containing fecun- dated eggs are found in shady and damp places, and at a considerable depth; many of these, however, perish. The capsules vary greatly in size; the smallest are hardly one millimétre, whilst the largest reach eight millimétres in length. ‘This difference is easily explained by the mode of formation of the capsules, since necessarily their dimen- sions must correspond to the size of the animal producing them. The shape of the capsules of L. trapezozdes is oval, with the ends pointed, or sometimes, on the contrary, slightly depressed; such depressions correspond to the primitive open- ing of the chitinous ring formed by the clitellus, which does not close till after deposition. Their colour resembles that of corn. The capsules of L. teres are in general smaller, more resembling a lemon in shape, often with the ends greatly elongated to form two fine processes. These capsules are olive-coloured. THE DEVELOPMENT OF THE EARTH-WORM, 207 The contents of the capsules of L. trapezotdes consist of an albuminous mass, in which, as Rathke has demonstrated in Nephelis vulgaris, two constituents are distinguishable, namely, a dense, transparent, strongly refracting substance, forming a kind of sponge, with very fine interstices, and a liquid which fills these interstices. The albumen, under the action of water, of acids, or of alcohol, assumes the appear- ance of an emulsion, in consequence of the precipitation of very fine granules, a decomposition which occurs during the progress of development in capsules which have been left intact. The albumen of the capsules of L. ¢eres is colourless or faintly tinged with greenish, is much more dense, and of a nearly uniform aspect; it does not dissolve, except very slightly, in water or in dilute acids. In this jelly the eggs are scattered, and between them bundles of spermatozoa. The number of the eggs in the capsules of L. trapezoides is from three to eight, in those of LL. teres, it is from four to twenty, all of which become fecundated and develop; on the other hand, in the capsules of L. trapezoides one egg only, or rarely, two or three, pro- duce embryos. The other eggs not undergoing the exciting influence of the male element, lose their spherical form and become transformed into flat plates, with more or less irregu- lar outlines; the protoplasm, by a kind of coagulation, changes into a dark substance, containing large granules, and the eggs gradually dissolve and vanish without leaving a trace, Methods of Investigation. T should have undertaken the study of the development of _ L. teres more willingly than that of ZL. trapezordes, since in the former the first stages are more simple and typical, and even the later stages clearer and more distinct. Accidental conditions, however, render the preparationextremely difficult. The density and viscosity of the albumen, together with the excessive delicacy and fragility of the embryos, make it very difficult to obtain any of them uninjured. Further, as they rapidly devour the whole of the albumen and store it up in the digestive cavity, their body-walls becomes so tense that the slightest pressure is enough to bust them. For these reasons my knowledge of the development of this species remains incomplete, and I shall limit myself at present to the description of the development of JL. tra- 1 Rathke, Beitrage zur Entwicklungsgeschichte der Hirudineen, Heraus- gegeben, von R. Leuckart. Leipzig, 1868, p. 3. 208 NIKOLAS KLEINENBERG. pezoides, whose embryos may be readily extracted from the albumen without injury. A great part of the earliest formations of the egg can be made out in the living state, the protoplasm being sufficiently transparent to allow the internal parts to be seen; but after- wards the precise outlines of the cells disappear, and nothing can be seen but the grosser structure. To make out the more delicate structure it is necessary to employ reagents. Of these I have employed several: osmic acid applied in the state of vapour gives good results; but the preparations obtained by the use of a mixture of picric with sulphuric acid were more satisfactory. This reagent, however, has the same drawback as osmic acid, namely, that of occasionally producing swellings in the primitive blastomeres, a circum- stance which, if it only slightly alters the normal conditions, renders the preparations less sightly. This difficulty is over- come by the addition of a little kreosote. As I am now able, after many experiments, to recommend strongly the method of preservation which I have here used, and for the majority of other animal tissues, especially for the more delicate and perishable, I think it may be useful to give the exact receipt. Prepare a saturated solution of picric acid in distilled water, and to a hundred volumes of this add two volumes of concentrated sulphuric acid; all the picric acid which is precipitated must be removed by filtration. One volume of the liquid obtained in this manner is to be diluted with three volumes of water, and, finally, as much pure kreosote must be added as will mix. The object to be preserved should remain in this liquid for three, four, or more hours; then it should be transferred, in order to harden it and remove the acid, into 70 per cent. alcohol, where it is to remain five or six hours. From this it is to be removed into 90 per cent. alcohol, which is to be changed until the yellow tint has either disappeared or greatly diminished. Alcohol of 90 per cent. is better than absolute for preserving the more delicate structures for a long time uninjured, and for keeping the preparation at the proper degree of hardness. For colouring I use crystallised hematoxylin dissolved in the following mixture:—Prepare a saturated solution of calcium chloride in 70 per cent. alcohol, with the addition of a little alum ; after having filtered, mix a volume of this with from six to eight volumes of 70 per cent. alcohol. At the time of using the liquid pour into it as many drops of a concentrated solution of hematoxylin in absolute alcohol as THE DEVELOPMENT OF THE EARTH-WORM. 209 are sufficient to give the required colour to the preparation of greater or less intensity, according to desire. This mixture, notwithstanding its chemical irrationality, gives good results. Aqueous solutions, especially when they contain traces of ammonia, are to be avoided, since they are very hurtful to many delicate tissues. The object must remain in the dye for a period varying frem a few minutes to six hours, according to its size and to the nature of the tissues composing it. It is a good rule, when intending to make sections, to stain deeply and to cut them very thin. When removed from the dye the preparation is to be washed in 90 per cent. alcohol, in which it may remain from six to twelve hours. Finally, to remove every trace of water, it should remain for half or a whole day in absolute alcohol. If the preparation is to be cut it must be removed from absolute alcohol to essential oil of bergamot, in which it should remain for some hours, in order to fit it for being embedded in paraffin, which is removed from the sections when cut by means of a mixture of four parts of essence of turpentine with one part of kreosote. Finally, the sections are mounted in resin dissolved in essence of turpentine.' I have made sections from the beginning of segmentation, but in the earliest stages these have not been of very much use, since it is impossible to place such small globular bodies in a determined position; the direction of the sections is either not that required or is altogether uncertain. In conse- quence I preferred studying the beginning of the development by means of optical sections of the entire object, always, how- ever, using real sections to control the results. Segmentation of the Egg and first appearance of the Embryos. I have failed to observe the phenomena in the fecundated egg immediately following the fusion of the sexual elements. The earliest eggs which I have observed were already divided by an equatorial furrow into two embryoplastic segments or blastomeres. In this stage the egg is still contained in the vitelline membrane, which is an oval capsule of about 0:24 mm. in length, whose very thin walls are without any trace of structure. Its contents consist of a limpid, colourless fluid, 1 Histologists are warned not to use a solution of resin in alcohol. The preparations mounted in this are at first beautiful but soon become spoiled, in consequence of the precipitation of crystals or of an amorphous substance. I have lost in this manner many hundreds of preparations, and the same results have occurred in the Zoological Station at Naples. 210 NIKOLAS KLEINENBERG. slightly refractive, and holding in suspension the egg, and near it two or three polar globules—protoplasmic corpuscles containing one or more large vacuoles. The egg itself is an ellipsoidal body, whose normal axes measure about 0:14 and0'10mm._ Its protoplasm is without vitelline corpuscles, and is therefore pale and transparent; it is divided, as in so many other eggs, into two substances : one, more compact and with fine granules, is disposed in a network, or rather in the form of a sponge, with relatively large spaces ; the other is a clear, uniform, albuminous liquid, which fills the spaces. On the surface the protoplasm is somewhat condensed, so as to form a very thin cortical stratum. The two hemispherical blastomeres sometimes fit them- selves with their plane surfaces so perfectly in contact that it is impossible to separate them. Sometimes the centres of the planes of contact beccme slightly excavated, and so separate, leaving between them a central lentiform space, while the margins still remain firmly adherent. This space might be called the beginning of the segmentation cavity, if the changes in form of the blastomeres did not soon make it disappear. In fact, after a short period of rest, a tendency arises in each blastomere to assume the spherical form, by which the peri- pheres of their respective bases are drawn towards the corresponding centres, and becoming curved separate from one another, so that finally they touch only at a single point, in the place where the lentiform cavity formerly existed. The first two blastomeres at one time show distinct nuclei ; at another are deprived of them; at another show with great clearness those stellate or radiating or fusiform groups of fine granules, which the beautiful researches of the last few years have shown to be phenomena constantly accompanying the formation of new cells. The process of segmentation of the eggs of L. trapezoides does not proceed in so simple and orderly a way as in many other animals, and in not a few of the Annelids; soon begins a series of alterations in shape and position, of divi- sions and buddings, of increasings and diminishings of volume of the single cells, which altogether make it very difficult to trace the type of this most important process, which, as the first manifestation of the formative forces hidden under the apparent sameness of the protoplasm, serves as a beginning for the building up of the complicated and definite'y disposed structure of the body. After the division into two hemispheres a stage is often observed in which the egg is composed of three blastomeres, arranged in the form of a triangle, already described by THE DEVELOPMENT OF THE EARTH-WORM, 21 Kowalewsky,! by Ratzel and Warschawski’ in Lumbricus agricola, by Rathke® and Robin in Nephelis vulgaris (in which I have also observed it), and by Claparéde and Metschnikow* in Spio fuliginosus ; this last observation I am also able to confirm from my own investigations. Such a stage of seg- mentation, though different enough from what is usually found in other animals, certainly cannot be considered ab- normal as in so many other cases, in which irregularities of segmentation are the first and certain sign that the egg is under unfavorable conditions and is about to break up before having attained any considerable development; it appears, on the contrary, certain that in these worms this phase, though departing from the general rule, leads on to a healthy development. But the division into three blasto- meres does not occur in all the eggs of L. trapezotdes, and is not indispensable to the regular progress of development. Sometimes it happens that the first two blastomeres each produces at the same time a new cell, so that four imme- diately succeed two. The process of segmentation then proceeds in the following peculiar manner:—In the midst of the protoplasm an accumulation of fine granules appears, which is easily distinguished as a dark spot; this aggrega- tion of the more solid parts of the protoplasm, which, how- ever, has not distinct limits, increases gradually in size and at the same time appreaches the surface of the segment. It is advisable to state that this concentration is not to be con- founded with the phenomena which prepare and accompany the first formation of nuclei; the nucleus appears later in the centre of the mass described above. ‘The mass, as soon as it has arrived at the surface, raises itself above the level of the surrounding protoplasm in the form of a slightly projecting cone ; then, by a narrowing of its base, it sepa- rates from the mother-cell and a new blastomere is formed. This observation agrees in nearly all particulars with that of Kowalewsky on the formation of the small segments in the ege of Huazes.° The two blastomeres of the second generation remain very much smaller than the first; at first situated symmetrically with regard to the long axis of the egg, they then approach one another, advancing towards the median line, and at the same * *“Embryologische Studien an Wiirmem und Arthropoden,” ‘Mém., Acad., St. Petersbourg,’ 1871. Tab. vi, fig. 3. 2 * Zeit. fiir Wiss. Zool.,’ T. 18, 1868. * Loe. cit., Tab. i, fig. 6. * “Beitrage zur Kentniss der Entwicklungsgeschiehte der Chetopoden,” ‘ Zeit. fir Wiss. Zool.” 1869, T. 19, Tab. xii, fig. 1, d. » Loe. cit., pp. 18, 14. 212 NIKOLAS KLEINENBERG, time two other small cells separate themselves from the first blastomeres ; the egg consists of six segments, two large and four small. A short time later two more cells are added to the last, and in this manner a little plate of small flattened cells is formed, which, resting upon the top of the two large blastomeres, covers like a roof the gradually widening furrow which separates them (P1. IX, fig. 1.) Such a stage of segmentation is much like one already described in the development of Nephelis, with the difference, however, that this, jinstead of two, possesses three large cells, covered in part by a layer of smaller cells. But there is a still more important difference: while in Nephelis the large blastomeres remain for a long time un- altered, those of Lumbricus soon divide repeatedly, and become blended with the general embryonic mass. At first they separate from one another, leaving in the middle a wide and deep space, one side of which is closed by the curved plate of small cells, whilst the other presents a somewhat restricted aperture opening into the cavity of the capsule. Now the two large blastomeres each divide contempora- neously into two, and at the same time some of the small blastomeres tend towards the centre, interposing themselves between the four large ones. After repeated divisions, which influence the large as well as the small blastomeres, the egg assumes a very characteristic appearance; there are in all sixteen blastomeres, and if sometimes there is one more or less it is always one of the small ones. Of the six large blastomeres three are grouped round the aperture of the segmentation cavity, which they have closed or reduced to a narrow slit; above and alternating with these are the three others, but these do not touch each other, being separated by means of three small blastomeres, which are placed like wedges between them. ‘The ring thus formed of three large and three small blastomeres embraces the seg- mentation cavity, and is covered above by a thin roof com- posed of five or six small blastomeres. Unfortunately such clear arrangements are of too short duration in the first days of development of the animal under consideration. Very soon it comes to pass that by the multiplication, as well of the large as of the small blastomeres, the differences in size between them presently disappear, and, further, the intro- duction of the small blastomeres between the offspring of the large ones, contributes to the destruction of the abovesmen- tioned order. For a time some of the first blastomeres remain upon the surface external to the others, but when these also are dis- THE DEVELOPMENT OF THE EARTH=WORM, 213 placed towards the centre we have a new form of the egg, which no longer shows any trace of the arrangement which preceded it. It is now a little spherical bladder, sometimes, as far as can be seen, perfectly closed ; sometimes furnished with a small opening, whose walls consist of a single layer of cells, which vary considerably in length. About one pole the cells are longer than they are broad, while at the oppo- site pole the wall of the segmentation cavity is composed of a series of cells, whose length is half that of the others or less. There is not, however, a distinct boundary between these two kinds of cells ; they rather pass the one into the other by numerous gradations. There is not even a differ- ence in the protoplasm; in all it is uniform and _ finely granular, since the reticular arrangement of the protoplasm of the egg and primary blastomeres has already disappeared some time; each cell now nearly always contains a very dis- tinct nucleus, whose volume varies with that of the cell. The egg in this manner is transformed into a germinal bladder, consisting of a single layer of cells of different length, surrounding a somewhat large eccentric cavity, which opens—if not always, certainly in some cases—by a narrow opening (Pl. IX, fig. 2). After this the reproductive activity is most marked in the flat cells at one pole of the egg; they increase in number, become longer and push into the segmentation cavity, pushing through its aperture or making their way between the neighbouring loosely connected cells. But at the other pole small cells detach themselves from the central extremi- ties of the long blastomeres ; in this manner the segmentation cavity, restricted on all sides, disappears, and the egg becomes a solid and compact multicellular sphere. I shall, perhaps, have wearied the reader with the minute description of the succession of changes, which, nevertheless still remains somewhat unintelligible in consequence of the scarcity of illustrations. But the importance of the argu- ment and the divergence existing between my results and those of such an excellent observer as Kowalewsky, must be my excuse for the detailed nature of the account I have given. According to the author above cited, the first phases of development in Z. agricola are very simple and regular. The segmentation produces. almost from the first cells of of equal size, and a disc-shaped body is formed, which be- comes divided by a fissure, representing the segmentation cavity, into two lamina, each consisting of a single layer of cells; these soon become distinguishable by the nature of their protoplasm, The circumference then raising itself 214 NIKOLAS KLEINENBERG. above the lamina of clear cells, the disc assumes the form of a cup, which by the narrowing of its mouth becomes gradu- ally a typical blastodermic bladder, that is, a double-walled sac, whose outer wall represents the ectoderm, while the internal gives rise to the epithelium of the mid gut with its glandular appendages. Oncomparing this with my descrip- tion of the changes during the corresponding period of development of ZL. trapezoides, considerable differences will be noticed. I do not believe that essential errors can have occurred on either side ; there must be a real difference in the facts observed, and this is, in part at least, explained by the peculiarities of the later development of L. trapezoides to be now described. Immediately after its formation the germinative sphere does not show a well-determined arrangement of the cells, though there are differences in size between them. With regard to the quality of the protoplasm it is the same in all the cells. But after some time a grouping of the cells into distinct layers begins, which leads to the formation of the germinal layers. The peripheral cells about one of the poles multiply and become flatter, but it is to be noticed that two of them—those situated at the most prominent point— do not take part in this, but, on the contrary, increase in size, and attain a considerable length; these cells then become covered by the small peripheral cells, and pushed towards the centre (Pl. IX, fig. 3, cm.). In the inside, upon these large cells, which I shall call mesoblastic, rests a layer of small and flattened celis (em), and at their sides are already distinguishable a small number of very thin flatter-shaped cells (mes); these cells are closely united together and arranged in two rows, which are directed from the sides of the cells (em) towards the opposite pole, where they meet the remains of the embryoplastic material, consist- ing of a layer of large and still undifferentiated cells. Thus, the constitution of the laminee of the germinal layers is in part marked out; the flat peripheral cells (ec) form the external layer (ectoderm), those collected in the interior produce the internal layer (endoderm), and the few cells grouped in two lateral columns (mes) are the first rudiment of the middle layer(mesoderm) ; all the large cells occupy- ing the other hemisphere undergo further changes, tending to produce an arrangement completely corresponding with that just described. But before this occurs a division of the germ into two hemispheres always becomes evident. While the egg is elongating in one diameter a transverse furrow appears half way between the two extremities ; it does not, THE DEVELOPMENT OF THE EARTH-WORM. 215 however, extend round the whole circumference, but is present on one side only. This furrow, deepening itself, either by the elevation of its borders or because the cells lining its floor force themselves into the lateral elevations, divides the germ nearly completely into two halves, which are joined only by a series of enlarged ectoderm cells. The process of the development of the transverse fissure goes on simultaneously with the differentiation of the cells of the hitherto inactive hemisphere. To explain better the entire process I will describe figures 4, 6, and 7 of Pl. IX. Comparing fig. 4 with fig. 3, which represent two stages very near together, the elonga- tion of the diameter which passes through the poles of the egg will be noticed, transforming it from a sphere to an ovoid ; at one extremity the arrangement of the cells remains exactly as it was in fig. 3, but in the middle the mass of cells is divided by a larger fissure, which represents the bottom of the transverse furrow; to the right of thisis seen, instead of the simple layer of large cells of fig. 3, two very distinct groups of cells, one peripheral, of nearly cylin- drical cells, and a mass of polygonal cells in the interior, which forms part of the wall of the furrow. In fig. 6, which appears a little less complicated in detail only because the plane of the optical section does not pass through the rudiments of the middle layer, which are, how- ever, easily recognisable in the preparation, the division into two halves of like structure may already be distinctly seen, though that on the right hand is still a little behind the other in development, not having the endoderm well defined. Of the two mesoblast cells on this side one only is represented, because the other is hidden by it. In the middle, between the two hemispheres, are to be noticed two large, transversely elongated cells, distinguished by the clearness of their protoplasm, which form a kind of ligament between the two halves. Fig. 7 shows the egg distinctly divided into two halves of very similar structure, joined together not very closely by a median cord of large cells containing large nuclei. While the transverse furrow deepens the entire egg changes its form and becomes kidney- or bean-shaped, and then the free margins of the groove arch inwards and approach one another in such a way as to narrow con- siderably the entrance. The bottom enlarges in the direction of the extremities and excavates the inside of each of the hemispheres, pushing the cellular layer (ex) towards the inside. In other words, the endoderm becomes invaginated, 216 NIKOLAS KLEINENBEKG,. beginning at the lateral margins of the furrow in both the hemispheres, which are thus transformed into sacs with double walls. This form of the embryo is represented in profile in fig. 8, and in front view of fig. 9, where the relations just described can be easily made out. Each of the compartments encloses a cavity (ed), which communi- cates with a common space opening to the exterior by a fissure, already much contracted, in fig. 9. The walls of each compartment consist everywhere of two or more layers of cells, a very distinct ectoderm (ec) and an endoderm (en) ; besides this, there are at the opposite extremities of each two mesoblast cells (em) and two rows of flattened cells (mes). Each of the lateral cavities (cd) will form the digestive cavity of an individual, their openings into the common groove will each become a mouth, and the single egg will produce two worms. Tocome to the end at once I will explain the manner in which the perfect separation into two individuals is accomplished. It is very simple; each embryo rotates about the axis of the uniting cord towards the side opposite the common aperture, and turns at the same time a little on its own long axis, but in the opposite direction to the movement of the other; from the first movement results the enlargement of the aperture and of the common cavity, which leads to their complete separation and the approximation of the sides of the two embryos, united by the median cord in such a way as to leave them nearly parallel with one another. The second rotation produces a want of symmetry between the planes of the longitudinal sections; that is to say, the corresponding meridians of the two embryos intersect nearly at aright angle. The point where the uniting cord holds together the two embryos corresponds to their necks, since it is between the cord and the oral apertures (which are now much restricted and ‘converted into narrow canals) that the two cephalic lobes take their origin. In this union the two embryos, forming a rather monstrous twin organism, remain for some time, growing’ and develop- ing and completing their internal organisation, turning gently in the albumen, without at all impeding one another, by the concordant action of their vibratile cilia, which have been some time developed. But little by little the commis- sure relaxes to such a degree that the least pull is enough to break it, a circumstance which can hardly fail to occur when the contractions of the bodies of the embryos begin. It thus happens that the Siamese twins dissolve their too close relationship, which had probably become a nuisance to each THE DEVELOPMENT OF THE EARTH-WORM. Di7 of them, and abandoning each other rove at their leisure through the albumen. But affairs do not always go on smoothly. There are cases, not at all;rare, in which this strange mode of development leads to true monstrosity ; this happens when the uniting cord does not relax in time to be able to be broken, or when it extends to an abnormal amount. In fact, among perfectly developed worms already hatched double monsters are met with in all grades of concrescence (more or less perfect), from those that are so firmly united along the whole extent of the body that it is impossible to separate them without breaking them to pieces, to others which are hatched coupled together, but only by so thin and frail a ligament that they yet succeed in effecting their sepa- ration, although it may be at a comparatively late period. All, however, have two heads and two tails, two mouths and two ani, well separated; it appears also that the junction never extends to any internal organ, but always remains con- fined to the epithelial layer of the body-wall. The above-described mode of formation of the twin embryos is realised in the great majority of cases, but not seldom embryos are found in other conditions, differing ehiefly with regard to the age at which the twins are produced. We have seen above how the differentiation of the layers of the blastoderm begins at one pole while the embryoplastic mate- rial of the other hemisphere is still in an undifferentiated state, but yet that this inequality disappears very soon. There are, however, cases in which a single embryo attains a considerable development before the first rudiment of its companion is formed. I have represented one of them in fig. 5; it is to be understood that this is much further de- veloped than fig. 4. The endoderm has already its peculiar appearance and forms a closed sac; the germinal streaks are very distinct, although the example lacked any sign of a second embryo if the large cells, which are obviously identical with those of the uniting ligament, do not indicate that a second individual may yet grow out. In fig. 10 is seena much more advanced embryo, in which, above the opening of the mouth, a small cellular excrescence (xz) of a rather irregular form appears, which passes without interruption into the germinal streaks, and is the rudiment of the second embryo. I have found also much further developed embryos, which produced similar buds on the margins of their mouths. On the other-hand, I believe the case to be most rare of an egg giving rise to only one embryo, or rather, I should say, I have never ascertained the existence of such a case. It is quite true that sometimes a single worm escapes from a cap- 218 NIKOLAS KLEINENBERG. sule, but then nearly always the remains of its companion are found. This mode of reproduction appears to me worthy of some remark, although it is not my intention to enter here into a discussion of the known facts of development of other animals which might be compared with it. Apparently in our case there is not a succession of individuals, in which only the first owes its existence to the co-operation of the sexual elements, while the other takes its origin from it by agamic generation; from the egg of L. trapezordes two in- dividuals arise directly and essentially independently of one another. In the cases described last, in which a well-de- veloped embryo produces the rudiment of the other, the second should be considered to be a bud, but such a case is abnormal; regularly, the second embryo, although formed a little later, and in connection with the other, does not de- velop from the embryoplastic material employed in the formation of the first, but from a portion of the blastomeres derived directly from the segmentation which remains intact until it becomes an independent formative centre. To interpret the division of the embryoplastic material as the expression of a fission that happened at first in the adult animal and then, in the course of generations, became put back by the help of natural selection to the beginning of development, would be to make a very arbitrary and little satisfactory hypothesis, which also would be in antagonism with the knowledge that we have of the fission and germina- tion of the annelids. As far as we know, this process takes place regularly in the posterior part of the body (not at the head end), and this is not merely an empirical law, but is explained by the fact that in many annelids the posterior extremity retains during life distinctly embryonic characters. Hence there is no more probable explanation of the double- ness of the embryos than what can be found in the original internal arrangement of the fecundated egg, a thing which is not so strange, since the experiments of Haeckel on the Siphonophore! have shown the possibility of multiplying the number of embryos by artificial division of the first mass of blastomeres. Nevertheless, the case we have before us appears to be without analogy in the development of other animals. Todaro established, three years ago, that the individuals of the compound stock of Salpa are to be considered, not as children, but as younger brothers of the solitary stock ; how 1*Zur Entwickelungsgeschichte der Siphonophoren.’ Utrecht, 1869, p: 73. THE DEVELOPMENT OF THE EARTH-WORM. 219 great soever may be the difference between the mode of pro- duction and the anatomical and physiological relations of the two alternate generations of Salpa and the gemelliparous de- velopment of Lumbricus trapezordes, it is not possible to fail to see the same principle ruling in both these forms of de- velopment. ‘Todaro was led to the conclusion that the explanation of the phenomenon is to be sought in the earliest steps of the process of sexual reproduction.' The following considerations may, perhaps, suggest a means, a little difficult, however, in the application, for solving the question definitely. The important labours of Fol? and of Hertwig*® have rendered it very probable that not only is the introduction of a single spermatozoon into the protoplasm sufficient to establish an orderly and efficient generative movement, but that the presence of more sperma- tozoa, instead of assisting the development, occasions a serious disturbance of the order of the molecular arrange- ments, producing a number of centres of activity, and thus leading to an irregular segmentation, and at last to the com- plete destruction of the embryoplastic material. Now, the thought naturally presents itself, that in some case, the action of two spermatozoa introduced into an egg of great vitality, regulated by means of special dispositions, might augment instead of turning aside and paralysing the productive force of the egg, inducing in it a transformation not, as is usual, into one, but into two perfect embryos, and this might be the case in Lumbricus trapezoides. The fact that each capsule of L. trapezoides produces two worms was known to Dugés,* who also observed and figured a double monster ; and Ratzel and Warschawsky describe a like abnormality in LZ. agricola. Itisapity that the descrip- tion which these authors give of the first stages of develop- ment is too superficial to allow a precise conception of them to be made.° This double reproduction is exceptional even in the single genus Lumbrecus. L. teres follows the ordinary rule, pro- ducing one embryo from an egg and no more; the same holds good, without doubt, for LZ. rubellus. As the duplicity of the embryos has no influence on the 1 © Sopra lo sviluppo e l’anatomia delle Salpe.’ Roma, 1875, p. 68, ef. Hatschek ‘‘ On Pedicellina,” ‘ Zeit. fiir Wiss. Zool.,’ T. xxix, p. 530 > «Sur le commenc2ment de l’hénogénie.’ Geneve, 1877, p. 25 3 “ Morphologisches Jahrbuch,’ T. N., 1878, p. 172. * “Annales des Sciences Naturelles,’ T. xv, 1828, pp. 331—332. ® Loc. cit. The processes described in this work as the first phenomena of development belong, as Kowalewsky has justly observed, only to the degeneration of the non-fecundated eggs. 220 NIKOLAS KLEINENBERG. internal development, I shall take no more notice of it and I shall treat of each embryo without heeding its companion. We left the embryo in the form of a depressed globe, now it is lengthened in its antero-posterior diameter, and a little compressed on the dorsal and ventral surfaces, and hence has the shape of an oval lens. The central cavity enlarges be- cause it begins to suck in to itself part of the albumen in which the embryo swims. This nutritive substance does not become employed and transformed immediately into the growing tissues, but, drawing itself together, forms a large and dense mass, which nearly completely fills the space. The mouth, although it serves as a passage for the introduc- tion of the albumen, becomes diminished to a very fine canal, which pierces the body-wall obliquely from below upwards. Sometimes it shuts completely, and then, being without the means of absorbing the albumen, the embryo remains very small and the lumen of the canal disappears, its walls ap- proaching each other till they touch. Notwithstanding this, all the tissues develop regularly and arrive at perfection, if in the subsequent changes the mouth reopens. The Germinal Layers and the Germinal Streaks. The way in which the blastomeres of one hemisphere be- come arranged in distinct layers, while the common rudiment of the two embryos is still a solid sphere, has been described above. The ectoderm (ec in all the figures) becomes defined by the separation of a single layer of cells around a solid central mass. Its cells from the first are cylindrical, with rather dense protoplasm, containing a great number of very fine granules. As the embryo increases in size the cells multiply and, losing their cylindrical form, become trans- formed into very broad and thin plates, which cover, as a single layer, the whole body of the embryo. In the middle line of the ventral surface a double or treble row of these cells, stretching from the aboral pole to the mouth, developes a great number of vibratile cilia, which produce by their movements the continual gentle rotation of the embryo about its transverse axis. The formation of the endoderm (e) is not so simple and easily explained. It appears possible, even probable, that when the germinal bladder (fig. 2) becomes solid some of the lower and smaller cells of one pole enter into the segmentation cavity; but, on the other hand, there is no doubt that other cells, which participate in the formation of the inner layer, separate themselves from the central ends of the long cells surrounding one side of the segmentation THE DEVELOPMENT OF THE EARTH-WORM. 921 cavity (figs. 3, 4,6, 7, en). It is certain, then, that before the hollowing of the embryo by an invagination, which produces the digestive cavity and the mouth, the layer which is to become the endoderm is already easily recognis- able. At that time, however, the aspect of all the cells is still uniform, but when the invagination begins, a peculiar change occurs in the endoderm cells. They increase much in length, and become prismatic; their nuclei approach the extremities and project freely into the digestive cavity; the protoplasm becomes soft and filled with numerous albu- minous corpuscles, a sure sign of the active nutritive changes going on in it. In this stage the endoderm cells, which never bear vibratile cillia, do net cover the digestive cavity alone, but also line the buccal canal as far as its external opening (figs. 8 and 10). Mention has already been made of two cells of the peri- pheral layer, which become pushed into the interior, and then covered by the flat cellsof the ectoderm. This happens near the aboral pole on the side which afterwards becomes dorsal. They are very easily recognised when their external surfaces still project freely on the surface by their size and by their rather more dense protoplasm, and in the figs. 3 and 4 (em) the way in which they become gradually covered with flattened cells, which extend from all sides towards a point of union, is seen. In figs. 6, 7, 8, 9,-en, they are completely covered and have moved further in- wards. Their longitudinal section is wedge-shaped, with the thin end diverted towards the periphery, and the base bordering upon the layer of endoderm. They each contain a large spherical nucleus. At the sides of each of these cells, between them and the ectoderm, appear very soon two or three small, very thin, disc-shaped cells placed one upon the other, with their bases firmly adherent (figs. 3, 4, mes.) ‘These cells, increasing rapidly in number, group themselves in two rows or cords, which, starting from the mesoblasts, are directed immediately towards the opposite edges of the lentiform body, where they turn up to join the oral extremity (figs. 5, 8, 9, 10, lla, 114, mes). They thus together make a nearly complete circle, interupted only behind by the two interpolated meso- blast cells, and in front by the mouth; they do not remain long in this state, but first widen and then become thicker, being now composed of two, three, or more rows of cells, placed side by side, and of as many layers placed one upon the other (figs. lla, 12,13). These cellular arches are the rudiments of the mesoderm. VOL. XIX,—NEW SER, P 222 NIKOLAS KLEINENBERG. Now, what is the origin of the cells of the mesoderm ? According to Kowalewsky, the two large cells produce the middle layer in Z. rubellus, while in L. agricola, where such cells do not exist, the well-developed endoderm pro- bably furnishes the material for the formation of the meso- derm. In Ewazxes the middle layer is derived directly from the division of the four first blastomeres.' Hatschek affirms still more decisively that in L. rubellus the mesoderm is derived from the two large cells.? There is no doubt that the mesodermic arches begin with the appearance of the few small cells at the sides of the mesoblast cells, and that their development proceeds from here towards the opposite extremity; this is certainly a remarkable fact, but is it enough to enable us to decide the part which the large cells play in the formation of the mesoderm? I have not met with states of incomplete division in the latter, but very little value can be attributed to such a negative result, especially because it is matter of general experience that, in rapidly growing tissues, cells in which the process of division has really begun without being completed are rarely observed. This fact may be explained by the rapidity of the process of fission, after the previous internal changes have been effected. But the observation that the large cells retain their volume apparently unaltered from the beginning to the end of the embryonic life may raise more serious doubts as to their reproductive activity. At least I have not been able to make sure of the exist- ence of oscillations in the size of the large cells which would have justified the supposition that they deprived themselves of a portion of their substance to give rise to the cells of the mesoderm. Kowalewsky represents a stage in which each of the large cells is divided into three smaller ones of nearly equal size.2 In L. trapezoides this never happens ; on the contrary, the cells of the mesoderm, which are in contact with the large cells, are always among the smallest and most compressed. Notwithstanding all this I am also of opinion that there must be a production of new cells from the two large ones, solely because they show very often the phenomena which may be considered with great probability as a necessary preparation antecedent to the formation of new cells. In this case the mode of reproduc- tion would be what is ordinary called gemmation ; cells greatly inferior in size to the mother-cell would separate themselves from a point of the surface, and the mother-cell ' Loc. cit., pp. 16, 23, 29. 2 «Zeit. fiir Wiss. Zool.,’ T. xxix, 1877, p. 545. 3 Loe. cit., pl. vi, fig. 14. THE DEVELOPMENT OF THE EARTH-WORM, 223 would regain almost immediately its original volume, by the aid of an extraordinarily energetic nutritive change. Now, the cells produced in such a way from the large ones cer- tainly would not be placed elsewhere than in the mesoderm, and would form a part of it. I say, a part, because another, and I believe the larger part, certainly has a different origin. It has been explained above how the ectoderm cells trans- form themselves into wide and flat plates; this is true for the dorsal and ventral surfaces, but the cells of those tracts of ectoderm which cover the cords of mesoderm either keep their longer or shorter prismatic or cylindrical shape or recover that form after having been depressed before the mesoderm comes to raise them (figs. lla, 114, 12, 13, ecc). Now, while the larger number of the ectoderm cells show little activity, and appear not to divide, except when their is no other way to prevent the interruption of continuity of the external covering of the embryo, those which cover the middle layer are in a state of the most rapid reproduction. The newly made cells do not become employed in the enlargement of the surface, but losing little by little their connection with the layer from whence they took origin, they force themselves inwards, when they unite with the cells of the mesoderm. This relation appears to me to be very easily and clearly recognisable. Sections, especially transverse ones, show how, here and there, the line of demarcation between the ectoderm and mesoderm disappears altogether, while in other parts of the same embryo it is very evident. It is impossible to decide whether certain cells belong to the external or to the middle layer ; indeed, it sometimes seems that the covering of the two cords is folded inwards round their proximal margins, cells of the external layer in this manner placing themselves below the already formed elements of the mesoderm. But the direct production of mesoderm cells from the external layer lasts only a short time. With the progress of development a very distinct demarcation becomes established between the two layers, and the very important increase which the mesoderm henceforward undergoes is produced solely by the multiplica- tion of its own proper cells. On the other hand, with the greatest attention, I have not been able to discover the least sign of the endoderm cells participating in the formation of the middle layer, and as in the stages under consideration their relative positions are very clear and distinct, I do not hesitate to say that the internal layer has no share in the formation of the mesoderm. But how can this be? I have admitted, at least for a part of 224, NIKOLAS KLEINENBERG, the mesoderm, an origin from the two large cells, and these, according to Kowalewsky, were originally elements of the endoderm, from which they separated and approached nearer the surface. In this case the large cells would merely be the part which unites the mesoderm with the endoderm ; and the derivation of the first from the second, though not direct, would be none the less a fact. But, as is indicated — in what precedes, I am unable to agree with the assertions of the Russian embryologist, because in L. trapezoides the mesoblast cells are distinguishable before the arrangement of the embryoplastic material into distinct layers is recog- nisable ; because at first these cells occupy a position on the surface, with a large part projecting freely, and, changing their position, become pushed from without inwards, instead of coming from a deep layer to the surface; and, finally, because in no respect, neither in the quality of their proto- plasm, nor of their nucleus, do they show any resemblance to endoderm cells. After this they should certainly be con- sidered ectodermic elements, if the earliness of their appear- ance, before the definite foundation of the layers, did not render the question almost insoluble. Besides, I am not at all convinced that the affair takes place in L. rudellus, as Kowalewsky supposes; the figures which should bear witness to his assertion! do not persuade me at all, and unless he is supported by less equivocal observations I think that his opinion rests on a very doubtful foundation. I shall call the two cords or mesoderm, together with the superposed ectoderm, the ‘‘ germinal streaks’’ (Keimstreifen), and shall use this term to make the topographical descrip- tions simpler. In tracing the true origin of the organs it would not be correct to use it, as each streak is composed of two layers of different value, of which the lower, the meso- derm, has precise limits, while the upper, the portion of ectoderm belonging to the “ streak,” is continuous with the general covering of the body. In treating of the original derivation of an organ I shall always go back to the primitive layers. The germinal streaks, when they have reached the head end, must naturally be closely approximated, since they extend over an oval body. But they do not unite at once, but, ceasing to progress, they widen so as to form two pro- jections, like the heads of nails, at the sides of the mouth. (Pl. X, fig. 15 pp). A little later, however, the most anterior cells tend from both sides towards the median dorsal line, and when they reach it fuse with those of the ' Loe, cit., plate vi, figs. 10 and 12. THE DEVELOPMENT OF THE EARTH-WORM. 225 opposite side; a semicircular commissure is thus formed, situated on the back between the mouth and the cells, which unite the two embryos. Figs. 16 and 17 represent sections of the head end, in which the formation of the commissure of the streaks is already completed, and its position relatively to the surrounding parts 1s easily recognisable. Fig. 16 disa tsection immediately behind fig. 16 a, and serves to show the continuity of the cephalic arch or commissure with the cords which occupy the lateral parts of the body. But if in the first stages the enlargement of the streaks 1s owing chiefly to the junction of cells derived from the ectoderm with the mesoderm, this holds good, above all for the formation of the commissure. It is certain that only a very few cells pre- formed in the mesoderm enter into this; the larger part are derived directly from the ectoderm, which thickens, until three or four layers of superimposed cells appear (fig. 22 pe), the deepest of which then separate themselves from the more superficial to become blended with the mesoderm of the lateral germinal streaks. Rathke speaks of the origin of the cephalic portion of the germinal streaks in Nephelis and Clepsine in such vague terms that it cannot be clearly understood,' and Kowalewsky does not make any explicit statements on this question, but he figures an embryo of Ewaxes, in which the union of the germinal streaks on the back is perfectly clear. Lastly, C. Semper, after having found a special germinal streak for the formation of the head in the reproduction by fission and gemmation of the Naide, describes also in Clepsine the origin of the cephalic streak from two lateral thickenings, which are at first independent of each other and of the ventral germinal streaks, and therewith strengthens his theory of the original distinction between head and trunk. In opposition to this I affirm that in Lwmbricus trapezoides there is never a special rudiment for the preoral ring, but that the cephalic lobe, whose subsequent changes are so important, is formed simply by the union of the germinal streaks on the back. This dorsal commissure, which I shall henceforward call the cephalic germinal streak, becoming greatly thickened, raises itself above the mouth in the shape of a semilunar fold or incomplete ring. After this the entrance to the digestive cavity, which till now was a small fissure some- times very difficult to recognise, becomes transformed into a semicircular fossa, deep at the dorsal side, where it is surrounded by the projecting cephalic germinal streak, and 1 Loe. cit. pp. 29, 95.. 226 NIKOLAS KLEINENBERG, becoming shallower as it approaches the ventral surface (Pl. X, fig. 22). At the same time that this fossa is being excavated, the simple layer of ectoderm covering the cephalic germinal streak folds itself round the edge of the projection and is reflected into the buccal fossa, which till now was lined with large endoderm cells (Pl. IX, fig. 10; Pl. X, figs. 22, 23, 24, eo). The inbending begins at the dorsal surface, and extending from here embraces little by little the sides, and finally the ventral portion of the fossa. Thus, the ingestive canal, which anteriorly represents the mouth, but posteriorly is converted into the cesophagus, becomes covered by a -plaster of ectoderm cells instead of its original endodermic covering, which is thrust towards the bottom of the digestive cavity. The newly formed epithelium of the mouth and of the cesophagus consists of a single layer of slightly granular, cylindrical cells, elongate in the interior, but becoming shorter as they approach the edge of the fold, where they are continuous with the external covering of the body. They soon put out vibratile cilia, very similar in form and movement to those already described on the ventral surface. A similar covering of cilia extends now also over a circle of the external ectoderm surrounding the mouth. The vibratile cilia in the embryo of ZLumbricus are thus confined to the tract of ectoderm cells which is situated on the ventral surface between the germinal streaks, and extends from the mesoblast cells at the aboral pole to the cephalic extremity, where it unites with the vibratile ring just described. This mode of distribution of the ciliated cells, which remains unaltered for nearly the whole of embryonic life, calls to mind that, not of the larvee properly so called, but of the young stages of many, and the adult of not a few, Cheetopods. It is obvious that, as the germinal streaks lengthen, their respective positions, as well as the general shape of the embryo, must alter, and the necessary changes take place, as is always the case in the mechanism of the animal body, according to the principle of least resistance. In fact, instead of producing directly the lengthening of the embryo (to which, perhaps, the endoderm and ectoderm, which at this period only follow passively the movements of the germinal streaks, would offer too much resistance) ; the streaks seek to meet the increasing need of space by leaving their lateral symmetrical positions and placing themselves on the convexity of the ventral surface, about a radius of curvature which constantly becomes smaller; at the same time their points of origin, that is to say, the two large cells, THE DEVELOPMENT OF THE EARTH-WORM, 227 become moved more on to the back and towards the oral extremity, in such a way that, in some sections through the posterior portion of the embryo, the transverse sections of the two streaks are found at the lower part.and at the upper part the two large cells, together with the last part of the streaks (Pl. IX, fig. 12). Leaving this point, on the dorsal surface, the germinal streaks descend abruptly downwards, embracing a somewhat triangular space at the top of the posterior extremity, and, having reached the ventral surface, approach, with their convexities, both each other and the median line, without, however, adhering or coming into mutual contact. Figs. 11, 12, 15, and 14 of Pl. IX make this process of displacement quite clear. ‘Thus approximated to one another the germinal streaks stretch along the ventral surface, but at the anterior part of the embryo they again separate, and arching over the lateral surfaces, ascend on the back to join in the cephalic commissure. Besides this displacement, the development of the germinal streaks must cause gradually an alteration in the general form of the embryo, and the more so since the streaks grow, not only in length, but also in width and depth. Hence the transverse section of the body loses its lens shape and be- comes circular, then the ventral surface becomes more and more convex, and the anterior and posterior ends, curving towards the dorsal surface, this becomes depressed and con- cave, so that the embryo assumes a kidney or bean shape. Turning to the development of the cephalic germinal streak, we find the mesoderm separated completely from the ectoderm, consisting of a mass of small roundish cells, which fills completely the space between the ascending external lamina and the descending inflexion of the fold of ectoderm. Some time later two narrow fissures appear in the lateral region of this mass of mesoderm, then enlarge towards the median dorsal line, where they then unite with one another, thus splitting the mesoderm into two concentric layers, one external and one internal. But as the split begins nearer the external surface than the surface bounding the cesophagus, the layers are, from the beginning, of unequal thickness ; the external consists nearly everywhere of a single layer of cells, while the internal has two or three layers. ‘The first adapts itself to the external wall of the cephalic ring, the second joins itself to the oral epithelium. The splitting of the mesoderm in the cephalic germinal streak is followed by an analogous process in the ventral germinal streaks, beginning from the front and progressing gradually towards the posterior end. About this most 228 NIKOLAS KLEINENBERG. important event, on which is in great part founded the typical structure of the body both of Annelids and Vertebrates, I shall only say a few words, because I do not wish to enter here into the consideration of the particulars of histogenesis ; I do not_know how to do better than to repeat the beautiful and most exact explanation given by Kowalewsky of the process in Euazxes and Lumbricus rubellus. In L. trapezoides, as in the above-named Oligocheta, the successive division of the mesodermic cords into segments as primitive zoonites precedes the splitting of the mesoderm. It appears that this division happens in ZL. trapezoides at a little later period than in the other species, because when, the first traces of it can be discerned, when, that is to say, the finest transverse lines of demarcation appear between suc- cessive portions of the mesodermic cords, these are already very thick and contain two, three, and more layers of cells; the space which divides the streaks in the median ventral line is, on the contrary, still very wide. Hence are formed two parallel rows of transversely elongated, rectangular plates. Afterwards each plate becomes split by a horizontal fissure, so that the mesoderm is divided into two unequal lamina, of which, unlike what we have noticed in the split- ting of the cephalic germinal streak, the external is much thicker than the internal, which only consists of a single layer of cells (Pl. IX, fig. 13). Andas the splitting does not pass beyond the limits of the primitive zoonite, nor reach to its boundary line, the cavity remains surrounded on all sides by mesoderm cells; each primitive zoonite is transformed into a compartment, or rather, into a four-sided prismatic case, with a central cavity whose external wall is thickened, while the internal consists of a single layer of cells: The anterior vertical wall of each compartment adheres firmly to the posterior wail of the segment in front of it, and thus are formed the septa, stretched between the body-wall and the intestine. They are thus at first each composed of two layers belonging to two adjoining zoonites; then, in conse- quence of the strong tension which they have to sustain, the cells group themselves into a simple, very thin membrane, which is not placed vertically to the long axis of the embryo, but goes obliquely from behind forwards. Hence, in almost all perfectly vertical transverse sections, are seen on each side two separate cavities ; the ventral is the posterior part of a segment and the dorsal the anterior part of the following segment ; the row of cells which divides them is the oblique section of the septum. Not rarely two cavities are formed in the same primitive compartment, but they soon unite. Later, THE DEVELOPMENT OF THE EARTH-WCRM. 229 the septa become perforated in many points, the cavities of the primitive somites communicate freely and form together the general “ somatic” or ‘‘ body” cavity. Of the horizontal walls of each zoonite the external is placed beneath the ectoderm, the internal encircles the epi- . thelium of the digestive cavity. The external layer resulting from the splitting of the mesoderm is called the somatic lamina, the inner the splanchnic lamina; their origin and the part they play in the formation of the body leave no doubt of their homology with the layers of vertebrates, dis- tinguished by the old and somewhat inappropriate terms fibro-cutaneous (Haut-faser-blatt) and fibro-intestinal (Darm- faser-blatt). This is an agreement of the highest theoretical importance, because the analogy in the development of the primitive zoonites, of the somatic cavity, and of the somatic and splanchnic laminz, shows with surprising clearness the close relation between the vertebrates and annelids. Now, it is clear that the differentiation of the cephalic germinal streak is essentially the same as that of the ven- tral germinal streaks, and differs only in points of secondary significance. The head cavityis formed by the fusion of two lateral fissures, which divide the mesoderm into a somatic and splanchnic lamina. But while the zoonites of the trunk generally embrace the whole circumference of the trunk and close in the dorsal median line to form perfect rings, the cephalic zoonite, which from the first is placed above the oral fossa, is unable to complete itself in the same way, because, when its lateral branches direct themselves downwards and backwards towards the ventral surface they meet the first zoonite of the trunk, and hence the cavities of this zoonite and of the head unite. The anterior end of the head segment becomes more and more prominent, and is transformed into a cylindrical process, the upper lip—a kind of proboscis. It is evident at the first view, from the chronological order in which the formation of the primitive segments and the splitting of the mesoblast takes place, that the segmen- tation begins in front and gradually proceeds backwards. But it is still necessary to know whether the first zoonite of the trunk or the cephalic zoonite is the first formed, because Semper has attributed great importance and a fundamental significance in the morphology of all articu- lated animals to the fact that, in the development of verte- brates and in the organic multiplication of the Naide, certain segments of the head appear later than those of the body.! The investigation of this point is not easy in the embryos ' Loe. cit. ad 230 NIKOLAS KLEINENBERG. of L. trapezoides, because the great curvature of the ante- rior end of the body, would easily conceal the existence of a very narrow fissure. Notwithstanding this, I am convinced that the splitting of the mesoderm appears first in the cephalic germinal streak ; that, namely, the cephalic segment is the first formed, although the first segment of the trunk - is formed nearly at the same time. The splanchnic layer of the cephalic ring, which at first covers only the upper side of the buccal fossa and cesophagus with a thick layer of mesoderm, extends gradually its lateral parts towards the central surface, and embraces the ingestive aperture completely. Then certain cells of its deeper layer begin to migrate into the inflected ectoderm which clothes the cavity of the head intestine, making their way between the bases of the epithelial cells and slightly raising them (Pl. II, figs. 19 d,¢,d, 23, 24). This process begins also from the dorsal side, and ends in the formation of strong and thick walls for the head intestine, which by their origin belong to the splanchnic layer of the mesoderm, from which they become distinctly divided. The epithelium becomes reduced to a thin almost cuticular membrane, which in the adult state lines the mouth and cesophagus. Thus, the walls of the ingestive end of the alimentary canal, at three successive periods of embryonic life, have a structure different both in form and in the origin of the material ; at first they are formed of endoderm, this then becomes pushed away and replaced by an inflection of the external covering of the body, and, lastly, they consist nearly entirely of mesodermic tissues, the ectodermic epithe- lium being reduced to a thin layer of cells fused with them. It is probable that the transformations of the splanchnic laminz in the cesophageal tube may correspond in some way with what Semper interprets in the development of the head intestine in Nats and Chetogaster as the forma- tion of true branchial slits, homologous with those of Ver- tebrates, which then become converted into part of the cesophageal walls.! Of canals and external orifices I have found no sign in Lumbricus, and I have found nothing resembling the branchial apparatus of Semper, unless it is the above-men- tioned passage of a part of the splanchnic lamina of the cephalic germinal streak into the walls of the head in- testine. During the time of greatest activity of the mesoderm, until a considerable number of segments are formed, the other two 1 Loe, cit, THE DEVELOPMENT OF THE EARTH=-WORM. 231 layers keep their primitive state nearly unaltered. The en- doderm shows no other change than the enlargement of its cells filled with numerous granules of dense albumen, and the displacement of their small oval nuclei towards the free surface. The reproductive activity of the ectoderm appears to be confined to the production of the secondary epithelium of the head intestine; in its other parts the cells become very much more stretched out into thin plates by the in- creasing internal pressure, which is greatest on the dorsal surface, where they become so thin that it is sometimes difficult to recognise them. They retain, however, their nuclei, placed in small thickenings, which project inwards, taking advantage of the less resistance at the lines of separa- tion of the endoderm cells. But when the anterior zoonites are marked out, the ectoderm resumes its reproductive activity, the first and most important result being the formation of the central neryous apparatus. Development of the Cephalic Ganglion. Theinvestigation of the first stages of the development of the supra-cesophageal or cephalic ganglion is rendered specially difficult by the rudiment being situated on a strongly curved projection. In investigating the differentations in a very small space, and of a tissue composed of very small cells, only the very thinnest possible sections are of use, which, to render the relations of the surrounding parts in- telligible, must pass exactly at a right angle through one of the principal axes of the rudiment, a condition which can only be obtained by chance in transverse sections; in longitudinal sections the median one is vertical, but all the others are necessarily oblique ; this is even more the case with horizontal sections. But since there is no other method of research, I have made sections in all directions; by combining the sections of a series with one another, and with those of other series made in different directions, I think I have formed a fairly precise conception of the way in which the cephalic ganglion is formed. Fig. 23, Pl. X, represents the anterior part of the exactly median section of a longitudinal series, made from an embryo of about 0-4 mm. in length. The structure of the cephalic ring, already described, is easily recognised; the head cavity, lined by the large splanchnic lamina (/sp) and by the so- matic lamina (/so), here reduced to a very thin layer of fusi- form cells. The ciliated epithelium of the mouth (eo) is tulded towards the external dorsal surface, where it becomes 232 NIKOLAS KLEINENBERG, continuous with the ectoderm, the cells of which are cylin- -drical on the edge of the projection, but on the dorsal surface from their plates, which appear fusiform in section. But what has lately happened is that for a small space the ecto- derm has become thickened; it consists here of two sets of cells, while a short time before it was everywhere composed of asingle layer. The cells of this thickening (gc) are not, however, arranged in distinct layers, but are closely united into a single mass; it is exactly and clearly limited by the somatic lamina. The unfigured sections of the same series, which are immediately to the right and left of the one de- scribed, show the same characters, with the difference only that the number of cells composing the thickening is smaller; the same is observed also in the following sections on each side, although these are very oblique. In the sections still more to the sides the thickening disappears altogether, and the ectoderm becomes again unicellular. Examining now the head end of a slightly more developed embryo by means of transverse sections, we see in the first (Pl. X, fig. 20 a), which passes only through the semilunar projection of the cephalic zoonite, a group of small cells (gc), rather thinned in the middle, completely separated from the mesoderm, which is here in an abnormally retarded state of development, not being yet split in the median line, and beginning to separate itself from the superficial layer of ectoderm. The section immediately following this (fig. 20 6) shows how these cells pass directly into a very conspicuou enlargement of the ectoderm in the median dorsal line, which here is composed of as many as four layers of cells. In the third (fig. 20 ¢) the thickening of the ectoderm, although diminished in the median line, is increased at the sides, where it descends for a good distance towards the ventral surface, becoming gradually thinner, and at last unicellular. This is shown best in the left side of the figure, the section being a little oblique. In the fourth section the ectodermic thickening may be still seen, though it is much diminished. In the following sections it exists no longer. The series shown in figs. 19 a,b,c, d, is taken from a still more developed embryo. In the first section (fig. 19 @) the thickening of the ectoderm embraces, in the form of a half circle, the superior convex part of the cavity of the head (cc), from which, however, it is separated by the thin membranous somatic lamina (/so). On the external surface of the thick- ening a single layer of flat pavement-cells (ec) is separated from the internal mass, composed of roundish cells with re- latively yery large nuclei; in other words, the rudiment of THE DEVELOPMENT OF THE EARTH-WORM. 2338 a new organ, the “cephalic medullary plate,” has become separated from the peripheral ectoderm, which once more forms a unicellular covering. Fig.-20 06 shows the same arrangement nearly unaltered; but in the third section (fig. 20 ¢), instead of a continuous semicircular thickening, there are two large projections of ectoderm (gc), which thrust themselves into the cephalic cavity, separated from each other by a largish tract of simple ectoderm. These projections are still more conspicious in fig. 20 d. At the ventral side are seen in the last section two eleva- tions, formed of small cells very like those of the rudiment of the cephalic ganglion, and separated from each other by a ) furrow, whose floor is formed of ciliated cells (m). This is the section of the rudiment of the first ganglion of the ven- tral chain. It is important to notice that there is no con- nection between this and the dorsal thickening (gc). In the three following sections the last are still recognisable although much reduced; further back they are altogether absent. Fig. 21 a, b,c, d, are longitudinal horizontal sec- tions of an embryo 0°6 mm. in length; 21 ais the fifth of the series, going from the ventral to the dorsal surfaces. It is to be understood that when the embyro is placed horizon- tally the first sections pass through the very prominent belly without touching the mouth or head end. The section is not perfectly at right angles to the vertical axis, but has fallen with its left side nearer the ventral surface than the right, hence the difference. On the left side the ectoderm appears thickened, and this is the section of the longitudinal ventral chain of ganglia (m) ; on the right side and in front the ectoderm consists of a single layer of pavement-cells (ec). In the segment which comes next (21 b) the ectoderm “ cells on the apex of the head have become long and cylin- drical, but are still placed ina single layer. A. little further back the ectoderm shows on each side a spindle-shaped swelling (gc), which loses itself again in the unicellular layer covering the body. The same conditions of the ecto- derm are seen likewise in the seventh and eighth sections, in which the lateral thickenings are still larger. But in the ninth (fig. 21 @) the cylindrical epithelium which separated the swellings in front has disappeared, and these are united by a largish commissure ; they form together an arch em- bracing the cephalic extremity. Finally, in the tenth sec- tion (fig. 21) no further trace of the lateral thickenings is found ; the ectoderm is, on the contrary, much thickened in the middle line. Now, the comparative combination of these sections will be 234 NIKOLAS KLEINENBERG. enough to give a clear idea of the way in which the rudi- ment of the cephalic ganglion is developed. In the first place, it is clear that it originates in the ectoderm, and in the ectoderm alone. In a narrow transverse tract, close to the apex of the head, the cells of the simple layer of ecto- derm divide, and group themselves into the form of a short and slightly curved arch. This, increasing in thickness and becoming distinctly separated from the peripheral layer of the ectoderm, extends along the lateral walls of the cephalic zoonite, but still more behind, where it ends on each side in a conspicuous club-shaped enlargement; it thus assumes a shape which may be compared to a _hernia- truss with a cushion on each side, which embraces the upper half of the cephalic cavity and of the csophagus, being directed obliquely from above downwards and from behind forwards. From the beginning till it has reached a considerable development the rudiment of the cephalic ganglion is without any connection with the ganglia of the ventral chain. I confess that I expected something different. The nature of the adult organ, the mode of formation of the ventral gan- gliated cord, and more general considerations, led to the anticipation of a double rudiment as the first sign of the central nervous apparatus of the head. But, on the other hand, my observations agree with what was before known of the development of the cerebral ganglion of the Hirudinea. This only consists, it is true, of a short notice by Rathke for Nephilis, and of a still shorter one by Leuckart for Hirudo medicinalis. Rathke affirms that the rudiment of the cere- bral ganglion is an arch placed on the upper side of the cesophagus, without connection with the ventral germinal streak.! Leuckart also says that the formation of this organ occurs, independently of the germinal streak, by the appear- ance of a cellular cord, which embraces the buccal aperture and adapts itself to the anterior ends of the streak, without at first uniting with it. He further adds that, in a subse- quent stage, two lateral swellings are found united by means of a pretty large commissure, both to each other and to the anterior processes of the first ventral ganglion.” These short notices, which do not take account of the embryonic layers, are not founded on investigations carried out by means of sections, and are not illustrated by any figures, certainly 1 Loe. cit., pp. 49, 50. Recently Biitschli has upheld the truth of Rathke’s observations (‘ Zeit. fiir Wiss. Zool.,’ 'T. xxix, 1877, p. 248. 2 ‘Die menschlichen Parasiten, T. i, Leipzig und Heidelberg, 1863, p. 705. THE DEVELOPMENT OF THE EARTH-WORM. 235 cannot have much authority. ‘They are open to the greatest variety of interpretations and objections, but it is a little too much when Semper, taking advantage of an easily explicable inexactness of expression in Leuckart’s notice, twists it in an extravagant manner to make it fit his own observations and speculations. In fact, the mode of formation of the cesopha- geal collar, which Semper thinks typical for all the Annu- lata, is not consistent either with the observations of Rathke and Leuckart on the Hirudinea, nor with my own on Lumbricus. During the gemmation of the Naide, according to the above-quoted observer, the ventral germinal streak in the cephalic zone splits into two parts, which grow up on the lateral walls of the cesophagus, arching over towards one another on the dorsal surface. As soon as they have em- braced the intestine a portion of them separates itself to form the commissure and the ganglionic substance of the brain ; the two halves of the supra-cesophageal ganglion thus formed then fuse to one another in the median dorsal line. This portion of the cesophageal collar is derived from the mesoderm. But then the ectoderm developes to the right and left a kind of bud, which Semper calls ‘‘ Sinnesplatte,”’ because in it is formed the eye of the Naide, which is directed towards the dorsal surface, where it enters into the composition of the supra-cesophageal ganglion. Hence the entire cesophageal collar would be a product of the ventral germinal streak, together with two lateral buds of the ecto- derm, without the intervention of a dorsal medullary plate, and thus would be an organ heterogeneous, even in its essential parts, being derived as much from the mesoderm as from the ectoderm.! I have no observations of my own on the development of this organ in the agamic generation of the Naide, but I know that in a group of animals, closely related to these, the embryonic development proceeds in quite a different manner. In Lumbricus the first rudiment of the cesophageal collar is a dorsal medullary plate, which arises independently of the ventral chain and exclusively from the ectoderm. I do not know what forms the sensitive plates of Semper, since it does not appear justifiable to identify them with the terminal enlargements of the medullary plate. Lastly, Hatschek, in opposition to Semper, describes the affair very differently. He says: “The first rudiment of the nervous system is found in Lumbricus in those embryos in which the foremost segments are developing the seg- mental organs. It appears as a thickening of the ectoderm 1 Loe. cit., pp. 206, 210, and elsewhere. 236 NIKOLAS KLEINENBERG. in front of the oral margin (Scheitelplatte). Soon two filamentous thickenings of the ectoderm begin to extend themselves from the lateral regions of the Scheitelplatte backwards along the sides of the mouth into the neighbour- ing segments, where they lie on either side of the middle line.” I should agree with this as regards the fact that a dorsal plate arises before any other part of the central apparatus if I were capable of forming a clear idea of what the author intends to express by these words, and if I were convinced that he really has observed the first stages. But the assertion that the ventral medulla is produced from two prolongations of the cephalic ganglion I believe to be entirely erroneous if the probability be admitted that, in two species of the same genus, the principal organs would be formed in the same way. A few words on the further transformations of the dorsal medullary plate. The whole rudiment separates at once from the ectoderm, and becomes enveloped in a sheath of the somatic lamina. From the anterior median part of the arch start two prolongations, which enter the upper lip, where they appear to become confounded again with the ectoderm, which here is transformed into sensitive epithelium. In like manner, the opposite side of the rudiment sends out processes directed backward, which are broader and longer than the anterior. Thus, the cephalic ganglion seen from above appears to consist of two pear-shaped halves broadly joined in the middle. The two lateral projections which form the dilated extremities of the arch, also separated from the ectoderm, extend gradually as much upwards as down- wards, and unite principally with the median arch of the medullary plate. In transverse sections this is seen to embrace already more than half the csophagus. In the median dorsal line is seen a deep impression where the dorsal blood-vessel is placed ; the margins of this groove rise a little, and these bendings descend nearly vertically towards the ventral surface, where they end in very fine extremities without joining the ventral chain. I do not wish here to enter into the description of histological differentiations ; I will only say that the transverse commissure which connects the two halves of the arch appears in this stage, and is the first to arise. All the cells on the ventral face become trans- formed into a finely granular substance, while at the sides 1 Beitrage zur Entwicklungsgeschichte und Morphologie der Anneliden,” ‘Sitzungsberichte der Akademie der Wissenschaften in Wien,’ T. lxxiv, 1876, p. 1. THE DEVELOPMENT OF THE EARTH-WORM. 237 and above a thick layer of ganglionic cells remains. As the extremities of the arch descend, these commissural cords lengthen proportionately, and the ganglionic cells on their external sides become scarcer, so that it may be said that the cesophagus is not embraced by the entire ganglion, but rather by the elongated branches of the commissure. These branches must themselves descend to the ventral wall to meet the first ganglion of the ventral chain, for I have never seen prolongations directed upwards from the latter. But the investigation of this point is extremely difficult, since the lateral parts of the collar are very closely enveloped by the mesoderm, whose cells resemble so closely those of the nervous ring that it is not easy to distinguish them with exactness. Hence I cannot say definitely that mesoderm cells do not at this time enter the lower extremities of the collar (this applies only to the lower extremities, since all the remainder is clearly separated from the middle layer) to take part in the formation of the commissure, but it would be still less possible to prove that they do so, and I think it is most improbable. When, at a relatively very late period, the definite union of the cerebral ganglion with the first ganglion of the ventral chain takes place, this first ganglion, as well as those following, possesses a well-developed commissural trunk with which the cord from the cephalic ganglion appears to be directly united. The Development of the Ventral Chain of Ganglia. I began the account of the development of the central nervous apparatus with the cephalic ganglion, because, even if it is not, as I believe, the first part formed, it certainly appears at least contemporaneously with the earliest traces of the ventral chain. It is known that the development of the latter progresses from before backwards, but its first rudi- ment extends rapidly along the whole length of the embryo, as far as the caudal extremity. On the other hand, the separation of the individual ganglia and their histological development takes place gradually, and much later in the posterior than in the anterior part; while the first ganglia have already attained a state of great perfection, those fur- ther back exhibit all imaginable gradations, till we reach the condition of the undifferentiated rudiment. Hence, for the investigation of the first changes, it is best to take early em- bryos ; for that of the following stages much older embryos answer very well, because the.most different stages of deve- lopment, united by the minutest gradations, are found in a single individual. VOL, XIX,.—NEW SER. Q 238 NIKOLAS KLEINENBERG, When the mesoderm of the germinal streak has fused in the median line, the ectoderm is still divided into two lateral sheets by the narrow band of ciliated cells, which runs along the whole ventral surface. ‘The cells of this band, besides being covered with vibratile cilia, are clearly distin- cuished from the rest of the ectoderm by their transparent appearance, their granular protoplasm beingreplaced toa great extent by a very transparent substance, and reduced to a fine network radiating from the large nucleus, and a condensed layer on the side which bears the cilia. These cells at first project and form a low crest, but afterwards become raised at the sides, so that a longitudinal furrow appears between them, which I shall call the ventral furrow. At this time the first trace of the developing nervous cord appears as two thickenings of the ectoderm, immediately on each side of the ventral furrow. These are still so little raised that it is impossible to detect them by looking at the embryo from the front ; but transverse sections show thatone, two, or three cells have been newly formed in the ectoderm, and are placed partly among and partly beneath the pre- existing cells. There can be no doubt as to their origin, for they are perfectly separated from the mesoderm, while they are united into a single mass with the ectoderm, from which many cells show the most evident signs of being in a state of division. Then, at each side of the groove, one of the deep cells of the ectoderm assumes an appearance rather different from the rest, becoming darker, in conse- quence of the condensation of its protoplasm; it is still further marked by its broader and more distinct outline, an outline which the other ectodermic cells do not possess. The two cells thus distinguished, separated from one another by the epithelium of the furrow, are the first stage of the ventral cord. Sometimes it appears that two or three ectoderm cells become changed at the same time, but in general the process begins in a single cell. This, however, divides without delay, and then two well-defined groups of two or three cells each are seen in the transverse section, on either side of the ciliated cells (Pl. IX, fig, 14). In this way are developed along the ventral furrow two cords, broad and clearly defined in front, becoming thinned away behind, where they finally blend with the primitive ectoderm. Here the process of division in the ectoderm cells continues, and hence the prolongation of the cords is principally effected by the addition of freshly separated cells, while the increase of their thickness is produced by means of the cells already transformed ; it is not, however, impossible that, in THE DEVELOPMENT OF THE EARTH-WOKM, 239 the region where the cords are already distinctly separated, some adjacent ectoderm cells may assume their specific characters and join them. From this time the cells of the neighbouring borders of the cords force themselves under the furrow, slightly raising the ciliated cells. They approach the median line, and there those of the two sides unite ; thus, the two primitive lateral cords join to form a single lamina, which I shall call the ventral medullary plate, and soon afterwards its cells begin to accumulate at certain points, producing a successive series of zones, alternately alike and unlike. This, as well as what follows, will be best explained by reference to successive transverse sections. Only perfectly vertical sections are of use; in these the sections of the longitu- dinal muscular fibres appear as circular points In the section fig. 26 a, which, together with 25 0 and 25, is taken from the tail end of an embryo 3:0 mm. in length, the junction of the cords has taken place. Beneath the bottom of the furrow sz the medullary plate () consists of a single layer of cells, but is raised immediately to the right and left into two parallel crests, which, becoming gradually lower towards the sides, terminate in a thin lamina. The dorsal surface of the plate is nearly flat, and is covered by a thin layer derived from the somatic lamina (/so). Thicken- ings of the somatic lamina are seen on each side of the plate, and between them and the ectoderm the rudiments of the muscular plates (m); above the medullary plate, projecting into the body cavity, is the ventral blood-vessel (v), attached to the splanchnic lamina (from which it takes its origin), that envelopes the mid gut (ez). The section 25 4, which immediately follows the last, shows a different arrangement ; here the conspicuous elevations at the sides of the furrow are wanting, and the medullary plate is reduced nearly every- where to two layers of cells; but in the third section (fig. 25 e) it has again the form and extension which it had in 25) a. Such a succession of thick and thin zones is repeated many times, with the difference, however, that further for- ward the size of the thick zones is greater, so that they occupy two or three sections instead of a single one, and the differences between the zones become less marked. On examining a series of sections taken from the middie of the body of the same embryo, the first thing which strikes one is the great enlargement of the medullary plate, which in this stage has, in fact, attained its largest relative dimen- sions. The ventral furrow has disappeared, and its cells, although still recognisable, have greatly changed their 240 NIKOLAS KLETNENBERG. appearance, in the first place having lost their vibratile cilia. This alteration in the cells of the furrow takes place bit by bit; in the same embryo, both behind and in front, the cells are found in their characteristic form, and show a lively vibratile movement. I thought that the cells might perhaps transform themselves at a certain time to take part in the production of new ones, and then return to their preceding state, but I have not been able to obtain proofs of this. It is certain that they have no relation with the mesoderm cells, which are found here for the first time interposed between the ectoderm and the medullary plate (fig. 26 a, mes), because these are derived from the somatic lamina, which, beginning in front, forces itself from the two sides towards the median line, and then backwards, separating the rudiment of the ventral medulla from contact with the ectoderm. The groove in the medullary plate, sometimes very deep, which divided the two elevations has now disappeared, or become reduced to a very small impression. The edges of the furrow do not become united, but, on the contrary, the fossa becomes wider and shallower before vanishing, in con- quence of the increase of the medullary cells placed above its floor. The cells which occupy the middle portion of the plate are larger, consist of clearer protoplasm, and have more precise limits than those placed in the lateral portions, from which, however, they are not in any way separated. In the following section (26, 5), the nervous plate has changed its form a little, its sides are thickened and form two elevations on the dorsal surface, between which is found a wide and pretty deep furrow. ‘The internal structure also shews some alterations, the greater part of the large median cells being changed and aggregated with the small ones. The proto- plasm of these is dense, and the nuclei fill nearly the entire body of the cell; they are placed so close together that a high power and great attention are necessary to make out their boundaries; signs of division are frequent. A meso- dermic sheath everywhere surrounds the medullary plate. Further in front (fig. 26 c) the rudiment of the nervous chain presents a new form. Till now its lateral wings were elongated, and ended in very sharp points; now they are rounded in such a way that their section is kidney shaped. The histological changes met with here are more important. In the dorsal side appear two small, clear-look- ing, finely granular spots, which stain feebly with haema- toxylin. They have not distinct limits, but lose themselves in the surrounding cells, whose outlines become little by THE DEVELOPMENT OF THE EARTH-WORM. 241 little less distinct ; no other fibres are seen, unless faint traces of prolongations of the adjacent cells, visible with a higher power, are regarded as such. These are the rudiments of the fibrous commissures. Fig. 26d shows the plate again in the form which it had further back, but the granular sub- stance of the commissure, which encloses some nuclei, is still more conspicuous than in the preceding section, and the two lateral rudiments are fused in the median line and form the bottom of the dorsal furrow. ‘The sides and the ventral portion consist of a continuous pretty thick layer of cells. The same succession of such alternate zones repeats itself again several times in the backward direction, then every trace of the commissure is lost, and the medullary plate passes by every gradation to the state of fig. 25. In front similar conditions are observed ; here, however, every section shows the presence of a commissure in a stage of very much more perfect development. To illustrate the subsequent changes I select a group of sections of an embryo of 4°5 mm. in length (Pl. XI, fig. 27 a,b, c,d,e). In the first preparation (27 a) the medullary plate has a shallow impression both on the ventral and dorsal surface. The cells occupy the surface, leaving the median part of the upper side free, and are especially accumulated in the lateral processes; from here they are continued round to the inferior surface, where they unite and penetrate deeply into the interior of the plate, so that this again appears to be divided into two lateral cords, whose centres are composed of the granular substance. Immediately in front (fig. 27 6) the plate becomes kidney-shaped. The septum, which pro- jects from the cortical layer of cells into the interior, is much more developed, and divides the commissure nearly com- pletely into two trunks. But in the same section the firm union of the cells is relaxed and they separate a little to the right and left, occasioning the appearance of a kind of vertical fissure, which is more distinct in the centre than at the periphery. ‘This is clearer still in fig.27c. The cellular process penetrates a little less deeply into the substance of the commissure, but the fissure which divides it into two parts is more evident, especially at the centre, where it ends in an enlargement. Further, the whole cellular covering is thickened considerably, diminishing the size of the commis- sure. But in the foliowing section (fig. 27 d) that constric- tion has entirely disappeared ; the commissure which forms a large mass containing some scattered nuclei, is surrounded by a uniform layer of cells. The median thickening of the cellular covering reappears once more in the section (fig.27 e), 242 NIKOLAS KLEINENBERG. énd thus begins the repetition of the successive variations just described. According to these observations the mode of development of the ganglionic chain would be the following :—Some of the ectoderm cells, situated on the two sides of the ciliated furrow, divide and form two parallel thickenings. One, or sometimes two or three, cells, of the newly formed deep layer acquire special characters, and separate themselves distinctly from the superficial layer and from the lateral parts of the ectoderm from which they originated. In this way are developed two cords, completely separated from each other by the cells of the ventral furrow. This is the original double rudiment of the subintestinal central nervous appa- ratus. Then the neighbouring margins of the cords raise themselves, and approach each other, forming between them a groove, sometimes very deep, but having only a temporary existence. The upper cells of the neighbouring sides force themselves above the groove towards the median line, where they meet and unite with each other; their number increasing the groove becomes little by little flattened out and finally dis- appears. The primitive cords are thus united into a median plate. As soon as the union has taken place, the cells group themselves into a series of swellings and constrictions. The first represent the ganglia, the second the connecting trunks. Now, certain cells placed beneath the dorsal surface on each side are transformed into an ill-defined granular substance, which gradually extends to the median line and forms the fibrous commissural cord. This developes sepa- rately for each segment of the chain, before the single segments become united among themselves by a special con- ducting tissue. The connecting trunks, which run through the whole length of the ganglionic chain, are formed later, simply by the fusion of the commissural trunks of the suc- cessive segments ; hence the first rudiments play the part of a common foundation for the transverse and longitudinal commissures, in which afterwards, by the development of rerve fibres, a regular apparatus;of conducting threads is established. In consequence of the formation of the fibril- lar substance, the parts of the nervous plate, which are destined to become changed into ganglion cells, extend on the sides and ventral surface ina more or less thickened, but everywhere continuous, layer. At intervals, thickenings of this cellular covering pene- trate deeply into the interior of the plate. They are formed in part by the central cells, which are’ not transformed into the substance of the commissure, in part by cells, which THE DEVELOPMENT OF THE EARTH=-WORM, 9438 migrate from the ventral surface. Then a fissure appears between the cells of the median septum; at first it is con- fined to each segment, but later extends the whole length of the nervous chain; this is the ventral fissure of the subintestinal nerve cord of the adult. My researches have fully confirmed Kowalewsky’s im- portant discovery that the subintestinal nervous chain of | the annelids arises solely from the ectoderm. Semper’s state- ment that it is made up of an unpaired median thickening of the ectoderm, comparable to the medullary groove of ver- tebrates, and of two cords of mesoderm, corresponding to the spinal ganglia, is definitely contradicted by the develop- ment of that apparatus in the Luwmbricinz. And further, this dogma, which had for its object the reconciliation of the differences in the structure and development of the nervous system, observed in annelids on the one hand, and verte- brates on the other, has missed the mark, since we have learned from the excellent researches of Balfour that the spinal ganglia of vertebrates are not derived from the mesoderm. Semper has already found an opponent in Hatschek, who upholds for Liwmbricus the origin of the entire ganglionic chain from ectoderm. But, beyond this, his own not very clear descriptions appear to me to be erroneous. We have already noticed that, according to this author, the ganglionic chain is formed from two prolongations of the cephalic medullary plate; that is to say, only the lateral parts of it, parts, which he calls lateral cords, since a medullary groove, very similar to that of the vertebrates, is then formed between them. It is true that in the development of the medullary plate a fissure, sometimes a very deep one, is seen (or), rather there are two, differing in time of appearance and in mode of formation. To my view Hatschek’s figs. 2,3 and 4! would represent the first. But here certainly is not a case of invagination; the groove besides is only the space which from the beginning separated the primitive cords, deepened in consequence of the great thickening of their neighbour- ing sides. With the development of the medullary plate this groove disappears. On the other hand, the fissure in fig. 6 cannot but be the second, whose formation we have described above,and which accordingly has nothing to do with the first. But what I do not know how to explain is the fact that Hatschek represents the walls of the fissure as being very obviously separated from the lateral cells of the plate; in Lumbricus trapezoides there is not the least trace 1 Loc. cit, 244. NIKOLAS KLEINENBERG. of this. The secondary groove may, perhaps, be compared to the posterior fissure of the spinal cord of vertebrates, but certainly not to the primitive medullary groove. Here I will end, merely adding further, that at the time of the differentation of the first cells of the medullary cords -the muscular fibres appear at their sides. The rudiments of the segmental organs resemble those of Ewaxes, represented by Kowalewsky, and do not develop from the septa, as the same author states that they doin Lumbricus rubellus. I confess also that I should not have hesitated to describe them as invaginations of the ectoderm, if the very clear figures in the above-quoted work had not obliged me to investigate the the subject from this point of view. Ofthe formation of the colossal fibres, which Kowalewsky believes to be homologous with the notochord of Vertebrates, I know nothing, but what Semper describes as the notochord of the Naidini is certainly nothing but the cells of the mesodermic sheath, surrounding the nervous chain. It is not possible to overlook the great similarity between the development of Annelids and Vertebrates, especially in the formation and transformation of the germinal streak. There would be no great inaccuracy in saying that the belly of Anne- lids is homologous with the back of Vertebrates, were there not serious divergences shown in the development of the neuro- muscular apparatus, which certainly are not diminished by the discovery of the independent origin of the cephalic ganglion. I, however, believe that every well-recognised fact, although it may be such as to appear to open an abyss between two so-called types, is in reality a step in advance towards the establishment of the unity of the organisation of the animal kingdom. I must defer general considerations to a second part of this work, in which I shall treat of the further development of the Earth-worm, and more especially of the formation of the tissues. THE NEMATOID HAMATOZOA OF MAN. 245 The Nematorp Hmmatozoa of Man.! By Trworny Ricuarps Lewis, M.B., Surgeon, Army Medical Department; Fellow of the Calcutta University. With Plate XII. Tue literature of this subject dates from the period of the publication in 1872 of a paper submitted by myself to the Government, entitled ‘On a Hematozoon in Human Blood.” Towards the beginning of July of that year, I found nine minute nematoid worms in a state of great activity ona slide containing a drop of blood from the finger of a Hindoo. They were about zy mlength, and...” in width, or slightly less than the average diameter of a human red blood-corpuscle (*3 mm. x ‘007 mm.). Unfortunately, after the observation had been made the man could not be found so as to be questioned as to his past history, so that the pathological conditions which might have been associated with this, the first recorded instance of the existence of nematoid heematozoa in man, must continue in obscurity. This observation was, however, followed by several others which have gone to show that the presence of this particular helminth in the blocd is very generally associated with Chyluria and with an allied affection known as Lymph-scrotum or nevoid elephantiasis. The extent of this connection may, insome degree, be inferred from the circumstance that whereas filarize may occa- sionally be observed in the blood of persons apparently free from disease of any kind, they are, sv far as my personal experience goes, invariably present when either of these diseases exist. It must be recollected, however, that the search for them sometimes involves very considerable labour. These parasites, or parasites very closely allied, have now been found in human blood in many parts of the world. Dr. Prospero Sonsino,® in January, 1874 (having no knowledge of previous observations of a like character), found them in the person of a Jew lad at Cairo. They have been found in China by Dr. Patrick ' This article forms a portion of a paper entitled “‘The Microscopic Organisms found in the Blood of Man and Animals,” which is shortly to appear as an Appendix to ‘The Fourteenth Annual Report of the Sanitary Commissioner with the Government of India.’—Ep. > *Kighth Annual Report of the Sanitary Commissioner with the Geer of India,’ 1872. Also ‘Indian Annals of Medical Science,’ vol. xvi. % *Richerche intorno alla Bilharzia heematobia in relazione colla ema- turia endemica dell’Egitto e nota intorno ad un nematoideo trovato ne! sangue umano,’ Naples, 1874, 216 TIMOTHY RICHARDS LEWIS, Manson! of Amoy, and in Australia by Dr. Bancroft* of Bris- bane. They have also been found in the blood in Brazil; and, within the last few weeks, in England, by Dr. Hoadley Gabb of Hastings. In considering the possible relation which may exist between the several parasites which have thus been found in different latitudes, it will be well to bear in mind the history of somewhat similar organisms in the circulation of dogs. There is another matter to be taken into consideration as regards the identification of like parasites in man,—namely, their association with diseased conditions. Are these conditions invariably of the same general character in all countries? If so, it would be sufficient to show that a distinct relation of some kind existed between the disease and the parasite ; but if it be found, notwithstanding the existence of a general correspondence between them, that nevertheless minor differences were more or less constantly present, this would indicate either that some slight difference existed in the parasite itself or that it bore no causal relation to the disease. It so happens that the nematoid heematozoa are found associated with a disease which, whilst manifesting a close general resem- blance in different countries, is nevertheless characterised by a marked difference. In Asia, or at least in India, this disease 1s known by its most characteristic appearance, viz. milky or chylous urine ; whereas in Africa and South America it is described as the “ hematuria”’ of various localities, or as ‘‘ hematurie chyleuse ” or “ graisseuse,” aterm doubtless adopted on account of its being a more correct description of the malady than chyluria. In India, however, although the term may be more or less applicable at some period or other of the disease, it is nevertheless not so appro- priate, in the great majority of cases, and, indeed, in some instances is wholly inappropriate, as occasionally no marked traces of red colouring matter can be detected in the urine from the beginning to the close of the attack. There is an instance of this kind under my observation at present (2 Kuropean born in the country) suffermg from a third attack, who has never detected the slightest trace of blood at any time. It is of im- portance that this feature in the character of the disease accord- ing to its geographical distribution should be borne in mind, as it may hereafter be found that what at present are generally considered as merely two phases of one malady may each have a distinctive etiology. 1 « Report on Hematozoa,” in ‘China Customs Medical Reports,’ vol. xiii, Shanghai, 1877. 2 On Urinary and Renal Diseases,’ by W. Roberts, 3rd Edit., 1876, p. 342. ; 3 The ‘ Lancet,’ June 22, 1878, p. 921. THE NEMATOID HEMATOZOA OF MAN, 24,7 When in March 1870! I detected a microscopic nematoid in urine of the latter character, | was under the impression that no nematoid of any kind had previously been found in any urine which could not be attributed to accidental circumstances. It proved, however, that the late Dr. Otto Wucherer had already found a parasite of a like character in 1868 in “ Hematuria Braziliensis,’ and had forwarded specimens to Prof. Leuckart for identification.? Dr. Jules Crevaux succeeded in confirming Wucherer’s discovery by finding (27th July, 1870) similar hel- minths in the urine of a young creole affected with a like disease.* It is possible that the parasite discovered by Wucherer and de- scribed by him in December, 1868,* may prove to be identical with the one found by myself in March, 1870; in such an event it will be necessary to seek forsome clue, other than specific differences in the helminths, to account for the circumstance that the disease with which they are associated presents different characters. In order to complete the sketch of the history of nematoid urinary parasites of this period it will be necessary to refer to two other observations, as it may be of assistance to future writers in Fie. 1.—TZrichina cystica: Embryo of an oviparous nematode, obtained in urine. (Reduced from Dr. Salisbury’s figure representing it as magnified 1000 diameters to = x 300 diam. deciding (1) as to the number of such helminths that may be found in the urine of man, and (2) whether any of them should be considered as pseudo-parasitic merely. In 1868 Dr. Salisbury published an account of a parasite which he had found associated with ova, in the urine of an insane old lady suffering from severe “cystinic rheumatism ;’ and affected with partial paralysis of the bladder and of other parts of the body. A drop of urine frequently contained 10 to 15 ova. It was not a case either of heematuria or chyluria, although it is sometimes erroneously stated that she was suffering from the latter disease. This impression has arisen from the fact of cystinuria having been confounded with chyluria, two totally different disorders. The helminth is described as Trichina cystica (fig. 1). 1 « Annual Report of the Sanitary Commissioner with the Government of India,” 1870. ‘ British Medical Journal,’ 19th November, 1870. 2 Leuckart’s ‘ Parasiten,’ Band. ii, p. 640. 3 Idem; and ‘Journal de l|’Anatomie et de la Physiologie,’ t. xi, 1875. * *Gazeta da Bahia,’ December, 1868. 248 TIMOTHY RICHARDS LEWIS. Writing in 1872 Dr. Cobbold, after describing the history ofa little girl who had been suffering from hematuria associated with the Distomum hematobium, refers to the circumstance that he obtained from the patient some other urinary parasites i the egg condition. ‘On five separate occasions,” writes Dr. Cobbold, “*T obtained one or more specimens of the eggs or embryos of a minute nematode. In one instance there were about fifty of these ova in the urine : their embryonic contents being well developed, and in a state of activity. Usually they were all in this advanced condition ; but on the 25th of July, 1870, several were observed in much earlier stages of development.” The fully grown eggs gave a longitudinal measurement of =,” by +5,” in breadth. Judging from the description of the ova and their contained embryos, it would seem that the parental form must have been oviparous. ‘The embryos, when freed artificially from the egg, measured 53,” in length by 5,,;” in breadth. On two occasions free dead specimens were observed which had been lying in water some time, and these measured —” by 5,45” The parents of the patient had mentioned that the latter had “ passed three small vermiform entozoa by the urethra.” Dr. Cobbold writes : “TI have been thus particular in recording these facts, because future discoveries may enable us to identify Fie. 2.—Ovaand freed embryos of an oviparous nematode; obtained in urine. (After Cobbold.) the species of nematode to which these ova are referable. I know only one set of observations on record which refer to this same species of parasite.’ The parasite referred to is the above-cited Trichina cystica. As it may be aconvenience to future observers to be able to judge of these matters for themselves in the absence of the original papers, I have reproduced Dr. Cobbold’s illustra- tions, together with a reduced outline of Dr. Salisbury’s figure. The reduction has been effected by means of a camera lucida, so 1 During the last seven years I must have examined the sediment of very many gallons of chylous urine, but never observed any ova of nematodes, though, from time to time, I have found many hundreds of embryos, THE NEMATOID HAMATOZOA OF MAN, 249 as to represent the helminth as magnified 300 diameters instead of 1000 as in the original. This will facilitate comparison with Dr. Cobbold’s figure representing his nematoid ova parasites! (fig. 2). Notwithstanding the discrepancy in size, Dr. Cobbold considers that the helminths are referable to one and the same species. They are both manifestly the offspring of some oviparous nematode; further than that it is, I think, hardly safe to carry the comparison. The figures will also serve to elucidate another matter, as Dr. Cobbold has since asserted that his parasite is not only identical with Dr. Salisbury’s, but also identical with the Filaria sanguinis hominis,* a figure of which under a somewhat like magnifying power will be found in Pl. XII (figs. 3 and 5). Dr. Douglas Cunningham several years ago pointed out that such a view was untenable ;? moreover, the mature Filaria sanguinis hominis 1s not oviparous but viviparous. CHANGES UNDERGONE BY THE LimBryos or NEMAtTOID HaMa- TOZOA WHEN INGESTED BY THE Mosquito. It would occupy too much space to attempt an epitome of all that has been written regarding the Filaria sanguinis-hominis and the somewhat numerous diseases which have been ascribed to its influence, so that for the present the foregoing must suffice. It remains to be considered how it is that the embryos get into the circulation and what becomes of them afterwards. A most important step towards the solution of these queries has recently been made by Dr. Patrick Manson of Amoy.* He has shown that, immediately after a mosquito has fed itself on the body of a filaria-affected individual, the insect’s stomach will contain living examples of the heematozoon ; and that the latter will attain con- siderable progress towards maturity therein, in the course of a few ' days. Itis believed that it then escapes from the mosquito when the latter dies in the water to which it betakes itself, and the filariee thus find their way into the human body. Dr. Manson’s highly interesting paper gives a full account of the various developmental stages, together with figures of the object as they appear from time to time. I have repeated many of Dr. Manson’s experiments and have been able to satisfy myself, from personal observation, that his statements as to what occurs in China may, in most particulars, be made applicable to India also. I had on many occasions ex- ' © British Medical Journal,’ July 27, 1872, page 92. * “London Medical Record,’ No. i, vol. i, 1878; the ‘ Lancet,’ July 13, 1878, p. 64. > The ‘ Lancet,’ June 14, 1873, page 835. * *China Customs Report,’ No. xiv, 1878. 950 _ TIMOTHY RICHARDS LEWIS. amined the stomachs of mosquitoes and of other suctorial insects in acursory fashion during the last few years, but had never de- tected parasites resembling the M/aria sanguinis. When, how- ever, I learnt of Dr. Manson’s success, I proceeded to make examinations in a systematic manner, and found, to my surprise, that 14 per cent. of the insects, caught at random and then ex- amined, contained such embryos.! It became, therefore, manifest that filarious blood must be atolerably common occurrence. At first I was not successful in being able to detect any but disintegrative changes in the ingested parasite owing to the circumstance that I had carefully restricted the examination to the contents of the stomach only. This was done in order to diminish the risk of confounding the various stages which the embryo-filariz might undergo with some other parasites which might exist among the tissues of this, as of other insects. The parasites were, in fact, found to be digested. Leuckart* mentions that a similar result was observed by Fedschenko to follow the ingestion of Dracunculus-embryos in the stomach of the Cyclops. The latter is believed to serve as an intermediary host for the development of the guinea worm, the embryos getting into the body of the Cyclops by piercing the cuticle. When, on the other hand, the embryos are swallowed they are digested. In the ccurse of the foregoing observations it was observed that all the mosquitoes captured in one of the servants’ houses contained heematozoa of the same character, and it was found that one of the five persons dwelling in this house harboured filarize in the blood. The man had been many years in the place and is not known to have suffered from any special disease. The circumstance that such a constant supply of filarious mosquitoes, of tolerably certain history, was available, materially simplified the course of investigation, which, briefly told, was as follows : Insects were caught early in the morning in the room in which this person had slept, justas Dr. Manson had done. Some were placed in bell glasses standing in water, others in test-tubes con- taining a little water at the bottom and covered with a strip of muslin. These were duly labelled and set aside for periodical examination. When the insect was examined with recently ingested blood in its stomach, it was found that the heematozoa, when present, did not differ materially from the aspect presented by them when extracted directly from the blood of its previous host (P]. XII, fig. 5), although, not unfrequently, parasites would also be seen which 1 « Proceedings of the Asiatic Society of Bengal,’ March, 1878, p. 89. 2 Op. cit., Band ii, p. 706. THE NEMATOID HZ MATOZOA OF MAN, 251 either belonged to a more advanced stage of the one under con- sideration, the result of a previous ingestion of filarious blood, or belonged to a totally different kind. There is always, therefore, a risk of confusing different parasites in the same insect. Re- peated examinations at the same periods tend, however, to minimise this source of error. During the first twenty-four hours no marked change takes place in the form of the organisms. On the second day, however, it will probably be seen that the blood has, to a considerable extent, undergone digestion, and the stomach will no longer manifest the distended condition of the first day. Probably a few altered heematozoa will be observed in it moving very languidly, presenting the appearance of partially disintegrated fungal filaments when the movements are not mani- fested. Some of them may be actually dead; these will be found to be stained by eosin solution very readily. Between the second and the third day further changes occur, but in order to be able to follow these it will be necessary to examine the other tissues of the insect, as possibly the stomach may contain none; it will, however, probably be found that some of them have migrated into the tissues immediately out- side this viscus. It will now be observed that some of the parasites have become considerably thicker (fig. 7); and occa- sionally specimens will be seen with the tail presenting the appearance of a lash (fig. 9); the movements are still very sluggish. . About the fourth day it is probable that examples in various stages of growth will be visible, rendering it extremely difficult or impossible to state precisely what it is that actually does take place ; at least hitherto I have not been able to satisfy myself. About this period, however, I have sometimes seen bodies, apparently composed of precisely the same material as figs. 6, 7, 9, undergoing something so very like cleavage (fig. 8) that J hesitate to state that this act is not one of the stages in the development of the filaria. The figure given (No. 8) is very carefully sketched, and, like all the others, accurately to scale. It will be noticed that one end is partially hidden by some granular matter. This I was not able to press away from the preparation. Other preparations of a like kind were also more or less hidden by granular matter, and in some cases (unassociated, however, with any indications of fission) the parasite appeared to be covered with an encrustation. With regard to the process of division suggested by the appearance of No. 8 I can offer no opinion ; it is quite possible that it forms a part of the develop- mental changes undergone by some other parasite,—such, for instance, as a gregarine. About the fourth day there will also be seen short, thick bodies (very appropriately described by Dr. 252 TIMOTHY RICHARDS LEWIS. Manson as “ sausage-shaped”), almost perfectly still (fig. 10), with a faint indication of a mouth; and, in some of them, a faint line may be detected suggestive of a commencing intestinal canal; the escape of a few granules on slight pressure towards the other, usually thicker, end, suggests the existence of an anal aperture. The chief difficulty which I have experienced in following these changes is to account for the transition of form at figure 7 to that represented in figure 10. ‘They are all, up to this figure, sketched as magnified by 300. The larval forms at fig. 10 now rapidly increase in size, and gradually acquire a more elongated outline, and between the fourth and fifth day they may be found presenting the form shown at fig. 11. The last figure, it will be noticed, is magnified 100 diameters only, and the length of the larve, therefore, is almost three times that of those delineated at fig. 10. They also manifest greater activity. The highest stage of development which has come under my notice is that figured at 12 as seen magnified 100 diameters. The anterior and posterior portions of a similar one, magnified 300 diameters, are delineated at fig. 13. This measured = of an inch in length, and its width towards the middle was 51,3 / near the anterior and posterior ends they measured =4,” across. The dimensions of another specimen which I measured were +;” in length by +350” in width at the broadest part. Dr. Manson mentions that he has on four occasions observed larger speci- mens than these. Notwithstanding their activity and apparently robust condition, they nevertheless are extremely fragile, very slight pressure of the cover-glass being sufficient to crush them. When examined in the unbroken condition it is only with difficulty that the ali- mentary canal can be distinguised beyond the junction of the cesophagus with the intestine, but when carefully ruptured (as in fig. 12) the tube may be distinguished. I have not been able to distinguish any other differentiated viscus in any of the speci- mens which have come under my observation, and, certainly, nothing suggestive of differentiation of sex. By the time that the larval filarie have attained to this degree of development, the mosquito will possibly have already deposited its ova and its own cycle will have been nearly completed. With the intention of following out the development still further, I have frequently kept insects until this stage was reached before examination, but all the attempts have proved fruitless, notwith- standing that the mosquito has been seen to go through its ordinary course of depositing its ova on the surface of water, and then perishing itself. Hither no filarize were found in its body, or if present they were dead, and careful examination of the THE NEMATOID H#MATOZOA OF MAN. 253 water invariably yielded negative results in my hands. It would seem that the larve had perished. As the quantity of water used was so small, it is hardly possible, had filarie in any stage of growth been present, that they could have so completely escaped observation. Possibly the more or less artificial condi- tions necessarily associated with the conduct of such experiments may account for these negative results. In the meantime I cannot, as a result of personal observation, affirm that a sojourn in the body of the mosquito, and subsequent transference to water, suffice to bring the Filaria sanguinis-hominis to maturity. A few words may be said regarding other heematozoic parasites which appear to find their way into the bodies of mosquitoes. In the first place, it may be mentioned that dogs appear to furnish a certain proportion, as I have repeatedly found Filariz in these insects in which not the slightest trace of the envelop- ing cyst, which characterises the human heematozoon, could be detected. Unfortunately the corpuscles of the dog’s blood are so like those of man, as to size and appearance, that it is not possible to distinguish them with certainty, so that the examina- tion of the fluid contents of the mosquito’s stomach does not tend to throw any light on the source of the hematozoa in this instance. It is probable that other animals also contribute to- wards rendering the diagnosis more difficult. Fie. 3 : : : . ™& 500 diam. Embryos of a nematoid helminth from a bird, obtained in the stomach of a mosquito. A few blood-corpuscles are included in the sketch. It is not uncommon, for example, to find the blood-corpuscles of birds forming a portion of the contents of the mosquito’s stomach, and I have on several occasions observed extremely small embryo-nematodes associated with such corpuscles. Some of these are represented in the accompanying woodcut (fig. 3). if these helmmths be compared with the figure given of the VOL. XIX.—NEW SER. R 254, > TIMOTHY RICHARDS LEWIS. heematozoon of the crow,! they will be found to bear a close resemblance to it. It is very possible that these embryos may not have been derived from the crow, but there can be but little doubt, judging from the character of the red blood-cor- puscles, that they had been derived from some bird. Facts of this kind also add to the difficulty of ascertaining precisely the various developmental processes which any particular species of heematozoon undergo. Tue Mature FORM OF FILARIA SANGUINIS-HOMINIS. A letter appeared in the ‘ Lancet? of 14th July, 1877, from Dr. Cobbold, announcing the discovery of Dr. Bancroft, of Brisbane, Australia, of what was believed to be the mature Filaria san- guinis. They had been found on two occasions ; on the first, a dead specimen was found in a lymphatic abscess of the arm ; and the second time four living specimens were obtained whilst tap- ping a hydrocele of the spermatic cord. Regarding these Dr. Bancroft had written the following description: ‘The worm is about the thickness of a human hair, and is from three to four inches long. By two loops from the centre of the body it emits the filarie described by Carter in immense numbers.” During the last six years I have taken considerable interest in questions of this nature, and have, through the kindness of pro- fessional friends in India, had frequent opportunities of searching for the parental form of the Milaria sanguinis-hominis, but only succeeded in obtaining it on one occasion. This was a little more than a year ago—7th August, 1877. Descriptions of the speci- mens were published at the time,” but, in a paper dealing with the organisms of the blood, a brief account of these particulars should find a place. For the opportunity of examining the particular case in which the filarie were found I am indebted to the kindness of the late Dr. Gayer. ‘The patient was a young Bengalee affected with well-marked neevoid elephantiasis of the scrotum, associated with the presence of embryo-filariz in the blood. The tumour and tle sanguineous exudation which escaped on its removal were collected, and submitted to careful examination, and, after a continuous search of eight hours, the long sought-for helminth was eventually obtained. The specimens were, however, so greatly mangled by. the needles used in teasing a clot under a dissecting ' We hope to be able to reproduce the section of the monograph dealing with the microscopic hematozoa of animals in our next number.—Ep. y 2 ‘Indian Medical Gazette, lst September, 1877 ; ‘ The Lancet,’ 29th September, 1877, p. 453; ‘Centralblatt fiir die medicinische Wissen- schaften,’ No. 43; 1877, p. 770. THE NEMATOID H#MATOZOA OF MAN, 255 microscope, that the description of parental forms cannot at present be so complete as desired. The specimens consisted of portions of two worms, male and female (Plate XII, figs. 1 to 4) ; the former, however, had unfortu- nately been torn across at two places, and the terminal ends could not be discovered. Both specimens manifested very lively move- ments, notwithstanding their mang‘ed condition. They were of a white colour, the cuticle was smooth and devoid of transverse markings, except such as were due to the contraction of the sub- jacent muscular walls, The fragment of the male specimen which was found measured half an inch in length, and — of an inch (*14 mm.) trans- versely ; it was thinner than the female, but of considerably firmer texture—so firm, indeed, that whilst endeavouring to make out its anatomy a considerable portion of it was lost by one of the needles used for dissecting snapping, and carrying a portion of worm along with it. On tearing the helminth across, the severed surface does not present a ragged edge, but an even outline (Pl. XII, fig. 4). The male manifested also a great tendency to coil, and it was only with difficulty that it could be separated from the specimen of the female parasite, around a portion of which it had twisted itself. It is unfortunate that its caudal end especially could not be found, as the definite decision of the genus to which it should be referred depends in a great measure on the characters which the posterior end of the male worm presents. The intestinal canal measured 51,” (059 mm.) across, and the sperm tube =,” (‘016 mm.). The caudal end of the female worm also had been severed, and could not be found; this, however, is of less moment. The length of the portion of the helminth secured was 14 inch, and its greatest width about =, mch. It was packed with ova and embryos in various stages of development; the latter, especially those of them which were mature, manifested active movements. The head is slightly club-shaped; the mouth does not manifest any very distinctly marked labial subdivisions, nor are there any chitinous processes evident, either before or after death. The cesophagus is faintly striated, and shades off imperceptibly into the intestinal tube, the latter being filled with moleculo-granular matter. The followmg measurements may be useful to future ob- servers : 236 TIMOTHY RICHARDS LEWIS. Oral aperture to end of cesophagus +. of an inch, or *45 mm, Diameter of oral aperture ; ‘ : - s000 i >, 0Smes Width of extreme end (anterior) . sa Ms » U2aeaes Ditto anterior end at SNe C Kiaee mene sis sn ay aims Ditto opposite junction of intestine with cesophagus . - ott BS jp “ATG Ditto about 4 inch from anterior end . ais = 55 Oe ae Width where packed with ova and embryos +35 + a bet: As aa 2? » 1 ” Width of uterine tube filled with ova Ditto alimentary tube : 666 2? 32 037 Pe) The ova do not possess any distinctly marked ‘‘ shell ;” from the smallest to the largest nothing but a delicate pellicle can be distinguished as enveloping the embryo in all its stages; conse- quently the form assumed by the ovum depends to a great extent on the degree of the surrounding pressure. In fig. 3 (Plate XII) ova of various shapes are depicted (spherical, triangular, oval), and with a considerable latitude as to size. The average of six measurements of the less advanced kinds of ova, 7. e. ‘those in ys the outline of the oe was not distinctly evident = soley” (018 mm.) by ey50” (012 mm.) ; whilst the average measurements of three ova in which the embryos were visible = -¢¢ (037 mm.) by -1,” (030 mm.). Ww hen the latter, after having arrived at this stage of deve- lopment, are examined during life, it is in many instances diffi- cult to state whether they are to be considered as freed embryos or not, as the ‘ egg-shell’’ has become so extremely attenuated and translucent as only with difficulty to be distinguished. By pressing the covering glass firmly the sac may often be ruptured. It, however, appears probable that, even when the embryo acquires worm-like appearances, the envelope is not lost in this species so long as it continues in the blood. It is of importance to bear this in mind, as, contrary to what is seen with regard to the nematoid hematozoa of dogs, the embryos in the blood of man are each contained in a translucent cecal tube. ‘This tube is readily recognisable during life when- ever the embryos can be properly observed in fresh clear serum, as also in spirit-preserved preparations. I possess at the present time specimens thus preserved of both species, one being con- tained in blood removed from the heart of a person, who during life, was known to harbour hematozoa, and the other obtained from the blood-vessels of a dog similarly affected. In not a single instance have I been able to distinguish the least trace of an enveloping tube in the latter, whereas in the former this tube can be clearly demonstrated in the majority of instances. Hence, notwithstanding their almost complete accord as to dimensions, the character just referred to is sufficient to distinguish slides prepared from either of these two specimens. A like distinction THE NEMATOID HHZMATOZOA OF MAN, 207 has been ascertained to exist between the two kinds of embryo filarie in China by Dr. Manson ; but, according to Dr. Sonsino, those of Egypt, and apparently those of the Brazils, do not pre- sent this distinguishing feature. As may be recollected it was mentioned that a distinction also exists between the disease with which the human heematozoon is associated in the different coun- tries—not a great difference certainly, but, nevertheless, one which should be borne in mind when deciding as to specific dis- tinctions between the parasites. It must also not be forgotten that the inhabitants of Brazil and of certain parts of Africa are, as has been known for at least a century, peculiarly liable to be the hosts of tissue-para- sites. The minute thread-like sub-conjunctival filaria (Filaria low), for example, though from two to six inches in length, has never been accurately described, and its precise thickness is not known yet, although it was discovered by Bajon so long ago as 1768,! and has since been frequently observed beneath the skin and conjunctiva of negroes and other persons. M. Guyon brought it before the notice of the French Academy in 1838, and again in 1864. On the former occasion, the specimens measured 30—40 mm., but the helminth described in 1864 was 150 mm., in length. It is not quite clear that they belonged to the same species. It is not impossible that the embryos dis- covered by Dr. O’Neill? in a disease of the skin termed Craw- craw, on the west coast of Africa, may prove to have been the offspring of some such helminth. Again, the minute, thread-like nematoid described in America by Leidy, five inches in length and ,!; inch in greatest breadth, is not to be overlooked. It was obtained from the mouth of a child, and derives its name—//aria hominis oris*—from this cir- cumstance. All these circumstances point to the necessity of exercising considerable caution in arriving at any decision as to the precise relation of any of these as yet obscure parasites. With regard to the helminths discovered by Dr. Bancroft in Australia, [ am not in a position to offer an opinion. It has not yet been shown that they are blood-worms in the ordinary sense of the term, nor is it known that the individual from whom they were obtained harboured embryo hematozoa. It is further to be remarked that the affections under which the persons laboured from which they were derived were not of the character of the dis- eases with which these hematozoa have hitherto been known to 1 ‘Comptes Rendus,’ t. lix, 1864, p. 745. 2 ¢The Lancet,’ Feb. 10, 1875, p. 265. feu ie ee of the Academy of Natural Science,’ Philadelphia, vol. v, 258 TIMOTHY RICHARDS LEWIS. be associated ; indeed, it would appear that one of the principal morbid conditions with which they are associated in this country —nzvoid elephantiasis—is unknown in Australia. It may also be noteworthy that no male worm was found among the specimens. Dr. Cobbold is, however, of opinion that they are identical, and it would be superfluous to say that the opinion of one who has devoted so many years to the study of helminths is entitled to consideration. This observer has lately (the ‘ Lancet,’ July 13, 1878) given a summary of the bibliography, &c., of these questions, in which I observea slight error. It is with reference to the mature nematoid helminths found in Australia. These, Dr. Cobbold states, were “ first discovered by Dr. Bancroft and first described by myself”? It seems to me, however, that not only did Dr. Bancroft discover the parasite, but also furnished the first account of them which appeared. It is possible that the descrip- tion supplied by Dr. Bancroft, which is quoted on a previous page, is not considered sufficiently precise to be accepted as such, from a naturalist’s point of view. Allowing this, if, as Dr. Cobbold maintains, the Australian and Indian parasites are identical, the first full account of the mature Li/aria sanguinis hominis, as found in India, was published, both in this country and in London, previous to the appearance of Dr. Cobbold’s description—having, indeed, been in the printer’s hands before Dr. Cobbold had even seen the Australian parasites. Dr. Cobbold, moreover, refers to such prior publication in the appendix to his own article. This trifling oversight will, I have no doubt, be duly corrected should this distinguished observer have occasion to write regard- ing these subjects in the future. In considering the question of the relation which may exist between the presence of organisms in the circulation and disease, the conclusion is forced upon us that in reality but little of a definite character is known. One thing, however, is clearly mani- fest, that the supposition that beings become asphyxiated as a result of the existence of living organisms in the blood, is untenable. The study of their natural history as they occur in man or animals does not afford the slightest support to such a view. Indeed, so far as we at present know, it would seem that the presence of embryos in the blood, no matter how numerous, exercises no marked deleterious effect on the organism. It 1s probable, however, that the parents of these organisms, especially when helminthic, do exert a deleterious influence on the well- being of their hosts,—as, for example, the lesions which exist in the walls of the blood-vessels caused by the /:laria sanguinolenta, would seem to indicate. With regard to allied conditions in man, it is to be inferred that the influence exerted by nematoid THE NEMATOID H#MATOZOA OF MAN, 259 embryos in inducing disease is apt to be overrated, as it would seem that the parasites may sojourn for long periods in the system without inflicting obvious injury. That certain injuries are effected, however, cannot well be doubted, but, judging from what we know of the lke condition in animals, the injuries result, not from direct action of living organisms on the blood current in which they dwell, but from their action on some of the delicate tissues through which the blood circulates—such in- jurious influence,being probably exerted, more especially during the migrations of the parents of future embryo-hzmatozoa. CALCUTTA ; August, 1878, y i“ - in af 4 a PA yigalie ac TEE Ee Gui ie fe tonics Wate ytd, ey Bs hi ewes WUeryh} irae mo eh) ian : tots Md ee a Re piBage ing sigs i walle ie el ee fer, 2 Ver eatir pe tad). ms as yew Saki Aah re (“< a * ~~ Je hee “ . . a hae ‘ | a a i Ee ay iat ON) ea LS, oe if wren he) i) “'. a = Pala .2 es bessis ty ’ ’ * . ‘ ey 0 ' “V Py ; i Wert - An ae PiYpeae! ' ‘ RU AEN lg New Series, No. LXXV. Price 6s. ae EY 1879. THE QUARTERLY JOURNAL SE UeG Fe LONDON: J. & A. CHURCHILL, NEW BURLINGTON STREET. MDCCCLXXIX. J.£E Adlard.j {Bartholomew C!ose Porcellanea. In no section of the subject has so little that is new been elicited from the “Challenger” results as in the Family Mixtoxipa of Carpenter, Parker, and Jones. Abundance of large Biloculine and the like are of course to be found in the Globigerina-ooze of deep-sea bottoms, and there is consider- able variety in the forms furnished by some of the shallower dredgings from the tropics, but there is no such range of well-marked modifications of the common types as one would be pretty sure to meet with, for example, in material from depths of five to fifty fathoms in the Red Sea; and as few or no shore-sands were collected during the expedition, there is a comparative absence of even the common littoral species. The Miliolida are to be regarded as essentially a shallow-water and littoral group. It is true that the very largest examples of certain genera are found amongst the Gilobiyerina-mud of 1000 to 2000 fathoms, or even at greater depths, but the species so occurring are very limited in num- ber, and the specimens as a rule comparatively few, whilst in shallow water and in shore-sands even the deep-sea species, with one or two exceptions, are common, though the in- VOL. XIX,—NEW SER. S CONTENTS OF No. LXXV.—New Series. NOTES AND MEMORANDA: Chlorophyll in Turbellarian Worms and other Animals ; . 434 A New Geuus of Protista : : : : : . 437 PROCEEDINGS OF SOCIETIES: Dublin Microscopical Club, : ‘ : ; . 438 MEMOIRS. Notes on some of the RericuLtariaAN Rutizoropa of the ““ CHALLENGER” ExpepiTion. By Henry B. Brapy, F.R.S. With Plate VIII. Il.— Additions to the knowledge of Porcellanous and Hyaline types. In a former paper (‘ Quart. Journ.’ for January) a brief notice was given of a few of the more interesting types of Arenaceous Rhizopoda occurring in the dredged stuff brought home by Sir C. Wyville Thomson and the scientific staff of the “Challenger” Expedition, and I propose now to describe a limited number of forms pertaining to other groups of the Foraminifera, concerning which fresh facts have been gathered, tending to elucidate the natural history of the order. Porcellanea. In no section of the subject has so little that is new been elicited from the “Challenger” results as in the Family Mriutoxipa of Carpenter, Parker, and Jones. Abundance of large Biloculine and the like are of course to be found in the Globigerina-ooze of deep-sea bottoms, and there is consider- able variety in the forms furnished by some of the shallower dredgings from the tropics, but there is no such range of well-marked modifications of the common types as one would be pretty sure to meet with, for example, in material from depths of five to fifty fathoms in the Red Sea; and as few or no shore-sands were collected during the expedition, there is a comparative absence of even the common littoral species. The Miliolida are to be regarded as essentially a shallow-water and littoral group. It is true that the very largest examples of certain genera are found amongst the Globigerina-mud of 1000 to 2000 fathoms, or even at greater depths, but the species so occurring are very limited in num- ber, and the specimens as a rule comparatively few, whilst in shallow water and in shore-sands even the deep-sea species, with one or two exceptions, are common, though the in- VOL, XIX.—NEW SER. s 262 HENRY B. BRADY. dividuals are often of smaller size. On the other hand, such genera as Vertebralina, Articulina, Nubecularia, and Dacty- lopora are unknown in deep water; whilst the helicoid and annular types, Peneroplis, Orbiculina, Orbitolites (except the anomalous O. tenuissimus), and Alveolina, are not to be found beyond the Coral Zone of Forbes. The Miziorrpa differ from the cther families of Foramini- fera in the structure of their shelly investment, which is normally porcellanous and imperforate. By ‘‘ porcellanous” is meant that it is of compact homogeneous texture, white and polished by reflected light, and, in thin sections, by transmitted light, of an even brownish tint. Young shells are opalescent and diaphanous rather than vitreous and transparent. In the adult condition all are imperforate, and being so the thicker portions are never tubulated, nor is there any supplementary skeleton. The tests of even the roughest of the sandy Miliole have a distinct imperforate shelly basis, easily recognised in transparent sections if sufficient care be taken not to disintegrate them in grinding. In respect to the genera Peneroplis and Orbiculina, it may perhaps be open to doubt whether in the very youngest condition the rule is quite absolute. Professor W. C. Williamson describes the test of Ordiculina as finely perforated ; Dr. Carpenter, on the other hand, believes the minute dots observable in sections of the shell in either genus to be caused by mere pittings of the surface. It may be that the latter is the correct interpretation, but it is by no means evident that it is so when very young specimens, the tests of which are little more than a film, are examined by transmitted light after one side has been ground off, so that only a single thickness of shell remains. Occasionally the appearance of the numberless dots, even in sections of the adult shell, is much more that of perforations which have been filled up by a subsequent deposit of somewhat different physical charac- ters, than that of mere superficial depressions. Dr. Car- penter’s view, however, receives considerable support from Milioline species like Quinqueloculina punctata, Reuss,' the surface of which, in adult specimens, is represented as regularly pitted. In one of the ‘ Challenger,” M:lolne, characterised by somewhat peculiar surface ornamentation, the old shells are often punctured in regular lines, but this is an accidental circumstance, and depends upon the raised pattern, which leaves the walls very thin and easily worn into holes at certain points, as indicated by the fact that young or otherwise perfect specimexs are never perforate. 1 ‘Neues Jahrbuch fiir Min.,’ for 1853, pl. 9, fig. 8, a—e. NOTES ON RETICULARIAN RHIZOPODA, 263 One of the most important modifications of the normal por- cellanous condition of the tests of the Mdho/e is exemplified in the forms with rough, arenaceous exterior. There are amongst the “Challenger” dredgings at least six tolerably dis- tinct species possessing this character, and probably not more than two of them have been previously described. One of the two is the well-known Quinqueloculine form, Q. agglutinans, d’Orb.; the other an elongate, compressed, biconvex species, of somewhat obscure structure (Spiroloculina celata, Costa), the test of which is composed of uniform fine sand-grains, the course of the chambers scarcely traceable on the exterior, and the aperture minute and round. Descriptions of two of the new species are given on a later page; the others, which it would be difficult to render in- telligible without the aid of figures, must be left for the present. Allusion has been made in my previous paper to the changes that take place in the composition of the tests of some of the’ Arenaceous Foraminifera which live in water containing less inorganic matter in solution than that of the open sea, and a like alteration is to be observed in the shells of certain Mtliole under similar local conditions. The brackish-water representative of this group, Quenqueloculina fusca, has a chitinous or chitino-arenaceous test in place of the normal calcareous shell, precisely resembling in its chemical and physical characters that of the arenaceous Trochammine, living under analogous deteriorating influences. But there is another modification of the chemical compo- sition of the Milioline shell which has not before been observed, which possesses even deeper significance, namely the substitu- tion of clear, homogeneous silica for carbonate of lime. This occurs in very few localities, at stations where the depth registeredisgreat (from 2500 to 4000 fathoms), and the bottom consists of Radiolaria-ooze. The specimens are never abun- dant, they are of small size, and consist of a very few inflated segments somewhat irregularly arranged, so as to form gibbous or subglobose shells. ‘The walls are delicately thin, so thin that the organism sometimes collapses on being taken out of fluid and allowed to dry, opalescent or nearly trans- parent, and when quite fresh iridescent. Placed in nitric acid under the microscope there is not a trace of effervescence, and no change in appearance is to be detected. It should be remarked that the arenaceous Foraminifera from the same bottoms, such as Trochammina (Ammodiscus) incerta, are, in like manner, unaffected by treatment with acids. The very close connection existing between the various reputed Milioline genera, or rather, one might say, the absolute 264 HENRY B. BRADY. continuity of the series, becomes abundantly manifest in the study of the “‘ Challenger” gatherings. Not only does the passage of the non-septate Cornuspira into the septate Hinaauer become easy, through an undescribed intermediate form (Hauerina exigua, nov.), but in one remarkable and beautiful species from the deeper waters of the tropics, the morphological characters of three distinct ‘‘ genera” are found combined. ‘The shells of this species commence growth in plano-spiral, non-septate fashion like Cornuspira’ but, after a number of convolutions, become angular and septate at two opposite points of the periphery, putting on a series of spiroloculine chambers; subsequently the septa become more frequent and at somewhat irregular intervals, and in so far assume the characters of Hauerina. For purposes of nomenclature it may be assumed that the final portions represent the affinities of the mature organism and Hawerina inconstans seems a suitable appellation for a species with such habits of growth. The morphological relationship between Biloculina and Spiroloculina is already well under- stood. Typically the plan of growth is the same, two cham- bers on the same plane to each convolution; but whilst Biloculina has wide, somewhat inflated segments, each of which in its turn encloses all those previously formed on the same side so that only two segments are visible externally, Spiroloculina has narrow, non-embracing chambers, arranged alternately and symmetrically so that every segment is seen on both sides of the shell. These are distinctions so generally ac- cepted, and under ordinary circumstances so easily recognised, that the occurrence of an occasional specimen with interme- diate charaeters is of no practical inconvenience. But with the Triloculine and Quinqueloculine members of the group the case is far otherwise. The subdivision of the Mliole, proposed by d’Orbigny in his ‘ Tableau méthodique de la classe des Céphalopodes,” has been employed by systematists, with a single exception, to the present time. It contains the two fol- lowing generic descriptions under the family AGATHISTEGUES. “ Genre IIJ.. Zriloculina.—Loges opposées sur trois cétés ; la méme forme 4 tous les ages ; trois loges apparentes.” “Genre V. Quinqgueloculina.—Loges opposées sur cing cotes ; cing loges apparantes.” The whole weight of the distinction embodied in these definitions hangs on the words “a tous les ages,” a most 1 It is an interesting fact that Ordctolites tenuissimus, Carpenter, is some- times spiral and non-septate in, its earliest stage, and in like manner, amongst hyaline forms, Patellina corrugata, Will. 2 «Annales des Sci. Nat.,’ 1826, vol. vii, pp. 299, 301. NOTES ON RETICULARIAN RHIZOPODA. 265 undesirable basis for the division cf an unusually variable group. The number of varietal forms that can be said to have uniformly only three external segments is exceedingly limited, whilst on the other hand, most of the Quinqueloculine have a triloculine stage of growth. Under d’Orbigny’s defi- nitions young specimens and adults of the same variety have over and over again been placed as new species in separate genera. Amongst smooth-shelled forms the anomaly might pass unnoticed, but amongst those in which peculiarity of surface-ornamentation affords the principal distinctive cha- racter the double nomenclature becomes a palpable absurdity. There is still another objection to these generic terms, which is brought into stronger light by specimens obtained from the “‘ Challenger” dredgings, namely, that the number of exposed segments is not necessarily either three or five. In one striking subarenaceous species, which I propose to name Miliolina alveoliniformis, there are often seven or eight, long, narrow chambers in the peripheral whorl. There is another arenaceous form (Miliolina triquetra, nov.), in which, instead of two segments, one up and one down, forming the axial cir- cuit of the test throughout, there are in the final circuit three segments, the contour becoming flattened in the same way as in Biloculina contraria, and more or less triangular. Neither of these could be included in any of the Milioline genera as hitherto constituted. Instances of the same sort might readily be multiplied, but enough has been said to show that Zriloculina and Quingueloculina ought now to be dis- carded as generic or even subgeneric names, just as Adelosina was long since abolished and for similar reasons, and that some general name less open to objection should be found for this portion of the group. The term Miliola naturally suggests itself, but that and the corresponding Miliolites were used by Lamarck for the entire series, whether bi-, tri-, quinque- or spiro-loculine, and in this sense it has also been applied by Messrs. Parker and Jones and others to the Serpula seminulum of Linné, as the | central type of the whole group. Prof. W. C. Williamson, after discussing the question with his usual shrewdness,’ employs the modified term Miliolina for the section under consideration. I cansee no objection to this course, and am inclined to think that with some modification of the charac- ters assigned to the genus, in the monograph referred to, its general adoption would be a distinct gain to zoologists. Concerning the other Milolida there is little that need be said in these preliminary notes. Some points of interest in . “Recent Foraminifera of Great Britain,’ p. 83. 266 HENRY B. BRADY. ; connection with the genera Nubecularia and Dactylopora will be alluded to presently in the notice of two species, NV, tibia and D. eruca. Concerning the spiral types there is, perhaps, even less that calls for remark. The genera Pene- ropolis, Orbiculina, Orbitolites, and Alveolina, are all well represented in the ‘ Challenger ” gatherings, but the results of their examination tend rather to diminish than to increase the number of forms to be recognised as “ species.” NUBECULARIA TIBIA, Jones and Parker, Pl. VIII, figs. 1, 2. Nubecularvia tibia, Jones and Parker, 1860. ‘Quart. Journ. Geol. Soc.,’ vol. xvi, p. 455, p. 20, figs. 48—51. The interest attaching to thissimple littleorganism depends upon the fact that until recently it has only been recognised as a Triassic or Rheetic fossil. It was described by Messrs. Jones and Parker, Joc. cit., in their paper upon the Fora- minifera of certain marls from Chellaston in Derbyshire. Within the last few months I have identified specimens in Mr. E. A. Walford’s collection of microzoa from the Upper Lias of Banbury, and this completes the record of its geo- logical history ; it is, nevertheless, quite possible that, owing to its minute size and inconspicuous appearance, it may have been overlooked in other habitats. A careful com- parison of specimens from all the known sources, recent and fossil, reveals no characters not common to the whole of them, none at any rate that can be regarded as zoologically distinctive. Nubecularia tibia occurs at two of the ‘ Challenger ”’ stations, both in comparatively shallow water, namely, amongst the Philippine Islands (95 fathoms), and in Hum- boldt Bay, Papua (37 fathoms). DactyLopora ERUcA, Parker and Jones. Pl. VIII, figs. 3, 4. Dactylopora eruca, Parker and Jones, 1860. ‘Ann, and Mag. Nat. Hist.,’ ser. 3, vol. v, p. 473; Carpenter, 1862, ‘ Introd.,’ p. 128, pl. 10, figs. 1—8. Haploporella eruca, Giimbul, 1872. ‘ Abhandl. der k. bayer. Akad. der W.,’ If Cl., vol. xi, p. 256, pl. D. J, fig. 1. Decaisnella eruca, Munier-Chalmas, 1877. ‘Comptes Rendus de l’Acad. des Sci.,’ vol. Ixxxv, p. 816. I do not propose to enter here upon the controversy con- cerning the true nature and position of the Dactyloporide, NOTES ON RETICULARIAN RHIZOPODA. 267 but as Dactylopora eruca occurs in considerable variety of form in some of the parcels of material which I have examined it can scarcely be passed over without notice. The latest contribution to the debate is a brief note by M. Munier-Chalmas (doc. cit.), in which Dactylopora and all it allies, including Acicularia, are assigned to a family of calcareous Algze, characterised as “ Stphonée verticillée.” It may be confessed that the multiform organisms hitherto associated under the term Dactyloporide have constituted an anomalous and unsatisfactory group, and any fresh light on their structure and relationship will be welcomed by syste- mafists, whether zoologists or botanists. It is not at all improbable that beings of widely different affinities have been placed together for want of accurate knowledge ; but if this be the case, to hand them in mass to another position will not mend matters greatly. It is difficult to see how irregularly constructed shells, hke those represented in PJ. VIII, figs. 3, 4, can have formed portions of a radiate or verticillate organism ; nor have I, after the examination, by sections and otherwise, ofa large number of fresh specimens of D. eruca, seen anything corresponding to the structures figured in M. Munier- Chalmas’ paper. Nevertheless, as we have only the author’s preliminary note, criticism would be premature, and we must await the publication of the promised detailed memoir. Meanwhile, it may be observed that the characters of Dactylopora eruca are easily reconciled with those of the rest of the Miliolida, and, so far as revealed by the dead shells, present no anomaly in the position in which the species has been placed by Messrs. Parker and Jones. Of the new Milioline forms alluded to in the foregoing para- graphs, the following will serve as descriptions, pending the publication of more detailed notice with the necessary figures. HAvERINA EXIGUA, 2. Sp. Characters.—Test free, thin, discoidal, planospiral ; com- posed of a number of convolutions of a narrow, slightly em- bracing, septate tube, but showing no indication of the spiral suture beyond the final circuit. Septa few, about three in each convolution, not marked by any external depression. Aper- ture simple, terminal. Diameter =; inch (0°5 millim.) or less. Found in shallow water in the tropics, notably about the Admiralty Islands and New Guinea. This species also occurs in the Red Sea and elsewhere, 268 HENRY B, BRADY. HAUERINA INCONSTANS, 2. Sp. Characters.—Test free, thin, commencing growth as a planospiral, non-septate tube, after a time becoming spiro- loculine in arrangement, and eventually forming convolu- tions, each consisting of several (two, three, or four) irregularly arcuate or sigmoid segments. Periphery bordered by a broad thin wing, seldom found entire. Diameter of large specimens, ;+; inch (1°6 millim.). Hauerina inconstans is widely distributed, geographically speaking, but the total number of specimens found is very small. In the “ Challenger” dredgings it occurs at depths varying from 210 to 2300 fathoms. MILIOLINA TRIQUETRA, 2. Sp. Characters.—Test free, compressed, subtriangular ; com- posed of few segments, of which. three, arranged on one plan, usually go to form each of the later convolutions. Aperture simple, situate on the produced neck-like extension of the terminal segment. ‘Texture roughly arenaceous externally. Diameter =! inch (1° millim.) A rare species, the best specimens of which are from anchor-mud in Humboldt Bay, Papua, 37 fathoms. MILIOLINA ALVEOLINIFORMIS, 2. sp. Characters.—Test free, elongate, fusiform; composed of narrow chambers arranged more or less spirally around the long axis. Segments numerous, sometimes seven or eight visible on the exterior ; ventricose or subcylindrical, arcuate. Aperture porous or radiate, obscure, terminal. Texture thin, porcellanous and nearly smooth in very young shells ; finely arenaceous in adult specimens. Length +‘; inch (2°5 millim.) or more. Not unfrequently met with in the shallow waters and shore-sands of tropical latitudes. Hyaline or Vitreous Types. Of the three families which constitute the Suborder PerroraTa of Carpenter, Parker, and Jones, namely, Lagenida, Globigerinida, and Nummulinida, tne last named may be dismissed in a word, The “Challenger” spoils NOTES ON RETICULARIAN RHIZOPODA. 269 have, in fact, added little or nothing to our knowledge of the Nummulinida, except in so far as concerns their geographical and bathymetrical distribution. LAGENIDA. Amongst the Lagenida it is far otherwise. The genus Lagena alone, as represented in these collections, supplies material for five or six crowded quarto plates, its varieties embracing modifications of contour and of surface decoration of which little was previously known. Of these it is im- possible to speak with any advantage in the absence of figures. It has been generally understood heretofore that the central home of the Lagene was in water of 100 to 200 fathoms, but some of the most beautiful and delicate mem- bers of the genus have been found at depths of 2000 to 3000 fathoms, and even in the black mud of almost the deepest of the ocean abysses hitherto explored by the dredge ; and in some of these localities the variety of the forms which have been met with has been scarcely less remarkable than their individual beauty. Amongst the Nodosarine types furnished by the ‘‘ Chal- lenger” dredgings the most noteworthy is the genus Frondi- cularia, which, with its subordinate Flabelline modifications, must now take a definite position in the category of recent genera. D’Orbigny, in his ‘Tableau Méthodique,’ 1826, mentions ‘the Adriatic”? as the habitat of Frondicularia alata and Fr. rhomboidalis, but it has been supposed by subsequent observers that his specimens were inter- lopers which had been washed out of one or other of the fossiliferous Tertiary clays that abound in the Italian Penin- sula. Messrs. Parker and Jones,! however, found the closely allied Fr. complanata in dredgings made by the late Mr. Lucas Barrett off the coast of Jamaica (100 to 200 fathoms), and as I have since identified the same species in beauti- fully fresh-looking specimens collected by my friend Dr. Tiberi, of Portici, on the coast of Sicily, it may be allowed that d’Orbigny’s habitat is probably correct. My friend M. Ernest Vanden Broeck” reports the occurrence of varieties of both Fr. complanata and Fr. alata in one of the soundings made by the late Professor Agassiz off Barbadoes, in 100 fathoms. This completes the record, so far as I know, of observations upon recent Frondicularie, and it is confined, 1 © Report Brit. Assoc.,’ 1863. Trans. sections, pp. 80 and 105. 2 ‘Ann. Soc. Belge de Micros.,’ vol. ii, p. 109, pl. 2, figs. 12—14, and pl. 3, fig. 2. 270 HENRY B, BRADY. as will be seen, to three species. But the series that has been collected from the ‘‘ Challenger” dredgings much en- larges the area of our knowledge. Not only have two of the forms which have been alluded to, together with their Fla- belline modifications, been found, but in addition a number of other smaller species of widely different contour, some of which are described and figured in the present paper. The little branching organism, named Ramulina by Pro- fessor T. Rupert Jones, hitherto only known by worn frag- ments occurring amongst fossil microzoa of Cretaceous age, has been found in sufficient numbers, and, notwithstanding its fragile nature, sufficiently complete in all its parts to yield accurate data as to its zoological characters. The genus Uvigerina has also received considerable acces- sions, and the connection, suggested by Messrs. Parker and Jones, between the normal spiral varieties and the dimor- phous shells constituting d’Orbigny’s genus Sagrina, is con- firmed and illustrated by certain new and_ interesting modifications of the typical structure. A notice of some of these will be found on a subsequent page. Genus—FRONDICULARIA, @’ Orbigny. FRONDICULARIA SPATHULATA, n. sp. Pl. VIII, fig. 5 a. 6. Characters.—Test long, narrow, tapering, compressed ; margin rounded, somewhat lobulate ; sutures but slightly excavated. Primordial chamber inflated; early segments more bent than the latter ones. Surface smooth. Length =, inch (1:0 millim.). ‘ This is one of the narrow compressed Nodosarian shells that might with almost equal propriety be placed either with Lingulina or Frondicularia, the slightly inflated primordial chamber and bent earlier segments suggesting the latter genus for preference. Terquem figures a somewhat similar form as Frondicularia sacculus (‘Sixiéme Mém. sur les Foram. du Lias,’ p. 482, pl, 19, fig. 20 a. 6.) and the Fr. linearis of Philippi (‘ Beitr. zur Kennt. d. Tert-Verstein,’ p. 5, pl. 1, fig. 32) is a Flabelline variety, with analogous general contour. Such varieties are very rare in the living condition, and there is only a single habitat to record for that now described, namely, off the Ki Islands, 129 fathoms. NOTES ON RETICULARIAN RHIZOPODA, 271 FRONDICULARIA COMPTA, ”. sp. PI. VIII, fig. 6. Characters.—Test long, spathulate; truncate or emarginate at the base, obtuse-angular at the apex; margin square, somewhat lobulate. Early segments larger than the later ones, sutural lines limbate. Surface otherwise smooth. Length ~; inch (1:0 millim.). A very beautiful little shell, with just sufficient irregularity in conformation to make it difficult alike to describe in well- defined terms or to reconcile with previously recorded species. The earlier portion of the test is built on a bolder, larger plan than the latter part, and the septal lines are thickened and raised. ‘The later segments are narrower and smaller, and the sutures, though still limbate, are not so prominent. The peripheral margin is nearly square. The figured specimen was found at Station 162, Bass Strait, 38 fathoms. Genus—FLABELLINA, @’ Orbigny. FLABELLINA CUNEATA (von Minster). Pl. VIII, fig. 7. Frondicularia cuneata, Von Minster,! 1838, ‘ Neues Jahrbuch fiir Min.,’ 1838, p. 383, pl. 3, fig. 10. Notwithstanding the more regular contour of the recent specimen and its somewhat larger number of segments, there is no real impropriety in identifying it with Von Miinster’s species; less impropriety, at any rate, than adding a fresh name to an already over-named genus, on insufficient grounds. Our recent shell, like Von Minster’s figure, is long, narrow, and tapering to a point at the base. The early segments are set obliquely and rather irregularly ; there is no external limbation or thickening of the sutural lines, and the surface is traversed by delicate, nearly parallel, longitudinal striz or riblets. The length of the specimen, which is not quite perfect, is about ~> inch (1:0 millim.). Habitat.—off the Ki Islands, 129 fathoms. FLABELLINA FOLIACEA, 2. sp. PI. VIII, figs. 8—10. Characters.—Test depressed, complanate; peripheral contour variable, often more or less carinate. Chambers slightly inflated. Spiral segments irregular; equitant ' In F. A. Roemer’s paper, “ Die Cephalopoden des Nord-Deutschen tertiaren Meersandes.”’ 272 HENRY B, BRADY. segments reaching far towards the base of the test ; in some specimens each ‘chamber completely encloses the lateral margins of the preceding one. Sutures excavated. Shell- wall, delicately thin; surface smooth. Length inch (1:0 millim.). Dr. Conrad Schwager, in his beautifully illustrated memoir on Fossil Foraminifera from Kar Nikobar,! describes and figures, under the name Frondicularia foliacea, a species having characters quite analogous to those of many of the recent specimens, with the exception that, whilst the fossil form appears to be symmetrical (Frondieularian); in its mode of growth, the still-living shells are all dimorphous, that is to say either irregular or Cristellarian, in the arrangement of their earlier segments. Some of the broader, complanate, recent specimens can scarcely be distinguished from Schwager’s species. Dimorphous growth is probably an indication of depauperating influences ; hence it seems better to retain the term Fladellina as distinct from Frondicularia, otherwise I should see no reason for separating the recent from the fossil form. Flabellina foliacea occurs at two stations near the Ki Islands (129 faths. and 580 faths.), in one sounding off the coast of New Zealand (278 faths.), and in one locality off the Eastern coast of North America (1240 faths.). 25 Genus—RAMULINA, Rupert Jones. RAMULINA GLOBULIFERA, 2. sp. PI. VIII, figs. 32, 33. Characters.—Test free, branching, composed of segments of different sizes connected by stoloniferous tubes. Segments numerous (two to eight or more), globular or subglobular, each with several (two to six) tubulated apertures extended from different portions of the periphery, some of which ter- minate in fresh chambers. Stoloniferous tubes narrow, cir- cular in section, about equal in length to the diameter of the larger chambers. Texture hyaline; surface hispid or aculeate. Length, when complete, +> inch (1'7 millim.) or more. In Mr. Joseph Wright’s ‘ List of the Cretaceous Microzoa of the North of Ireland” there appear figures of two obscure organisms under the generic name Ramulina, given to them by Professor T. Rupert Jones. The Seay from which 1 «Novara-Exped., Geol. Theil.,’ vol. ii, p. 286, pl. 6, fig. 76. > «Report and Proc, Belfast Nat. Field Club,’ 1873. 4; “Appendix, p. 88, pl. 3, figs. 19, 20. NOTES ON RETICULARIAN HIZOPODA, 273 these figures are taken are probably merely fragments, and no description of genus or species is given beyond that con- veyed in the terms “simple, calcareous, subsegmented, branching, Nodosarian form.” The diagnosis is further complicated by the author referring to the same genus, ‘‘ the so-called Dentalina (?) aculeata”’ of the Chalk. D’Orbigny’s Dentalina aculeata, as far as I can gather from the original description and figure,’ is a characteristic and easily recog- nised true Dentalina, and why it should be associated with any ‘‘ Ramuline” form it is difficult to understand. Having for some time past been collecting materials for the study of the Cretaceous types of Foraminifera I have become quite familiar with the organisms figured by Mr. Wright, and I believe them to be closely allied to the recent species above described. I have, therefore, adopted the generic term pro- posed by Professor T. Rupert Jones, and must leave the determination of the distinctive characters of the recent and fossil species until better specimens of the Cretaceous forms can be found to serve as a basis for their more accurate treatment. The test of Ramulina globulifera is always hyaline and perforate, and usually more or less hispid. The genus is probably nearly related to the Nodosarine, as suggested in the foregoing quotation, but its branching habit of growth is an essential and distinctive feature. The “ Challenger” dredgings have yielded examples from at least nine or tei stations. These are, for the most part, at no great distance from island groups, either in the North Atlantic or in the South Pacific; the depth of water ranging from 145 to 600 fathoms, and the bottom commonly consisting of coral debris or shelly sand. Genus—UVIGERINA, @’ Orbigny. The specimens from the “ Challenger’’ collections repre- senting the genus Uvigerina form an exceedingly interesting series, and there is one group in particular, namely, that embracing the dimorphous varieties, on which considerable new light is thrown by them. The general characters of Uvigerina (proper) are well understood, but this is far from being the case with the forms assigned to the genus or sub- genus Sagrina, Normally, Uvigerina may be described as having an elon- gated spiral test, the clustering chambers of which are 1 *Mém. Soe. Geol. F'r.,’ 1840, vol. iv, p. 13, pl. 1, figs. 2, 3. 274: HENRY B. BRADY. arranged with more or less regularity on a triserial plan. The aperture is simple, and usually situated on a produced neck of some sort, either a mere rounded conical projection or, more characteristically, in a tube of greater or less length, terminated by a phial-like lp. The surface of the test is almost invariably ornamented by strie or coste (continuous or interrupted), spines, bristles, or other exostoses. It is, however, on certain divergences from this typical plan of growth, which elucidate the connection ofthe extreme modifications of Sagrina with the generic type, that the chief interest of the forms to be described depends. UvVIGERINA PORRECTA, 2. sp. PI. VIII, figs. 15, 16. Characters.—Test elongate, subspiral ; earlier segments compactly arranged, obscurely triserial; later segments uniscrial, alternating irregularly, more or less distinct and interrupted. Surface marked by delicate, irregular, longitu- dinal coste. Aperture produced, tubular. Length 5 inch (0:5 millim.). ? | Habitat.—Off Bermuda, 435 fathoms; off Papua, 155 fathoms ; and at a point about 10° north of the Equator, in nearly the same longitude as the latter, 1850 fathoms. UVIGERINA INTERRUPTA, ”. sp. Pl. VIII, figs. 17, 18. Characters.—Test elongate, subspiral, composed of a number of inflated or subglobose segments, gradually in- creasing in size, arranged around a long axis. Larlier seg- ments combined so as to form a compact spire; the one or two last formed placed independently, in single irregular series, terminating in a tubular neck. Surface hispid or aculeate. Length =4 inch (0°5 millim). Habitat.—Humboldt Bay, Papua, 37 fathoms. Genus—SAGRINA, @ Orbigny. The range of morphological variation in Uvigerina runs nearly parallel to that of Zextularia. The latter genus, which is normally biserial, has subtypical modifications which, on the one hand, may be uniformly triserial, or on the other, may run into uniserial forms; or, taking a dimorphous character, may be spiral, triserial, or biserial in their early stages, and biserial or uniserial in their later growth. Uvigerina has normally a spiral arrangement of its cham- bers, but in like manner runs into dimorphous forms, and NOTES ON RETICULARIAN RHIZOPODA, 275 these constitute d’Orbigny’s genus Sagrina. They have been much misunderstood, and have been placed by German systematists, without exception, in the same family with Textularia. Of the two species named by d’Orbigny, one is biserial, and only betrays its affinity to Uvigerina by its aperture, which is placed in an erect mammillate protuberance at the top of the terminal chamber; the other is a Creta- ceous species” with an arenaceous test, which is spiral in its earlier growth and finishes biserially. Continental Rhizo- podists have only recognised the latter of these, and Sagrina has consequently been spoken of as an exclusively fossil genus, with characters founded on those of S. rugosa. Messrs. Parker and Jones, however, have shown the rela- tionship which exists between these and some similar forms, and have described two recent dimorphous species,® in both of which the arrangement of the segments is partly alter- nate or triserial and partly uniserial. To these the “ Chal- lenger’’ material has brought two additional and even more abnormal varieties, which have been named Sagrina virgula and S. divaricata respectively. The generic term is written Sagraina by Reuss and by Zittel. There is no doubt that d’Orbigny named the genus in honour of De la Sagra, the historian of Cuba, but his par- ticular method of doing so does not concern us, and as it is quite clear that the final @ was dropped intentionally, we must take the genus as he left it. It is the old story of Textularia and Textilaria, of Orbitolites and Orbitulites ; the only chance of uniformity in nomenclature lies in the rule of precedence. The systematic names for which classical authority and exactitude can be claimed are few indeed. SAGRINA VIRGULA, 2. sp., Pl. VIII, figs. 19—21. Characters.—Test linear, straight or curved, cylindrical, ta- pering, composed of many segments. Early segments minute, clustering, obscurely spiral, sometimes wanting ; later ones subglobular, united end to end, and somewhat embracing. Aperture wide, with a turned-over phial-like lip. Surface hispid or setose. Length, ; inch (0°5 millim.). The relationship of S. virgula with the hispid varieties of Uvigerina may be seen by comparing the figures with those of U. interrupta immediately preceding them in the plate. * Sagrina pulchella, ‘¥oram. Cuba,’ p. 140, pl. 1, figs. 23, 24. ? Sagrina rugosa, ‘Mém. Soc. Geol. Fr.,’ vol. iv, p. 47, pl. 4, figs. 31, 32. * Sagrina raphanus aud §. dimorpha, ‘Phil. Trans.,’ vol. clv, p. 364, pl. 18, figs. 16—18, hee? ta : 276 HENRY B, BRADY. It is a rare form, and individuals like that represented by fig. 21 may easily be mistaken for minute Nodosarie. Specimens of this species have been found at three localities in the Eastern Archipelago, all in shallow water (15 to 37 fathoms) and in one deeper sounding on the coast of South America, off Pernambuco (675 fathoms). SAGRINA DIVARICATA, 2. sp., Pl. VIII, figs. 22—24. Characters.—Test free, moniliform ; spiral chambers few and minute, forming an obscure rounded mass, altogether but little larger than one of the later segments. Later segments two to four in number, subglobular, arenaceous externally, united by clear, non-arenaceous, stoloniferous tubes, of length equal to about half the diameter of the larger chambers. Aperture an elongate, tubular neck, often longitudinally fur- rowed, and with an irregular, expanded lip. Length, =5 inch (0°5 millim.). The occurrence of arenaceous modifications of the dimor- phous Uvigerine is quite in harmony with the parallelism that has been suggested between them and the Textularian series. One species of Sagrina, hitherto undescribed, but not uncommon at some of the ‘‘ Challenger ’’ stations, can only be distinguished with difficulty from the Clavuline group of Textularie, its most recognisable character, as in so many other instances, being a tubular neck. In confor- mation it accurately resembles S. dimorpha, P. and J.; the test is thin, but it is composed of fine sand-grains, of uniform size, firmly compacted. This species helps to connect the clear-shelled forms with the rough Cretaceous species de- scribed by d’Orbigny. But the form now under consideration, Sagrina divaricata, presents in some respects a further deviation from the typical structure than the Clavuline variety alluded to, or, indeed, than any previously noticed. Its general features will be readily gathered from the description and figures. Specimens are rarely found entire owing to the tenuity of the con- necting stoloniferous tubes, but in certain tropical shallow- water sands, fragments showing the neck, and sometimes one or two segments, are not unfrequent. In complete specimens the initial chambers are clustered into a little ball scarcely bigger than one of those subsequently formed. The best examples that have been found occur in material from Humboldt Bay, Papua (57 fathoms), and off Tongatabu (18 fathoms). NOTES ON RETICULARIAN RHIZOPODA. 2% bt | ~y GLOBIGERINIDA. The Globsgerintda form a large and diverse group, and almost every section of it acquires some fresh significance from the “Challenger” collections. Of the simple non-septate genus Spirdlina several new forms are now to be described. The genus Chilostomella, first found in the recent condition two or three years ago by the Rev. A. M. Norman, is shown by the “ Challenger ”’ dredgings to have a wide distribution as a living type, and its near ally, Allomorphina, aforetime regarded as a rare Cretaceous and Harly Tertiary fossil, is represented by recent specimens from two to three localities. Pavonina, concerning which little or nothing has been known beyond its general external appearance as depicted by d@’Orbigny, is met with at two or three stations, and the difficulty which has been experienced by later Rhizopodists as to its zoological affinity is found to have arisen from the inaccuracy of the original figures. Of the Rotaline genera it is difficult to speak briefly, the number of species obtained is so large. Probably the result of their examination will be of value rather in the more accurate definition and better understanding of forms already known and named than in the number of new species to be described. There are, however, a few very distinct forms not previously recorded. Of these, two somewhat important Pulvinuling! have already been noticed, the published descriptions being founded upon “‘ Challenger” specimens, and a striking little Planorbulina is described and figured in the present paper. Of the genus Globigerina and its immediate allies a some- what longer summary is needful—one that may serve as the basis of a subsequent detailed exposition of so important a group—and to this end certain new species, of which illus- trative figures cannot at present be given for want of space, are introduced, as well as circumstances permit, by verbal descriptions. Genus—SPIRILLINA, Ehrenberg. The genera Spirillina, Cornuspira, and Ammodiscus, are isomorphous, and represent vitreous, porcellanous, and are- naceous types of structure respectively. The resemblance of the tests of some of these simple forms to the shells of pteropods and annelids, whilst often a source of difficulty where the imperforate Cornuspira and the sandy Ammodiscus are concerned, scarcely affects the diagnosis of Spirillina, “ Pulvinulina favus, and P. Menardii, var. tumida,? ‘Geol. Mag.,’ 1877, Dec. 2, vol. iv, p. 535. VOL. XIX. —NEW SER, T 278 HENRY B. BRADY. the shell-wall of which, especially in the young condition, is delicately thin and transparent, and conspicuously perforated. But for these characters, such forms as that now described under the name Sp. inequalis might easily be mistaken for minute adherent annelids. Several well-marked modifications of the genus, which have hitherto escaped the notice of naturalists, have been found amongst the minuter Foraminifera of shallow water, especially of tropical seas, and some of these have been selected for description. The enumeration of their dis- tinguishing zoological characters with the drawings figs. 25 to 28 of Plate VIII, will be sufficient to show the lines in which they diverge from the few already known species. SPIRILLINA INZQUALIS, ”. sp. PI. VIII, fig. 25, a, b. Characters.—Test free or adherent, discoidal, thick; in- ferior face flat, broader than the superior; superior surface excavated at the umbilicus. Composed of a number of convo- lutions (three to five) of a non-septate tube. Inferior peripheral margin acute or sub-carinate, superior obtuse. Shell- wall conspicuously foraminated. Diameter, —, inch (0°56 millim.). Compared with the typical Spirdlina vivipara, this species presents a small thick shell, with a sloping instead of a rounded peripheral wall. Though it has never been met with attached to any hard body, the appearance of its in- ferior surface and the fact of its being brought up upon minute shreds of alge and the like, leave little doubt that it is of parasitic habit. The extension of the margin of the inferior surface is due mainly to the thickening of the shell- wall, which on the superior side remains thin, perforate, and delicately transparent. Spirillina inequalis has been found in several localities, notably off Nightingale Island (100 to 150 fathoms), off Honolulu Reefs (40 fathoms), and from the Admiralty Islands (17 fathoms), SPIRILLINA LIMBATA, 2. sp. PI. VIII, fig. 26, a, d. Characters.—Test planospiral, thin, equilateral, discoidal ; peripheral margin square. Spiral sutural line marked ex- ternally by a raised band of shelly deposit; surface other- wise smooth. Diameter, ;); inch (0°4 millim.) This is a well-marked form differing from Sp. vivipara in NOTES ON RETICULARIAN RHIZOPODA. 279 its less delicately thin shell-wall, its distinct sutural limba- tion, and its square periphery. ' The “ Challenger’’ specimens are from Prince Edward’s Island, 50 to 150 fathoms, and Bass Strait, 38 fathoms. SPIRILLINA OBCONICA, 2. sp. Pl. VIII, fig. 27, a, d. Characters.—Test free, spiral; contour elliptical, superior surface conical, inferior surface concave; composed of several (seven or eight) convolutions of a narrow non-septate tube. Shell-wall very thin, foramina minute. Diameter, —; inch (0:25 millim.). An exceedingly minute and fragile form, resembling not a little the initial convolutions of Patellina, which are often non-septate. Its oval contour and the fact that it is found in places where Patellina has not been met with, favour the assumption that its represents an independent species. Spirillina obconica occurs with some of its congeners off Prince Edward’s Island, 50 to 150 fathoms, and off Christ- mas Harbour, Kerguelen Islands, 120 fathoms. Perhaps also in one or two other localities, which I cannot at the moment refer to. SPIRILLINA TUBERCULATA, Brady. Pl. VIII, fig. 28, a, 0. Spirillina tuberculata, Brady, 1878. In Siddall’s “ Foraminifera of the Dee,”’ ‘Proc, Chester Soc. Nat. Sci.,’ pt. i, p. 50. Characters (amended).—Test free, planospiral, the two sides seldom quite symmetrical ; peripheral margin rounded in large specimens, often somewhat square in smaller ones. Surface more or less covered with exogenous deposit, filling the sutural depressions except that bounding the final con- volution; the exterior of the whole shell beset with well- defined raised tubercles, generally more strikingly developed on one side than on the other. Diameter, ;'; inch (0°64 millim.). This species is by no means new, though it remained un- described until a few weeks ago. Many years since I obtained specimens from the south coast of England (off Eddystone), and my friend David Robertson, F.G.S., subse- quently found it in one or two other British localities. In Mr. J. D. Siddall’s collection of Foraminifera from the Estuary of the River Dee, a very similar, probably identical, variety occurs. But the British examples are relatively very poor representatives of the species, and they are perhaps a 280 HENRY B. BRADY. connecting link between the fully developed form and Williamson’s Spirillina margaritifera,' hence the description furnished to my friend Mr. Siddall (doc. czt.) needs a little revision. In the specimens from our own shores the tuber- cular exostoses are frequently confined to the central portion of the test, which is otherwise a flat or slightly concave disc, bearing no indication of the spiral internal structure. Well-marked individuals of this species are found in two of the dredgings off Kerguelen Islands, namely, in Royal Sound, 20 to 60 fathoms, and off Christmas Harbour, 120 fathoms. Genus—CHILOSTOMELLA, Reuss. CHILOSTOMELLA OVOIDEA, feuss. PI. VIII, figs. 11, 12. Chilostomella ovoidea, Reuss, 1849. ‘ Denkschr. d. math.-nat. Cl. k. Akad. d. Wiss.,’ vol. i, p. 380, pl. 48, fig. 12. _— Czjzeki, id. ibid., pl. 48, fig. 13. The genus Chzlostomella has until quite recently remained almost unknown to English Rhizopodists. It has never been found amongst the fossils of our microzoic deposits, and before its discovery by the Rev. A. M. Norman,’ in sands dredged off Valentia (112 fathoms), and amongst material brought by the scientific staff of the ‘“‘ Valorous’’ from the far north, its range of distribution was supposed to be limited to certain Tertiary marls of Central Europe. It is never- theless to be regarded as a locally or partially distributed rather than as a very rare recent type, for it occurs in con- siderable abundance in many areas far apart, and the wonder is that it remained so long unobserved. The structural features of Chzlostomella and its near ally Allomorphina, are so remarkable that Reuss very properly placed the two genera in a family by themselves, which he characterised as follows (oc. cvt.): « Enallostegia cryptostegia.—Testa libera, irregularis, ineequilatera, conflata e loculis perfecte amplectentibus, alternantibus, ad axes vel duos oppositos vel tres in triangulo positos. Contextura teste vitrea, pellucida, nitens.”’ Seguenza’s interesting genus Ellipsoidina is, I am con- vinced, very nearly related to the types included by Reuss in this family; and the descriptive characters above quoted would need but little modification to admit a form which differs chiefly from Chilostomella in the segments springing 1 «Rec. Foram. Gt. Br.,’ p. 98, pl. 7, fig. 204. 9 2 *Proc. Roy. Soc.,’ vol. xxv, p. 214. NOTES ON RETICULARIAN RHIZOPODA. 281 uniformly from one end, instead of alternately from the two extremities. The test of Chilostomella may be described in general terms as composed of a series of nearly symmetrical, ovate, or elliptical segments, each enclosing the whole of that previously formed, with the exception of a small portion of its end. The order of the segments is alternate, that is to say, they are put on first from one end, then from the other. The line of union is not directly transverse but dips towards one side, so that more of the penultimate chamber is exposed at one side than at the other. The aperture is crescentic, sometimes bordered by a thickened lip, and always situated on the margin of the final segment in the region nearest to the apex of the shell. In shape the test varies from an elongate, sub-cylindrical, to a short, rounded, oval, between which extremes every variety of contour may be met with ; the ends are sometimes blunt and rounded, sometimes more or less tapering, so that, unless Professor Reuss’s two species (Ch. ovoidea and Ch. Czjzeki) have some better dis- tinguishing feature than mere size and external form, they may very safely be resolved into one. In deep water the specimens are often more delicate and transparent, and also more elongate than in shallow seas, but this is by no means an invariable rule. One or two individuals of this species have been found amongst the gatherings of surface Forami- nifera, but there seems no reason to suppose that the type is essentially a pelagic one. Chilostomella ovoidea has been met with at “‘ Challenger ” stations in the North Pacific, South Pacific, and North Atlantic. It also occurs in one.or two of the ‘* Porcupine” dredgings from more northerly areas in the Atlantic than any point of the “‘ Challenger” voyage, and the Rev. A. M. Norman has obtained the species in some abundance on the coast of Norway. The recorded depths of the “Challenger” dredgings in which it has been found are nearly all between 300 and 600 fathoms, but one of them is as deep as 2300, and another as shallow as 95 fathoms. Genus—ALLOMORPHINA, Reuss. ALLOMORPHINA TRIGONA, Reuss. Pl. VIII, figs. 13, 14. Allomorphina trigona, Reuss, 1849. ‘Denkschr. d. math.-nat. Cl. k. Akad. d. Wiss.,’ vol. i, p. 380, pl. 48, fig. 14. = cretacea, Reuss, 1850. § Haidinger’s Abhandl.,’ vol. iv, p. 42, pl. 5, fig. 6 The genus Allomorphina differs from Chilostomella in 282 HENRY B. BRADY, having three chambers to each circuit instead of the alter- nating two, and, as its growth takes place on one plane, the test assumes a sub-triangular and more or less depressed contour. There does not appear to be any morphological distinction between the two “species” above quoted, and mere difference of geological age is of little value from a zoological standpoint; nor can the fossil specimens be separated from the recent ones by any character of specific or even varietal significance. In the living condition Allomorphina is exceedingly rare, and the individual specimens are small and delicate. The genus is supposed to have made its appearance earlier than its ally Chilostomella, and it may in like manner be the first to die out. In two dredgings only has llomorphina trigona been found recent; one of these is from the Hyalonema-ground to the south of Japan, in 845 fathoms, the other, off Tahiti, in 620 fathoms. Genus—PAVONINA, d@’ Orbigny. PAVONINA FLABELLIFORMIS, @ Orbigny. Pl. VIII, figs. 29, 30 ~ 9 . Pavonina flavelliformis, VOrbigny, 1826. ‘Ann. Sci. Nat.,’ vol. vii, p. 260,. No. 1, pl. 10, figs. 10, 11:—Modeéle, No. 56. D’Orbigny obtained this rare and interesting Foraminifer from Madagascar prior to 1826, and from that time until a year or two ago, when I had the good fortune to meet with it in some sand dredged by my friend Dr. E. Perceval. Wright, in shallow water in the Seychelle Islands,! it had not been found by any subsequent naturalist, and much doubt had been expressed as to its structure and affinity. Messrs. W. K. Parker and T. R. Jones suggested, in one of their papers on the Nomenclature of the Foraminifera,’ that it might ‘possibly be a symmetrical Peneropolis, more probably a semi-discoidal modification of Orbitolites.”” But the specimens now brought to light show that its place is far from the porcellanous series, and that the morphological difficulty has arisen from a slight inaccuracy in d’Orbigny’s figure and Model, which has probably arisen from defective microscopic powers. Careful examination of the specimens reveal the fact, not very clear at first sight, that the early chambers are not spiral or subspiral, as they appear to be, 1 «Ann. and Mag. Nat. Hist.,” 1877, ser. 4, vol. xix, p. 105. 2 Tbid., 1863, ser. 3, vol. xi, p. 440. NOTES ON RETICULARIAN RHIZOPODA. £83 and further that they do not reach the entire width of the test, but are laid on alternately. In other words, that the shell begins growth as a Textularia, and subsequently constructs a single series of large, flat, arched segments, which give it its fan-like contour. The shell-wallis thin and transparent, the perforations numerous and large, and the sutures limbate. The general aperture takes the form of a row of small orifices on the outer face of the terminal segment. The diameter of the largest specimen which has been found is ~, inch (about 1:0 millim.). Pavonina flabelluiformis has been taken at three of the ** Challenger” stations, namely, Nares Harbour, Admiralty Islands, 17 fathoms; off Culebra Island, West Indies, 390 fathoms; and off the reefs, Honolulu, 40 fathoms. These, with the habitats furnished by the researches of d’Orbigny and the material collected by Dr. Perceval Wright, represent our knowledge of the distribution of the species. Genus—PLANORBULINA, @’ Orbigny. PLANORBULINA ECHINATA, 7. sp, Pla VIE, fic. dia, b;'c. Characters.—Test nearly spherical ; composed of few seg- ments, about four in the last convolution. Segments ven- tricose, unequally arched, embracing. Shell coarsely perfo- rated and usually armed externally with short, blunt spines. Aperture large, round, sometimes partially closed by a ely plate within the bordering lip. Diameter ~5 inch (0°52 millim.). The affinity of this little organism to the Rotaline is easily determined, notwithstanding its anomalous shape ; and the bordered neck which forms the aperture, together with the coarse perforation of the shell-wall, suggest its more intimate connection with the genus Planorbulina. It is a minute, inconspicuous species, and cannot well be confounded with any previously known. Planorbulina echinata has its home amongst the coralline sands of shallow seas, and has been found at ten or twelve of the ‘‘Challenger” stations, chiefly amongst the islands of the Pacific. Except in one locality, Nares Harbour just south of the Equator, the number of specimens from any single habitat is very small. 284. HENRY B. BRADY. Genus—GLOBIGERINA, @ Orbigny. The extent and variety of the “‘ Challenger” soundings and the large area over which the tow-net was employed during the expedition have furnished opportunity for a somewhat comprehensive examination of the shells of Globigerina and the allied genera. It would be impossible in a mere preli- minary paper like the present one to treat the subject even briefly, in its numerous aspects, neither could it be done to any good purpose without the assistance of a large series of illustrative drawings. These will appear in due course, and with them some attempt at a complete history, but in the meantime there are one or two points that may be concisely touched upon, such as the range of morphological variation presented by the shells of the Globigerine, and the better definition of the quasi-specific forms, together with certain more general questions affecting the surface-fauna of the ocean so far as it consists of calcareous Rhizopoda. Professors W. K. Parker and T. Rupert Jones, in their philosophical and valuable memoir on ‘ Foraminifera from the North Atlantic and Arctic Oceans,” record the occur- rence of only two species of Globigerina (proper), the typical Gl, bulloides and Gl. inflata ; and in their supplementary tables recognise but two others, Gl. helicina and Gl. hirsuta. The limited number may be accounted for by the researches of these authors having been conducted chiefly amongst the northern and relatively stunted representatives of the group, and the characters assigned to the genus are, no doubt, more or less affected by the same circumstance. Their generic definition, which agrees in all essential points with Dr. Carpenter’s more extended description,” runs as follows : “The shell of Globdcgerina is composed of a series of hyaline and perforated chambers, of a spheroidal form, arranged in a spiral manner, and each opening by a large aperture around the umbilicus, in such a manner that the apertures of all the chambers are apparent on that aspect of the shell, and form a large ‘umbilical vestibule’ ”’ (doc. cit., p. 365). It will be seen as we proceed that these characters only apply to one section of the genus, and that possibly not the most important, and it may even be open to question whether Globcgerina bulloides, the hitherto accepted type of the group, is really its best representative. I propose, there- fore, to enumerate the “species” which I have found it 1 ¢ Phil. Trans.,’ 1865, vol. clv. 2 ‘Introduction,’ p. 18]. NOTES ON RETICULARIAN RHIZOPODA. 285 necessary to recognise and to give briefly the distinguishing characters of each. Globigerina bulloides, d’Orbigny (‘ Annales des Sci. Nat.,’ 1826, vol. vil, p. 277, Modéles No. 17 and 76).—D’ Orbigny Gescribed this species at four or five different times and never in quite identical terms, but his Model No. 76 may be accepted as a fair summary of the characters intended, and this presents the general features of the variety most abundant in the northern seas. ‘The test is convex, the segments spherical and few in number, that is, about four in each convolution and seldom more than two convolutions, and the inferior surface is excavated at the umbilicus, forming a recess or vestibule into which the apertures of the indi- vidual segments are directed. In this simplest form we have a tangible and easily recognised starting-point. Though it does not represent the best development ‘of the type it is the beginning of a chain, the successive links of which, some of greater some of less ‘morphological significance, have none of them any pretension to rank as true species, but which collectively extend over an area of variation so large that the salient points must, of necessity, be distinguished by trivial names. The following notes indicate the directions in which these variations take place, the right precedence in nomenclature being as far as possible observed. Globigerina dubia, Egger (‘ Neues Jahrb. fir Min,,’ 1857, p- 281, pl.9,figs.7—9) —represents the best development of the “bulloides” type. It hasa fine, thick, regular shell with about three convolutions,each consisting of five or sixsegments. The segments_are relatively small, the peripheral margin rounded and lobulate, and the umbilical vestibule deeply sunk. Globigerina cretacea, VOrbigny (‘ Mém. Soe. géol., Fr.,’ vol iv, p. 34, pl. 3, figs. 12—14)—is, on the other hand, a starved form, of eal dimensions, thin and flat-topped, the inferior surface concave. It also shows the umbilical vestibule, and differs from GJ. bulloides chiefly in its depressed contour, and the more compact fitting of the segments, especially the earlier ones. Globigerina equilateralis, nov.—This is a variety approach- ing Hastigerina, in general form. The test is plancspiral and symmetrical, not Rotalian ; ; 1t consists of but little more than a single convolution, and the whole of the segments are sometimes visible on both sides. The final segment is often smaller than the penultimate, as is sometimes also the case with GU. cretacea. 286 HENRY B. BRADY, Globigerina digitata, nov.—is a very singular modification of the type, and one that has not hitherto been described. The earlier segments are commonly regular and trochoid, but the later ones are much elongated and spreading. In some specimens, generally of small size, the final segment only is extended, like the index finger of the hand, but in others, two, three, or more chambers radiate in palmate fashion. The apertures of the chambers have thickened or lipped borders. It is a rare form, and usually of small size, =. inch (0°5 millim.), but in one dredging specimens have been met with measuring ;. inch (1°5 millim.) in diameter. 17 Globigerina inflata, VOrbigiiy (‘ For. Canar., p. 134. pl. 2, fig. 7—9)—is of plano-convex shape, the superior or spiral face being flat, the inferior convex. There is no umbilical ves- tibule, and the aperture of the last segment is the only orifice _which is visible externally ; this is large and gaping, and con- stitutes a distinctive feature. GJ. inflata is the isomorph of Rotalia Soldanti and Pulvinulina crassa, and it is even difficult sometimes to distinguish it from the latter species. Globigerina Dutertret, d’Orbigny (* Foram. Cuba,’ p. 99, pl. 6, fig. 22—24).—I am disposed to recognise this as a convenient name for a small, thick, rounded variety, more compactly built than Gl. bulloides, and having no um- bilical vestibule, but a single, comparatively small, arched orifice, with thickened lip. It has neither the fiat superior surface nor the gaping aperture of Gl. inflata. Globigerina rubra, dOrbigny (¢ Foram. Cuba.,’ p. 94, pl. 4, fig. 12—14)—exhibits, perhaps, the most important deviation of all from the type of structure with which we started. ‘The test is more or less trochoid, often relatively very tall, and has about three segments in each convolution. The inferior surface has one arched aperture on the umbilical margin of the last segment, but many of the segments have either one or two large, more or less rounded orifices on their superior surface, close to the sutural depressions. Fresh specimens have a pink tinge, and the earlier cham- bers especially are often of very bright colour. It is to be regretted that d’Orbigny’s name for this species should have. been associated with so variable a characteristic as colour, the more so as in his description he makes prominent allusion to the numerous apertures. Several of the Globigerine show a tendency to pink colouration, though none to the same extent as Gl. rubra. Globigerina conglobata, nov.—is a large subglobular modi- NOTES ON RETICULARIAN RHIZOPODA, 287 fication of the rubra”? type, in which the early segments are small and compactly arranged, and the spire convex rather than trochoid; the later segments are large, particularly the three forming the final convolution, and disposed so as to give a convex base. ‘The apertures on the superior surface are numerous, and the test is thick and coarsely perforated. Globigerina sacculifera, Brady (‘ Geol. Mag.,’ Decade ii, vol. iv, p. 535).—This is a distinct and conspicuous variety, briefly noticed ina short paper on the Foraminifera of a piece of white friable limestone from the New Brita Group (Joc. cit.). It is characterised by its large outspread test, of of which the terminal chamber or chambers are pouch-shaped or pointed. The apertures on the superior surface are numerous ; that of the final segment is sometimes directly over the inferior orifice, making a passage, as it were, right through the shell. Globigerina helicina, VOrbigny (‘ Ann. Sci. Nat.,’ vol. vii, p. 279, No. 5;—Soldani, ‘ Testaceographia,’ vol. i, pt. 2, pl. 130, figs. pp, gg, 77)—is an anomalous oblong form and one rarely met with. It is not easy to describe it intelligibly without the aid of figures. It most resembles an ordinary small Globigerine shell, with the addition of a little inflated chamber at two opposite points of its periphery. The superior surface is obscurely spiral and shows two, three, or more apertures. The inferior side has four visible segments; two large and oblong, laid side by side, and two- small and in- fiated, one at each end of the test; the later have inferior apertures. It is possible that G7. helicina may represent a monstrous condition rather than one of the more permanent varieties of the type. I have met with precisely analogous specimens in two other allied genera, and these have been treated as abnormal developments of the species to which they are related, namely, Pullenia obliqueloculata and Can- denia nitida, Justice has, perhaps, scarcely been done to the accuracy of Soldani’s drawings in the present instance. Dr. Carpenter (‘Introd.,’ pl. 12, fig. ) employs the name Gl. helicina for what appears to be only an immature speci- men of a quite different variety (GU. sacculifera). Of the three figures in the ‘ Testaceographia,’ referred to by VOrbigny, that marked gq, which gives both the superior and inferior aspects of the shell, is the most cha racteristic, and leaves nothing to be desired in point of defi nition. There is little difficulty in distributing the Globerigine of 288 HENRY B. BRADY. the “ Challenger” collection amongst the salient types above enumerated, and the few exceptions that occur are chiefly in the case of specimens which are obviously monstrous. Nothing has been said of the spinous or hirsute surface- armature in the light of a zoological character, because it appears to possess no specific or even varietal value. Examples of almost every “ species’? embraced in the foregoing descriptions are met with from time to time, more or less covered with long silky spines, but such speci- mens are naturally much more common amongst those taken at the sarface of the sea than in the contents of the dredge, and the spinous condition is more generally noticed in young and small than in fully-grown shells. There are a few recorded forms, though very few, that cannot properly be asigned to any of the species in the fore- going summary. Of these, Globigerina marginata (Reuss)? is, perhaps, the most important, as it is one of the best defined Cretaceous forms. It belongs to the ‘* budloides ” group, and to repeat the comparison with the genus Pe/lvinulina, it is the isomorph of P. Menardii, just as Globigerina imflata is the isomorph of P. crassa. Ido not recollect ever having seen Gl. marginata in the recent condition, nor, indeed, otherwise than as a Cretaceous fossil.” Two other species, GU. elevata, d@Orbigny, and Gi. trochoides, Reuss, have also been de- scribed from Cretaceous specimens, but I have been un- able to identify them with any forms I am acquainted with. Both of them bear some resemblance to Gilobigerina rubra in their general features, the latter especially so, but the published drawings have no indication of orifices on the superior surface. It will have been gathered from the foregoing résumé that the spiral Globigerine may be roughly divided into three groups on the basis of the position and character of the general apertures, and, to a less degree, on the contour of the test. These are—Ist. The forms with an excavated cavity on the inferior surface (“umbilical vestibule”), into which the orifices of all the segments open—type, Glodigerina bul- loides. 2nd. Those with only one external orifice situated on the face of the terminal segment, at its point of junction with the previous convolution—type, GU. inflata. 3rd. Those in 1 Rosalina marginata, Reuss, 1845. ‘ Verstein, Bohm. Kreid,’ pt. 1, p. 36, pl, 13, fig. 74. Figured better in a subsequent paper ‘ Denkschr. d. k. Akad. Wiss.,’ vol. vii, pl. 26, fig. 1. * It is possible that the Rosalina Linnei (‘Foram. Cuba,’ p. 106, pl. 5, fig. 10—12, called R. Linnetana in the text), found by d’Orbigny on the coast of Cuba, may be the living representative of this species. NOTES ON RETICULARIAN RHIZOPODA,. 289 which the inferior aperture is single and relatively small, but is supplemented by conspicuous orifices on the superior or spiral surface of the test—type, Gl. rubra. Bat, in addition to the spiral Globigerine, or rather those that appear so externally, there are certain spherical forms constituting the reputed genus Orbulina. Without entering into minutiz, Orbulina may be defined as a minute, thin- walled, Globigerine shell enveloped in a large globular final chamber. Examples are not wanting, amongst other genera, of varieties leading up to similar conditions, but in none is the phenomenon so completely developed. In my previous paper I have indicated the fact, suggesting, by its uniformity, a general law, that when a Foraminifer forms an abnormally Jarge segment, growth is arrested and no more chambers are produced. Amongst spiral Foraminifera Cymbalopora bul- loides affords the most familiar example of a species with a balloon-shaped final segment, but the same peculiarity 1s developedina less degreeincertain modifications of Discorbina and Pulvinulina. All these forms have another character in common with Orbulina, namely, a double series of perfora- tions; that is to say, the wall of the inflated chamber has two sorts of orifices, differing in size, the one set numerous and uniformly very minute,-the other uniformly large and fewer in number. The question arises whether the characters exhibited by these Orbuline forms are to be regarded as of mere varietal significance or as sufficient to warrant subgeneric or generic distinction. ‘The reply seems to be, that the close affinity to Globigerina is best expressed and zoological convenience is best served by accepting Orbulina as a subgeneric type of that genus. j Globigerina (Orbulina) universa, dOrbigny (‘ Foram., Cuba,’ p. 35, pl. 1, fig. 1)—is figured by d’Orbigny, William- son and others as a small spherical shell of yellowish hue, with a neat, round, general aperture in addition to the per- forations that have been already alluded to; but Pourtales, Williamson, and Carpenter have all dwelt on the fact that this large orifice only appears in a minority of the specimens found. Iam inclined to go a good deal further and, though not prepared to say that it does not sometimes exist, I believe it to be very rarely indeed that a fresh shell possesses what has any claim to be considered a general aperture. After looking over thousands of specimens I have not been able to find one from which a drawing like those of the text- books could be made. In dredged specimens large orifices 290 HENRY B, BRADY. are not uncommon, but they occur, as often as not, two or three to a shell, and they either have abrupt angular edges, indicative of accidental fracture, or they are found at spots where the shell has been previously worn very thin. It must be remembered that the nature of the perforations which already exist in the shell-wall is one peculiarly favor- able to the formation of larger orifices by abrasion or pres- sure. The matter, perhaps, is not one of very great conse- quence, seeing that it is admitted on all hands that a general aperture is not an essential or even a usual characteristic of Orbulina. In Cymbalopora under similar circumstances the general aperture is wanting, and a series of large per- forations, in addition to the normal minute ones, takes its: place, and there are other types of Foraminifera that have a number of conspicuous pores on the face of the terminal seg- ment when it is of abnormally large size. It appears to me clear, therefore, that of the two sets of perforations in Orbu- lina, the larger ones stand in lieu of the aperture or aper- tures of the normal Globigerine shell. G1. (Orbulina) neojurensis, Karrer (‘ Sitzungsb. d. k. Akad. Wiss.,’ vol. lv, p. 368, pl. 3, fig. 10).—The surface of the test in many species of helicoid Globigerine often bears a sort of honeycombed or reticulate ornamentation, best observed in specimens collected at the surface of the sea. This pecu- liarity is seldom met with in the Orbuline varieties, but Dr. Karrer has described and figured such a specimen amongst other fossil microzoa from the ‘“‘ White Jura” of St. Veit, near Vienna, under the name above quoted. Dr. Wallich has a drawing of a similar shell in his memoir on the ‘North Atlantic Sea-bed,” pl. 6, fig. 9, and examples of the same form have been met with both by the Rev. A. M. Norman and myself in recent Gilobigerina-ooze ; but, both in the recent and fossil condition, the variety is exceedingly rare. Under the name Gilobigerina bilobata (‘ For. Foss. Vien.,’ p. 164, pl. 9, fig. 11—14) d’Orbigny has figured what appears to be only a double Orbulina with slightly reticulated surface. Monstrosities of this kind are by no means uncom- mon wherever Globigertne abound, and sometimes, though ‘less frequently, specimens with two supplementary chambers, one on each side of the parent-cell, may be met with. On these grounds it does not seem worth binomial distinction. NOTES ON RETICULARIAN RHIZOPODA., 291 Genus—HASTIGERINA, Wyville Thomson. HAsTIGERINA PELAGICA, (d’Orbigny). Nonionina pelagica, @Orbigny, 1839. ‘Foram. Amér. Mérid.,’ p. 27, pl. 3, figs. 18, 14 Globigerina pelagica, Parker eh Jones, 1865. ‘Phil. Trans.,’ vol. clv, Ds . Hastigerina Murrayana, Wy. Thom., 1876. ‘Proc. Roy. Soc.,’ vol. xxiv, p. 534, pls. 22, 23. An organism very closely allied to Glodzgerina, with which it corresponds also in its pelagic habit. It is not easy to find zoological characters to separate the two genera, but the nautiloid symmetry of the test of Hastigerina, its extreme tenuity, the embracing contour of the successive convolutions (the constituent chambers of which spring from the umbilicus on either side), and the large opening on the face of the ultimate segment that serves as the aperture, are perhaps its distinctive peculiarities. The empty shells are seldom found amongst dredged sand or ooze, and when they do occur they are invariably much broken, owing to the delicacy of the calcareous walls. When living the test is armed with long spines, but the bases of these alone are left in the dead shells found at the bottom. Under the name Nonionina pelagica, d’Orbigny describes and figures what is manifestly the present species (oc. cit.), and appends the following remark :—*‘ Cette espéce est une rare exception parmi les Foraminiféres essentiellement cotiers, puisque nous l’avons prise en pleine mer, a une grande distance des cotes du Pérou, dans l’océan Pacifique, par 20° de latitude sud et 89° de longitude ouest de Paris, ou elle nous a paru trés rare.” His figure represents a shell somewhat flatter than most of the ‘* Challenger”’ specimens, with the sutures and umbilicus rather more depressed, and if these characters should be found sufficient to distinguish the two, Sir Wyville Thomson’s specific or varietal name might be retained for the more spheroidal form. Genus—CANDEINA, d@’ Orbigny. CANDEINA NITIDA, @’ Orbigny. Amongst the Foraminifera from various habitats figured by d’Orbigny in the final plate of his “‘ Vienna Basin ” mono- graph," are several that have been a source of difficulty to subsequent Rhizopodists, perhaps none more so than Can- ' * For, Foss. Vien.’ p, 598, pl. 21, fig. 28. 292 HENRY B. BRADY, deina nitida. Except its recent mention by name amongst the species found by the Rev. A. M. Norman 1 in the dredged material obtained on the “ Valorous ” cruise, I cannot find that it has been the subject of actual observation with any author since d’Orbigny’s time, and hence conjectures as to its position and affinity have fallen somewhat wide of the mark. Max Schultze, in his scheme of classification,' places Candeina in the Subfamily Uvellida, between Guttulina and Globulina, two sections of the genus Polymorphina ; and Von Reuss,? after expressing uncertainty as to its right zoo- logical position, suggests that it possibly represents a new and distinct family, or if not, that perhaps it might be classed with the Polymorphine. The genus Candeina does represent a distinct type of Fo- raminifera, but not a distinct family. Its affinity is to Glo- bigerina, and, with specimens to refer to, its characters are easily comprehended. The test is spiral and trochoid, the segments globose, and usually three to each whorl. The earlier chambers are minute, the later ones relatively very large; the test is exceedingly thin and smooth and has a slightly yellowish tinge; the perforations are so fine that under a moderate magnifying power 1t appears imperforate. Instead of a single general aperture it is provided with a series of little rounded orifices, following the septal lines, most noticeable on the sutures of the later chambers, and seen on both the superior and the inferior surface of the test. In this respect it resembles the Globigerine of the “rubra” group, but the orifices are smaller and more numerous and they are regularly disposed. I have found Candeina nitida amongst other pelagic Foraminifera from one surface gathering (Philippine Islands). Its occurrence in the “ Challenger” bottom- dredgings is pretty much confined to the South Atlantic and South Pacific. D’Orbigny states (doc. ezt.), “ Nous n’en avons qu’une seule espéce des Antilles. Nous dédions ce genre a M. Ferdinand de Candé.” Notes on Pelagic Foraminifera. The employment of the towing-net during the cruise of the “ Challenger” to an extent never before attempted, and the careful preservation of the animal and vegetable organisms collected by its means, have furnished the ground- work, not only for a better appreciation of the nature and 1 “Ueber den oa Polythal.,’ p. 52. 2 «Sitzungsb. d. k. Akad. d. Wiss.,’ vol. xliv, p. 384. NOTES ON RETICULARIAN RHIZOPODA. 293 conditions of life at the surface of the ocean, but also for a more accurate comparison of its fauna with that of the sea- bottom than has heretofore been possible. The earliest allusion to Foraminifera taken at the surface of the sea is probably d’Orbigny’s note on ‘‘ Nonionina” pelagica which has been already quoted ; this was in the year 1839. There is no difficulty in identifying the drawings of the specimens then found with Sir Wyville Thomson’s Hastigerina Murrayana, ox its congeners. In 1857, Mr. J. D. Macdonald! figured a small spinous Gilobigerina, which he describes as “the species most usually taken at the surface of the ocean.” In the spring of the same year Dr. Wallich and Captain and Mrs. Toynbee appear also to have collected pelagic Globigerine, but no considerable addition was made to our knowledge of the subject until ten years later, when Major S. R. I. Owen con- tributed to the ‘Journal of the Linnean Society’? a paper “On the surface-fauna of Mid-Ocean,” which contained our first detailed account of pelagic Rhizopoda, and the first intimation of the fact that the genus Pulvinulina was almost as important a constituent of the surface-fauna as Globigerina itself. Major Owen’s gatherings contained the following forms——I give them under the names employed in his paper— Globigerina bulloides, d’ Orb. | Gl. (Orbulina) acerosa, Owen. — hirsuta, W’Orb. | Pulvinulina Menardii, VOrb. — inflata, V Orb. _— canarinesis, Orb. Gl, (Orbulina) universa, V’Orb. — Micheliniana, Orb. _ continens, Owen. | _ crassa, @ Orb. Three of these have, as I think, no claim to rank as species or even as named varieties—but this is a question that need not be debated here. Since Major Owen’s memoir the only recorded observations bearing on the subject are to be found in the brief notes sent home from time to time by the “ Challenger” staff, and in the summary of the zoological work accomplished on board the vessel, furnished by Mr. Murray for the ‘Proceedings of the Royal Society’ in 1876.° These refer chiefly to points connected with the life-history of Globigerina and Hastigerina. Facilities have been afforded me for the examination, not merely of the extensive series of mountings made by Mr. Murray on the spot from the contents of the tow-net, but also of portiens of the various bottles of surface organisms * Ann, and Mag. Nat. Hist.,’ ser. 2, vol. xx, p. 266, pl. 7. x ‘Journ. Linn. Soc. Lond.,’ 1867, vol. ix, ‘‘ Zoology,” pp. 148 —157, pl. 5. * «Proc. Roy. Soc.,’ vol. xxiv, p. 471—544. VOL, XI1X.—NEW SER, U 294, HENRY B. BRADY, which were preserved in bulk, and I have been enabled thereby to increase considerably the category of known pelagic species. The following list is as nearly complete as I am at present able to supply, but it is not improbable that there may be one or two varieties of Globigerina still to add. The Globigerina hirsuta, Gl. (Orbulina) acerosa, and Gl. (Orb.) continens, of Major Owen’s paper, are all abundant in the “Challenger” gatherings, but their characters do not appear to be sufficiently distinctive nor sufficiently uniform to warrant separation from their congeners, and they have, therefore, been omitted from the list, or rather, are included in the species to which I believe them to belong. Globigerina bulloides, d’Orb. Pullenia obliqueloculata, P. and J. — inflata, VOrb. Spherotdina dehiscens, P.and J. — rubra, VOrb. Candeina nitida, dOrb. — _ sacculifera, Brady. Pulvinulina Menardii (WOrb). —_— conglobauta, nov. — — var. tumida. — equilateralis, nov. — canariensis (d’Orb). Gl. (Orbulina) universa, VOrb. — crassa (d’Orb). Hastigerina pelagica (d’Orb). — Micheliniana (d’Orb). — — var. Murrayana,| Cymbalopora bulloides, d’Orb. Wy. T. Chilostomella ovoidea, Reuss. Some few of these, notably Candeina nitida and Chilo- stomella ovoidea, are of extreme rarity in the surface gather- ings, whilst Hastigerina pelagica and Cymbalopora bulloides, though tolerably abundant at times, are very local in their distribution. So much has been written on the relation of the surface Rhizopod-fauna to the organic remains found at the sea- bottom, and the conclusions arrived at by different observers are so diverse, that a brief statement of the facts brought into prominence by these investigations, may not be without its use. On a question concerning which so little in the nature of positive evidence can be adduced, it is necessary to speak with great caution, and it is possible that even now we are not ina position to arrive at more than pro- visional inferences. My own observations have been directed, firstly, to the comparison of the general aspect of the fauna of the surface with that of the bottom ; and secondly, to the comparison of individuals of the several species found under the two conditions, in respect to their shell-structure and similar particulars. The list that has just been given includes all the species known to enjoy a pelagic existence, and of the forms enume- rated two or three of the rarest need not be taken into account. Hastigerina may be dismissed in a word; it is NOTES ON RETICULARIAN RHIZOPODA. 295 probably an exclusively pelagic type, and I have never met with a dredged specimen the shell of which was more than approximately complete. A comparison of Cymbalopora bulloides with two or three species of the same genus not having the large globular chamber would lead to the belief that it also may be of essentially pelagic habit. But it is with the genera Globigerina and its immediate allies, and Pwlvinulina, that we are chiefly concerned in the present inquiry. Of nine recent species, or well-marked varieties of Globigerina (proper), at least two-thirds occur in the surface gatherings ; indeed, though there are three or four forms that have not been satisfactorily traced, the only ones conspicuous by their absence are Gl. dubia, which represents the most finely developed modification of the “bulloides”? type, and Gil. digitata, the most divergent of all from the normal form in its structural features. The Orbuline Globigerine are represented by O. wniversa in thin-shelled condition, and the absence of the very rare O. negjurensis need not excite surprise. Amongst the Spherotdine, the thick-shelled Sph. dehiscens, with its coarsely tubulated walls, is not uncommon, whilst the thin-shelled Sph. bulloides has never been met with at the surface. One species of Pullenia (P. obliqueloculata) is found sparingly at the surface, whilst the two smaller forms, P. spheroides and P. quinqueloba, are only known from dredged specimens. Lastly, Puleinulina supplies at least five forms to the surface fauna, all of them pertaining to one section of the genus: of these, two are rare, P. crassa and P. Menardii, var. tumida, and of them the number of specimens found is insufficient for purposes of comparison or argument; the rest are very common. Other Pulvinuline, found in abundance in dredgings from great depths, have never been obtained by the towing-net. If the Globigerine obtained from the surface of the ocean are compared with specimens of the same species collected by the dredge, certain differences are at once apparent, the most conspicuous of which is the frequency of hirsute or spinous shells in the former, and their comparative absence from the latter source. This is so readily accounted for that it need not be dwelt upon. It has already been stated that nearly all the morphological varieties of Globigerina may be found at times covered with these long silky spines; and on the other hand, though the spinous condition is very frequent in pelagic shells, it is by no means invariable. Another point of some importance is the relatively smaller size of the surface specimens. This has been made the 295 HENRY B. BRADY. subject of careful investigation, the largest pelagic specimens of each species having been measured side by side with good average examples from bottom-dredgings. The result has been to demonstrate that, with the possible exception of the Orbuline, concerning which I shall have to speak presently, the largest of those collected at the surface are smaller than average adult bottom specimens. In all the species this difference in size is apparent, though in some more than others, but if drawings are made to the same scale the rule becomes strikingly manifest. It would be easy to give measurements in support of this point, but it seems better to wait until the matter can be fully discussed with the aid of plates. The thickness of the tests of some pelagic specimens has been the ground of remark, and viewed by themselves the largest examples of certain species are very stoutly built, but as a matter of actual measurement they will not bear com- parison with those found at the bottom. Thus, the stoutest specimen of Spheroidina dehiscens which I have been able to find amongst the surface gatherings has a test of about =, of an inch (0°05 millim.) in thickness, and the heaviest- shelled Gilobigerina conglobata so collected is not more than sia of an inch (0:032 millim.), whilst bottom specimens of either species, having shells =4, of an inch (0°085 millim.) in thickness, are not unusual. The case of Orbulina is somewhat different. The shells of surface specimens are nearly as large as those of average size from the bottom, but, whether spinous or not, they are invariably very thin and delicate. Bottom specimens are not only thicker, but vary very much amongst themselves in shell texture and other particulars. The most noteworthy structural condition found amongst the bottom specimens is one in which the shell consists of a number of distinct superimposed layers—sometimes four or five separate shelly envelopes—one enclosed within the other, yet without any absolute adhesion of their walls. In such cases the inner- most layer is usually very thin and perforated with large foramina, the outer ones coarser and thicker. Nothing resembling the thick-shelled Orbuline, still less those with multiple tests, has, so far as I know, been noticed amongst the surface organisms. There is another fact connected with the subject which has a certain amount of weight, namely, that though the towing-net has been largely used in the British seas and in areas at which Globigerine are found to a greater or less extent at the bottom, no single specimen has been met with NOTES ON RETICULARIAN RHIZOPODA. 297 amongst the Entomostraca and other pelagic microzoa that have been captured. At best the evidence afforded by comparative observations is collateral rather than direct, and the only positive testimony that could be adduced would be such as the sea- bottom itself could alone furnish, and of a sort not easily procured. Material brought up in large quantities by heavy dredges and trawls is manifestly valueless for the purpose. Under any circumstances living microzoa would not be found except in the superficial film of the ocean-floor, and even there they would be largely mixed with dead and empty shells; it would therefore be simple waste of time to decalcify Globigerina-ooze obtained in the ordinary way with the idea of finding the protoplasmic bodies of the constituent shells. Indeed, it would be almost as reasonable to expect to find sarcode animals in a fossil deposit as in material possibly representing a layer several inches in thickness of the sea-bottom. The old methods of taking soundings, either with the lead and tallow or with some of the smaller appliances that succeeded it, though of com- paratively little utility for the general purposes of zoological investigation, were perhaps better adapted for securing a knowledge of the superficial layer; and it is even possible that some of the discrepancies in the results obtained by different observers may be explained through the different methods by which their material has been collected. But, in addition to dredge and trawl, another appliance was used from time to time by the “Challenger” naturalists in bottom-collecting. This was a towing-net attached to the trawl, intended to receive the organisms thrown up by the rough disturbance of the superficial layer of the bottom-mud. It was without any great expectation of positive results that I determined to experiment on some of the material obtained by its means, inasmuch as shells more or less filled with sarcode might not be those longest held in suspension, though the difference in specific gravity between sarcode and sea-water cannot be very great. But the result has been satisfactory as far as it goes, and in one case the sarcode bodies of six or eight per cent. of the shells operated upon were left after treatment with acid. Amongst these were easily recognised specimens of Globigerina, Pulvinulina Menardi and Spheroidina dehiscens. The sarcode was yellowish-brown and granular, precisely resembling that of in-shore Rhizopoda that have been kept some time in alcohol before being decalcified. ~The soft, jelly-like lobes of Spheroidina retained the form of the pseudopodial tubulation 298 HENRY B, BRADY, of the shell as minute, cylindrical projections from the surface.1 Without departing from an attitude of caution in accepting evidence upon a subject so beset witb difficulty, I will endeavour in a few words to summarise the facts bearing upon it, chiefly on those concerning the two genera Globigerina and Pulvinulina. 1. We have positive evidence that Foraminifera do live at the bottom of the deep sea, from the common occurrence at great depths of certain forms with composite or arenacous tests; and we have negative evidence in the same direction in the entire absence from the surface fauna of many hyaline genera, which are abundant in bottom dredgings. 2. Both in Pulvinulina and Globigerina (but notably in Pulvinulina) species closely allied to the surface forms are common in the bottom ooze, though they never occur at the surface ; amongst others, Globsgerina dubia and Gi. digitata, Pulvinulina elegans, P. Karsteni, P. pauperata,and P. favus. Hence there is no d prior’ improbability that the other members of the same genera are capable of supporting life at the bottom. 3. A comparison of specimens of the same species, taken at the surface and at the bottom, demonstrates at least that the average size of the former is less than of the latter, and that the thickness of the shell-wall of the largest surface specimens bears no comparison with that of adult bottom specimens, 4. Nothing comparable to the thick-shelled Ordulna, still less to those with tests composed of several layers, is to be met with in the surface fauna. 5. No surface Globigerine have hitherto been obtained by means of the towing net from points on our own shores at which they are found at the bottom. 6. A fact adduced by Dr. Wallich, of some weight, as I think, namely, that Globigerina shells are found in the 1 T find a note of Dr. Wallich’s, in a lecture delivered before the Royal Institution, in 1861, the substance of which appeared, I believe, in one of his earlier papers, which is quite in accordance with these results. Speak- ing of a particularly pure Glodigerina deposit he says :—“ The specimens from the immediate surface stratum of the sea-bed alone retained their normal appearances, both as regards the perfect state of the sarcodic contents of the shells and the presence of the pseudopodia. ‘The latter - organs were never seen by me in an extended position, but in the specimens alluded to, and in those only, the pseudopodia occurred as minute bosses, resembling in shape the rounded rivet heads on boilers, closely adpressed to the external surface of the shell.” NOTES ON RETICULARIAN RHIZOPODA, 299 digestive cavities of Ophiocome living at the bottom at great depths. 7. The testimony of many experienced observers (Ehren- berg, Parker and Jones, Wallich, and others) that the Globigerine in the small soundings which they had for examination contained the sarcode bodies, the colour and nature of which each has described, with which statement my own results from the material taken in the ‘“‘ tow-net attached to trawl” generally agree. It may be that some of these arguments bear an explana- tion other than that which appears the most natural one. The only facts that I know of, per contra, are— 1. The dredged or trawled material consists of nothing but dead or empty shells. 2. Dredged specimens from great depths have never been observed to extend their pseudopodia. The first of these propositions, as I have already shown, scarcely, in reality, affects the question. In respect to the second, it is to be observed that the same holds good of the arenaceous Rhizopoda, which we know live at the bottom. Neither will any one who has had much experience in hand- ling shallow-water Foraminifera, and knows the difficulty there often is in inducing a common fotalia to extend its pseudopodia after being taken out of an aquarium and put into a watch glass, wonder much at the want of this particular evidence of life in specimens whose whole environment has been thus suddenly changed—released from enormous pressure and brought from darkness into strong light. In addition to itsemployment at the surface of the sea, the tow-net was used by the “ Challenger” naturalists suspended at different depths in the water, and pelagic Foraminifera were collected with other forms of animal life hundreds of fathoms below the surface. I confess, therefore, that I can see no anomaly in the supposition that organisms so simply constituted as this group of Protozoa may be equally at home at the surface and at the bottom of the ocean. 300 DR, A. MILNES MARSHALL, The Morruotocy of the VERTEBRATE OLFACTORY ORGAN. By A. Mitnes Marsuatt, M.A., D.Sc., Fellow of St. John’s College, Cambridge. (With Plates XIIJ and XIV.)! Or the two parts into which the present paper is divided, the first deals with the development of the olfactory nerve in certain selected types of vertebrates; the second with the development of the olfactory organ in the same types. Since the value and interest of anatomical and embryo- logical facts consist largely in their application to the solution of morphological problems, I have not hesitated to draw inferences freely from such facts as I have been able to bring to light, or to point out the conclusions to which these facts seem to me to lead. However, in order to separate facts from theories as sharply as possible, each part of the paper has been further subdivided, those portions which are con- cerned with matters of direct observation being considered before those which are of a more theoretical or speculative nature. I. The Development of the Olfactory Nerve. a. In the dogfish—For the opportunity of investigating the development of Elasmobranchs I am indebted to Mr. Balfour, who, on the completion of his monograph on Elasmobranch fishes, very kindly placed at my disposal the whole of his stock of uncut embryos. In addition to this I have had the great advantage of free access to the very complete series of preparations made by Mr. Balfour in the course of his investigations, and have availed myself of his permission to figure four specimens, illustrating stages of which I had not prepared satisfactory sections my self, The greater number of the embryos thus placed in my hands were those of the Sceyliwm canicula, some few of Pristiurus ; but inasmuch as the two genera have yielded identical results so far as the subject in hand is concerned, I have made no attempt to distinguish between them either in my descriptions or figures. Some few of the specimens were hardened in picric acid, and afterwards stained with hematoxylin ; but all my best sections were from embryos hardened and stained in a 3} per cent. solution of chromic acid, to which a few drops of a weak solution of osmic acid had neon added. 1 An abstract of this paper was read before the Royal Society on Feb- ruary 13th, ‘ Proc, Roy. Soc.,’ No. 198, 1879. MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 3801] With regard to the earliest stages in the development of the olfactory nerve, I have, unfortunately, been unable to make any satisfactory observations, for all the specimens younger than Balfour’s stage K werein bad condition. The chief points I wished, if possible, to determine were—firstly, whether the neural ridge extends to the anterior end of the fore brain in Elasmobranchs, as I have already shown it to do in the chick ;! secondly, whether the olfactory nerve is de- - veloped from this ridge; and, lastly, the exact date of appearance of the olfactory nerve. On all these points I have, owing to the unsatisfactory condition of my specimens, failed to obtain reliable evidence. . Plate XIV, fig. 19, represents a section through the head of a dogfish embryo at stage m of Balfour’s nomen- clature; the section is made ina plane transverse to the longitudinal axis of the head, and passes through the fore _brain (f.6.), the olfactory sacs (o/f.), and the olfactory nerves (I). This figure, which is taken from one of an excellent series of preparations in perfect histological preservation, illustrates several features of considerable interest—(1.) In the first place it will be noticed that the fore brain presents no trace whatever of a division into cerebral hemispheres ; in other words, that the olfactory nerves come into existence before the cerebral hemispheres, and are therefore con- nected at first with the forebrain, and not with the hemi- spheres. As confirmation of this point, I may repeat that fig. 19 is taken from an embryo at stage mM, while Balfour has already shown, and my own observations are in complete accordance with his on this point, that until stage o there is no trace whatever of a division of the forebrain into cerebral hemispheres.? (2.) There is no trace of an olfactory lobe or vesicle. This is a point of considerable importance, and one on which I desire to lay stress. The figure shows that at stage m the olfactory nerves are solid, and present no trace of a central lobe or vesicle, either at their roots or at any part of their length. (3.) The olfactory nerve at stage m agrees closely in its general relations and in its histological characters with the other cranial nerves, either at the same or at slightly younger stages. Like these, it arises from the upper part of the : rege Journal of Microscopical Science,’ January, 1878, pp. 13—16. * ‘Elasmobranch Fishes,’ p. 178. 3802 DR. A, MILNES MARSHALL. sides of the brain, and takes a course downwards and outwards, at right angles to the longitudinal axis of the head. Histologically it consists of roundish or oval nu- cleated cells, with, as yet, very few nerve fibres, agreeing completely with corresponding stages of development of the other cranial nerves. Fig. 20 is taken from a section through the same region as fig. 19, but from a dogfish embryo at the commencement of stage 0. The magnifying power employed is the same in the two drawings, so that an exact comparison can be made between them. There is still no indication of a division into cerebral hemispheres ; the forebrain, as in fig. 19, is still undivided. Though the embryo has grown con- siderably the olfactory nerve (1), though somewhat thicker, is no longer in fig. 20 than in fig. 19, a fact of some interest ; its point of attachment to the brain has, however, shifted down somewhat towards the ventral side. The most im- portant fact shown by fig. 20 is, however, the existence of the earliest rudiment of an olfactory lobe (o/. v.). This, as may be seen from the figure, is exceedingly small, and might indeed be easily overlooked; it is a small shallow pit, formed almost entirely at the expense of the inner wall of the forebrain, and situated opposite the root of origin of the olfactory nerve. In fig. 21, taken from one of Mr. Balfour’s specimens, the same parts are shown at a stage intermediate between stages oand p. The olfactory vesicle (o/. v.) is seen to have grown very rapidly, and is now a conspicuous object. The olfactory nerve (1), on the other hand, has remained almost stationary as far as size is concerned; it has, however, undergone con- siderable histological change; the cells composing its proxi- mal part or root of origin are more elongated and fusiform than before, while beyond this part the nerve presents a ganglionic expansion consisting mainly of roundish cells, similar to those which previously constituted the whole nerve, and which gives off, distally, bundles of nerve fibres distributed to the, Schneiderian folds of the olfactory mucous membrane. The condition of the olfactory nerve and lobe at stage @ is shown in fig. 22, also taken from one of the specimens lent me by Mr. Balfour, who has described this stage as follows :—‘ The lateral ventricles are now separated by a median partition, and a slight external constriction marks the lobes of the two hemispheres ; these, however, are still united by nervous structures for the greater part of their extent. The olfactory lobes are formed of a distinct bulb and stalk, MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 803 and contain, as before, prolongations of the lateral ven- tricles,’”! It will be noticed that, while in fig. 21 the olfactory lobe projects out at right angles to the brain, and the olfactory nerve arises from its extreme tip, in fig. 22 the olfactory lobe is bent downwards, so as to lie against the side of the cerebral hemisphere, and the olfactory nerve no longer arises from its apex, but slightly from its dorsal surface. From the condition here represented to that of the adult the changes are unimportant. The earlier stages of the olfactory nerve I have not been able to work out satisfactorily, for reasons already mentioned. In fig. 15 the nerve is represented in longitudinal and ver- tical section at stage mM. It is easily recognisable at stage Lt, and I have also succeeded in satisfying myself of its existence as far back as stage K. Fig. 14 represents a transverse section through the ante- rior part of the head of an embryo at the commencement of stage K; the section passes through the forebrain, and through both olfactory pits; on the right side a small mass of cells (1) in contact with the bottom of the pit is stained rather more deeply than the surrounding mesoblast cells. From comparison with the condition of what is undoubtedly the olfactory nerve at slightly later stages, I consider it very probable that these cells form part of the olfactory nerve, but cannot, of course, speak with any certainty on this point. Apart from the insufficient material at my disposal, the inhe- rent difficulties of the investigation are very great, for at these early stages the olfactory nerve consists entirely of cells, which differ but little from the surrounding mesoblast cells ; the nerve is also exceedingly short, owing to the close proxi- mity of the olfactory pit to the brain, while a new difficulty is introduced by cranial flexure, which is increasing rapidly about this time, and so causes a constant shifting in the relations of the surrounding parts to one another. My investigations, then, lead me to give the following account of the development of the olfactory nerve in Elasmo- branchs. The nerve arises at some period earlier than stage K 3; it is at first connected with the upper part of the side of the forebrain; between stages 1~ and 0 its root shifts downwards to a certain extent towards the ventral surface ; the nerve itself is, from the earliest period at which it can be recognised, solid ; the earliest trace of an olfactory lobe ap- pears at the commencement of stage o as a shallow depres- sion of the inner wall of the forebrain opposite the root of 1 Op. cit., p. 179. 304 DR. A, MILNES MARSHALL. the olfactory nerve ; this olfactory lobe grows very rapidly, and soon attains a large size, while the olfactory nerve re- mains almost stationary; the nerve is at first connected with the apex of the olfactory lobe, but subsequently mounts somewhat on to its dorsal surface ; finally, the olfactory nerve, throughout its development, agrees closely in histological characters and in the changes which it undergoes with the other cranial nerves. Balfour has given a somewhat different account of the development of the olfactory nerve. After noticing that the olfactory lobes first arise during the stage 0, he says :— “‘From the peripheral end of each olfactory lobe a nerve, similar in its histological constitution to any other cranial nerve, makes its appearance; this divides into a number of branches, one of which passes into the connective tissue between the two layers of epithelium in each Schneiderian fold. On the root of this nerve there is a large development of ganglionic cells. I have not definitely observed its origin, but have no reason to doubt that it is a direct outgrowth from the olfactory lobe, exactly similar 7” its mode of deve- lopment to any other nerve of the body.’ A little further on he remarks: “ Even the few preparations of which I have given figures appear to me to provethat . . . from the (olfactory) bulb a nerve grows out which has a centrifugal growth like other nerves of the body, and places the central olfactory lobe in communication with the peripheral olfactory sack.’ The differences between this account and my own are suffi- ciently obvious. According to Balfour, the olfactory lobe exists before the olfactory nerve, and the nerve is a “ direct outgrowth from the olfactory lobe.’ A minor point of difference is that, according to Balfour, the connection be- tween the olfactory nerve and the olfactory pit 1s not acquired till towards the end of stage 0. I believe, however, that these differences are due to Balfour having overlooked the exist- ence of the olfactory nerve during its early stages. The first stage at which he has described the olfactory nerve is — that which I have represented in fig. 21,° while the specimens I have figured (figs. 19 and 20) appear to me to prove indis- putably the existence of the olfactory nerve at a much earlier period, and the connection between the olfactory nerve 1 Op. cit., p. 178. 2 Op. cit., p. 183. 3 The section from which this figure is drawn is one of the same series, if not the identical specimen, as that described by Balfour, and figured by him in Pl. XV, fig. 2. MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 305 and olfactory pit appears to be acquired at least as early as Stage K. b. In the chick.—1 propose to consider the chick next, partly because, having devoted more time to the embryology of the chick than of other vertebrates, I have a better and more complete series of preparations to refer to, and partly because I wish to direct particular attention to the very close correspondence that exists between the chick and the dog- fish in the mode of development of the olfactory nerve. Concerning the early stages of the olfactory nerve in the chick J have little or nothing to add to the account I have already given in this Journal.! The result of a careful re-examination of my former preparations, and the investiga- tion of a considerable number of new specimens prepared since my former paper was published, has been to confirm my previous description on all points. Though I have again failed to trace satisfactorily the changes that occur between the thirtieth and fiftieth hours my further work has shown no reason for altering the view I have previously expressed, that the olfactory nerve is developed, like all the other cranial nerves (except the optic, the sixth, and (?) the fourth nerve), from the neural crest®. However, whether this be so or not is of comparatively little importance to the subject with which we are now concerned. Plate XIII, fig. 10, represents part of a transverse section through the fore part of the head of a duck embryo towards the end of the fourth day. This figure, which is repeated with slight alterations from a former paper,® happens to show the points to which I wish to call attention rather better than any of my chick preparations, the specimen from which 1 * Quarterly Journal of Microscopical Science,’ January 1878, pp. 17—23. To avoid repetition, I beg to refer the reader to the detailed account of the early stages contained in this paper. 2 I take this opportunity to make a slight alteration in the nomencla- ture adopted in my former paper. I have there suggested the term neural ridge for the longitudinal ridge of cells which grows out from the re- entering angle between the external epiblast and the neural canal, and from which the nerves, whether cranial or spinal, arise. Since this ridge appears before closure of the neural canal is effected, there are manifestly ¢z0 neural ridges, one on either side; but I have also applied the same term, neural ridge, to the single outgrowth formed by the fusion of the neural ridges of the two sides after complete closure of the neural canal is effected, and after the external epiblast has become completely separated from the neural canal. I propose in future to speak of this single median outgrowth as the newral cresf, limiting the term zewral ridge to the former acceptation. Thus, while there are two neural ridges, there is only one neural crest, a distinction that will be at once evident on reference to my former figures. * ¢ Journal of Anatomy and Physiology,’ vol. xi, plate xxi, fig. 13. 306 DR, A. MILNES MARSHALL, it was taken being in unusually good preservation. The section passes through the forebrain (f.d.), the olfactory pit (oif.), and the olfactory nerve (1). From it we learn (1) that the olfactory nerves exist prior to the cerebral hemi- spheres, of which latter there is in this specimen no trace whatever ; (2) that in this stage there is no indication what- ever of an olfactory lobe; (3) that the olfactory nerve is in its early stages connected with the upper or dorsal part of the side of the forebrain ;} (4) that the connection between the olfactory nerve and olfactory pit is very early acquired ; (5) that the olfactory nerve at this stage agrees closely in histological characters with the corresponding stages of the other cranial nerves, consisting almost entirely of roundish or oval nucleated cells with few or no nerve fibres. This figure may be advantageously compared with fig. 19, which represents, as already described, a section through the same region in a dogfish embryo at stage mM. The resem- blance between these two figures is indeed very striking, and extends even to the minute histological details. I would lay great stress on this resemblance, and submit that this close correspondence, amounting almost to identity, in the condition of the olfactory nerve at similar stages in two vertebrates so widely separated as the chick and the dogfish, © affords very strong evidence in favour of the correctness of my observations. Such differences as do exist are of very minor importance. Apart from the slight difference in general configuration, the most significant are the rather larger relative size of the olfactory nerve and pit in the dogfish, obviously correlated with their condition in the adult, and the fact that in the duck the attachment of the olfactory nerve is rather nearer to the summit of the forebrain than in the corresponding stage of the dogfish. The appearance of the cerebral hemispheres towards the close of the third day in the chick causes considerable altera- tion in the position and relations of the olfactory nerves. The hemispheres are lateral outgrowths of the forebrain, and are from the first situated on the dorsal side of the roots of the olfactory nerves. They grow forwards and upwards with exceeding rapidity, and by so doing drive the olfactory nerves down to the base of the brain, and so cause these nerves to appear to arise from their under and anterior part ; a change 1 Though the nerve is in close contact with the brain, the actual connec- tion between the two is not seen in the specimen figured ; it is clearly visible in one of the sections of the same series immediately adjacent, which, how- ever, does not show the whole length of the nerve, and is, therefore, less suitable for figuring. MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 307 which has proved a fruitful source of misconception as to the true nature and relations of the olfactory nerves, especially as these latter are usually not recognised wntil they have taken up this secondary position. The change to which I have just referred is well illus- trated by fig. 11, a transverse section through the anterior part of the head of a chick embryo at the ‘eightieth hour. The section shows the commencing cerebral hemispheres (c. h.) growing upwards and outwards from the forebrain ; it also passes through the margins of the two olfactory pits (olf.), and on the ‘left side through the root of the olfactory nerve (1) at its point of origin from the brain ; the figure shows very clearly the effect of the appearance of the cerebral hemispheres on the position of the olfactory nerves, and shows further how the secondary connection of these nerves with the hemispheres is acquired. Fig. 12 represents a section from the same series as fig. 11, but taken a little further back, passing through the olfactory pits (o/f.) at their deepest parts. On the right side the section passes through the distal portion of the olfactory nerve (1), which is seen to be in continuity with the bottom of the olfactory pit. In figs. lland 12 the olfactory nerve has the same histo- logical character as in fig 10; it is, however, relatively, if not indeed absolutely, smaller than at the earlier period. The figures further show clearly that there is as yet no trace whatever of an olfactory lobe. I have elsewhere! given figures and description of the con- dition of the olfactory nerves at the ninety-third hour in the chick, at which date, excepting a general increase in size, their condition differs bnt little from that at the eightieth hour. Figs. 7 and 8 represent longitudinal and vertical sections through the anterior part of the head of a chick embryo to- wards the end of the sixth day of incubation. As the olfac- tory nerve did not lie exactly in the plane of section it has been necessary to figure two sections, of which the more superficial one (fig. 7) shows the greater part of the length and the peripheral distribution of the olfactory nerve ; while the second section (fig. 8), taken at a slightly deeper level, shows the root of origin of the nerve from the brain. The olfactory nerve, which is still short, presents a proximal gan- glionic swelling at its point of origin from the hemisphere, seen best in fig. 8; along the greater part of its length the nerve consists of very elongated fusiform cells, with a few 1 Loe. cit., p. 20, and Plate II, figs. 17—19. 308 DR. A. MILNES MARSHALL. spherical ganglionic cells at intervals; distally, at its connec- tion with the olfactory pit, it presents a second ganglionic swelling, fig. 7. A point of very considerable interest, shown in the clearest possible manner by these figures, is that up to this date there is no indication of an olfactory lobe; indeed, instead of a hollow process of the hemisphere at the point of origin of the olfactory nerve, there is at this point, as is shown by both figures, but especially by fig. 8, a slight external de- pression, with a very obvious internal projection of the wall of the hemisphere. Fig. 9 represents a similar section, in a longitudinal and vertical plane, through the nasal region of a chick at the end of the seventh day; passing through the cerebral hemi- sphere (c. /.), the eye (0. ¢.), the anterior extremity of the oph- thalmic branch of the fifth nerve (v. a.), the olfactory pit (o/f), and the olfactory nerve (1). The nerve itself presents the same histological characters as in fig. 7,7. e.'a proximal gan- glionic enlargement at its root of origin, a trunk consisting mainly of nerve fibres, but with a few ganglionic cells at inter- vals along its whole length, and a distal ganglionic expansion at its point of fusion with the olfactory epithelium. There is, however, one important difference between this figure and the two preceding ones; opposite the point of origin of the olfactory nerve there is a small conical depression (o/. v.) of the inner wall of the cerebral hemisphere. From a comparison with fig. 20 there can be little doubt that this is the earliest appearance of an olfactory lobe. As in the dogfish, this lobe is formed at first entirely at the expense of the inner wall of the hemisphere, there being as yet no perceptible projection cn the exterior of the brain. The olfactory lobes, after their first appearance, grow ra- pidly. By the twelfth day they form a pair of small conical processes, about 1 millimétre in length, springing from the extreme anterior ends of the cerebral hemispheres: the two lobes lie side by side, their apposed surfaces being slightly flattened. Each lobe contains a prolongation of the ventri- cular cavity of the corresponding hemisphere. Fig. 36 represents a longitudinal and vertical section through the olfactory lobe and the anterior part of the cere- bral hemisphere of a twelfth day chick embryo: it shows how the ventricle of the hemisphere (c./.) is prolonged to the extremity of the olfactory lobe (o/.v.) ; and also the mode in which the olfactory nerve arises from the end of the olfactory lobe as a series of bundles of nerve fibres. Fig. 37 is a transverse section through the olfactory nerve MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 309 of a chick embryo of the same age as fig. 36; it shows the bundles of nerve fibres, bound together by connective tissue, which together constitute the olfactory nerve; it shows also how the majority of these bundles are arranged in a circle round the margin of the nerve, while a few smaller bundles lie in the centre. Figs. 38 and 39 represent sections taken from the same embryo as the preceding figure. Fig. 38 is a transverse section through the olfactory lobe, and shows the laterally compressed ventricular cavity. Fig. 39 is a transverse section through the anterior part of the hemisphere: the outer wall of the hemisphere is seen to have increased greatly in thickness while the inner wall still remains thin; so that the ventricle, which is greatly compressed laterally, no longer occupies the centre of the hemisphere, but lies close to its inner side. In the adult fowl the olfactory lobe has much the same appearance as at the twelfth day: it is about two and a half millimétres in length, and still contains a central cavity, though this latter is relatively smaller than at the earlier date ; the relations of the olfactory nerve to the lobe are the same as at the twelfth day. ‘In my former paper I stated that there ts no trace of an olfactory vesicle at any period in the life of a chick.| This statement my later work now shows to be erroneous; the chick has an olfactory vesicle, but, as in the dogfish, this vesicle does not appear till an exceedingly late period of development. The principal points then, in the development of the olfactory nerves in the chick to which I desire to direct attention are : 1. The olfactory nerves arise from the forebrain, before the cerebral hemispheres have begun to be developed. 2. They are at first connected with the dorsal surface of the forebrain, but on the appearance of the hemispheres become driven down to the ventral surface of the brain, and acquire a secondary connection with these latter. 3. From their earliest appearance the olfactory nerves are solid, and present the same histological characters as the other cranial nerves. 4. There is not the slightest indication of an olfactory lobe till the latter part of the seventh day of incubation. Though these conclusions are in complete accordance with my earlier work, they are directly opposed to all other accounts with which I am acquainted, with one solitary exception, to which I shall refer immediately. As the date 1 Loe. cit., p. 20. VOL, XIX.—-NEW SER, Xx 310 DR A. MILNES MARSHALL. of appearance of the olfactory lobe is the point in which there is the greatest discrepancy between the descriptions. of previous writers and my own, I have made sections in very various planes in order to detect any appearance that could possibly be interpreted as an olfactory lobe at an earlier date than the seventh day, but have failed completely to observe any such. As far as I can ascertain, the earliest account of the deve-. lopment of the olfactory nerve is that given by Remak ; this description, which only occupies about three lines, and is unsup- ported by figures, is as follows :—‘* An ihrem Boden (Hemis- pbaren) zeigen sich gegen das Ende des dritten Tages jederseits kleine birnférmige Blaschen (Geruchsblaschen) tiber deren weiter entwickelung ich keine Beobachtungen besitze.”? This observation was repeated later on by von Baer, who, however, went further than Remak, and described this vesicle as the rudiment of the olfactory nerve ; he also described an olfactory pit distinct from this vesicle. Concerning these statements Remak speaks thus :—‘ Halte ich diese Angaben mit meinen eigenen Wahrnehmungen zusammen, so wird es mir sehr wahrscheinlich, dass Baer am vierten Tage die Geruchs- blaschen und die Nasengruben nicht gleichzeitig beobachtet, dass er vielmehr dasselbe Gebilde bald als Anlage des Riechnerven, bald als Nasengrube gedeutet hat. Ich habe mich namlich tberzeugt, dass die Geruchsblaschen, die zu Ende des dritten Tages auftreten, die nasengruben sind, und dass weder alsdann, noch bis zum finften Tagen ein eutspre- chender Auswuchs des vorderhirnes wahrzunehmen ist.’ This very definite statement shows with perfect clearness not only that Remak recognised and corrected his original mistake, recognised, ¢.e. that what he had originally taken for outgrowths of the cerebral hemispheres were really the olfactory pits, a mistake doubtless due to his relying on surface view of whole embryos; but also that he discovered and recorded the fact that as late as the end of the fifth day there is no trace of an olfactory lobe. Strange as it may seem, this exceedingly definite and accurate statement of Remak’s has been completely over- looked, while his earlier, vague, brief, and avowedly imper- fect observatiou actually furnishes the basis of the descrip- tions of the development of the olfactory nerve given in our text-books of embryology at the present day. Thus, Professor Kolliker, in the second part of his text- 1 «Untersuchungen tber die Entwickelung der Wirbelthiere.’ Berlin, 1855, p. 33. 2 Loc. cit., p. 74, note 55. MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN, 31] book of embryology, published in the course of the present year, dismisses my previous account of the development of the olfactory nerve as ‘ eine Angabe, die mit der Darstellung von Remak, der zufolge die Lodz olfactorw des -~Hiihnchens am Ende des zz. Tages als kleine birnformige Blaschen am Boden der Hemisphirenblasen liegen, nicht zu vereinen ist.”! Professor Kolliker’s words show, beyond doubt, that he is quoting from Remak’s earlier statement ; had he been acquainted with the latter part of Remak’s work he would have known that my observations confirmed instead of con- tradicting Remak. Again, Foster and Balfour describe the development of the olfactory nerve in the chick thus:—‘ At the under surface of each of the vesicles of the cerebral hemispheres there appears towards the end of the third day a small, some- what elongated vesicle—the olfactory vesicle—which is the rudiment of the olfactory nerve or bulb.”* The authors make this statement on their own authority, but since the first part of their description is an almost literal translation of Remak’s earlier account, it is, I think, a fair inference that they have fallen into the same error as Professor Kolliker. Remak, however, is not responsible for the statement that this olfactory vesicle is *‘ the rudiment of the olfactory nerve or bulb.” Any further discussion of the literature of this subject would be unprofitable ; it is, however, only fair to add that at the time of writing my previous paper I had not referred to Remak’s work, and was under the impression that my description was completely at variance with his account; it is, therefore, a matter of great satisfaction to myself to find my statements corroborated by such high authority. - ¢. In the salmon and trout.—Though my observations on Teleostean embryos are not nearly so complete as those I have just recorded concerning the chick and dogfish, yet, inasmuch as they have yielded definite, and in some respects important and unexpected results, I have thought it well to record them here. The ova were obtained in the early part of last year from Mr. Capel, of the Foot’s Cray Fishery ; for the opportunity of hatching them I am indebted to Mr. F. Buckland, to whom my best thanks are due for the liberal and courteous manner in which he met my requests. I am also much * Kolliker, ‘ Entwickelungsgeschichte des Menschen und der hdberen Thiere ;* Zweite Auflage. Zweite Halfte, 1879, p. 609. * «Elements of Embryology.’ Part 1, 1874, p. 117. 312 DR. A. MILNES MARSHALL. indebted to Mr. Edon, of the South Kensington Museum of Pisciculture, to whose care and experience I owe the success- ful hatching of the ova. The early stages of development of the olfactory nerve are unfortunately even more difficult to investigate in Teleosteans than in either the chick or dogfish; and my observations on these stages are exceedingly imperfect. The earliest stage at which I can speak with any confidence as to the existence of an olfactory nerve is shown in fig. 29, which represents a transverse section through the anterior part of the head of a trout embryo on the twenty-seventh day after the fertiliza- tion of the ova. The section passes through the forebrain (f.6.), and through the olfactory pits (o/f) ; on the left side of the section a small mass of cells, somewhat more com- pactly arranged and more deeply stained than the mesoblast cells, connects the upper part of the forebrain with the olfactory pit. This mass of cells (1) I believe to be the olfactory nerve, mainly from its relation to what is un- doubtedly the olfactory nerve a few days later. I do not wish, however, to speak at all positively on this point. Between the thirtieth and fortieth days the olfactory nerves, though still extremely short, can be easily recognised. Though my observations are far from complete, they suffice to establish the following points for both the salmon and trout: 1. The olfactory nerves appear before the cerebral hemi- spheres, and are at first connected with the dorsal side of the forebrain. 2. The nerves are, from the earliest period at which their existence can be determined with anything like certainty, solid ; z.e. there is no olfactory lobe. 3. The connection between the olfactory nerve and the epithelium of the olfactory pit is acquired at a very early date. Plate XIV, fig. 33, is taken from a transverse section through the head of a salmon embryo two days after hatching. The section, which is a little oblique, passes on the left side through the eye (0. ¢.) with the superior (7. s.) and inferior (7. 2.) recti muscles ; on the right side through the olfactory pit (o/f.) The forebrain (/. b.) ), which hes in the centre of the section, is seen to have a small vesicular cavity in its upper part; its roof is thin, its floor and sides very thick. From the lower part of its sides a pair of nerves (1) arises ; these nerves run downwards for a short distance towards the ventral surface, then turn directly outwards, and the nerve on the right side is seen to divide into two branches, which can be readily traced to the thickened MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 3139 epithelium lining the bottom of the olfactory pit (o/f.). It will be noticed that there is no trace of an olfactory lobe, and that the olfactory nerve presents no ganglionic enlargement at any part of its course. In its general relations, mode of origin, and course, the nerve agrees remarkably closely with the ona cranial nerves, while in histological characters it is identical with them. In fig. 34 the olfactory nerve (1) is seen in longitudinal and vertical section in a salmon embryo of the same age as that just described. This section shows well the relations of the olfactory nerve to the brain; it also shows the roots of the optic nerves (11), the infundibulum (zf.), and the trabecule crani (tr.). It would seem, therefore, that if an olfactory lobe is present at any period in the life of a salmon or trout, it does not make its appearance till very late—so late, indeed, that it could have no claim to be considered as an embryonic structure at all: there is no trace of it at the time of hatching, or, indeed for some days afterwards. d. In other vertebrates.—In the Axolotl! the olfactory nerve is at first connected with the forebrain, not with the hemispheres. Throughout the whole period of embryonic development it is very short, and in the early stages ex- ceedingly so: it is solid, and agrees completely in histologieal characters with the other cranial nerves. I have failed to detect an olfactory lobe in any of the stages I have examined ; v.e€. up to the time of hatching. L have also made some observations on the earlier stages of development of the olfactory nerves in the frog, which show that in these stages the nerves are extremely short, and that there is no trace of an olfactory lobe. The resemblance between the frog and axolotl is, as might be expected, exceedingly close. In some lizard embryos, for which I am indebted to Mr. Balfour, I have noticed the existence of solid olfactory nerves, with no indication of olfactory lobes, at stages apparently corresponding to the fourth or fifth day of incubation of the chick; and I believe I have succeeded in establishing the existence of olfactory nerves at still earlier stages, before the appearance of the cerebral hemispheres. In the later stages the olfactory lobes are more prominent objects than in the chick. I will, in conclusion, quote from Professor Parker the fol- ‘ For the opportunity of investigating the development of the Axolotl, I am again indebted to Mr. Edon, of the South Kensington Museum. 314 DR. A. MILNES MARSHALL. lowing description of the development of the olfactory nerve in the green turtle :—‘‘ In embryos of the green turtle of the size of a horse-bean I find the nerves (olfactory) solid. When the embryos are two or three times that size, these nerves each acquire a large cavity proximally, from the fore wall of which the branches seem to spring. ‘The foremost of these branches spring from the top of the vesicle ; they arose at first from the top of the forebrain.”? e. General considerations.—Before proceeding to the development of the olfactory organ, I propose to summarise the results to which we have already been led, and to consider briefly certain questions of a more theoretical character. The first point I desire to call attention to is the remark- ably close agreement in the mode of development of the olfactory nerves presented by the several types examined, types which, it will be noticed, embrace examples from each of the vertebrate classes, with the exception of Mammalia. In all these types alike—dogfish, trout and salmon, axolotl, frog, lizard, turtle and chick—the mode of development is fundamentally the same ; while the resemblance between the dogfish and the chick, the most generalised and the most specialised of these types is, as I have already shown, complete. I would direct special attention to this agreement as affording very strong testimony of the correctness of my observations. The fundamental points common to all the above types are the following :—1, the olfactory nerves appear very early ; 2, they are at first connected with the forebrain, and not with the cerebral hemispheres ; 3, they are solid, and agree completely in histological characters with the other cranial nerves ; 4, an olfactory lobe, when present at all, does not appear till an exceedingly late period of development. Though the several types agree so closely in the above fundamental points, they present well-marked differences among themselves. The dogfish appear to form a central type round which the others may be grouped, and from which they may be supposed to be derived. Curiously enough, of the other types the chick appears to resemble the dogfish _ more closely than any of the others do, with the possible exception of the lizard and turtle, whose earlier stages are as yet unknown. The Amphibia are chiefly characterised by the extreme and long persisting shortness of their olfactory 1 “On the Development of the Skull and its nerves in the Green Turtle (Chelone Midas).” ‘ Proc. Royal Society,’ 1879. MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 315 nerves, and are in no way intermediate between the dogfish and such Sauropsida as I have examined. Finally, the Teleosteans, if the salmon and trout may be taken as typical of that group, while they resemble the Amphibia in the extreme shortness of their olfactory nerves in the early stages of development, seem to differ somewhat from the other types in the exceedingly late appearance of the olfactory lobes, and in the striking resemblance in general anatomical behaviour between the olfactory and the other cranial nerves. The nomenclature of the olfactory nerve is, unfortunately, somewhat overburdened with synonyms, a_never-failing source of confusion and inaccuracy. The “ olfactory nerve” of an adult vertebrate is, perhaps, best described as con- sisting of three parts; a proximal ¢ractus olfactorius arising from the cerebral hemisphere, an intermediate ganglionic enlargement or dulbus olfactorius, from whose distal extremity the third part or nervus olfactorius arises.1_ Of these parts the two former are commonly and correctly described as being properly parts of the brain, and as togetner con- stituting the rhinencephalon. By some authors, however, the term rhinencephalon appears to be limited to the bulbus olfactorius, the tractus olfactorius being then snoken of as the rhinencephalic ecrus.2 By olfactory lobe or olfactory vesicle is usually meant the hollow diverticulum of the fore- brain or cerebral hemisphere in the embryo, from which both the tractus olfactorius and bulbus olfactorius of the adult are developed, and which has hitherto been erroneously sup- posed to be the earliest part of the “ olfactory nerve” to be developed. It would, perhaps, be well to limit the term olfactory lobe to this embryonic structure ; Owen employs it in the adult as synonymous with budbus olfactorius. From the descriptions I have already given it follows that the nervus olfactorius is the earliest of the three elements to be developed, and that it alone is the direct homologue of the other cranial nerves. The term olfactory nerve ought then to be strictly limited to the nervus olfactorius. Since, however, there is considerable inconvenience in disturbing established nomenclatures, it may perhaps be well to con- tinue to use the term olfactory nerve in the ordinary ana- tomical sense, and to confine oneself to the term nervus ' Vide Max Schultze. ‘ Untersuchungen tiber den Bau der Nasensch- Jeimhaut bei dem Menschen und Wirbelthiere.” Halle, 1862, pp. 18, 19; and Stannius, ‘Handbuch der Anatomie der Wirbelthiere,’? 2 Auflage, 1854, p. 165, seq. ? Owen, ‘ Anatomy of Vertebrates,’ vol i, p. 283, 1866. 316 DR, A. MILNES MARSHALL. olfactorius when wishing to speak of the third or distal ele- ment, the olfactory nerve proper; in this case, however, it must be clearly understood that olfactory nerve and nervus olfactorius are by no means equivalent or mutually con- vertible terms.! Though the dulbus olfactorius and tractus olfactorius are considered as together equivalent to the olfactory lobe of the embryo, it must “be noticed that the proximal ganglion of the nervus olfactorius may fuse so completely with the bulbus, that it is, even in comparatively early stages, “‘ rather diffi- cult to fix on the exact line of demarcation between the bulb and the nerve.’” The three elements of the olfactory nerve, but especially the first and third, vary much in the relative proportions they attain in the adult. Thus, in the dogfish there is a large bulbus olfactorius, connected proximally with the hemispheres by a short, thick, tractus olfactorius, and giving origin distally to the numerous filaments of the nervus olfactorius. In the skate, while the bulbus and nervus ‘ retain much the same proportions as in the dogfish, the tractus olfactorius is of very great length. Among osseous fishes the variations are still greater; in the pike, salmon, perch, gurnard, &c., on the one hand, there is a very long nervus olfactorius, springing from a bulbus olfactorius which is in close contact with the hemispheres; on the other hand, the cod, carp, &c., as in the skate, the bulbus olfactorias is situated near the olfactory organ, and is far removed from the rest of the brain, with which it is connected by a long tractus olfactorius. A question of far more mor orphological i interest is the relation of the olfactory nerve to the other cranial nerves. My ob- servations, if confirmed, prove that in the chick up to the end of the sixth day,in the dogfish up to stage o, and in the salmon and trout, at any rate up to the time of hatching, the olfactory nerve agrees very closely in histological characters and in general anatomical relations with the other cranial nerves. I propose now to consider these resemblances more in detail, and specially in reference to the question of the segmental value of the olfactory nerve. Certain of the cranial nerves—e. g. the facial and glosso- pharyngeal—have long been acknowledged to possess seg- mental value. If we consider the mode of development of these segmental cranial nerves, we find that they agree among themselves, and differ sharply from other nerves 1 Vide ‘Quain’s Anatomy,’ 8th edition, vol. i, p. 526. ? Balfour, op. cit., p. 178. P MORPHOLOGY OF THE VEKTEBRATE OLFACTORY ORGAN. 317 or branches of nerves in the following embryological characters : 1. They appear very early. 2. They arise, at least in the chick, from the neural crest on the mid-dorsal surface of the brain. 3. Shortly after their appearance their roots undergo a shifting downward of their points of attachment, so that they no longer arise from the dorsal surface, but from the sides of the brain. 4, They present, at least in their early stages, ganglionic enlargeménts on or close to their roots of origin. d. Their course is at right angles to the longitudinal axis of the head. ' 6. Finally, they have very definite relations to the seg- ments of the head, as indicated by the visceral clefts, each nerve supplying the two sides of a cleft. The true cranial segmental nerves, such as the facial and the glosso-pharyngeal, agree in presenting all these charac- ters. On the other hand, the non-segmental nerves, or branches of nerves, though they may possess some of the cha- racters above enumerated, yet never present all, and rarely more than one or two. ‘This test suffices to dispose of the claims to segmental rank of the optic, the auditory, the fourth, and sixth nerves, and of the ophthalmic branch of the trigeminal nerve ; while, on the other hand, it serves to demonstrate the segmental value of the third nerve. I propose now to apply this test to the olfactory nerve. 1. In all the types examined the olfactory nerve appears very early. Though the exact date of its first appearance has not been determined with certainty in any case, yet there is no reason for thinking that it arises later than the other cranial nerves. In all the types considered it appears before the cerebral hemispheres.’ In the dogfish it makes its appear- ance earlier than stage K, and in the chick there are strong reasons for thinking that it is “one of the first nerves in the body to appear.’”? 2. Ihave already attempted elsewhere to prove that in the chick the olfactory nerve is developed from the neural crest.* 1 Though I have but little doubt on the matter myself, I have not yet succeeded in determining this point with absolute certainty in the case of the lizard. ? “Quarterly Journal Microscopical Science,’ Jan., 1878, p. 23. 3 Loe. cit., pp. 17—19. With reference to the extension forward of the neural crest in the chick to the forebrain, Prof. Kdélliker suggests (op. cit., pp. 661—2), that I have been misled by certain folds which appear during closure of the medullary canal, and to which His has already directed attention, With all due respect for Prof, Kélliker’s authority, I cannot 318 DR. A, MILNES MARSHALL, I have nothing to add to the arguments already given, though I am fully aware that the point is not yet proved. In the Elasmobranehs, the only other vertebrates in which the presence of a neural crest has been accurately described,* the anterior limits of this crest have not been fixed with certainty. 3. The shifting down of their roots of origin, one of the most striking features of the segmental nerves, is a very constant and well-marked point in the development of the olfactory nerves. It is well shown for birds in figs. 10 and 11, and for the dogfish in figs. 19 and 20. In the dogfish the displacement of the roots is less extensive than in the ehick—a point obviously correlated with the greater develop- ment of the cerebral hemispheres in the latter. 4. The course of the segmental nerves in their early stages is, speaking within certain hmits, at right angles to the longitudinal axis of the head at their point of origin. The facial and the postauditory nerves arise from a part of the head in which this axis is a straight line ; the nerves conse- quently run parallel to one another, as is seen in figs. 4 and 6. In front of the origin of the facial nerve the axis of the head is, owing to cranial flexure, no longer a straight line, but a curved one. The trigeminal nerve is disturbed only to a very slight extent, but it will be seen in fig. 4 that instead of running parallel to the facial, the two nerves con- verge slightly towards their distal ends. In the region of the midbrain the effects of cranial flexure are very well marked ; but fig. 6 shows that the course of the third nerve, the segmental nerve arising from the midbrain, is still at right angles to the longitudinal axis at its point of origin. Since the direction of the axis at this point is almost at right angles to its original direction, so also the third nerve is seen to take acourse almost at right angles to the facial or glosso-pharyngeal. Similarly, the course of the olfactory nerve is at right angles to the longitudinal axis of the head at its point of origin; and its direction is such that if cranial flexure were corrected and the head straightened out the olfactory nerve would run parallel to the third, trigemi- accept this explanation. My specimens leave no room for doubt that whatever may be its morphologieal importance, the neural erest is a per- fectly continuous structure, extending in the chick at the twenty-ninth hour from the anterior end of the optic vesicles nearly to the end of the hindbram. I am acquainted with folds such as Prof. Kélliker deseribes, but have only met with them in imperfectly-prepared specimens, and espe- cially in specimens hardened in chromic acid, which, in my hands, at least, has always proved a peculiarly unreliable hardening agent. 1 Ballour, ‘ Elasmobraueh Fishes,’ pp. 191, 192. MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 919 nal, facial, and other segmental nerves. I have investigated very carefully this point, which I am disposed to regard as of some importance, and find that in the chick, at a time when cranial flexure has attained its maximum development, the angle formed by producing the direction of the olfactory nerve and of the facial or glosso-pharyngeal nerves until they meet, is almost identical with that which measures the amount of cranial flexure; the angle in either case being about 120°. The course of the olfactory nerve in dogfish embryos is shown in figs. 17 and 18, and in the salmon in figs. 33 and 34. 5. This is a point of comparatively little importance, inasmuch as in the embryo ganglia, or local accumulations of nerve-cells, appear to be developed in a very irregular manner, and at very various points in the course of the nerves. Still it is a point not altogether destitute of weight, since those cranial nerves which appear for other reasons to have no claim to rank as segmental, are also peculiar in not possessing ganglionic enlargements at or near their roots of origin in the early stages. In the chick these ganglia are shown for the olfactory nerves in figs. 7, 8, and 9; for the third nerve in fig. 6; and for the trigeminal in fig. 4. In the dogfish the ganglia of the olfactory nerves are shown in figs. 20 and 21. 6. The discussion of the question whether the olfactory nerve is related to a visceral cleft in the same manner as the segmental nerves are to their respective clefts, will find a more suitable place after the development of the olfactory organ has been considered. The distance between the root of the fifth nerve and that of the third is somewhat greater than that between the fifth and the facial, while that between the third and the olfactory is greater still. These facts, which are obviously correlated with the great hypertrophy of the anterior part of the brain, from which the nerves in question spring, can certainly not be used as arguments against the segmental nature of the olfactory nerve. Though the olfactory nerve, from the earliest period at which it is recognisable as such, is thus seen to agree with the segmental nerves in all essential characters, it yet presents one or two minor points of difference. In the first place, owing to the close proximity of the forebrain to the nasal pit, the olfactory nerve is shorter than the other cranial nerves at the same age. Secondly, the olfactory appears to lag behind the others in development ; thus, at a time when the other nerves are fibrillar along the greater part of 320 DR. A. MILNES MARSHALL, their length, and only present nerve cells in any considerable number at certain points, the olfactory nerve still presents nerve-cells along its whole length. This second difference appears, however, to depend on the first, since as the nerve elongates with age, we find it gradually taking on the histo- logical characters of the other nerves, 2. e. the greater part of its length becomes fibrillar, and the nerve-cells confined to the two extremities, where they form ganglionic swellings. The practical importance of these differences is, however, considerable, since, owing to the olfactory nerve consisting for some time after its first appearance almost entirely of rounded cells, it is very difficult to distinguish from the surrounding mesoblast, and may, therefore, very readily be overlooked. The olfactory nerves are by most authors considered as of totally different morphological value to the othercranial nerves. According to Gegenbaur, ‘‘the cerebral nerves ... .. are seen to break up into two very distinctly marked divisions, when examined after the comparative method. One division, the larger, contains nerves which more or less agree with, or might even be derived from, spinal nerves, while the other contains those which have not the faintest resemblance to spinal nerves. ‘This latter divison contains two specific sensory nerves, the olfactory and the optic.’”! Again, Prof. Huxley says, ‘The greatest number of pairs of nerves ever given off from the vertebrate brain is twelve, including the so-called olfactory nerves and the optic nerves, which, as has been seen, are more properly diverticula of the brain than nerves in the proper sense of the word. The olfactory ‘nerves’ (olfactori) constitute the first pair of cerebral nerves. They always retain their primary connec- tion with the cerebral hemispheres, and frequently contain, throughout life, a cavity, the olfactory ventricle, which com- municates with the lateral ventricle.” Finally, Balfour considers that the ‘‘ very late appearance and peculiar relations” of the olfactory nerve ‘are, at least for the present, to my mind sufficient grounds for excluding it from the category of segmental cranial nerves.’ I have already attempted to show that the existence of an olfactory lobe or vesicle can in no way be said to mili- tate against the establishment of a complete homology 1 «Elements of Comparative Anatomy,’ English translation, p. 515. The italics are mine. 2 «Anatomy of Vertebrated Animals,’ p. 71. The italics again are mine. 3 Op. cit., p. 215. s MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 3821] between the olfactory and the other cranial nerves. Astructure that does not make the slightest appearance till the seventh day in the chick and stage o in the dogfish; a structure that, in the chick, does not appear till long after the nerves have acquired their connection with the cerebral hemispheres, a connection which I must repeat is a purely secondary one, and not, as Prof. Huxley would have it, primary ; such a structure can hardly be deemed of sufficient morpho- logical importance to outweigh the very obvious and striking resemblances between the olfactory and the other cranial nerves to which I have already referred. Again, if my observations are correct, the olfactory nerves cannot be said to appear “ very late ;” while, if I may assume that I have fairly disposed of the olfactory vesicle difficulty, I fail to see what are the “ peculiar relations”’ of the olfactory nerve that would justify its exclusion “ from the category of segmental cranial nerves.” The condition of the central nervous system appears to me to afford evidence of some value in favour of the segmental nature of the olfactory nerve. There is certainly no obvious reason why the anterior cerebral vesicle, or forebrain, of the embryo should be considered to be of a different nature to the middle cerebral vesicle, or midbrain, or to any one of the vesicles of the hindbrain. ‘he early embryonic stages afford no evidence whatever of a break of any kind between the fore and midbrains ; and, if the nerves arising from the mid and hindbrains have segmental value, there is surely a presumption in favour of the nerve that takes its origin in the forebrain having a similar and equivalent value ; a presumption greatly increased in probability by the close similarity between the early stages of development of that nerve and of the nerves arising further back in the brain. It still remains to be considered what is the morphological import of the olfactory lobe or vesicle ; but this is a question to which, in the present state of our knowledge, any answer that may be given must partake very largely of a specu- lative nature. The principal facts we have to guide us appear to be: 1. The very late appearance of the olfactory lobe. %. The fact that though the olfactory lobe is obviously connected with the root of origin of the olfactory nerve, yet it has no relation to the original position of the root of the nerve, and does not appear till this root has acquired a new, and purely secondary position. 3. The fact that the olfactory lobe does not appear at 322 DR. A. MILNES MARSHALL. equivalent periods in the development of different verte- brates. In the dogfish the olfactory lobe appears before the division of the forebrain into cerebral hemispheres takes place; in the chick not till long after the appearance of the cerebral hemispheres; and in the salmon, at any rate, not till after the time of hatching. These facts would appear to indicate that the olfactory lobe is to be viewed rather as an adult or adaptative than as an embryonic or primitive structure ; a view that is materially strengthened by the great variations in relative size of the three elements of the olfactory nerve in various adult verte- brates, to which attention has already been directed. One of the most remarkable features of the early stages of development of all vertebrates, is the enormous preponderance of the central nervous system to which at first everything appears to be subordinate, and which exercises a most important influence on the shape of the embryo. The rapid growth of the neural surface causes the body to become curved towards the ventral surface ; this curvature is naturally most marked at the free extremities of the body, and at thehead end is the main, if not the sole, cause of cranial flexure. Owing to this cranial flexure the forebrain gets carried in front of the olfactory sacs, and, consequently, the olfactory nerves, which, as we have seen, acquire their connection with the olfactory sacs at a very early age, at first run in a direc- tion downwards and backwards. Vide figs. 2, 15, 17, and 18. Having attained this enormous relative development the nervous system stops for a while, and the face begins to grow more rapidly, causing the so-called rectificatiou of the cranial flexure; the olfactory sacs get carried further and further forwards, so that the olfactory nerves, instead of running downwards and backwards, now run directly down- wards, or downwards and outwards as seen in fig. 33. The face still continuing to grow rapidly, while the brain under- goes little or no increase in length, the olfactory sacs get carried in front of the forebrain, so that the olfactory nerves now run downwards and forwards. A continuation of this process carries the olfactory sacs still further forwards, to an extent varying much in different vertebrates, so that the olfactory nerves ultimately run directly forwards as in most adult vertebrates. Vide tig. 36. . All the nerves of the body undergo during their develop- ment a considerable lengthening, owing to the gradual separation of their central and peripheral ends; but while in the case of all the other nerves this is a gradual and con- MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 323 tinuous process, commencing with their earliest appearance, the olfactory nerves are somewhat peculiarly situated. In their early stages, owing to. the close proximity of the olfac- tory sacs to the brain, the olfactory nerves are exceptionally short; and, owing to their origins being at first further forward than their insertions, the growth forwards of the face, carrying the olfactory sacs with it, does not at first cause any lengthening of the olfactory nerves. It is not till the sacs get in front of the forebrain that any lengthening is necessary, but no sooner does this occur than a sudden call is made on the olfactory nerves, which, previously quies- cent, now have to commence growing rapidly in length and to continue so doing. I would therefore suggest, without wishing to attach too much weight to the suggestion, that this elongation of the olfactory nerve, occurring under these exceptional conditions, may take place partly at the expense of the nerve itself, and partly at the expense of the brain; and that it is in this way that the olfactory lobe is produced. It is certainly worthy of notice that in the two types—chick and dogfish—in which I have ascertained with precision the date of its first appear- ance, the olfactory vesicle comes into existence just about the time that the most rapid growth of the nose and snout occurs, and consequently just about the time when a sudden and rapid lengthening of the olfactory nerve becomes neces- sary. It is also a significant fact that the olfactory lobe grows very rapidly at first, the nerve itself remaining nearly stationary.: The above suggestion renders it easily intelligible that much variety should exist as to the relative lengths of the nervus and tractus olfactorius, even in nearly allied verte- brates; while it is quite possible that, at any rate in some forms, the skeletal elements may have an important share in determining the relative growth of nerve and brain. Il. The Olfactory Organ. a. Development of the olfactory organ.—The consideration of the olfactory nerve having taken up far more space than I had originally anticipated, I shall be compelled to deal with the olfactory organ in a somewhat more summary fashion. The points to which I wish here to call attention are the remarkable resemblances that exist between the olfactory pits and the visceral clefts. As in the first part of the paper I shall deal first with matters of direct observation, and afterwards consider the theoretical side of the subject. 824 DR. A. MILNES MAHSHALL. The vertebrate olfactory organs make their first appear- ance as “a pair of slight thickenings of the external epiblast on the under surface of the forebrain, immediately in front of the mouth. . . . Each thickened patch of skin soon becomes involuted as a shallow pit.’”! In the dogfish these thickenings appear “ during a stage intermediate between L and kK” (Balfour). Their condition during stage kK is well shown in figs. 13 and 14 (o/f.); the former figure being a longitudinal and horizontal section, the latter a vertical and transverse one. ‘The exceedingly close proximity of the bottom of the olfactory pit to the brain is well shown by both figures. Fig. 13 shows also that at a time when the nose is in a very rudimentary con- dition, the eye (0. c.) has already made considerable progress in development, a point to which Balfour bas already directed attention. The communication between the visceral clefts and the exterior is established almost simultaneously with the first appearance of the olfactory pits. At stage 1 there are ** three visceral clefts, none of which are as yet open to the exterior.”* At stage K, according to Balfour, “ four visceral clefts are now visible, all of which are open to the exterior, but in a transparent embryo one more, not open to the exterior, would have been visible behind the last of these.’ The visceral clefts, then, first become open to the exterior between stages L and kK, and we have already seen that it is between these same two stages that the thickenings of the epiblast appear which form the earliest rudiments of the olfactory pits. In the chick the early stages of development of the olfac- tory pits closely resemble those just described in the dogfish. Fig. 1 represents a longitudinal and horizontal section through the head of a fifty-four hours’ chick embryo; the » section, which may with advantage be compared with fig. 13, shows on the right side the olfactory pit (o/f.), formed by the thickened and involuted epiblast, and in close proximity to the forebrain (f.6.); on the left side the section, which is a little oblique, passes through the thickened epiblast forming the margin of the olfactory pit, and through the eye (0. c.). ‘Two visceral clefts (v. c.) are shown, both open to the exterior. The earliest period in the chick at which I have noticed the thickening of the olfactory epithelium is about the 1 Balfour, op. cit., p. 184. 2 Balfour, op. cit., p. 77. 3 Op. cit., p. 78. MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 325 forty-eighth hour; a period almost identical, as in the dog- fish, with the opening of the visceral clefts to the exterior. In the trout the mode of development of the olfactory pits corresponds very closely with that occurring in the chick and dogfish ; and, as in these two types, their first appearance coincides almost exactly with the opening of the visceral clefts to the exterior. The connection between the olfactory nerve and the bot- tom of the olfactory pit is, as already noticed, acquired ex- ceedingly early, very shortly indeed after the appearance of the latter. The condition of the olfactory organ in the dog- fish is shown at stage m in figs. 15, 16, and 19; and at stage o in figs. 17, 18, and 20. In the chick the olfactory organ is shown at the sixty-fourth hour in fig. 2, at the sixty-seventh in fig. 3, and at the ninety-sixth hour in figs. 5 and 6. Throughout their early stages of development the olfaetory organs present a striking resemblance to the visceral clefts, both in form, position, and general relations—a resemblance which it will be necessary to consider in some detail, inas- much as it has been very generally overlooked hitherto. Fig. 3 represents a longitudinal and vertical section through the head of a chick embryo at the sixty-seventh hour. The section, which is taken in a plane not far from the surface, passes through the hind, mid, and forebrains, through the auditory vesicle (aud.), the eye (0.c.), the trigeminal (v), and auditory (vi11) nerves, through the anterior visceral clefts and arches, and through the olfactory pit (o/f.). The olfactory pit is seen to bear a marked resemblance to the visceral clefts : like them it is situated on the ventral surface of the head ; it is open below; its axis is at right angles to the longitu- dinal axis of the head, so that were the head straightened out it would be parallel to the clefts ; and its general ap- pearance and relations are such as to strongly suggest the view that it is one of the same series of structures as the visceral clefts. It is indeed separated from the next cleft, that in front of the maxillary arch (Mz.), by an interval somewhat greater than that separating the hinder arches from one another; but when we consider the enormous hypertrophy which the part of the brain with which it is connected has undergone, this becomes rather an argument in favour of than against the comparison. Figs. 4, 5, and 6 are three sections taken from the same embryo, a uinety-six hours’ chick. Of these sections, which are taken in a longitudinal vertical plane, that given in fig. 4 is the most superficial, that in fig. 6 the deepest of the VOL, XIX.—NEW SER. Y 326 DR. A. MILNES MARSHALL. three. Figs. 5 and 6 are drawn from consecutive sections, but between figs. 4 and 5 two sections intervened. These figures illustrate well the points to which I have just called attention ; they show that the visceral clefts form a conti- nuous series of structures, of which the most anterior is, not the mouth cleft (between Mn. and Mz.), but the cleft in front of the maxillary arch; a cleft that, following Prof. Parker, I propose to speak of as the lachrymal cleft: they show further that just in front of the lachrymal cleft is the olfactory pit (o/f.), and that the relations of the pit are such as to inevitably suggest that the olfactory organ is one of the same series of structures as the visceral clefts. Correct the cranial flexure, and straighten out the head, and the resemblance would amount almost to identity. I have only to add that, though these figures are semi-diagrammatical, yet as far as the outlines go, which alone concern us at present, they are as absolutely accurate as I have been able to make them. The resemblance between the olfactory organ and the visceral clefts is quite as marked in the early stages of the dogfish as in the chick; but to convey anything like an adequate idea of it would require a much more extensive series of figures than I am able to give here. Fig. 16 is taken from a longitudinal and vertical section through the head of a dogfish embryo at stage mM. The section which is taken very near to the surface passes through the auditory vesicle (awd.), parts of the trigeminal, facial, auditory, glosso-pharyngeal and vagus nerves, the second head cavity (A. 2), the eye (0.c.), the mandibular, hyoid, and first four branchial arches, as well as through the olfactory pit (o/f.). The section is a little deceptive, inasmuch as, owing to the head being somewhat constricted just behind the eyes, the buccal and lachrymal clefts do not appear at all, while the constriction just referred to presents somewhat the ap- pearance of a visceral cleft between the olfactory organ and the mandibular arch, and might possibly be mistaken for one on a superficial examination. The figure illustrates well the resemblance between the olfactory organ, which is larger than at a corresponding stage in the chick, and the visceral clefts. : Fig. 18 shows the same parts in a dogfish embryo of stage o; as in the preceding figure, and for the same cause, the buecal and lachrymal clefts do not appear in the section, but the figure shows the general resemblance in position and relations that exists between the olfactory organ and even the hinder visceral, or branchial, clefts. MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN, 327 In connection with this point, the study of whole embryos affords evidence fully as striking as that yielded by sections. I would here refer especially to certain of the figures given by Professor Parker in his monograph on the “ Structure and Development of the Skull in Sharks and Skates,” published in the ‘ Transactions of the Zoological Society ’ for 1879: on Plate XXXIX side views of the heads of embryos of Raia maculata are given (figs. 1 and 2), in which the re- semblance between the slit-like aperture of the olfactory organ and the gill slits is shown with remarkable distinct- ness. The direction of the slit forms an angle of about 120° with the hyomandibular or spiracular cleft, which angle is almost exactly that made by the longitudinal axis of the forebrain with that of the hindbrain, i.e. is the amount of cranial flexure; hence, but for cranial flexure, the external slit-like aperture of the olfactory organ would be parallel to the perfectly similar gill slits. The figures of dogfish embryos of stages K and 1, given by Mr. Balfour on Plate VII of his monograph on Elasmo- branch Fishes, illustrate the same points. The reference to these two works acquires additional weight from the con- sideration that the figures which | have named were drawn, I have reason to believe, without the slightest intention on the part of the authors to direct attention to the resem- blance. Even in an adult skate the similarity between the olfactory organ and the gill slits is sufficiently striking. The same points appear, if possible, still more clearly in axolotl and salmon embryos, especially in the former. I have found, however, that to give any adequate representa- tion of these would require a large number of figures, which figures would also serve to illustrate other points in the development of the axolotl, which I hope to deal with on some subsequent occasion. Fig. 30 represents a longitudinal and vertical section through the head of a trout embryo on the thirtieth day after fertilisation of the ova. The section passes through the hind and midbrains and the eye (0.¢.). ‘The ventral sur- face of the section presents a series of undulatory folds, corresponding to the bases of the visceral arches, with their intervening clefts. The olfactory pit (o/f.) is seen to form the most anterior of these depressions, and to differ from the hinder clefts in little but the greater thickness of its epithelium, and the somewhat greater interval between it and the next cleft. The cleft next but one to the olfactory pit is that over which the trigeminal nerve forks—z. e. the buccal or mouth cleft; it is situated between the maxillary 328 DR, A. MILNES MARSHALL, (Mz.) and mandibular (Mn.) arches. Behind the mandibular arch, between it and the hyoidean arch, is the cleft, the two sides of which are supplied by the facial nerve. Between the buccal cleft and the olfactory pit a cleft intervenes—the lachrymal cleft; so that the number of clefts in the trout agrees completely with that we have already found in the chick. The resemblances between the olfactory pit and the visceral clefts are, however, not simply those of general appearance and relations; they are of a far more intimate nature, and extend even into the details of histological structure. For studying these more intricate relationships the dogfish has proved the most suitable. The. olfactory organ of a dogfish does not long remain a simple pit; very soon after its first appearance its walls become thrown into a series of folds—the rudiments of the Schneiderian folds of the adult. I wish here to call atten- tion to the resemblances between these folds and the series of folds which, arising from the sides of the visceral clefts, form the rudiments of the gills. Ihave not myself observed the presence of the rudimentary Schneiderian folds in embryos younger than stage M, but Balfour has shown that they not only exist, but have acquired the characteristic adult arrangement in embryos “a little older than K.”1 With regard to the gills, Balfour’s descrip- tion is as follows:—“ Towards the close of stage kK there arise, from the walls of the second, third, and fourth clefts, very small knob-like processes, the rudiments of the external gills. These outgrowths are formed both by the lining of the gill cleft and by the adjoining mesoblast.”? If, udec the times of appearance be not absolutely identical in the two cases, the correspondence is, at any rate, sufficiently striking. Fig. 23 is a horizontal and longitudinal section through the head of a dogfish embryo at stage N, magnified twenty diameters ; 1t passes through the fore and hind brains, the notochord (mz), the eyes (0.¢.), the oculo motor (111) and tri- geminal (v) nerves, and through the olfactory pits (o/f.). The bottoms of these pits are seen to be thrown into a series of small equidistant folds—the Schneiderian folds. Fig. 24 is a transverse section through the body of the same embryo, taken a short way behind the head, and pass- ing through one of the branchial arches on either side. The section which, like the preceding one, is magnified twenty 1 Op. cit., p. 184, and Plate XIV, fig. 14. 2430p. citi, ps las MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN, 3829 diameters, shows also the spinal cord, with the anterior and posterior roots of a spinal nerve, the notochord (7.), muscle plates (m. p.), pharynx (a/.), parts of the vagus nerve, the cardiac and.dorsal aortz, and on either side the branchial arteries (b.a.) The free surface of each branchial arch presents a series of small equidistant folds, the rudiments of the gills (g.), which, even under this low magnifying power, have a close resemblance to the Schneiderian folds. In order to show this resemblance more satisfactorily I have given figures of the parts in question on a larger scale. Fig. 25 represents the right olfactory pit of fig. 23, and fig. 26 the left gill of fig. 24; both figures are thus taken from the same embryo, and the magnifying power employed —ninety diameters—is the same in the two cases. These figures show that the correspondence between the two structures is by no means confined to their coarser anatomy, but extends even to histological details. ‘The folds are seen to be in the two cases—gills and Schneiderian folds —of the same width, and the same distance apart; in both cases, though consisting mainly of epithelium, they yet involve the underlying mesoblast to a certain, though slight, extent,! but as nearly as possible to the same extent in the two cases. The epithelium that forms the greater part of the folds is of the same thickness in the two cases, and of the same histological character, consisting mainly of columnar cells in close contact with one another, and arranged, as a rule, in two rows. The same folds are shown, at a somewhat later period, in figs. 27 and 28, the former representing the Schneiderian folds, the latter the gills of the same embryo. Though the resemblances are still strong, there are now well-marked differences between the two structures; thus, in fig. 27 the epithelium is somewhat thicker than in the gills, while the mesoblast enters more largely into the gills than the Schnei- derian folds. Most of the gill folds already present a central blood-vessel ; it is very difficult to satisfy oneself of the ex- istence of distinct walls to these blood-vessels, which appear in many Cases to be simply channels in the mesoblast form- ing the axis or core of each gill fold. Similar blood-vessels exist, especially at a rather later stage, in the Schneiderian folds, and their relations are similar to those in the gills. Even in adult Elasmobranchs the Schneiderian folds re- semble the gills closely in their great vascular supply, in 1 Balfour notes this in the case of the gills, but describes the Schnei- derian folds as folds of epithelium. Op. cit., p. 184. 330 DR. A. MILNES MARSHALL. the arrangement and distribution of the blood-vessels, and in the characters of their surface epithelium. b. General considerations.—Hitherto we have been con- cerned simply with matters of observation ; though, indeed, I have not attempted to give a complete account of the development of the olfactory organ, but have limited my description to certain developmental features, in which it strongly resembles the visceral clefts; still I have dealt simply with facts, or what I believe to be facts. I propose now to consider the subject from a more theoretical point of view. In the first place I would submit that the very close resemblance as to form, structure, general relations, time of appearance, &c., existing between the olfactory organ and the gill clefts, whether these be considered as wholes or in their separate parts, is sufficient to raise a strong probability that they are homologous structures. This probability is strengthened by the complete absence of similar structures in any other part of the body at any period of development. Not only do the Schneiderian folds and the gills appear at the same time and agree completely in structure, but in no other part of the body do similar structures occur, either at this or any other period. Again, this probability gains very material support from the conclusion arrived at in the first part of this paper, viz. that the olfactory nerve is a segmental nerve; for we have seen that one of the most important diagnostic characters of a segmental nerve is its distribution to the two sides ofa vis- ceral cleft, and, since the olfactory nerve is distributed to the olfactory organ, and to that alone, if there be a visceral cleft with which it is in relation, the olfactory organ must be that cleft. The conclusions, then, to which I have been led concerning the morphology of the vertebrate olfactory organ are—that the olfactory organ is the most anterior visceral cleft; that the olfactory nerve is the segmental nerve supplying the two sides of that cleft in a@ manner precisely similar to that in which the hinder clefts are supplied by their respective nerves ; and that the Schnecderian folds are homologues of gills. The suggestion that the nasal organs are gill clefts was originally made by Dr. Dohrn, in his essay on the origin of vertebrates. In discussing the question whether the pair of gill clefts, which by their median fusion formed the verte- brate mouth, was the most anterior pair, Dr. Dohrn says: ** Aber auch betreffs der vorderen Kiemenspalten ist noch MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN, 30d] die Vermuthung zu dussern, ob nicht vielleicht inden Nasen- gruben ein Paar solchen Spalten, freiiich in wesentlich veranderter Function uud darum auch Structur, zu erkennen seis, ! Dr. Dohrn does not enter into any details concerning the suggestion thus made, and does not discuss the question of the olfactory nerve. 1 am not aware that he has since pub- lished any further observations on this point. The sug- gestion appeared to me, if not untenable, at any rate unprovable, so long as the ordinary account of the develop- ment of the olfactory nerve continued to find acceptance. In addition to what has been already said there are, I think, many arguments in favour of this view. Even if we leave out of consideration the buccal and lachrymal clefts, it is well known that in all vertebrates above Amphioxus more or fewer of the visceral clefts undergo modification to a greater or less extent, and that this modification is first felt by the clefts at the two extremities of the series, especially by the anterior ones; and it is a point worthy of notice that, while the posterior clefts tend simply to disappear, the anterior clefts with their gills are peculiarly prone to persist in a modified form. ‘Thus, the first post- oral or hyomandibular cleft is the only one which remains in Sauropsida and Mammalia. Among Ichthyopsida this cleft is apt to assume the modified form of a spiracle, while its gill loses its respiratory function, and persists as a pseudobranchia. Similarly, the carotid gland of the frog and the choroid gland of Teleosteans are probably other instances of the persistence, in an altered condition, of anterior gills. Onthe other hand, when reduction is effected in the number of the gills from the posterior end of the series, as in nearly all fishes, the gills and their clefts usually disappear absolutely and completely. Again, if the olfactory organ is a gill, we should expect to find the resemblance between the two structures strongest in the most primitive vertebrates. From what has been said already this obviously is the case. Of the various types of vertebrates examined it is in the dogfish alone that we find the intimate relation between the development of the gills and that of the Schneiderian folds. Whatever view we may hold as to the ancestry of verte- brates, there can be little doubt that they have not inherited their olfactory organ as such. At any rate, we know as yet of no invertebrates that possess olfactory organs from which the vertebrate olfactory organ could possibly have been 1 *Ursprung der Wirbelthiere.’ Leipzig, 1875, p. 23. 302 DR. A. MILNES MARSHALL. derived by inheritance. Hence it follows either that verte- brates must have acquired or developed an olfactory organ completely de novo, or else that their olfactory organ has been formed by gradual modification of some pre-existing structure with accompanying change of function’. ‘The first of these alternatives may, I think, be at once dismissed as untenable, and then we are left with the second alternative. I do not propose to enter here into a detailed discussion of the physiology of smell, but will only remark that what little we do appear to know definitely about it is quite in accordance with the view that smelling is only a modified form of breathing, and that no very violent physiological change would be necessary to convert a gill into an olfactory organ. On the other hand, the sense of smell is something of a totally different nature to sight or hearing; the essence of these latter consists in the appreciation of the relative wave lengths of undulations conveyed by air or ether; while smell appears to be due to direct chemical action on the nerve-endings, requiring the presence of free oxygen (Graham). In the first part of this paper I have attempted to show that the cranial nerves afford very definite evidence as to the segmentation of the anterior part of the vertebrate head— evidence, indeed, quite as definite as that which they have long been recognised as affording concerning the hinder part of the head. ‘The second part of the paper has shown that the visceral clefts afford equally definite evidence on the same point. In a former paper? I have called attention to the fact that the early stages of the brain also afford evidence on this point. It is a matter of considerable interest that the evidence yielded by these three types of structures respectively, as to the number and situation of the cephalic segments, is identical. The brain consists in an early stage of a series of vesicular dilatations separated by slight constrictions ; of these vesicles the most anterior is the forebrain, and the next the mid- brain; while the succeeding vesicles, which form a series decreasing in size from before backwards, and of which the first two at any rate appear to possess considerable constancy, are spoken of collectively as forming the hindbrain. From each of these brain-vesicles a segmental nerve arises: the forebrain gives origin to the olfactory nerve; the midbrain to the third or oculomotor nerve ;° from the 1 Cf. Dohrn, op. cit., *‘ Princip des Functionswechsels.” 2 ¢ Journal of Anatomy and Physiology.’ vol. xl, p. 510. 3 For a full discussion of the reasons which have led me to consider the MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN. 9333 anterior vesicle of the hind brain the fifth or trigeminal nerve arises, and the second hindbrain-vesicle appears to give origin fairly constantly to the seventh er facial nerve; behind this I have not observed any definite relation between the cranial nerves and the brain-vesicles, which latter become very small and of doubtful constancy as to number and relations. This is, however, a matter of little moment, as the evidence afforded by the cranial nerves themselves and by the visceral clefts in the post-auditory part of the head is of an un- impeachable character. As to the clefts, the most anterior is the olfactory cleft ; vide figs. 3, 4,5, and 6. Next to that is the cleft which, following Prof. Parker, I have spoken of as the lachrymal, d.e. the cleft in front of the maxillary arch: the relations of the third nerve to this cleft are well shown in fig. 6; it only remains to be added that, of the two branches into which the third nerve divides beyond the distal ganglionic swelling shown in fig. 6, one lies at first behind this cleft, the other in front of it. We next come to the buccal or mouth cleft, between the maxillary and mandibular arches; the relations of the fifth nerve to this cleft are well known. Behind this is the hyomandibular or spiracular cleft, supplied by the facial nerve ; and then the branchial clefts, supplied by the glosso- pharyngeal and by the several branches of the vagus. These relations are exhibited more clearly in the following table. In the first column are the numbers of the segments, of which, if we count seven branchial clefts, the full ver- tebrate number, there are eleven in all; two of these being preoral, and eight postoral. The second column contains the brain vesicles, the third the segmental nerves, and the fourth the corresponding visceral clefts. third nerve as a segmental nerve, and the fourth and sixth nerves as having no claim to segmental value, vide ‘Quart. Journ. Micros. Sci.,’? Jan., 1878, pp. 23—28, and pp. 32—33. The observations there recorded for the chick I have since verified in the dogfish. 334 DR. A, MILNES MARSHALL. Head Segments of Vertebrates. Segment. Brain-vesicle. Nerve. Cleft. Preoral 1 | Forebrain I. Olfactory Olfactory. 3 2 | Midbrain TIL. Oculomotor Lachrymal. Oral 3 | Hindbrain, Ist vesicle. V. Trigeminal Buccal. Postoral 4 + 9nd ,, |VLE. Facial Spiracular or hy- omandibular, i 5 | Hindbrain IX. aes - pharyn- | 1st branchial. gea 3 6 33 X. Vagus, Ist branch | 2nd es ” 7 22 2”? 2nd ” 3rd 33 4 8 - mo cory ys; Atl Fe 9 9 2? 2» 4th ” 5th ce) geet EO 9 bth 6 | Gth 3 ” 11 oP) +e) 6th 99 7th 3 This table, which has been modelled after the one given by Balfour,! differs from this latter in some important points. The differences are most marked in the anterior part of the head, where I have added an olfactory segment, and have attempted to define more accurately the constituents of the second segment by removing the fourth and sixth nerves, and assigning, for reasons discussed elsewhere, the third nerve as the true segmental nerve. At the hinder end of the head I have added two segments for the two hinder branchial clefts of Notidanus and the Marsipobranchii, so that the table is intended to include the full number of head segments of which we have any definite indication in any vertebrate, excepting Amphioxus ; though it is by no means intended to exclude the possibility of additional segments having existed at the hinder end of the head in former vertebrates, or actually existing in some living forms. It will further be noticed that I have placed the visceral clefts, and not the visceral arches, as indicating segments ; this is a point of some importance, but one which I do not think we are yet in a position to decide with certainty. The question is, whether the visceral clefts are to be viewed as intersegmental, i. e. as corresponding in position to the lines of separation of the original segments by the fusion of which we suppose the vertebrate head to have been formed; or whether they should be considered as tntrasegmental, as apertures formed in the substance of the segments ; in other 1 Op. eit., p. 216. MORPHOLOGY OF THE VERTEBRATE OLFACTORY OBGAN. 335 words, whether the visceral clefts are formed between succes- sive segments, or through the middle of the segments. Though the former of these views is usually assumed to be the true one, yet there are, I think, considerations of some weight in favour of the opposite view. In the first place, we must bear in mind that the original proto-vertebral segmen- tation does not extend to the head, and that the secondary, visceral cleft segmentation appears late, and differs totally from the segmentation of the body, inasmuch as, instead of starting on the dorsal side in the mesoblastic tissue on either side of the neural axis, it arises in, and is limited to, the lateral and ventral walls of the alimentary canal. Instead of arising primarily in the mesoblast, it is a segmentation in which the mesoblast takes no share whatever, except a purely passive one; it 1s a segmentation produced by the growth of diverticula from the alimentary canal, which come in contact with, and fuse with the external epiblast, and, finally, by perforation of this latter open on to the exterior. Now, it is more in accordance with what we know of the occurrence of lateral diverticula of the alimentary canal in Inveitebrata, that these should be segmental rather than intersegmental. Again, while each cranial segmental nerve supplies two visceral arches, it only supplies one cleft; and, from the analogy of Invertebrata, we should expect that the distribu- tion of each nerve would be to its own segment; while it certainly would be a very remarkable fact that each seg- mental nerve should supply adjacent halves of two seg- ments. The distribution of the branchial arteries may also be cited as additional evidence in the same direction; the corresponding vessels in Invertebrata do not occupy the middle of each segment, but follow the intersegmental septa, which septa, according to the view here advocated, would occupy the centres of the vertebrate visceral arches, and so corre- spond in position with the branchial arteries. On the same view the skeletal elements of the visceral arches would also correspond in position to the intersegmental septa, from which, indeed, they may conceivably have been derived. This view acquires some additional interest in connection with Dr. Dohrn’s suggestion that the visceral clefts are homologues of segmental organs.! The theory above propounded as to the morphology of the vertebrate head, will, I venture to think, throw some light on the nature of the skeletal elements of the head. I will * Op cit.,. pp. 10; 11: 306 DR. A. MILNES MARSHALL. here only notice briefly one or two points of importance. On the view here put forward the trabecule cranwi, which lie at the base of the brain, run parallel to the longitu- dinal axis of the head, and at right angles to the segmental structures, such as the third and olfactory nerves and the corresponding clefts, must be regarded as axial struc- tures, and not as arches, whether neural or hemal.} . Again, my investigations appear to leave no room for doubt that the maxillary arch, the rudiment of the upper jaw, is as fully entitled to rank as a distinct visceral arch as the mandibular, hyoid, or branchial arches. Figs. 3—6 appear to me to afford conclusive evidence on this point. The morphological nature of the labial cartilages has been matter of much dispute; if the determination of the olfac- tory organ as a gill cleft be accepted, those at least of the labial cartilages which are grouped round the external aper- ture of the olfactory organ, and very possibly those* also in connection with the gape of the mouth, would appear to be homologues of the extra-branchial cartilages, a suggestion in which I find I have been anticipated by Professor Parker.” I cannot refrain here from referring to the remarkable manner in which the views here put forward agree with the results arrived at by Professor Parker, and embodied in his latest paper.? He there expresses himself ‘satisfied that, in spite of the doubling up of the basis cranii, at the time of its greatest flexure, there are rudiments of three preoral arches, related to two preoral clefts, the lachrymal and the nasal.” ‘Thus we get four pre-auditory, and eight post- auditory clefts, with their nerves; if we add the twelfth (hypoglossal), of the ‘ Amniota,’ we have obtained signs and proofs of thirteen cranial (segmental) nerves, all of these, ex- cept the last, forking over visceral clefts, and hedged i all but the lust by visceral bars. The first of the bars is in front of the first or nasal cleft, the last, or thirteenth, is the hinder bar of the lamprey’s branchial basket work.” The italics in the above quotation are mine. Though I see no reason for regarding the hypoglossal as a segmental cranial nerve, this extract from Professor Parker’s work shows that the study of the skeletal elements of the head 1 Cf. Parker, “ On the Development of the Skull and its Nerves in the Green Turtle,” ‘ Proc. Royal Soc.,’ 1879. 2 «Trans. Zool. Soc.,’ 1876, ‘‘On the Structure and Development of the Skull in Sharks and Skates,” pp. 212 and 224. 3 “On the Development of the Skull and its Nerves in the Green Turtle.” ‘Proc. Royal Soc.’ 1879. This was read before the Royal Society on the same evening as the abstract of the present paper. MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN, 9357 leads to results almost identical with those at which I have arrived, and affords perhaps the strongest possible confirma- tion of these results. Though in the above enumeration of the segmental cranial nerves I have left out the optic nerve, for reasons stated elsewhere,! it is quite possible that this nerve may ultimately prove to be of segmental value; in which case it would indi- cate the existence of a cleft between the olfactory and lachrymal cleft. However, I have as yet completely failed to find any evidence of its segmental nature, and must, for the present, regard it as of a totally different nature to any of the other nerves. The case of the auditory nerve is very different, for there can be little doubt that this is to be viewed as merely a specialised branch of the facial.” If the olfactory organs are really a pair of gill slits, then they must have originally communicated with the mouth cavity; and it becomes a matter of considerable interest to determine whether any traces of such a communication still exist. Itis quite possible that the grooves which con- nect the nasal sacs with the angles of the mouth in the skate and other Klasmobranchs, and which form the rudi- ments of the posterior narial passages of higher vertebrates, are remnants of this communication. It is difficult to under- stand what function these grooves subserve in Elasmobranchs, and their apparently irregular presence or absence in closely allied genera would well accord with their being disappear- ing rudiments. In connection with this point some obser- vations [ have recently made on trout and salmon embryos, though incomplete, appear to possess some interest. Fig. 31 is a transverse section through the anterior part of the head of a salmon embryo just about the time of hatching: the section passes through the anterior borders of the olfactory pits (o/f.), through the cartilaginous plate formed by the fusion of the two trabecule (¢7.), and, on the ventral side, through a large flattened cavity (al’.) ; this. cavity is found, by a study of the sections in front of and behind the one figured, to be an anterior prolongation of the buccal cavity, extending forwards in front of the mouth, underlying the olfactory sacs, and reaching almost to the extreme ante- rior end of the head. Fig. 33, which has been already described, is a section taken through the head of an embryo of about the same age as that in fig. 31, but a little further back; it shows this same cavity, which, however, is now not completely closed 1 Quart. Journ. Micros. Sci.,’ January, 1878, pp. 23—27. ? Balfour, op. cit., p. 213, and self, loc. cit., pp. 34—36. 338 DR. A. MILNES MARSHALL. in the median ventral line, the section passing through the anterior part of the oral aperture. In figs. 34 and 35 the same structure is shown in longi- tudinal and vertical section; fig. 35, which is the more superficial of the two, shows the pharynx (a/’.), with the branchial arches and the anterior continuation of the buccal cavity (al’.) Fig. 34, which passes through the root of origin of the olfactory nerve, and therefore, as is evident from fig. 33, very close to the median line, passes also through the mouth; it shows very clearly the manner in which this anterior prolongation (a/’) extends forwards in front of the anterior margin of the mouth. I have unfortunately not yet succeeded in tracing the development of this prolongation, and do not even know for certain whether it appears before or after the formation of the mouth, or whether it is lined by hypoblast or epiblast. At a stage a little later than that just described, when the growth of the anterior part of the head has carried the nose considerably further forwards, this prolongation exists in the form of a pair of ceecal diverticula, stretching for- wards from the anterior part of the buecal cavity towards the olfactory pits. ‘These are well shown in fig. 52, a trans- verse section through the anterior part of the head of a salmon embryo about a week after hatching. The section passes through the extreme anterior end of the forebrain (f. 6.) in front of the*origin of the olfactory nerves, through the two eyes (0. ¢.), the superior recti muscles (r. s.},the trabe- cular plate (¢7.), the hinder end of the two olfactory pits (o/f), and the diverticula of the buccal cavity (al’.) close to their anterior terminations. Ata stage a little later still, these diverticula appear to shrink and disappear; at least | have failed to recognize them in sections. Whatever these diverticula may prove to be, their exist- ence is certainly of some interest in connection with the visceral-cleft theory of the olfactory organ; they show, at any rate, that there do exist diverticula of the alimentary canal towards the olfactory organs ; they may possibly be taken as indications of a former extension forwards of the alimentary canal to the anterior end of the head; while their paired condition, shown in fig. 32, may perhaps be an indica- tion of relationship to the paired lateral diverticula of the alimentary canal, which form the rudiments of the hinder visceral clefts. Again, if the olfactory organs are gill clefts and the Schnei- derian folds gills, not only must these clefts have originally communicated with the buccal cavity, but the vertebrate MORPHOLOGY OF THE VERTEBRATE OLFACTORY ORGAN, 339 mouth must originally have been in front of them. Accord- ing to Dr. Dohrn the present vertebrate mouth is formed ‘by the median coalescence of a pair of gill slits; my own investigations lead me to the conclusion that, though these gill slits do contribute to the formation of the mouth, there is in addition a median involution of the epiblast of the under surface of the head, as described by Balfour! and others, so that the mouth consists of three elements, a median epiblastic involution and a pair of gill slits. I am inclined also to believe that the fact of the olfactory organs appearing in front of the mouth is due to two causes ; firstly, the hypertrophy of the forepart of the head carrying the olfactory sacs forwards ; and, secondly, an actual shifting backwards of the median element of the mouth, of which [ think there is a certain amount of independent evidence. The anterior end of the notochord is, as is well known, bent completely round on itself, through an angle of fully 180°, 2. e. as Balfour has already noticed, to a much greater extent than cranial ffexure alone will account for. Now, assuming that the notochord is a hypoblastic structure, and that its anterior end remains for a time in connection with the hypo- blast, a shrinking back of the hypoblast of the anterior end of the foregut would at once account for this condition of the notochord, and would at the same time cause a displace- ment backwards of the mouth. It would appear therefore quite possible that the median element of the present verte- brate mouth is the original vertebrate mouth which has under- gone a slight displacement backwards, and so has become severed from the olfactory organs. Perhaps the most serious objection to the visceral-cleft theory of the olfactory organ that is likely to occur at first sight, is the fact that these organs are involutions of the external epiblast, while the visceral clefts are formed by diverticula of the hypoblast of the foregut. While fully admitting the force of this objection, I venture to think that the arguments I have brought forward—the evidence in favour of the segmental value of the olfactory nerve, the close relation, both anatomical and histological, between the olfactory organ and the visceral clefts, the fact that these relations are much more marked in the more primitive than in the more specialised vertebrates, the various identities in time of appearance and in histological structure, and the con- current testimony of the various incidental circumstances to which I have alluded—are sufficient to outweigh this objec- tion. Moreover, we must bear in mind that slight ingrowths 1 Op. cit., p. 189. 340 E. T, NEWTON. of the external epiblast towards the hypoblastic outgrowths ef the pharynx may occur, and that it is still a matter of uncertainty whether some of the gills are not epiblastic rather than hypoblastic;' while, if the diverticula of the alimentary canal described above in the trout and salmon should prove to be hypoblastic, the principal differences between the olfactory organs and the gill clefts would be the gradual shrinking of the most anterior pair of diverticula of the buccal cavity, the ultimate failure on their part to reach the surface, and a corresponding exaggeration of the epi- blastic surface involutions, which changes can readily be con- ceived as following on, and eaused by, a slight displacement backwards of the mouth. Since the funetional activity of the gills as such depends on the constant passage of a stream of water through the mouth into the buccal cavity and then out through the gill slits, it follows that if the mouth were changed in position so as to be situated behind instead of in front of, the first pair of gills, the function of these gills would be materially interfered with, while their position at the anterior extremity of the head and their consequent potential utility, would favour their preservation in a modified form, and with modified function. On the Brain of the CocKRoacH, BLATTA ORTENTALIS. By E. T. Newton, F.G.8.,H. M. Geological Survey. With Plates XV and XVI. THE common cockroach, Blatta orientalis, has been found a very convenient insect to take as a type of its order, both on account of its generalised structure, and the readiness with which it may be obtained, in any numbers, at all seasons of the year; consequently it has been dissected largely in our biological schools. It seemed desirable, therefore, when the structure of the brain of certain insects was being investigated by several continental naturalists, that we should make ourselves some- what better acquainted with the brain of our typical insect the cockroach, for this had not been worked out as eare- fully as it merited. And further, inasmuch as in certain particulars this insect is less specialised than some of those, the brains of which have been examined, it seemed 1 Balfour, op. cit., pp. 210, 211. ON THE BRAIN OF THE COCKROACH. od) probable that we should here find the brain in a less special- ised condition. The facts which have now been made out show that, in the structure of its brain, the cockroach holds a median position; possessing as it does all the struc- tures (excepting the ocelli nerves, unless, indeed, the white spots near the bases of the antenne should prove to be rudimentary ocelli) which have been described in other insects; but at the same time certain of these parts are not quite so complicated and are, therefore, more easily understood. It was not until I had nearly finished my own investiga- tions, and was about to publish the results, that 1 saw the memoir by Dr. Flogel (‘ Zeitsch. wissen. Zool.,’ 1878, vol. Xxx, supple., p. 556), 1m which the internal structure of the brain of Blatta is very fully described. On the whole the results which I had obtained agreed with those of Dr. Flogel ; but as my paper did not cover the same ground, and, more- over, as little or nothing had appeared in British journals on the minute structure of insects’ brains, it still seemed desirable to publish the results of my own work. And, fur- ther, as the Blatta’s brain seems likely to be taken as the type for comparison in future investigations, it is the more necessary to have it fully illustrated, and the photograph of one section only, which is all that is given by Flogel of the Blatta brain, seemed to me quite inadequate for its proper comprehension. Even with a series of sections and drawings before me, it was by no means easy to get a clear conception of the forms of some of the internal parts, and I therefore ‘constructed a model from a series of sections (vide ‘ Quekett Journal,’ 1879, vol. v, p. 150), which gave me a far better knowledge of these parts than I had found it possible to get in any other way. The complicated internal structure of the brain of insects, appears to have been first pointed out by M. Dujardin, and attention is more especially directed to this, because the cor- rectness and clearness of his descriptions do not appear to me to have been sufficiently appreciated. M. Dujardin, in 1850 (‘ Ann. d. Sci. Nat.,’ t. xiv, p. 195), pointed out that in some insects there were to be seen upon the upper part of the brain certain convoluted portions which he compared to the convolutions of the mammalian brain, and, inasmuch as they seemed to be more deve- loped in those insects which are remarkable for their intelli- gence, such as ants, bees, wasps, &c., he seemed to think the intelligence of insects stood in direct relationship to the development of these bodies. VOL. XIX.—NEW SER, Z 342 E. T. NEWTON, The form of these structures is described by the same author as being, when fully developed, as in the bee, like a pair of discs upon each side, each disc being folded together and bent downwards before and behind, its border being thickened and the inner portion radiated. By very careful dissection he found these bodies to be connected on each side with a short pedicle, which bifurcates below to end in two tubercles. One of these tubercles is directed towards the middle line and approaches, but does not touch, the corre- sponding process of the opposite side. The second tubercle is directed forwards and is in close relation to the front wall of the head, being only covered by the pia mater. These convoluted bodies and the stalks upon which they are mounted are compared by Dujardin to certain kinds of mushrooms, and this idea has been retained by more recent writers on the subject. The physiological experiments of Faivre in 1857 (§ Ann. d. Sci. Nat.,’ t. vili, p. 245) upon the brain of Dytiscus in relation to locomotion, are of very considerable interest, showing, as they appear to do, that the power of co-ordinating the movements of the body is lodged in the infra-cesophageal ganglia. And such being the case, both the upper and lower pairs of ganglia ought to be regarded as forming parts of the insect’s brain. Dr. Franz Leydig, in 1864 (‘Vom Bau des thierischen Korpers,’ &c.), entered fully into the structure of the nervous system of insects, and described the histology of the various parts of the brain. The method of preparation which he adopted was to preserve the insect in absolute alcohol, then to remove the brain, and render it transparent with dilute potash solution, or glycerine. As regards the general structure of the so-called mushroom body and its stem, Leydig makes little advance upon what was done by Dujardin, but, in consequence of his method of preparation, as it seems, was misled into describing as a giant nucleus upon each side of the middle of the brain, the peculiar mass of nervous matter, which Dujardin had correctly described as a process extending forwards to the front surface of the brain. In 1875 Dr. Rabl Ruckhard (‘ Archiv. f. Anat. u. Phys.,’ p- 480), described the structure of the brain of the black ant (Camponotus ligniperdus), adopting chiefly the method of preparation made use of by Leydig. He was enabled to make out the head of the mushroom body with its stalk; he also saw the appearance described by Leydig as a giant nucleus, but believed it to be the optical section of cylindri- ON THE BRAIN OF THE COCKROACH. 343 cal commissures passing from the front to the back of the brain. He mentions also that, in the bee, he has been able to dissect out the process which passes to the front of the brain, as described by Dujardin. It is this which, when seen from before, gives the appearance of a central nucleus in each hemisphere. The head of the mushroom body he described as forming a complete ring, which he was. able to separate from the surrounding parts. From what we now know of the structure of these mushroom bodies, it is clear that these parts must have been separated from their attachments before they could give the appearance of closed rings. We shall, I think, see presently that Dujar- din was much more correct in speaking of them as folded discs. Dr. Dietl, in 1876 (‘ Zeitsch. wissen, Zool.,’ Band xxvii, p. 488), published an elaborate description of the brains of the bee, mole-cricket, grasshopper, &c. The method em- ployed by this author was, to cut up in definite directions brains which had been hardened in osmic acid. In the main the results of his observations accord with those of Dujardin and Rabl Riickhard. He agrees with them as to the existence in the bee of two mushroom bodies in each hemisphere, mounted upon downwardly-directed stalks, and also as to the cylinder “of nervous matter passing forwards to end abruptly upon the front of the brain. He further agrees with Rabl Riichkard that the giant nucleus of Leydig is the optical section of this nervous cylinder. In the mole-cricket Dietl describes only one mushroom body on each side, and the stem passing downwards from this is said to divide into two parts, one of these ending in the middle line, whilst the other forms the cylinder ending upon the front of the brain. The various histological ele- ments are described in detail, as they are found in the various parts of the brain. Dr. Dietl finds the nervous matter in invertebrate brains under the three following conditions :—1l. Ganglionic cells, as they are called, and allied structures, free protoplasmic nuclei. 2 Nerve-fibres of the most different sizes. 3. ‘‘ Marksubstanz,” a peculiar arrangement of nervous matter, which appears sometimes as fine fibrille, with an axial arrangement, sometimes as a very fine network of different thicknesses, and sometimes as thin lamellz, or altogether homogeneous. Under all these forms this third group of textures is characterised by turning very dark under the influence of osmic acid, whilst the other elements are only turned brown. Another valuable addition to our knowledge of insect 344 E, T, NEWTON. brains was made by the publication of the memoir by E. Berger in 1878 (‘ Arbeiten des Zoolog., Instituts zu Wien.,’ Bd. i, Heft 1, p. 173). This memoir is largely occupied with the description of the retina and the structures to be found in the optic lobes of Arthropods. It is extremely interesting to find that the peculiar oval bodies which Leydig ‘figured as occurring in the optic lobe of Dytiscus (‘ Tafeln z. Vergleich, 1864), and were afterwards described and figured by me as “ lenticular bodies ”’ in the eye of the lobster (‘ Quart. Jour. Micro. Sci.,’ 1873, vol. xiii, p. 336), are to be found in a more or less modified form in all the insects and crustacea described by E. Berger. The remarkable crossing of the nerve-fibres between the retina and the lenticular bodies is seen not to be peculiar tothe lobster. The kidney- shaped body, which is such a distinct part in the lobster’s optic ganglion, appears to be represented in the Squilla by the body marked G in Berger’s figure 32. The brains of a number of insects are described, including examples from the Neuroptera, Coleoptera, Diptera, Lepidoptera, Hymen- optera, and Orthoptera, and in each of these the author seems to have found the homologues of the mushroom bodies, although in some—the Diptera, for example—they are very rudimentary. Not a little important are the facts recorded relative to the transverse commissures of the brain. It seems to me somewhat doubtful whether the paired structures which have been shown by several authors to be present in the brains of Crustacea, are really the homologues of the mushroom bodies of the insect’s brain. Dietl has shown (‘Sitz. Kaiser. Akad, d. Wissen.,’ 1878, Band 77, p. 584) that in the crayfish these bodies are connected with the optic nerve, and he calls them optic lobes. Among the Insecta this connection, if it exists, has yet to be demon- strated. Dr. Flogel, in his paper already referred to (loc. cit.), takes the Blatta brain as a typical form, and describes its internal structure. Great stress is laid upon the persistent presence in all orders of insects of that peculiar median laminated structure, described by Dietl, which is now called by Flégel the central body “ Centralkérper.” In Blatta there is a pair of mushroom bodies in each hemisphere. The cylinder of fibres passing to the front of the brain is very large, and is termed the anterior horn “ Vorderhorn.’ The desctiption of the minute elements agrees with Dietl’s observations mentioned above. In the latter part of this paper the brains of various insects are described, which have been taken from the different orders, and a tabular scheme is given of ON THE BRAIN OF THE CGCKROACH, 345 the relations of these orders, based chiefly upon the degree of development of the mushroom bodies. Blatta (Periplaneta) orientalis. General form of the brain.—When the chitinous covering of the upper and front part of a cockroach’s head is removed, together with the tissues which he just within it, the brain, or supra-cesophageal ganglion, is displayed as a pearly white body, occupying but a small portion of the cavity of the head (fig. 1). In this view the brain is seen to consist of two rounded masses above, separated from each other by a deep median fissure. From the outer sides of these hemispheres, as they might be termed, the large nerves are given off to the eyes (op.). Below are two smaller rounded masses, marked off from the upper ones by a depres- sion, these are the antennary lobes (am/.), from the outer side of each of these a nerve passes off to one of the antennae. A side view of the head dissected so as to expose the brain (fig. 2) shows the latter to be placed very near the front wall, while the space behind it is occupied to a large extent by the muscles of the jaws. At first sight the only nerves given off from this upper division of the brain seem to be the optic and antennary nerves, but I have now been able to trace four other pairs ; these, however, are very small. (1.) On more than one occasion, when opening the head of a cockroach, I have observed a very delicate white fibre passing from the front surface of the brain towards the front wall of the head; but thinking it was merely a tra- cheal vessel, I had not troubled to trace its distribution. After seeing Dr. Flogel’s statement that a nerve passes out from the front of the brain on each side, in the region where I had noticed this white fibre, I searched again, and now had the satisfaction not only of finding the nerves in the position indicated (fig. 1 nws), but also of tracing them most clearly to those peculiar oval, silvery patches, which are situated on the front of the head, just above and within the antenne (ws.). It appeared to me that one of these nerves, before reaching the silvery patch, gave off a branch which passed round to the side of the brain, just above the optic nerve ; but I could not trace it upon the opposite side, and I failed altogether to see it in another specimen. (2.) Another nerve is to be found passing off from just underneath the antennary lobe on each side (figs. 1 and 2 anm.), and these I have been able to trace to the muscles of 346 E. T. NEWTON, the antennze, which lie within the head just below the base of the antennee. (3.) Upon each side of the brain, a little behind the an- tennary nerve, a third very small nerve may be found (fig. 2), the distribution of which I have not yet traced. (4.) The stomato-gastric ganglia join the brain at its back part (fig. 4 a. ség.). From the lower and back part of the brain on each side, the large pair of commissures (fig. 2 0. com.) pass downwards and backwards to the infra-cesophageal ganglia (inf. g.). From the front of each commissure a broad band of fibres arises, which passes forwards for a short distance upon the sides of the cesophagus, and then divides into two branches ; one of these curves forwards aud upwards to meet with its fellow of the opposite side in the frontal ganglion (fig. 2 fg.). The second branch appears hitherto to have escaped notice, it passes forwards and downwards (fig. 2 dv.), and the two may be traced into the labrum, as far as the round white spots, which are situated, one on each side, upon the inner surface of that appendage. The infra-cesophageal ganglia are situated quite close to the back part of the head, being only separated from the submentum by a thin band of muscles. The nerves arising from these ganglia are shown in figures 2 and 3. The majority of them were most easily traced when approached from the back. For this purpose, the head was fixed in wax with the front surface downwards, the submentum re- moved, and then the parts below gradually displayed. Fig. 3 is the result of careful dissections of numerous individuals. If the commissures passing into the head from the body ganglia be traced forwards, it will be found that, just within the foramen magnum, where they join the infra-cesophageal ganglia, a minute nerve is given off on each side (figs. 2 and 3 xf.), which appears to be distributed to the muscles in the immediate vicinity of the foramen. In one instance there seemed to be two or three of these minute fibres. With the exception of the nerves just mentioned, no fibres were to be found passing off from the hinder surface of these ganglia; at the lowermost angles the pair of nerves (Jm.) pass off, one to each side of the labium; each of these nerves at length divides into two, sending a branch into the inner and outer divisions of the labium. Immediately in front of each labial nerve, or perhaps arising from it, there is another very minute one, which passes outwards and is lost in the surrounding muscles. A little further forwards, on each side, a nerve is given off to the maxilla (mzx.). From ON THE BRAIN OF THE COCKROACH, 347 the base of this, and close to the ganglion itself, a minute nerve is given off, which, passing directly outwards, could be traced to the proximal part of the stipes. Further down the maxillary nerve divides into two, and then the outer division into two again, thus forming three branches, which no doubt supply the three distal divisions of the maxilla. From the front and lower part of the ganglia, two large nerves pass downwards and forwards, close together for some little dis- tance, and then diverging, each passes into the mandible of its own side. At the base of this nerve again, a minute fibre arises, as in the case of the nerves of the maxilla and labium, and this was found to pass into the mandible at its most proximal part. Although the distribution of the fine fibre accompanying the labial nerve could not be traced, it seems probable that it supplies the basal portion of the la- bium; and if such should prove to be the case, then each of the mouth appendages will be seen to be supplied with two nerves, a larger and a smaller one. At present I have been unable to trace any nerves or nerve into the lingua. The stomato-gastric nerves, as stated above, arise by two roots, one from each cesophageal commissure, which unite in the frontal ganglion. The single nervus recurrens (fig. 4 fn), passing back from the frontal ganglion (figs. 1 and 2 fg.), runs along the cesophagus under the brain, and is connected with the stomato-gastric ganglia, situated at the back of the brain. The most successful dissection of these ganglia which I have been able to make is represented in fig. 4, but this has been verified by several other preparations. It will be seen that the nervus recurrens becomes much thickened at the point where it joins, on each side, a short stem connected with the hinder end of an elongated, some- what spindle-shaped, ganglion. Each of these ganglia is connected posteriorly with a second oval ganglion, and ante- riorly a short bundle of fibres connects it with the back part of the brain. In one or two dissections I could trace these nerves some little way under the back of the brain, but failed to convince myself as to whether they joined the brain or not; however, in another dissection of a very large cock- roach, these nerves could be seen joining the back of the brain well underneath, but no nerve could be traced passing forward from this point. Neérvous filaments are given off from the posterior pair of ganglia; and in another prepara- tion fibres were seen to be given off from the anterior pair also. In the Sphynx moth, according to Newport (‘ Phil, Trans.,’ 313 E, T, NEWTON. 1834), these stomato-gastric ganglia are connected with the brain; and Leydig states that the same thing occurs In Dytiscus. Flégei states, on the authority of Kupftter, that this connectionisalso found in Blatta ; and, on tlre-same authority: they are said to send fibres to the salivary glands. Internal Structure of the Brain. The internal structures of the brain, which are described in the following pages, have been worked out chiefly by means of series of sections, cut in definite directions, but this has to some extent been supplemented by dissections. Brains hardened in osmic acid, after the manner adopted by Dietl, were found to be most satisfactory, but others hardened in alcohol and stained with carmine were very useful for comparison. The most instructive sections were those which have been called “frontal sections ;’ that is, cut as nearly as possible parallel with the front surface of the brain; the first section including portions of both the hemi- spheres and the antennary lobes. One brain, which had been hardened in osmic acid, was cut in this way into thirty- four sections, each about the -—,th of an inch in thickness, and from these I was enabled to construct the model already alluded to. From this series of section those have been selected for illustration which it was thought would best explain the various structures, and will be found repre- sented on Plate XVI. Some of the internal parts of the insects’ brain have received different names from different authors, and hence several names have in some cases been given to one and the same part. Dr. Flégel, evidently seeing the difficulty likely to arise from this loose nomenclature, has suggested certain terms which might be used by future writers on the subject. Most of these terms-would, no doubt, have been at once adopted ; but, unfortunately, they are given in German, and it would be necessary for other than German writers to render them in equivalent terms of their own language. IT would suggest, therefore, that we now, once for all, latinise these terms, and thus obviate this difficulty also. The mass of nervous matter found at the lower part in each hemisphere (marked ¢ in the accompanying figures), and called by Flogel the “ Balken,’ may be called the trabecula. That peculiar mass of nervous tissue passing off from the ¢rabecula, and ending abruptly on the front of the brain, termed by the same author ‘‘ Vorderhorn,” would then become the anterior cornu; but this name ON THE BRAIN OF THE COCKROACH. 349 cannot be adopted, as it is already in use for a region in the human brain, and would certainly lead to much confu- sion. L-ropose, therefore, to name this part the cauliculus {een figures). It will be convenient to call the hinder branch given off from the ¢rabecula (that is, the “ Hinterast ” of Flogel, and the “ Pilzsteil”’ of Dietl) the peduncle (p. in figures) in allusion to its being the support of the so-called mushroom body. It seems tome undesirable that this latter name should be altogether abandoned, seeing that it has been much used, and I propose, therefore, that each of these structures, taken as a whole, be known as a corpus Sungiforme, while the inner trough-like portion of it, called by Flogel the “ Becher,’ will become the caliz; as there are two of these on each side, they will be distinguished by the prefix ener or outer (tcx., ocz., in figures). And the calicular cells may then be distinguished according to the portion they occupy in the calz. The ‘ Centralkorper” will become the corpus centrale. I should prefer to retain the name of antennary lobe for that part from which the antennary nerve passes off, until we are more perfectly acquainted with the functions of the antenne. It is proposed, in the first place, to describe in a general way the series of sections, and afterwards to consider each part separately. ‘The first section consists very largely of the cortical cells of the hemispheres, but includes a portion of one of the antennary lobes, At the upper part on each side is tlie rounded end of the cauliculus. In section No. 2 (fig. 5), the cauliculus, which is strongly curved, occupies a large portion of each hemisphere; it is sharply defined from the surrounding parts, more especially from the mass of cells arching over it above, which are coloured yellow by the osmic acid. Fibres, arising from the middle line of the brain, are seen passing outwards and crossing the lower part of the cauliculus. In section No. 3 the first traces of the calices of the corpora fungiformia are seen as elongated patches above the cauliculus, and within the cellular cap. In section No. 4 the calices have increased in size. In section No. 5 the trabecule are seen for the first time, passing on each side from the lower end of the cazliculus downwards to the middle line. In section 6 (fig. 6) we have the first indica- tion of the peduncle. In the following sections these processes increase in size, while the cauliculi decrease; the calices also increase and become more and more deeply curved (fig. 7), until in 350 E, T, NEWTON. section 13 (fig. 8) the peduncles have reached and joined the outer calix on each side, the cauliculus having- almost disap- peared. In section 14 the peduncles have joined tie inner calices also, and this connection is seen in each section ‘a far as the 19th, the calices at the same time exhibiting their deepest curvature. In section 20 (fig. 9) the peduncle on each side has entirely disappeared, the ¢rabecula alone being seen in the middle line below. In the succeeding sections the ¢rabecule become gradually less, but can be traced as far as the 28th section. Passing back from the 18th or 19th section, the calices get less curved and smaller, and traces of them are last seen in the 25th section. The commissures to the infra-cesophageal ganglia are reached in the 18th section, and become larger and larger through the remainder of the series. The Trabecule with their Cauliculi and Peduncies.—The trabecula in each hemisphere commences abruptly in the 5th section, and is seen extending from the middle line below (where it abuts upon, but apparently does not join, its fellow of the opposite side) obliquely upwards and out- wards to join the lower part of the cauliculus (fig. 6). Passing backwards the ¢trabecula continues about the same size until it has received the peduncle, behind which point it gradually decreases (fig. 9), and is altogether lost before the back of the brain is reached (see figs. 15 and 17). Each cauliculus isa large mass of nervous matter, contin- uous with the outer part of the trabecula, the junction extending as far back as the hinder part of the peduncle (fig. 15). Seen from the front it curves upwards and out- wards, preserva a convex surface inwards, and a concavity outwards (figs. 5, 6, and 17). Its thickness from before backwards is greater than it is from side to side, and conse- quently it presents an oval figure in horizontal sections. The upper portion is truncated” by being closely applied to the under surface of the outer caliz, ile the inner convex surface is closely overlaid by the inner calzv. The line of demarcation between the calices aud the cauliculus is very distinct, and there seems to be no nervous connection between them. Above and in front this cawliculus extends to the front surface of the hemisphere, where it appears to be merely covered by the thin investing membrane of the brain. The peduncle, or stem of the corpora fungiformia, arises from the ¢rabecula by a wide base extending from the 6th to the 20th section. Its upper part is very much smaller than the cauliculus. In a front view the peduncle is seen to continue upwards the curve of the trabecula, and to present ON THE BRAIN OF THE COCKROACH, 851 a convex surface outwards (figs. 8 and 17). Quite towards its upper end the peduncle divides into two parts, one of which joins the outer (fig. 13), and the other the inner calix. With regard to the histology of these structures | am now able to give the following particulars :—The upper part of the peduncles, where they join the calices, shows a most definite fibrous structure even with a low power of the microscope, and this is seen extending downwards more or less distinctly as far as their junction with the ¢radecule. The trabecule themselves and the cawliculi present only a finely granular or dotted appearance unless examined with a high power. Under a ;'; immersion both these parts exhibit a fine reticulation, the meshes of which have, perhaps, a diameter of +~,35, of an inch, but they are extremely diffi- cult to define. The peduncles, with the same amplification, show a similar network, but not quite so fine, and the meshes are more elongated (fig. 14), especially towards the upper part, and it is this which gives it a fibrous appear- ance. It is, in fact,a bundle of fibres which freely anas- tomose with each other. The peculiar system of bent lines, mentioned by Flogel, is to be seen in horizontal or oblique sections, where the cauliculi join the trabeculae, and in frontal sections where the latter join the peduncles (figs. 7, 8 p.). The manner in which these remarkable nervous structures are connected with the other parts of the brain and nervous system have yet to be established. The only parts at present known to be connected with them are the corpora fungiformia. The nervous fibres which surround them on all sides seem to be merely in close apposition, and not to be really united with them. Towards the back of the brain, where the ¢rabecule become reduced in size, they also become less and less clearly separated from the surrounding parts, and it seems possible that there is some connection in this region. Possibly some of the fibres which extend down- wards from the large cortical ganglionic cells at the back of the brain (fig. 10) join the trabeculae, but I have been unable to trace any such connection. One would naturally expect that such large and important parts of the brain, as the trabecule and its appendages, the cauliculi, peduncles, and corpora fungiformia, would be very obviously connected with the rest of the brain, or, at least, that we should find fibres extending from it into the esophageal commissures. Corpora fungiformia.—There are two of these bodies in each hemisphere, an inner and an outer one, both extending from near the front almost to the back of the brain, Each 352 E, T, NEWTON. of these consists of a caliz (figs. 15, 16 ocx., tez.), and acap- like covering of small cells. Each caliz is, perhaps, best described as having the form of a trough, the sides of which are deepest in the middle and much shallower towards the ends, more especially towards the front. The inner caliz is rather larger than the outer one, and the two are closely applied to each other and covered by the mass of cells, which forms one cap over the pair of calices. The appear- ance presented by these bodies in frontal sections may be seen in figs. 0 to 10, but the general form will be best under- stood by reference to figs. 15 to 17, which represent those parts in the model already mentioned. The peduncles are connected with the calices a little behind their middle region, and where this takes place the calices have their greatest depth. When stained with osmic acid the calices become very dark and ordinarily appear in sections to be composed of small dark bodies, which, at first, might be mistaken for cells. Their inner surfaces, more especially near the peduncles (fig. 8), are covered with fine fibres, which run in the direc- tion of the peduncles. The small cells which fill the calices extend just over their margins both before and behind, as well as at the sides. They are stained a bright yellow by osmic acid, and are regarded by both Dietl and Flogel as being cells in which the protoplasm is so reduced that the nuclei only are visible. However this may be, they certainly seem to me to be of quite a different nature from the cortical ganglionic cells, from which they always seem to be sharply separated. The ganglionic cells, wherever they are clearly shown, are seen to possess not only a nucleus, but also a very definite nucleolus, whilst in the calicular cells I have failed to find any nucleolus, even in those larger ones which occupy the base or deepest part of each caliz. Very fine dark fibres are seen branching out and penetrating in between these cells, enclosing them, apparently, in a complete network. Passing inwards these fibres collect into larger branches, and these meeting at the walls of the caliz#, form a kind of festoons (fig. 6). In the neighbourhood of the peduncles these branches may be seen passing into the fibres of the inner walls which run down into the peduncles (figs. 8 and 12). Whether these fibres are wholly composed of nervous matter, or are to some extent accompanied by connective tissue, it is not easy to say. When extremely thin sections are examined with a high power, the ultimate structure of the calicular walls still remains obscure; but with care one can see that the fibres ON THE BRAIN OF THE COCKROACH. 300 forming the inner part of the wall anastomose freely, so as to form a network of broad fibres, with elongated interspaces having the appearance of cells. These fibres are intimately united with a similar, but much finer, network, which makes up the greatest part of the calicular walls. In the latter portion may be seen rounded transparent areas of very different sizes, and other irregular patches of a darker and granular substance. Corpus centrale.—The peculiar laminated arrrangement of nervous matter, described by Dietl in the bee and mole- cricket as a median commissural system, is called by Flégel the central body. This structure is not so clearly defined in my preparation of the cockroach as it is in the two insects just mentioned. In the series of frontal sections (34) from which this description is taken, the lamination of the central granular substance is first seen in the thirteenth from the front (fig. 8 ¢). Here the granular mass is indis- tinctly divided into four parts, and is surrounded by irregular cells and interlacing fibres; from the latter fibrous bands are seen passing upwards and outwards, some of which may be traced to the optic nerve. Below the granular mass, the cells are partly divided into groups by dark fibres passing down among them. In the 12th section only a small portion of the granular substance is seen, while the cells and fibres are more abundant and evident. In the 14th section the granular substance is clearly divided into six parts, which occupy nearly the whole width between the trabeculae. Below this the cells are beginning to give place to granular matter, and this shows some indica- tion of being divided into plates (fig. 11). Passing to the 19th and 20th sections, we find that in the upper portion the divisions of the granular mass have increased in number to twelve or fourteen, these divisions, however, are not so clearly marked off asin the more anterior sections. Above this there is a row of very transparent cells, and below there is little else than granular matter and fibres, from among which dark branches pass upwards, and dividing, separate the granular matter into its lamine. In this region fibres are seen passing off from the sides of the corpus centrale, and arching over the now reduced trabe- cule, extend in the direction of the esophageal commissures. The divisions of the granular matter are still to be traced in the 22nd and 28rd sections, and continue to occupy as great a width; notwithstanding this, the granular matter has almost entirely given place to cells in the 24th section. Throughout its length, the upper surface of the 854 E. T. NEWTON. corpus centrale is intimately connected by a network of fibres with the large mass of the ganglionic cells lying above them. But here, again, itis probable that connective tissue combines with the nervous tissue to produce the appearance presented by their sections. When the thinnest sections of the corpus centrale are very highly magnified, the fibres from the surrounding cells may be seen collecting together and forming the partitions which give this body its laminated appearance. ‘These partitions seem to be intimately connected with the enclosed granular matter, which itself gives evidence of being made up of a network of fibres; but this was not clearly shown. With regard to the general form of the corpus centrale, if we restrict this term to the laminated granular matter, it will be obvious, from what has been said above, that it has a broad truncated hinder end, and diminishes in size towards the front, the number of the lamine gradually increasing from before backwards. In frontal sections the upper surface is convex. The form of the lower surface will be best under- stood by reference to the figures (8, 11, 9). Anteriorly, it passes gradually into the cells lying below, which fill up the space between the trabecule. Posteriorly the granular substance occupies the whole of this space, and is, there- fore, pointed below. The sides are rounded. I find that Flogel’s description of the central body does not agree with my own observations, as given above; but this, to some extent at least, is due to our sections not being in precisely the same plane, and partly, perhaps, to our not including in the description exactly the same parts. With regard to the number of the lamine (Flégel mentions eight), my specimens show most clearly an increase in number, from before backwards, as above described. Optic ganglion—I have not yet had the opportunity of working out the structure of this complicated apparatus so fully as it deserves, and can only in the present paper give the following brief description. Horizontal sections show two lenticular bodies placed obliquely and surrounded by a thick layer of cells. The nerve fibres passing from the front and back parts of the eye cross before entering the first and smallest lenticular body; they cross again on leaving it, and before entering the second and larger lenti- cular body. Between the latter and the brain the fibres cross for the third time. After entering the hemispheres some of the fibres may be seen passing forwards into the mass of cells lying in front of the corpus centrale ; while there are indications of others passing across near the ON THE BRAIN OF THE COCKROACH, 355 back of the brain to join similar fibres from the opposite side. Antennary lobes —These are large in the cockroach, and in sections present very much the same structure as Dietl has described in the bee. _In whatever direction they are cut they present the appearance of being composed of a number of large cell-like bodies, with fibres passing in between them in every direction, the whole being surrounded by a layer of large ganglionic cells. The interior cell-like bodies are found throughout the mass of the antennary lobe in the cockroach, whilst in the bee they are confined to the periphery. When examined more closely the large cell-like bodies are found not to be cells, but to be made up of a delicate network of fibres, as described by Dietl and Flégel. It was only with a high magnifying power (1; immersion) that this network could be traced, and then it was by no means distinct; the interspaces still appeared granular, with minute translucent spots. The spaces between the rounded bodies are seen to contain cells as well as fibres; indeed, it may be said that the cortical ganglionic cells extend into the interior cf the lobe. The fibres anas- tomose with each other, and are continuous, on the one hand, with the fine network of the rounded bodies, and, on the other, with the antennary and commissural nerve-fibres. The ultimate structure of these rounded bodies is very similar to that of the calices, but it is coarser, and many of the transparent spaces are much larger. From the inner side of the antennary lobe fibres are given off, which pass under the ¢radecule, and unite with similar fibres from the opposite side. Posteriorly, this lobe is con- nected with the cesophageal commissure, and certain fibres may be traced inwards to the cells around the corpus centrale. Just below the antennary lobe, and in the cesophageal commissures, close to the spot where the nerve to the frontal ganglion arises, there is a small rounded body, composed of dots of granular matter, not unlike that of the calices. This body seems to be the homologue of a similar structure in the mole-cricket described by Dietl. I have not been able to trace its relations to the surrounding parts. Cortical ganglionic cells.—The brain is almost surrounded by these large cells, excepting above, in the region occupied by the corpora fungiformia, and, probably, they do not extend over the cauliculi. These ganglionic nucleated cells vary much in size, some of them being very large, and they 356 TIMOTHY RICHARDS LEWiS. are not stained so bright a yellow by the osmic acid as the cells of the corpora fungiformia. These ganglionic cells are very numerous at the back of the brain (fig. 10), they extend inwards between the corpora fungiformia and the so-called primary lobe; they fill the median groove above the corpus centrale (figs. 5 to 10); they are found in abundance in the angles and spaces between the antennary lobes and the rest of the brain ; and, as already mentioned, they form a thick layer over the optic ganglion. These cells appear to be surrounded by connective tissue, which also seems to form a large part of the fibrous bands, seen passing off from them, especially at the back part of the brain (fig. 10), but at the same time the granular cell contents may be seen in some instance, ex- tending into the fibres (fig. 13). These fibres at the back of the brain (fig. 10) pass downwards almost vertically to the region of the ¢rabecule and then turn outwards. The cells of the median sulcus are connected, as we have seen, with the fibres and cells of the corpus centrale, and just in front of the trabecule large fibres pass down in the middle line into a peculiar fan-like arrangement of cells found on the base of the brain in this region. The Microrvuytss which have been found in the Boon and their Renatron ¢o DisEasz.! By Timorny Ricuarps Lewis, M.B., Surgeon, Army Medical Department ; Fellow of the Calcutta University. (With Plate XVII.) Berore entering on a minute description of the microscopic organisms found in the blood which are nore allied to plants than to animals, it will be advantageous to consider to what special subdivisions of the vegetable kingdom these bodies seem to belong. No small amount of confusion has arisen from want of a clear knowledge of this point, especially on the part of strictly medical writers who have discussed the subject of the connection of disease with vegetable parasites. Nageli, in his remarkably suggestive work,” recently published, has placed this 1 Forms Part I of the Memoir on the Microzoa and Microphytes of the Blood, which appears as an Appendix to the ‘ Fourteenth Annual Report of the Sanitary Commissioners with the Government of India.—[Ip. ] 9° 2 «Die Niederen Pilze in ihren Beziehungen zu den Infectionskrankheiten und der Gesundheitspflege,’ Miinchen, 1877. MICROPHYTES FOUND IN THE BLOOD. 357 matter in a very clear light, and, being an authority of the first rank, especially on the botanical phase of the subject which forms the text of this paper, his statements on this particular point are worthy of exceptional attention. The forms of plant- life which have been recognised as having been more or less closely associated with changes in living animal substances are the lower kinds of fungi. These Niageli separates into three groups: (1) Moulds, characterised by branched, segmented, or unsegmented filaments ; (2) Sprouting fungi, yeast cells of various kinds, consisting of more or less oval corpuscles, which multiply by means of sprouts from their surfaces ; and (3) Cleft-fungi or Schizomycetes—minute spherical or oval bodies, which are multi- plied by fission only, and which sometimes remain isolated, at others form unbranched rows (rods, threads, &c.), but only occa- sionally present a cubiform aspect. To this group the dacterium, vibrio, vibrio-bacillus, spirillum, &c., belong. Nigeli writes: “I have separated the lower forms of fungi into three groups. On account of many practical questions it is of importance to know whether specific differences really exist, or whether we have to do with the same species under different conditions, it being possible that different fungi possessed a ‘mould,’ a ‘sprout,’ or a ‘cleft’ form. This is a subject which has formed the subject of debate during the last sixteen years, and many observations have been recorded for the purpose of showing that, as a result of cultivation experiments, the most opposite forms have been seen to pass from one into the other.” With reference to this point Nigeli forcibly points out the falla- cies to which men are liable in drawing conclusions from cultiva- tion experiments, and says that, in many respects, it would be as rational for the husbandman to assert that the weeds in his field were the result of transformations which the seed of wheat pre- viously sown had undergone. No one would believe such a state- ment, for the seeds of weeds are largé enough to be easily recog- nised, whereas the germs of fungi are of microscopic dimensions —those of the schizomycetes often barely distinguishable with the highest powers ; hence the assertions which have been made regarding the transition of such minute organisms cannot easily be controlled. ‘ Moreover,” adds Niigeli, “ the rapid and super- ficial observer has a marked advantage; the conclusions which he has arrived at as the result of a so-called uncontaminated cul- tivation [Recnkultur] of a single week’s duration may require years of labour on the part of the thoroughly competent observer to disprove.” This question has of late years been investigated by many dis- tinguished savants, notably by Professor de Bary, of Strasburg. He has shown that a fungus undergoes but a very limited and VOL. XIX.—NEW SER, AA 058 TIMOTHY RICHARDS LEWIS. well-defined range of changes. Niigeli, as the result of his own observations, declares that, of the three groups of fungi above referred to, the “ mould” and “sprout” fungi are closely related, but that, with one exception, they have not yet been seen to pass from one form into the other. The exception consists in the cir- cumstance that a certain species of mucor (a mould) has been observed to present the two forms of vegetation—the filamentous and the sprouting. Fission-fungi, however, do not stand in any genetic relation to either of the other two groups, for they ‘neither give rise to other fungal forms nor originate from them ; hence it is distinctly laid down that they do not germinate. In this it would appear that Niigeli and de Bary are completely in accord. Niigeli states that it is comparatively easy to demon- strate that the “ fission” group of fungi are not transformed into other groups, from the circumstance that members of the latter, when present in a solution, are killed at a lower temperature than those of the former. ‘This peculiarity, however, renders it much more difficult to show that other (the “mould” and “ sprout”) groups do not give rise to schizomycetes, as it is im- possible so to isolate the germs of other fungi as to exclude this group. Eventually, however, he was able to satisfy himself on this point also by first destroying by heat all the fungal forms in a nutrient solution, and then permitting a mould to extend its filaments into it. In this way he kept some solutions thus pre- pared for four years with only the “ mould” form of vegetation in them. Of the foregoing three groups of organisms the only one which requires to be dealt with here is the third—the schzzomy- cetes—as it is only the various forms of this group of the fungal family which have hitherto been unequivocally found in the blood. Another distinguished botanist, Professor Cohn of Breslau, has also paid much attention to these low forms of life, and has recently devised a new system of classification for them, taking as his starting-point the dictum that the schizomycetes are more closely related to a/g@ than to fungi, and suggests, therefore, the term schizophyte for the family, in place of the name given by Nigeli, which has been in general use hitherto. Cohn has, moreover, advanced the supposed differences in physiological properties manifested by some of these low growths as sufficient rounds for assigning to them specific designations. In doing this Niigeli says Cohn has given expression to a generally enter- tained opinion, and one especially affected by the medical pro- fession; but he (Niigeli) is unacquainted with any facts in support of such a view. “TI have,’ he writes, “during the last ten years examined some thousands of different forms of MICROPHYTES FOUND IN THE BLOOD. 359 fission-yeast cells, but (excluding sarcive@) I could not assert that there was any necessity to separate them into even two specific kinds.”1 On the other hand, there is not sufficient evidence to show that all the forms constitute in reality but one species.” Notwithstanding the circumstances that the schizomycetes assume, within certain limits, such different aspects (and the experience of such an authority as Niigeli on such a matter as this cannot be lightly set aside), it is, nevertheless, convenient, irrespective of any particular theories, that terms should be adopted which will suffice to distinguish the leading forms. Dujardin suggested three terms for the group: (1) dacterium, (2) vebrio, and (8) spiridlum. Notwithstanding the great advance which has been made in our knowledge of these organisms since the date of Dujardin’s classification, there still remains very much to be done before anything like a satisfactory settlement of the matter can be accomplished. It will, therefore, perhaps be Fig. 1.—Various forms of fission-fungi—Schizomycetes. a, Spherical bac- teria (Bacterium punctum) ; 8, Elongated bacteria (Bacterium termo) ; c, Vibrions; p, Bacilli; ©, Spirilla. x 600 diam. better for the present to accept these simple terms, especially as, with very trifling modifications, they are sufficient to indicate all the forms which have hitherto been found in the blood. The following brief description will suffice to explain what forms of this group of organisms are comprehended by the terms adopted : 1, Spherical bacteria—minute, vitalised bodies, barely visible with the highest powers (fig. 1, a); 2, Hlongated bacteria—almost equally minute cylindrical rods (fig. 1, 8); 3, Vibriones—short, undulating filaments manifesting somewhat screw-like movements (fig. 1, c); 4, Bacilli, or Vibrio-bacilli—fine, short filaments, indistinctly jointed, which, when they attain considerable length, are sometimes described as Jeptothrix filaments (fig. 1, D); 5, 1 Op. cit., p. 20. 2 Op. cit., p. 22. Also A. de Bary, ‘Ueber Schimmel und Hefe,’ 1869. 360 TIMOTHY RICHARDS LEWIS. Spirilla—fine, more or less flexible, spiral filaments, which manifest well-marked screw-like movements (fig. 1, £.). It may be mentioned, in passing, that examples of each of these forms may commonly be detected in the muco-salivary fluid from the mouth of healthy persons. The question which naturally suggests itself now is: Under what condition are organisms of this character found in the blood ? M. Pasteur states that the blood in health is absolutely free from anything of the kind. His words are: “ Le sang d’un animal en pleine santé ne renferme jamais d’organismes microscopiques ni leurs germes.”! Dr. Beale, on the other hand, says, “ The higher life is, | think, interpenetrated, as it were, by the lowest life. Probably there is not a tissue in which these germs are not ; nor is the blood of man free from them.” It may appear strange that the satisfactory settlement of a question, apparently so very simple, should hitherto have proved impossible, and that many eminent observers should have arrived at opposite conclu- sions regarding it. It may be that to a certain extent both classes of observers are in the right, for if, as is not uncommonly affirmed, very many of these extremely minute organisms con- stantly find their way into the circulation through the lungs and pass through the walls of the intestinal tract along with the food (that dacteria pass with fluids through a membranous septum is a well-ascertained fact, as also that they will pass through porous earthenware and other filtering media), it is very certain that their existence in the plasma of healthy blood is of comparatively short duration. This point has been definitely settled as the result of observa- tion by many pathologists, and Dr. Douglas Cunningham and myself were, some years ago, able to satisfy ourselves that dacteria, vibriones, bacilli, and so forth, very speedily disappear from the liquor sanguinis, even when introduced into it during life in considerable numbers. Out of forty-nine experiments which were conducted by us with a view of clearing up this matter, twelve of the animals were examined within six hours of the organisms being injected into the veins, and dacteria, &c., were found to be present in seven, or at the rate of about 58 per cent. ; and out of thirty examined within twenty-four hours, their presence was detected in fourteen, or 47 per cent.; whereas in nineteen specimens of blood derived from animals which had been inoculated in this manner from two to seven days previously, these bodies could only be detected in two of them, or a little over 10 per cent., just 6 per cent. higher than we had observed to be the case out of a number of ordinary preparations of 1 ‘Comptes Rendus,’ t. Ixxxv, p. 108; 16th July, 1877. 2 ‘Disease Germs,’ 1870, p. 64. MICROPHYTES FOUND IN THE BLOOD, 3861 healthy blood which we had examined.! It is however, obvious that though it is possible that the blood may be constantly replenished with a greater or less number of these organisms, yet they do not accumulate to any great extent therein, and it may be safely affirmed that their presence in appreciable numbers is, judging from experience, incompatible with a state of perfect health. It will hereafter be seen that the same remarks does not hold good as regards parasites of, apparently, animal nature. It may be affirmed, further, that in certain diseased conditions microphytes are very generally present, though perhaps not invariably, nor is their number coincident with the gravity of the malady. Omitting the cases in which these organisms have been found associated with disease in insects (on account of the diffi- culty of isolating and clearly identifying such organisms as are found in the blood in these cases from those found in the tissues generally), it may be stated that it has been clearly established that one or other of the forms of fission-fungi have been found in the blood in two diseases, viz. in charbon, mat de rate or splenie fever, and in recurrent fever. M. Pasteur has recently main- tained that a third should be added to the list—septicemia ; and, still more recently, a fourth has been added by Dr. Klein, namely, the disease commonly known as. “ typhoid fever” of the pig. These matters have, during the last few years, received great attention from thoughtful members of the medical profession, and probably at the present time no subject of a scientific character is being more closely investigated. The importance of thoroughly sifting the evidence on which the interpretations which have been placed on the significance of such organisms in theblood can scarcely be over-rated, seeing that, should the view now commonly advanced, prove to be correct, the theory and practice of medicine would be radically affected and, possibly, the future action of the State with regard to disease be materially modified. Before making an attempt to institute such an exami- nation, it may be well to refer briefly to the more salient cireum- stances which have conduced to make the present doctrine of the causative relation to disease of these low forms of plant-life so attractive to botanists and to the medical profession. “The foundations of the germ theory of disease in its most commonly accepted form,” writes Dr. Charlton Bastian,’ “ were laid in 1836 ‘ Cholera: “A Report of Microscopical and Physiological Researches,”’ Series, 1, Appendix A, ‘Eighth Annual Report of the Sanitary Commis- sioner with the Government of India,’ 1872. 2 Paper read before the Pathological Society of London, April 6th, 1875. ¢ ee vol. i, p. 501, 1875. ‘British Medical Journal,’ vol. i, p. 469, 1875. 362 TIMOTHY RICHARDS LEWIS. and shortly afterwards. The discovery at this time of the yeast- plant by Schwann and Cagniard-Latour soon led to the more general recognition of the almost constant association of certain low organisms with different kinds of fermentations. But it was not till twenty years afterwards that Pasteur announced, as the result of his apparently conclusive researches, that low organisms acted as the invariable causes of fermentations and putrefactions ; that such changes, in fact, though chemical processes, were only capable of being initiated by the agency of living units.” These observations and the interpretations applied to them very rapidly caught the ear of the medical profession, as from a very early period in the history of medicine the supposition that disease was propagated by means of a ferment—a leaven—had taken a firm hold. Previous to the publication of M. Pasteur’s observations, a physico-chemical theory had been almost universally acknow- ledged as sufficiently explanatory of the phenomena manifested by certain classes of disease. ‘This was notably the case with regard to the fermentation-doctrine of Liebig, a doctrine the truth of which he strongly advocated until the day of his death in 1873, and which, somewhat modified as a result of later researches, is still upheld by some of the most eminent chemists of our own time. The leading features the “ vital” and the “ physico-chemical ” theories of fermentation’ have recently been lucidly summarised by Mr. C. T. Kingzett in a paper read before the Society of Arts. With regard to the first of these views and in illustration of them this chemist remarks: ‘“ When a solution of sugar is exposed to the action of healthy yeast it suffers a change; the atoms comprised in its molecules are broken up and rearranged into new forms, which are recognised as alcohol and carbonic dioxide. Glycerine and succinic acid are also formed at the expense of the sugar, but the lactic acid which generally accom- panies alcoholic fermentation is considered as proved to be due to the presence of a ferment distinct from, but accompanying, the 1 ¢Certain organic compounds, when exposed to the action of air, water, and a certain temperature, undergo decomposition, consisting either in a slow combustion oroxidation by the surrounding air, or in a new arrange- ment of the elements of the compound in different proportions (often with assimilation of the elements of water), and the consequent formation of new products. The former process, that of slow combustion, is called Hrema- causis or Decay ; the latter is called Putrefaction or Fermentation—putre- faction when it is accompanied by an offensive odour, fermentation when no such odour is evolved, and especially if the process results in the formation of useful products ; thus, the decomposition of a dead body, or of a quantity of blood or urine, is putrefaction ; that of grape-juice or malt-wort, which yields alcohol, is fermentation. —‘ Watt’s Dictionary of Chemistry,’ vol. ii, p. 624, 1872. 2 * Journal of the Society of Arts,’ March, 1878. MICROPHYTES FOUND IN THE BLOOD. 363 yeast. . . . The fermentation alluded to is regarded as a particular instance of a biological reaction, manifesting itself as the result of a special force residing in organisms ; or, in other words, fermentation is essentially a correlative phenomenon of a vital act, beginning and ending with it. On this hypothesis, where there is fermentation there is organisation, development, and multiplication of the globules of the ferment itself. The instance quoted above is by no means solitary; it is exemplary of many other changes, induced by the same or other fermented matters in media suitable for their growth and reproduction. Thus, we have mannitic, lactic, ammoniacal, and butyric fermentations, besides many others, all of them having one feature in common, viz. the reproduction of the ferment.) It has not yet, however, been satisfactorily ascertained—a very essen- tial matter to be settled before the foregoing interpretation of fermentative processes can be established—that the several processes are the result of the action of specifically distinct growths. Baron Liebig vigorously opposed this doctrine, and Mr. Kingzett suggests, probably ignored the influence, of vital action to too great an extent ; all that was required in his opinion for inducing the fermentative change was contact with matter which was itself undergoing change. Mr. Kingzett thus sums up the physico-chemical doetrine of fermentation as advanced by Liebig :—Mechanical or other motion exerts an influence on the power which determines the state of a body. Thus, a crystal of sulphate of sodium, a speck of dust, or grain of sand, when dropped into a saturated solution, say of sulphate of sodium, may determine the entire crystallisation of the fluid. Or, again, when fulminates of silver and mercury are tickled lightly by a feather or glass rod, they suddenly explode with violence. A still better instance is the reaetion which occurs between peroxide of hydrogen and argentic oxide; these sub- stances, when mixed, give rise to the production of metallic silver and free oxygen ; the peroxide of hydrogen, being un- stable, is constantly undergoing decomposition from the moment of its formation, and this decomposition results in the pro- duction of water and free oxygen; immediately, therefore, that this change comes into contact with oxide of silver, it gives to that body the same tendency to change. A.— The Organisms found in the Blood in Splenic Fever. On the assumption that certain diseases which are undoubtedly communicable by inoculation, and several others commonly be- 1 «Journal of the Society of Arts,’ March, 1878. 36 4 TIMOTHY RICHARDS LEWIS. lieved to be communicable in other ways, are in reality the result of a ferment of some kind, the various theories of the causation of the fermentive processes have always proved anattractivesubject of study to the more thinking section of the medical profession. As already stated, the physico-chemical theory of Berzelius, and subsequently of Liebig and his followers, was very commonly accepted as fairly sufficient in connection with the etiology of disease, so long as it was favorably received by the majority of the chemists of the time ; but latterly Schwann’s views, as expounded and ampli- fied by Pasteur and others, have undoubtedly taken the lead. Probably no single incident has tended so much towards en- listing the attention of the medical profession to it than the pub- lication of the experiments of M. Davaine, which went to show that minute organisms were, to a greater or less degree, constantly present in the bodies of animals which had died of the disease known asmalignant pustulein man—the “I/idzbrand” of Germany ; the *‘ charbon”’ of cattle and pigs, and “mal de rate’’ of sheep, in France. The terms “splenic fever” or “splenic apoplexy,” “anthracoid disease,” &c., are commonly adopted in England in describing the affection. Birch-Hirschfeld' states that the organisms found in this affection were first described by Brauell in 1849 and by Pollender in 1857; but, undoubtedly, it was M. Davaine’s researches which were the means of draw- ing serious public attention to the matter. In August, 1850, M. Davaine, in conjunction with M. Rayer, published an account of these organisms, describing them as minute filamentous bodies, motionless, and about double the length of the diameter of a red blood-corpuscle. M. Pasteur? maintains that the time just men- tioned represents the date of the first publication of the exist- ence of these bodies in charbon, but this idea is manifestly erroneous. Instigated thereto by the publication of M. Pasteur’s re- searches (which went to show that butyric fermentation was not, as believed, due to an albuminoid body in process of spontaneous decomposition, but to vibriones, which presented the greatest resemblance to the ‘‘corps filiformes,’ found in the blood of animals dying of charbon) M. Davaine returned to the subject in 1863 and 1864. The organisms were at first considered by M. Davaine to be bacteria; but finding in certain cases that the filaments or rods varied in length, he modified the name, and they have consequently been, until lately, commonly desig- nated dacteridia. At this period it was supposed that they were more closely related to animals than to plants. He satis- 1 Schmidt’s ‘ Jahrbiicher,’ Band elxvi, 8. 205, 1875. j 2 « Ktude sur la maladie charbonneuse ;” par MM. Pasteur et Joubert. ‘Comptes Rendus,’ t. Ixxxiv, p. 900, 1877. MICROPHYTES FOUND 1N THE BLOOD. 365 fied himself that they were found in the blood during life ; that they developed in this fluid and not in the spleen; in fact, he had been able to transfer the organisms to animals whose spleen had been removed. He also ascertained that bacteridia are not found in feetal blood, although the blood of the mother and of the placenta was crowded with them.’ ‘The disease was found to be communicable with the food by mixing with it some of the tissues of diseased animals; the effects were less rapidly induced, but the blood became equally affected with bacteridia. He refuses to accept the doctrine of identity of the poison of septicemia and charbon, on the grounds (1) that the - symptoms produced by inoculating animals with putrefying blood are not constantly the same, and that bacteridia do not develop in the circulation of the affected animal; (2) that ani- mals which have swallowed fragments of putrefied tissue rarely died; and (3) that animals which had swallowed fragments of the fresh tissue of animals which had died of septicaemia had been in no way affected. He therefore concluded that the active principle of septicemia was not regenerated in the animal economy, as in the case of charbon, the latter in fact being a virus and the former a pozson.* In the following number of the ‘ Comptes Rendus’ (p. 429), MM. Davaine and Raimbert announce that they had demon- strated the existence of bacteridia in a man affected with pustule maligne, the excised pustule having contained a great number.® Portions of this pustule-tissue having being introduced beneath the skin of some animals, the latter succumbed, and after death their blood was found to contain a considerable number of bacteridia. Such, in a few words, were the observations which drew the special attention of pathologists to this question, and gave marked impetus to the doctrine of disease germs. Since this time very many observations have been recorded, but those of the past two or three years have been particularly valuable from the circumstance that distinct parts of the subject have been taken up by observers peculiarly qualified to deal with the different phases of the extremely complex phenomena which come under 1 «Comptes Rendus,’ t. lix, p. 3938, 1864. 2 Loe. cit., p. 396. As will subsequently be seen, some of these conclu- sions are no longer tenable. 3 Dr. Crisp writes: ‘As I described in my work on the spleen (1852), dogs, cats, ferrets and pigs, that ate the flesh of these animals, died in a short time, and men that flayed the oxen were affected. In 1832 M. Barthelemy inoculated sheep from the blood of sheep that died of splenic apoplexy, and the inoculated animals died in from thirty-six to sixty hours.’ —A footnote to the remarks made regarding the ‘Germ Theory,’ at the Pathological Society, 24th April, 1875. 366 TIMOTHY RICHARDS LEWIS. notice. In the first instance, notice will be taken of the principal observations which are considered to give support to MM. Davaine and Pasteur’s views. In 1875 Professor Ferdinand Cohn published the result of his examinations of these organisms, and having pronounced them to be dacilli, suggested that they should bear the name Bacillus anthracis’ This term has been generally adopted in Germany and England, as, notwithstanding the theory implied in both words, it is convenient to have some such brief designa- tion. Cohn’s figure of this bacillus is reproduced (fig. 2), as a Fie. 2.— Bacillus anthracis, obtained, after death, in the blood of an ox which had died of splenic disease. (After Cohn.) x 600 diam. graphic representation from the hand of so accomplished a my- cologist is of special value, and will serve to aid in forming an estimate of the relation of these organisms to others found under other, though somewhat similar, conditions. In 1876 an important contribution to our knowledge of these organisms was published by Dr. Koch, of Wollstein (Posen), who had had excellent opportunities of studying the disease.? Koch had observed that several of the statements and conclusions of M. Davaine had been called in question.. Some observers had been able to induce fatal charbon by inoculating animals with bacteridial blood without obtaining any bacteridia? in the blood of the animal thus affected, although the latter (bacteridia- free) blood had also induced the disease, and, moreover, given rise to bacteridia in the third animal, although none had been present in the second. Others, again, maintained that the disease was not due solely to contagion, but was, somehow, dependent on the soil, seeing that the disease was only endemic in moist, swampy districts, valleys, and sea coasts ; and that the mortality was greater in rainy years, and especially during August and September, months in which the temperature of the soil reached its highest. These circumstances could not be ex- 1 Cohn’s ‘ Beitrage zur Biologie der Pflanzen,’ Band i, Heft. 8, 1875. 2 Cohn’s ‘ Beitrage,’ Band ii, Heft. 2. MICROPHYTES FOUND IN THE BLOOD. 367 plained on Davaine’s supposition that the organisms, retaining their vitality for a long time in dry air, were conveyed by air currents, or that inoculation was effected by insects, and so forth. Koch’s experiments lead him to believe that Davaine’s explana- tion of the mode of propagation of the disease is only partially correct. He found that bacteridia-staves were not so hardy as Davaine had supposed, Blood which contains only rods will retain its property in the dry state for but a few weeks, and when moist only for a few days. How, therefore, could the contagion remain dormant in the soil for months and years? If bacteridia had anything to do with the matter, it must be assumed that during some stages of their development they were inert, or that, as Cohn had suggested,' resting spores were formed which had the power of retaining their vitality for a long time, and of giving rise anew to bacteridia. The existence of such spores is what Dr. Koch believes he has been able to demonstrate. As this question is a very important one, it is necessary that the evidence adduced should be submitted to careful examination. The experiments of Davaine and others were repeated, mice having been found to furnish the most satisfactory results. The tail was seized, and a small portion of its skin being abraded, a drop of the fluid containing the bacilli was placed in contact with the small wound. Such inoculations proved to be invaria- ~bly fatal when fresh material was used. In order partly to ascertain whether the bacilli passed into some other form by successive inoculations, and also to provide himself with a constant supply of fresh material, he inoculated one mouse after another, the last mouse supplying the material for its successor, until eventually a series of twenty inoculations had been con- ducted ; consequently twenty crops of bacilli had been cultivated without any marked change in their character being noticeable.? The pathological results were always of the same character—en- larged spleen, and motiondess, translucent bacilli (fig. 3). The latter in mice were more numerous in the spleen than in the blood, but different animals showed different results as regards their distribution in the tissues—the blood of inoculated rabbits, for example, being often so free from them as to be traced with difficulty, though the spleen and glands contained plenty, whereas in guinea-pigs the number of bacilli in the blood was often so great as to equal, if not exceed, that of the red blood- corpuscles. On adding a little of the spleen affected with bacilli to per- fectly fresh aqueous humour and subjecting the preparation to a temperature of 35-37° C. for from 15 to 20 hours, the bacilli 1 Cohn’s ‘ Beitrage,’ Band i, Heft. 3. 2 Davaine had conducted a similar series of inoculations. 368 TIMOTHY RICHARDS LEWIS. became elongated to from twice to eight times their original length, and gradually still further imcreased, till more than a hundred times this length (fig. 4). Some of the filaments now were finely granular, and, here and there, dotted with strongly Fig. 4. Fic. 3.—Bucillus anthracis from the blood of a guinea-pig. Translucent bacillus-rods, undergoing segmentation. Blood-corpuscles are scat- tered throughout the field. (After Koch.) x 650 diam. Fic. 4.—Bucillus anthracis from the spleen of a mouse after a three-hour mom etge ” in a drop of aqueous humour. (After Koch.) x 650 iam. refractive molecules, which are believed to be the desired “ rest- ing-spores.” Very soon nothing remained visible but these ‘spores,’ as the filament appeared to undergo solution, but the persistence of the arrangement of the former in rows is suffi- ciently marked to identify them. ‘They will remain unaltered in this state for several weeks. It will be remarked that the interpretation placed on the cha- racter of these refringent bodies clashes with what is so strongly maintained by Nageli, who, as mentioned already, declares em- phatically that the group of lower organisms to which these be- long multiply so/e/y by fission. It is, therefore, of greater impor- tance to note precisely what the facts adduced are, to prove that in this special instance germinating spores are produced. Dr. Koch states that the fact of his being able to induce splenic fever, together with a plentiful crop of bacilli in the blood, with fluid in which not a trace of bacillus filament is any longer to be found—the minute refractive corpuscles alone remaining, is proof sufficient to show that the latter are in reality spores, and not products of disintegration MICROPHYTES FOUND IN THE BLOOD. 369 merely. _ Cultivation-experiments were, however, also under- taken, and it was found that in the course of 3 to 4 hours the development of these bodies could be observed under suitable conditions. On careful examination each ‘ spore’ is seen to be an oval-shaped body embedded in a translucent substance which appears to surround the former in a ring-like fashion, but is seen to be in reality spherical, on being rolled over. This sub- stance loses its spherical form and becomes elongated at one end in the direction of the long axis of the contained ‘ spore.’ The latter remains at one end, and very soon the translucent tube assumes a filamentous aspect and, contemporaneously, the ‘spore’ becomes less refringent, pale, and small, and possibly breaks down into fragments, until it eventually disappears com- pletely. Dr. Koch’s figure (fig. 5), representing the various stages of the supposed germination process, is reproduced. ie § 98 ° ° = Q Oo ‘ ne e wo @ So Cie) a Wie 4 Fie. 5. Fie. 6. Fic. 5.— Bacillus anthracis: Germination of the spores (after Koch). x 650 diam. Fic. 6.— Bacillus anthracis: Germination of the spores (after Coln). x 1650 diam. This interpretation of what occurs is made particularly im- portant from the fact that it has been resorted to very lately by M. Pasteur to account for the circumstance that, although it has been proved, beyond all reasonable doubt, that splenic fever, together with blood-bacilli, may be induced by inoculation with virus after the total destruction of the filament-bacillus which the morbid material had contained, yet because the ‘ spores ’ remained (it would seem that they are considered nearly inde- structible) the virus had retained its property—the ‘ spores’ in fact being the virus. Professor Cohn favoured Dr. Koch with a sketch of the same developmental process as seen under a higher power. This figure is also reproduced for purposes of comparison. Koch suggests that probably the ‘spore’ consists of a strongly refractive sub- stance, probably oil, which is enveloped by a thin layer of pro- toplasm—the latter being the substance capable of germination, and the former, perhaps, serving as nourishment during the ' Loe. cit., p. 289. 370 TIMOTHY RICHARDS LEWIS. germinating process. The foregoing, according to various writers, represents the complete cycle of development undergone by Bacillus anthracis. Davaine, it will be recollected, had found that animals eating diseased tissues mixed up with their food became themselves affected, and he believed that the spread of the disease could thus to some extent be easily accounted for. Koch, on the con- trary, finds that animals very susceptible to infection by inocu- lation, such as mice and rabbits, may devour such a mixture with impunity. Attempts to inoculate two dogs, a partridge, and a sparrow, proved fruitless. The latest contribution which has been made towards this in- quiry is from the pen of Dr. J. Cossar Ewart.1 Dr. Ewart confirms Dr. Koch’s experiments in many points, and his descrip- tion of the development of the rods into filaments [fig. 7, and — = = ne ————— FT om) —S— SS SSNS Soo. ——— Fic. 7.—Bacillus anthracis : Rods undergoing segmentation and lengthen- ing into a filament (after Ewart), x ? diam. fig. 8 (a)] corresponds with that of previous writers; but his description and figures of the germination of the ‘spores’ are Fic. 8.—Bacillus anthracis: (a) A filament containing spores, becoming granular at one end, and showing transverse lines between the spores ; (b) part of a filament containing a spore in process of division ; (c) shows the different stages through which a spore passes in its develop- ment into a rod (after Ewart). x ? diam. totally different. ‘The spores,” writes Dr. Ewart, “ when free, according to previous observers, at once grow into rods, and, according to Dr. Koch at least, the rod is formed out of a gela- tinous-looking envelope surrounding the spore. My observations 1 ‘Quarterly Journal of Microscopical Science,’ April, 1878, p. 161. MICROPHYTES FOUND IN THE BLOOD. 371 lead me to believe that the spore does not always at once grow into a rod, but that it divides into four sporules by a process of division, in which the envelope as well as the spore takes part. This division I have seen beginning before the spore escaped from the filament [fig. 8 (b)], and that it is not a degeneration is certain, for | have watched the sporules thus formed lengthen into rods [fig. 8, (c)]. Dr. Koch states that the rods are deve- loped from the gelatinous-looking capsule, and not from the bright, shinmg spore. From what I have seen I think there can be no doubt whatever that the capsule takes no active part during the formation of the rod. ‘The sporule thus slightly elongates (fig. 9), and then from one of its poles an opaque © Ss © © Fic. 9.—Baeillus anthracis: A sporule developing into a rod (after Ewart). x ? diam. process appears, which, as it slowly lengthens, pushes the cap- sule before it, as it would an elastic membrane. The capsule, as this stretching goes on, becomes at last so thin and transparent that it can no longer be distinguished from its contents.” It is, I think, extremely probable that MM. Cohn and Koch may suggest as an explanation of the discrepancy between their description and figures and those given by Dr. Ewart, that the latter has described and figured the spore (or conidium) of a totally different plant, accidentally present; and MM. Niageli and de Bary would (in the absence of exact data as to size), in all probability pronounce the germination depicted in the last figure reproduced as being that of a conidium of one or other of our ubiquitous moulds. Like Koch, Dr. Ewart found that mice could be fed with splenic-disease material mixed with their food without any evil effects ensuing, and that ‘the spores may be found in the ali- mentary canal of such mice, sometimes as if in process of develop- ment into rods and filaments.” With reference to the last remark, a person constantly engaged in microscopic work may question whether it is possible to distinguish these glittering free ‘spores’ from the myriads of other glistening molecules found in the intestinal canal of all animals. Contrary to the results hitherto obtained and published by others in support of the view that Bacillus anthracis is itself the 372 TIMOTHY RICHARDS LEWIS. specific virus of splenic fever, Dr. Ewart finds that the filaments are not absolutely motionless, but that, at certain stages, they manifest active movements, so that the strongest argument which has hitherto been adduced in favour of these organisms being a peculiar species has disappeared.1 Dr. Ewart found also that the bacilli of splenic fever in guinea- pigs differed in size from similar bodies in affected mice, the bacilli of the former being always longer than those of the latter. It was also ascertained that the bacilli and their ‘spores’ were killed after being boiled for only two minutes, the fluid after this treatment becoming absolutely inert. A like result ensued on similar fluid being subjected to a pressure of twelve atmospheres of oxygen.” Considering the position into which the supporters of the germ doctrine had latterly been driven by their anta- gonists, the announcement made above regarding the instability of the ‘spores’ will be unwelcome, and none the less so by the circumstance of its having been made by one of their warm adherents. A few years ago Mons. P. Bert announced that he had ascer- tained that compressed oxygen rapidly kills all living beings and tissues. He had paid special attention to ferments in the in- vestigations which he had conducted, and had satisfied himself that such of the fermentation processes as were dependent on living matter were immediately suspended when subjected to this influence, whereas those fermentations which were due to some material in solution, such as diastase, pancreatine, myrosine, emulsine, &c., were in no way affected. He then turned his atten- tion to certain poisons secreted in health or disease in animals, the venomous secretion of the scorpion, vaccine matter, &c.3 The venom of the scorpion, whether liquid or dried and re- dissolved in water, resisted the action of compressed oxygen, as was expected, since it owes its activity to a chemical substance akin to the vegetable alkaloids. Fresh liquid vaccine matter was submitted for a week to the action of compressed oxygen, and still retained its power undiminished. Pus from a case of glanders, after beg subjected to similar treatment, rapidly killed a horse inoculated with it; hence M. Bert infers that the 1 Since this was written I have observed that A. Frisch had on three occasions seen independent movements of the staves of Bacillus anthracis in blood obtained immediately after the death of the animals, ‘ Centralblatt fiir die wissensch, Medicin,’ April 7, 1877, p. 247. 2 Since this was in type a note has appeared in the ‘ Comptes Rendus,’ 15th July, 1878, which confirms this observation. M. Felz found that compressed oxygen, if applied for a sufficiently long period, killed the “germs” as well as the “ vibrions” of septic solutions. 3 ‘Comptes Rendus,’ t. Ixxxiv, p. 1130, May, 1877. MICROPHYTES FOUND IN THE BLOOD. 373 active principle im vaccine and in glanders is not a living being or living cell. M. Bert then exposed some blood from a case of splenic fever (in which were myriads of bacilli) to the action of compressed oxygen, and found that, although the blood had been exposed in very thin layers, it had retained its virulent properties intact, as was proved by its having killed several guinea-pigs inoculated one from the other, but the blood of these animals did not contain bacilli. He submitted some other charbon blood containing numerous bacilli to further examination. Some absolute alcohol was very cautiously added to it, drop by drop, until the volume of the original fluid was quadrupled, and the mixture thus obtained was filtered. The coagulum, well washed in alcohol, was rapidly dried im vacuo. A fragment of this dried material, on being in- serted beneath the skin of a guinea-pig, killed the animal in less than twenty-four hours. ‘The blood obtained from this animal proved fatal to another guinea-pig, as also to a dog. Inocula- tions were conducted from one animal to another, but the virulent blood of none of these animals contained bacilli. M. Bert went still further. A watery solution was prepared (by exhaustion) of the alcoholic precipitate, and having satisfied himself that this liquid contained the active principle in solution (for, on the addition of more alcohol, a white flocculent precipi- tate was induced), three successive inoculations of guinea-pigs were conducted. ‘This rather severe treatment, however, had manifestly diminished the virulence of the material, as inoculation was not successful beyond the third animal, and the material proved too weak to kill a dog. From these observations M. Bert concluded that the blood in splenic fever contains a toxic and virulent principle, which resists the action of compressed oxygen, and can be isolated in the same manner as diastase. These observations had been published in an abbreviated form previous to their being submitted to the Academy.1 M. Pasteur had promptly taken up the subject, and, as he himself was not versed in the medical and veterinary arts, had associated himself with M. Joubert, of the Collége Rollin, for the purpose of more satisfactorily dealing with the matter. Their joint paper? was published a few weeks before the publication of the details of M. Bert’s experiments ; it was their remarks, indeed, which led to the latter being published. They obtained charbon blood, and made numerous cultivations of it, transplanting it from vessel to vessel or from animal to animai. Outside the body it was found ' *Comptes Rendus de la Société de Biologie,’ January, 1877. 2 “Comptes Rendus,’ t. Ixxxiv, p. 900, April, 1877. VOL. XIX.—NEW SER. BB 374 TIMOTHY RICHARDS LEWIS. that almost any fluid adapted to the nourishment of minute organisms was suitable to the cultivation of the bacilli“ one of the best and most easily obtained in a pure state being urine made neutral or slightly alkaline.” In this way, it is affirmed, poisonous bacilli could be prepared by the kilogram, if required, in the course of a few hours. When the material was. filtered, the clear fluid was found to be inert, even though from ten to eighty drops were taken, whereas a single drop of the same un- filtered proved fatal to the inoculated animal ; hence it is inferred that the organisms were left behind on the filter, and were the cause of their death.' The foregoing paper was followed by another in July, 1877,* by the same authors, in which it is stated that they had repeated M. Bert’s experiments, and found that he was perfectly correct as to the destruction of the bacilli, and of the poisonous property of charbon blood at a certain stage under the influence of com- pressed oxygen, and that, too, even with but a moderate amount of pressure; but that when the bacilli had proceeded to the formation of spores they withstood the heat of boiling water, the prolonged action of absolute alcohol, as also the influence of compressed oxygen (= 10 atmospheres for 21 days). The ‘spores, therefore, are most remarkable organisms, seeing that they withstand influences which are destructive to every other form of vegetable or animal life. True, “ invisible germs” are accredited with this marvellous power, but, as yet, these ‘spores’ are the only wisedle bodies for which such persistent vitality has been claimed by eminent authorities. Now, how- ever, that it has been shown by Dr. Cossar Ewart that they are not more exempt from “the tendency to death” than other organisms of a like kind, seeing that they can neither withstand the action of compressed oxygen nor boiling, it is probable that MM. Pasteur, Koch, and their adherents will apply the doctrine 1 A similar result was obtained by M. Onimus, but the interpretation was very different. M. Onimus found that if the blood of an ox, horse, or person suffering from “typhoid fever,’ be placed in a dialyser, and the latter placed in distilled water at a temperature of 35° C., a prodigious quantity of organisms would appear, identical in appearance with those in the putrefying blood. But whereas all the animals which were inoculated with a drop of the blood contained in the dialyser died in a short time, those which were treated with the dialysed material (though crowded with organisms) were unaffected. The same result followed when putrefying blood from a rabbit. was subjected to similar treatment. Hence M. Onimus infers that the poisonous material is an albuminoid substance, and therefore not dialysable (‘ Bulletin de la Académie de Médecine,’ March, 1878. Cited by M. Ch. Robin in ‘Legons sur les Humeurs,’ p. 251, 1874). Clementi and Thin, Schmitz, Bergmann, and others, have obtained more or less similar results. 2 «Comptes Rendus,’ é. Ixxxv, p. 101. MICROPHYTES FOUND IN THE BLOOD. 375 at present fashionable, and aver that, though the “ spores” may be dead, their invisible germs still live, and, under favorable circumstances, will reappear. With the foregoing explanation as to the difference between bacilli and their ‘ spores,’ in their power of withstanding agencies ordinarily destructive to life, M. Pasteur was able to convince his former pupil, M. Bert, of the cause of the discrepancies in their respective results, and this the more readily from the cir- cumstance that when a little of the dried alcoholic precipitate of charbon blood was placed in urine the fluid not only manifested virulent properties, but also gave rise to a plentiful crop of bacillus-filaments identical in appearance with those which had existed in the-blood previous to its being treated with alcohol. It does not seem to have occurred either to M. Pasteur or to M. Bert that under certain circumstances the addition of any dried organic substance to suitable urine would probably be fol- lowed by acrop of bacillus. Indeed, it not unfrequently happens that such a crop may be obtained without intentionally adding anything. Whilst this paper was in preparation it occurred to me to place such a sample of urine under different conditions as to temperature, &c., and to carefully observe the results. Some specimens were made slightly alkaline, others made neutral, and others again left untouched. All the specimens were kept at temperatures varying from 35° to 40° C. (95° to 104° Fahr.), and it was found on the following day that nearly half the speci- mens were coated with a thin pellicle consisting of bacilli in all stages of development, the spore-stage included, notwithstanding that considerable care had been taken to keep out particles and foreign matter of every description. These appearances are familiar to all who have devoted much attention to microscopic studies. It need hardly be added that organisms thus obtained would produce no effect on animals if freed from the decomposed urine. B.— The Vegetable Organisms in Septicemia. The belief that septicemia is produced by organisms belonging to the lower group of fungi has had almost as many adherents as the doctrine just considered, and the literature in support of it is even more extensive. ‘The virus secreted by animals suffering from this disease is, when transferred to the circulation of other animals, as fatal in its results as that of charbon. It can, more- over, be transferred from animal to animal 1 almost indefinitely. 1 Observations illustrative of this have long been known. Hamont, for example, in 1827, injected matter from a gangrenous abscess from one horse to another, and from the inoculated horse to a second horse, and found 376 TIMOTHY RICHARDS LEWIS. The symptoms induced by such inoculation are frequently so very like those witnessed in splenic fever that it is often impossible satisfactorily to distinguish them. ‘There is, however, this marked distinction, namely, that whereas the presence of organ- isms in the blood before death is, to a greater or less extent, the rule.in what is known as charbon, it is the exception in septic poisoning. The fluid exuded into the peritoneal cavity, and frequently also into the pericardial sac, is peculiarly prone to give rise to the development of various forms of fission-fungi, and the abundance with which they are sometimes found very shortly after death has given rise to the doctrine that they were the initiatory agencies by which the fatal results were produced. The publication of Panum’s experiments, which went to show that the active morbid principle in such fluids could not by any possibility be vitalised, served for a time to diminish the popu- larity of such views, but they have since been revived again and again, and never with a greater show of circumstantiality than has recently been the case in a paper submitted by MM. Pasteur and Joubert before the French Academy. ‘This paper, notwith- standing that it exceeded the prescribed length, was, on account of the importance attached to it by the Academy, published x eaxtenso." The paper deals in the first place with M. Bert’s experiments, and explains the discrepancies between M. Bert and M. Davaine’s results in connection with charbon-blood, as already described. But it goes further than this. It will be recollected that the toxic material submitted to experiments by M. Bert did not give rise to bacilli in the blood, although its virulent properties were most marked, and the possibility of inoculating the disease from animal to animal without bacilli was quite as manifest as in charbon-fluid crowded with them. Similar results have been published by many observers ; for imstance, MM. Jaillard and Laplat did so very soon after Dr. Davaine’s paper was read in 1863, and formulated their conclusion in this wise : (1) charbon is not a parasitic disease ; (2) the presence of bacteridia is to be considered as an epi-phenomenon, and not asa cause; and (3) that the fewer bacteridia the blood in sang de rate contains, the more virulent it is. It thus became common to hear of cases of charbon with, and cases without, bacteridia. Davaine has also shown that the virulent properties of the virus of septicemia manifest a marked increase when transferred from animal to animal. -It had been found that after twenty-five such successive inoculations, a millionth, and even a billionth or that death resulted with pretty much the same symptoms in both cases.— MM. Coze and Feltz in ‘ Les Maladies Infectieuses,’ p. 58, 1872. 1 *Comptes Rendus,’ t. Ixxxv, p. 101, 16th July, 1877. MICROPHYTES FOUND IN THE BLOOD. 377 trillionth, part of the original poison was sufficient to produce death. Rabbits were found to be very susceptible ; guinea-pigs somewhat less so. Rats were found to be capable of resisting a considerable quantity. It was also observed by Davaine that decomposing blood lost its virulent properties when exposed to the air in a few days; out of 27 animals inoculated with 1 to +i,th of a drop of blood, which had stood from 1 to 10 days, 12 died, whereas out of 26 animals inoculated with like material which had stood from 11 to 60 days only 1 perished.? M. Pasteur, bearing in mind the difference between bacilli of charbon and their ‘ spores’ as regards tenacity of life, determined to ascertain whether a similar condition did not exist in septi- cemia. Three animals which had died of charbon were examined —a sheep, dead 6 hours; a horse, dead 20 to 24 hours; and a cow, dead over 48 hours. The blood of the sheep, which had only recently died, contained charbon-bacteridia only ; that of the horse bacteridia, together with “vidrions de putréefaction ;”’ whereas that of the cow contained only “ vibrions ” of the kind last mentioned. Inoculations with the blood of all three animals were followed by death. The autopsies (conducted immediately after death) of the guinea-pigs which had died after inoculation with material from the two last-mentioned animals, revealed extensive inflam- mation of the muscles of the abdomen and limbs, with accumu- lations of gas here and there, the liver and lungs discoloured, the spleen normal in size, but often diffluent, the blood of the heart not coagulated, although this characteristic was more evident in the liver—quite as evident as in any case of charbon. Strange to say, writes M. Pasteur, the inflamed muscles contained mobile “vibrions ; ” these were still more numerous in the serosity of the abdominal cavity, and some of them were of great length? A drop of this fluid would rapidly kill an inoculated animal, but ten or twenty had no effect after it had been filtered. The ‘vibrions’ are not found in the d/ood till after or very shortly before death, and such blood is said to manifest no virulent properties if taken direct from the heart without contamination with the tissues outside it. ' “Ynoculation de la matiere septique,” ‘Bulletin de l’Académie de me ey. ovember, 1872, January, 1873; cited by Birch-Hirschfeld, loc. Cit;, Pelifox 2 M. Pasteur, on noticing this condition, asks why it is that a circum- stance so general in deaths of this kind had hitherto escaped notice ; and replies to the query, that it was doubtless owing to the attention of previous observers having been devoted solely to the blood. It seems strange that M. Pasteur’s specially selected col/aborateur, and adviser in medical matters, did not inform him that this very appearance was about the best known of all the phenomena characterising septic poisoning. 378 TIMOTHY RICHARDS LEWIS. The movements of these “‘ vibrions ” were stopped on subjecting them to the action of compressed oxygen, but they were not killed, because on coming into contact with the oxygen they were transformed into corpuscles-germes, the ‘spores’ of Dr. Koch. This, it may be remarked in passing, is a novel and rapid method of producing reproductive elements in plants. 7 Not only do these ‘ vibrions” of septicaemia withstand the action of compressed oxygen, or rather become transferred by its action from perishable filaments to apparently imperishable cor- puscles-germes, but they, like the ‘spores’ in charbon, also with- stand the action of absolute alcohol. Hence, M. Pasteur infers that septicemia, as well as charbon, is caused by organisms—the parasite of the former being mobile, but that of the latter not. It will be more convenient to analyse these results hereafter. c.—Vegetable Organisms in Pneumoenteritis—*< Typhoid fever” of the Pig. In February of the present year Dr. HE. Klein, F.R.S., brought before the Royal Socicty a portion of the result of an experi- mental inquiry (which had been conducted for the Medical Officer of the Local Government Board) into the etiology of a disease sometimes described as typhoid fever of the pig, also as hog plague, mal rouge, red soldier, and malignant erysipelas. Dr. Klein, however, proposes to show that the disease is not typhoid fever, nor anthrax, but an infectious disease of its own kind, which he proposes to call ‘‘ infectious pneumo-enteritis ”’ of the pig (Pxeumo-enteritis contagiosa).1_ ‘The disease appears to present considerable pathological resemblance to septicaemia and to charbon, except that, as regards the latter, the fresh blood does not, as a rule, contain any foreign matter, and in most instances does not possess any infectious property. Of five animals inoculated with the fresh blood, one only was affected, but the specimen of blood which produced this retained its activity when closed in a capillary tube for several weeks. The peri- toneal exudation, however, always contains the virus in an active state, and solid lymph obtained from such an exudation will, if dried at about 38° C., prove active. This accords pretty closely with what has usually been observed in septiceemia. Inocula- tion can also be effected by means of portions of diseased lung, intestine, or spleen, as also with the frothy sanguineous exudation in the bronchi, and infection may take place when the virus is introduced directly into the stomach. 1 «Experimental Contributions to the Etiology of Infectious Diseases with special reference to the Doctrine of Contagium Vivum,” ‘ Quarterly Journal of Microscopical Science,’ April, 1878, p. 170. MICROPHYTES FOUND IN THE BLOOD. 379 It would seem that like organisms were discovered by Leisering sothe eighteen years ago, in apparently the same affection of the pig as that now described by Dr. Klein. Dr. Falke, in referring to the bacilli of splenic fever, and after alluding to the circumstance that Delafond had been able to induce the disease in other animals by inoculating them with zi)th of a drop of bacillus-blood, states that Leisering, in his ‘ Dresden Report’ for 1860, mentions that it is quite correct that such bacilli are found in the blood in splenic disease, but that he (Leisering) had also found that they were present in four pigs which had suffered from well-marked typhus (abdominalis) with ulcers in the intestines and swelled follicles! There is no indi- cation here that the bacilli seen by Dr. Leisering in pig-typhoid differed in appearance from those which he had seen in charbon ; on the contrary, he seems to assume that they are identical, and hence questions their being pathognomonic of the latter disease. Seven cultivation-experiments were conducted by Dr. Klein of the bacilli observed by him “ to prove that the virus can be cultivated artificially, z.e. outside the body of the animal.” Minute portions of peritoneal exudation were added to aqueous humour on a glass side in the usual manner and kept at tempera- tures ranging from 32° to 39° C. fora day or two; then a portion of the cultivated substance was transferred to a second slide with fresh aqueous humour, and so on till from a third to an eighth generation was reached. With material thus obtained seven animals were inoculated at different stages of the cultivations. All the animals are described as having been affected, but it would appear that death did not result. Doubtless further information as to the symptoms, &c., manifested by the inoculated pigs will be furnished when full details of the experiments are published. In the meantime, it may, however, be noted that it is not mentioned that bacilli were found in the blood of the inoculated animals. Dr. Klein states that the cultivated liquids proved, on micro- scopic examination, to be “ the seat of the growth and develop- ment of a kind of bacterium which has all the characters of Bacillus subtilis (Cohn) ”’—a figure of which, copied from ' “ Bericht iiber die Thierarzneiwissenschaft,” Schmidt’s ‘ Jahrbiicher,’ Band 114, p. 131. The original is as follows: ‘‘ Leisering sagt im Dresd- ner Bericht f. 1860, dass man nach den vorliegenden Beobachtungen mit Recht annehmen konne, dass im Milzbrandblute diese eigenthiimlichen Korperchen stets vorkommen. Er habe jedoch dieselben auch bei vier Schweinen gefunden, welche an ausgepragtem Typhus litten, der mit Darmgeschwiren, geschwelten Follikeln, blassgraulicher Farbung der Musklen und keiner Blutiiberfiillung der Kingeweide einherging.”—Cited by Professor Klob in his ‘ Pathologisch-Anatomische Studien tiber das Wesen des Cholera Processes,’ Leipzig, 1867. 3380 TIMOTHY RICHARDS LEWIS. Cohn’s paper, will be found on another page (lig. 13). The rods of the pig-dacit/us (fig. 10) are referred to as being thinner than those described by Cohn as occurring in hay solutions, also thinner than those of the Bacillus anthracis, and, unlike the latter (according to Davaine, Pasteur, Koch, and others), possess a moving stage.! It will, however, be recollected that Dr. Ewart has shown that Bacillus anthracis may also manifest very active movements. Under favorable circumstances the filaments grow into leptothrix-like filaments (fig. 12) just as other bacilli are known to do. Fre. 10. Ines IT dite, 1). Fie. 10.—The Bacillus of infectious Pxewmo-enteritis of the pig, cultivated in aqueous humour of rabbit, showing spores germinating into rods, isolated rods, and series of rods. Fig. 11.—F rom a similar specimen, as in fig. 10, at a later stage ; most of the rods have grown into long filaments. Fic. 12.—Showing the formation of bright cylindrical spores in the fila- ments at a later stage. The drawings are represented as the objects appear when seen under a Zeiss’s F objective, and Hartnack’s III eye-piece, fitted to a Hartnack’s small stand (after Klein). “Jn these filaments,” writes Dr. Klein, “highly refractive spores make their appearance (fig. 12). These become free after the disintegration of the original filamentous matrix. The fully developed spores of our bacillus differ from those of hay-bacillus and anthrax bacillus by being more distinctly cylindrical and much smaller.” Ina footnote it is mentioned that in the figures accompanying Koch’s first paper in Cohn’s ‘ Beitriige’ (1876) ‘the spores are represented in many places as more or less 1 The letters A, B, used in the original figures (as given in the ‘ Micro- scopical Journal’), appear to have become accidentally transposed by the lithographer, as what is referred to in the text under “ A, Bacillus of infec- tious Pueumo-enteritis of the pig, cultivated in agueous humour, showing spores germinating into rods, isolated rods, and series of rods,” evidently refers to B in the plate, and not to the figure marked A. MICROPHYTES FOUND IN THE BLOOD, 381 spherical in shape ;” but if the very valuable micro-photographs of these bodies accompanying Koch’s subsequent paper! be referred to, it will be found that the ‘ spores” are very decidedly of a long-oval form. The pig-bacillus ‘spores’ have according to Klein ‘along diameter of 0:0005 mm., whereas those of anthrax =0°0015—: 002 me eS At first,” ae Dr. Klein, “ I misin- terpreted the spores, regarding them as a kind of micrococet, and only after repeated observations have I succeeded in tracing them through their different stages of development.” Unfortunately Dr. Klein has not detailed the grounds on which this very important statement is based, nor are figures given. It can scarcely be supposed that any of the figures in the plate are intended to represent the germination of a particular spore. As this distinguished observer well knows, it is not what takes place before the supposed germination, or after it, which has been the subject of debate for so many years in connection with the development of the schizomycetes, but the act itself. None of the figures furnished by Dr. Klein present any resemblance to Dr. Ewart’s germination-figure (fig. 9) m which the process is unmistakably depicted, but some of them are somewhat like those of Koch (fig. 5); on the other hand, Dr. Klein writes regarding the conclusions of the observer who first ventured to pronounce these bodies in Bacillus anthracis to be spores, “ I entirely differ from Dr. Koch with regard to the mode of germi- of the spores of bacillus.” The points of difference are matters of secondary moment, and ueed not be specially referred to here. Dr. Klein concludes his paper thus: ‘ Seeing that splenic fever, pneumo-enteritis, and specific septicaemia possess a great affinity in anatomical respects, and seeing that in splenic fever and pneumo-enteritis there is a definite species of bacillus,—the difference of species being sufficiently great to account for the differences in the two diseases—we may with some probability expect that a/so the third of the group, viz. specific septicaemia, is due to a bacillus, This, however, remains to be demon- strated.” Dr. Klein, therefore, believes that whilst the evidence adduced by himself in support of the cause of pneumo-enteritis in the pig being a bacillus is sufficient to warrant a positive statement in the affirmative, that adduced by Davaine, Pasteur, and others in favour of a like cause for septiczemia is not. 1 Cohn’s ‘ Beitrage,’ Band ii, Heft. 3, Taf. xvi, 1877. 382 TIMOTHY RICHARDS LEWIS. p.—The Vegetable Organisms in the Blood in Recurrent Fever. There is one other disease in which vegetable organisms have been found in the blood, namely, recurrent fever (/edris or Typhus recurrens). In this affection also the organisms belong to the lower fungi-group, the schizomycete—that is to say, the fungi which multiply by cleavage, in contradistinction to the groups which multiply (1) by sprouting or (2) by germination. ‘The fission-fungi, however, present themselves in this disease in a different form from that witnessed in the preceding, anthracoid, class of affections. In the latter the organisms recognisable range from the spherical bacterium to the bacillus or vibrio- bacillus form—the bacillus being by far the predominating form ; but in recurrent fever the representative of the schizomycetes is a spirillum—a form of the fission-fungi which, so far as I am aware, has not hitherto been detected in any of the anthracoid affections referred to in the preceding pages. We owe the discovery of this organism in the blood to Vir- chow’s former assistant, the late Dr. Obermeier. ‘They were found in the blood and also in the mouth of persons suffering from this form of fever, and minutely described by him in 1873.4 It would appear that this observer had already seen them as far back as 1868. In all the cases observed by him they were present in the blood during the height of the fever, but were absent during the remission or intermission, as the case might be; nor were they observed, except rarely, after the crisis. Obermeier describes them as fine fibrine-like threads, equal in length to the diameter of from 13 to 6 red blood-corpuseles ; and manifesting screw-like, progressive movements, which may con- tinue from one to eight hours after removal from the body. The inoculative experiments which he undertook, consisting of the injection of spirillum-blood of fever patients into the veins of dogs, rabbits, and guinea-pigs, proved abortive, nor was there any effect produced by the injection, by means of a subcutaneous syringe, of small quantities of such blood into the bodies of healthy persons. Obermeier’s observations as to the existence of the spirilla in blood in this kind of fever were speedily confirmed by numerous observers, and the negative results which followed his attempts at inoculating persons and animals likewise characterised the attempts of several who followed in his footsteps. Motschut- kowsky, however, states that, although he also had failed to inoculate animals, yet he had succeeded in inoculating persons 1 *Centralblatt fiir die medicinische Wissenschaften, No. 10, March, 18738, and in subsequent numbers during the same year. MICROPHYTES FOUND IN THE BLOOD, 383 with the blood of patients suffering from the fever, no matter whether it contained spirilla or not.! It was, however, soon found that whereas spirilla could generally be detected in cases of fever of this kind, nevertheless cases every now and then occurred in which perfectly competent observers failed to detect them in the blood from first to last, and this too in cases not a whit less severe than those in which the organisms abounded and which were under the care of the same observers during the same period. Some discrepancy exists in the results of different observers as to the presence of spirilla during apyrexia periods, as well as regards their absence during the height of the paroxysm ; Birch- Hirschfeld, for example, observed them two days after the crisis ;? and Laskousky, basing his observations on thirty-two cases, says that they increase contemporaneously with increase of tem- perature ;> whereas Heydenreich maintains that high temperature tends to destroy them—he having found that not only were they most numerous in the blood shortly before the fever was at its height, but that, also, outside of the body they would retain their movements longer in a room at 18° to 21° C. than at a higher tem- perature. He had been able to keep active spirilla in a prepara- tion from a week to a fortnight at this temperature, whereas the spirilla died in from 15 to 21 hours when kept at blood heat (87°—388° C.). At 40°—41° C. they were found to perish still sooner—namely, in from 4 to 12 hours.* Although, as above shown, they can be preserved alive for a comparatively long time outside the body, nevertheless, every attempt which has been made to ‘cultivate’ them has proved abortive ; no change has been observed to take place in them either in size or in number, notwithstanding that they have been ‘cultivated’ in media of various kinds and at different temperatures. E.— The relation of Microphytes to Disease. In the preceding sections the leading facts regarding the con- nection of living organisms with the occurrence of disease have been detailed ; it now remains to consider what grounds there are forbidding the adoption of the doctrine of a germ theory of disease ;—why, for example, we should not at once admit that splenic disease is caused by bacteria-rods, and that the aim of treatment should be the destruction of the vitality of those rods ; or that recurrent fever is cause by screw-bacteria, and such remedial measures resorted to as tend to destroy them. 1 Heydenreich, ‘ Ueber den Parasiten des Riickfallstyphus,’ 8. 88, 1877. 2 Schmidt’s ‘Jahrbicher,’ Band. exvi, S. 211, 1875. 3 Heydenreich’s ‘ Riickfallstyphus,’ p. 39. 4 Loe. cit., pp. 100 and 101. 384 TIMOTHY RICHARDS LEWIS. Before such views can serve as the basis of anything like rational treatment it must be shown :—(1) either that these or- ganisms, as ordinarily met with, are injurious when introduced into the animal economy ; or, (2) that the forms found in disease are in some respects morphologically different from those known to be innocuous—such a difference, at least, as Virchow suggests, as exists between hemlock and parsley.' With regard to the first point, it has been shown over and over again that all the representatives of the group of fission- fungi can be introduced into the system with the greatest im- punity. Not only is their complete imnocuousness practically put to the test by every individual at every meal, but observations have been published which have conclusively demonstrated that they may be introduced directly into the blood by injection into the veins, or indirectly, through the lymphatics in the subcu- taneous tissue, without the slightest evil consequences. These facts are so well known and generally accepted that it is not necessary to refer to special observations. With regard to the second question, however, diametrically opposite opinions are held—all the advocates of the germ theory, with very few exceptions, maintaining that the particularorganism, in the particular disease in which they are specially interested, is wholly distinct from all others; that is, if the organism happens to be anything more definite than a granule or molecule. The diseases which have been specially cited in the previous pages as being associated with microphytes may be divided, roughly, into two classes according to the form of the attendant microphyte —the septinous group, consisting of malignant pustule, septi- czemia, and the malignant erysipelas or ‘‘ typhoid ” of the pig, on the one hand, and a low form of fever commonly known as Typhus recurrent, Bilious remittent, &c., on the other. With reference to the organisms which have been found as- sociated with the first-named group, taking Malignant Pustule as the type, it is to be observed that M. Robin® in 1865 pro- nounced the bacteridia of Davaine to be identical with Leptothrix buccalis ; and the well-known botanist Hoffmann has stated his opinion that they do not differ from like bodies which appear in milk and in meat solutions. Ferdinand Cohn,* again, in his observations as to the growth of bodies of the same character in hay solutions, declares that the bacilli in the latter are identical in form and size with those found in splenic disease, and that the 1 “Die Fortschritte der Kreigsheilkunde, besonders im Gebiete der In- fectionskrankheiten,’ 1874, p. 34. 2 j57> of a drop of septiceemia-blood would kill a rabbit in 86 hours when inoculated by means of a lancet ; that the virulent property existed before the appearance of rod-bacteria; and that the pernicious character of the fluid ‘OQ. Bollinger, ‘Zur Pathologie des Milzbrandes,’ Miinchen, 1872. Quoted in ‘Schmidt’s Jahrbicher,’ Bd. clxxi, p. 205, 1875. 4.02 TIMOTHY RICHARDS LEWIS. became evident contemporaneously with the advent of very minute spherical bodies, the consequences, as Colin believes, of the altered character of the blood.1 It has been repeatedly demonstrated that the poisonous pro- perties of septinous blood and of other decomposing animal solutions gradually disappear towards the third or fourth day, a fact which is scarcely reconcilable with the doctrine that the poison resides in the apparently almost imperishable ‘ spores’ of the bacilli which existed during the earlier stages of decomposition. A like feature characterises the virus of splenic disease, of small- pox, and of syphilis. Hiller,? in summarising the results of filtration of septinous fluids, writes that the most decisive ex- periments have demonstrated that after filtration through finely porous material, such as charcoal, porous earthenware, compressed wadding, &c., until the fluids have been shown to be absolutely free from visible molecules of every description, they are, never- theless, still competent to induce all the symptoms which characterised their action before such filtration. These results Hiller says, were arrived at by Panum, Bergmann, Weidenbaum Wolff, Kiissner, and others. To the first-named of these observers belongs the merit of having contributed some of the earliest and most valuable ob- servations which have been, hitherto, recorded in connection with the nature of the poison existing in certain solutions of decom- posing animal matter. Panum’s researches were published so far back as 1855, but having originally appeared in Danish they had for several years been to a great extent overlooked. ‘They were brought more prominently into notice on their publication in 1874 in ‘ Virchow’s Archiv.’ In 18752 Dr. Cunningham and myself drew attention to these experiments, as we have found that the results of observations made by us, with a like object, based on a series of experiments which included the inoculation and dissection of about 170 dogs, were, in so far as they were come parable, almost in complete accord with those which had been obtained by this distinguished experimentalist. Panum found that the coagulmn produced by boiling a sep- tinous fluid was more virulent than the fluid itself. The principal facts demonstrated by him may be thus summarised :— (1)—That the perfectly clear fluid which may be obtained by filtering solutions of putrefying animal substances through several 1“ Nouvelles recherches sur l’action des maticres putrides et sur la septicémie.” ‘Bulletin de Académie,’ October, 1873; cited by Birch- Hirschfeld, 1. c., p. 174. aie pace Caan putrides Gift,” ‘ Centralblatt fiir Chirurgie,’ Nos. 10, 11, and 12, 1876. 8 ‘Cholera: Microscopical and Physiological Researches,’ Series TI. MICROPHYTES FOUND IN THE BLOOD, 403 layers of filtering paper would induce the characteristic symptoms of the same kind as the unfiltered material. (2)—That boiling such a fluid for even 11 hours would not materially impair its toxic properties. (3)—That although an alcoholic extract of sucha fluid proved to be inert, the virulent action of a watery extract of the same fluid was very intense. Panum therefore concludes that a fluid which can retain its specific property after being filtered, boiled, evaporated to dryness, and the residue digested in cold and in boiling alcohol, then re- dissolved and again filtered, cannot owe this property to living organisms of any kind. In 1865 Dr. W. B. Richardson showed that the sero-san- guineous fluid from the peritoneal cavity of a person suffering from pyzemia would communicate fatal disease from one animal to another in a direct series, and that the poison (designated “septine ”) which effected this could be made to combine with acids so as to form salts which retained the poisonous qualities of the original substance. A few years later (1868), Bergmann succeeded in obtaining apparently a similar substance and named it Sepsin.” This poison induced symptoms of a like character to what are induced by putrefying solutions, and was frequently even more fatal, in very small doses. Still it appears to reproduce symptoms exactly similar to the original material, in this respect differing slightly from Panum’s “ putrid extract,” which repro- duces the ordinary symptoms of septic poisoning without any modification whatever. To Pasteur and his adherents, who ascribe what may be almost termed supernatural powers of resistance to the “ resting spores ” of anthracoid and other diseases, the facts adduced in the fore- going paragraphs can carry but little weight. But another series of phenomena have been recorded which point in the same direction. It has been shown that the living tissues of the body will under certain conditions, when irritated by means of purely chemical irritants—such, for example, as a strong solution of iodine or liquor ammonia-—secrete a fluid which, when transferred from animal to animal, proves not one whit less virulent in its properties than an exudation which has resulted primarily from the introduction into the system of material which has swarmed with bacilli. Observations to this effect have been published by many observers, and Dr. Cunningham and myself have placed on record that we found a large number of bacteria in the blood of a dog which had died as a result of such chemical irritants. ‘ «The Lancet,’ April 3rd, 1875, p. 490. ? *Centralbl. f. d. medicin. Wissensch.,’ 1868, p. 497; cited by Dr. Arnold Hiller, op. cit. i aii 404 GLANDULAR EPITHELIUM AND DIVISION OF NUCLEI. These bacteria could not have been the cause of death, nor, most assuredly, could they have derived their origin from the liquor ammonia which had been resorted to to excite the inflammatory process. It would seem from these results that the living tissue elements of the body itself play a much more important part in the elaboration of septinous and allied poisons, than what has been of Jate ordinarily ascribed to them. Such, so far as I have been able to learn, are the main facts which have been recorded with regard to the microphytes of the blood in health and in diseased conditions. CALCUTTA; August, 1878. OBSERVATIONS on the GLANDULAR EPITHELIUM and Division of Nucier im the Sxin of Newr. By E. Kiem, M.D., F.R.S. (With Plate XVIII.) In number 17 of the ‘ Centralblatt f. med. Wiss.,’ 1879, I have described giant nuclei of the huge epithelial cells lining the large saccular glands of the skin—tail—of newt (Triton cristatus). I have shown that these nuclei, when examined fresh in aqueous humor of frog, show an exceedingly distinct netwotk of more or less uniform fibrils and trabecule ; owing to the large size of the nuclei their network can be seen in all its details even under a low power. Many of these giant nuclei show in the network of the highly refractive fibres and trabecule cylindrical or irregular accumulations corresponding to nucleoli, others are free of them. I have also shown that both the nucleoli, when they exist, and the fibrils and trabecule, possess vacuoles; and further, that on the warm stage the intranuclear network shows contraction, whereby the outline of the nucleus changes in a similar manner as in cells while undergoing amoeboid movement. Of the gland cells themselves I have mentioned that they likewise show amoeboid movement, in the course of which larger or smaller knobs are pushed out, which become with- drawn or constricted off altogether, and then move inde- pendently. These cells are also in other respects remarkable, viz. that they are capable of ejecting their nucleus (the above giant nucleus), and after this continuing their move- ment. Some of them are filled with discoid or spherical fat molecules of various sizes, and they are capable of ejecting GLANDULAR EPITHELIUM AND DIVISION OF NUCLEI, 405 with a sudden jerk the whole or part of their fat molecules and continuing afterwards their ameboid movement. The above giant nuclei vary considerably in size, the smallest being 21 by 22 mu (0:021 by 0°022 mm.), the largest 126 by 129 pw (0°126 by 0°129 mm). Their shape is very various, some being spherical, others oval or egg-shaped; the largest examples are oval and slightly compressed. ‘This latter condition is ascertained in vertical sections through the glands when the lining epithe- lial cells and their nucleus present themselves in profile view. The intranuclear network? contains fibrils of various thickness, either uniform or possessed of irregular thicken- ings, and larger or smaller trabecule. Different parts of one and the same nucleus vary greatly in this respect. The intranuclear network presents itself in its best form in the perfectly fresh and living nuclei, that is, in nuclei that on the warm stage (in blood or humor aqueous) show the amceboid movement. ‘Treated with reagents, the network is less distinct. Sections obtained of tail hardened with chromic acid or picric acid, or a mixture of picric acid and osmic acid, and subsequently stained in carmine or hema- toxylin, show in some of the nuclei a distinct network, in others it is not so easily perceived; but even in the best examples the network is incomparably less perfect and clear than in the fresh state under the above conditions. The arrangement of the network varies very much; it is either a more or Jess uniform reticulum, or the fibres of the peripheral part of the network are arranged in a transverse manuer, §0 as to give it the appearance of a “ basket,”’ or its fibrils and trabecule are more or less radiating towards a central point or central-line. Of great interest are those forms which consist of two nuclei joined by a broader or narrower neck through which the fibrils of the network of one pass into that of the other. When the gland cells possess two nuclei these are either completely separated or in the state just mentioned. The nuclei with this latter quality are generally the smaller examples. Some of the giant nuclei, both the smallest as well as the largest,in fresh as well as in hardened specimens, are possessed of several larger or smaller knob-like projections, whereby the outline becomes notched and the nucleus looks as if lobed. In figures 2,3, 4, 5, 6, and 7 I have represented several of * I purposely avoid the expression “ framework’’ (geriiste) used by Flem- ming, but use the term (intranuclear) network ; the former is bad, for the simple reason that the network is the chief and living part of the nucleus ; the term “ framework” (geriiste) implies a passive stroma. VOL. XIX.——-NEW SER. DD 406 DR. E. KLEIN. the more characteristic forms of these giant nuclei examined in the perfectly fresh state on the warm stage. Those in figs. 2, 3, and 6 show the basket-shaped arrangement of the intranuclear network. Figs. 4 and 7 are probably dividing forms. Fig. 7 had been observed on the warm stage, and it showed slight amceboid movements. The large thickenings, nucleoli, in figs. 2 and 3 contain vacuoles just like some of the broader trabecule of the network. The interstitial or interfibrillar substance of the intra- nuclear network is, in the fresh state, quite homogeneous, but not fluid, as can be readily ascertained by applying pressure to the preparation. The limiting membrane becomes then indistinct, and the nucleus, as a whole, greatly flattened ; the parts of the reticulum are then seen embedded in a distinct homogeneous matrix, the refractive power of which is higher than the fluid menstruum, but lower than the reticulum. After hardening bits of tail in chromic acid (¢ per cent.) or picric acid (two or three parts of saturated solution of picric acid and one of water) and staining the sections in carmine or hematoxylin, the interstitial substance appears slightly stained in some, more deeply in others. In the first instance, the intranuclear network appears in all its delicate details; in the latter, it is difficult to ascertain the fibrils of the network, and sometimes it even looks as if it were altogether absent, the whole nucleus being composed of a uniformly and deeply stained interstitial substance. If bits of tail be treated with osmic acid (especially in the shape of a mixture with picric acid), and the sections be stained in hematoxylin, the interstitial substance appears uniformly and finely granular, and hence greatly interferes with the distinctness of the network. The epithelial cells lining, or, rather, filling the large saccular or tubular glands situated in the tissue of the tail and opening hy means of a very narrow canal through the epidermis on the free surface, are of a very huge size, and of a nature different from what they have been represented by Leydig (‘Archiv f. mikr. Anat.,’ Band. xii., p. 210). This observer describes them (of Coectliaand Salamandra maculosa) as composed of (a) the cell proper, viz. a protoplasmic portion containing the nucleus, and (0) a frothy excretion attached to the former; the cell proper is placed against the membrana propria of the gland sac, whereas the latter is directed towards the duct. I find the cells filling the gland-sacs in the tail of newt considerably differing from this description. In some glands GLANDULAR EPITHELIUM AND DIVISION OF NUCLEI. 407 the outlines of the individual cells cannot be distinguished ; in others they appear of the nature as represented in fig. 1 of Plate XVIII, viz. of various sizes; their shape is either cylindrical or, more commonly, truncated and conical, with their base situated on the membrana propria. Some appear uniform, others consist of (@) a transparent, apparently finely granular substance, forming about one half of the cell ina longitudinal direction ; (6) the other half is less transparent, being filled with coarse, highly refractive particles. In sections of hardened specimens (especially picric acid specimens) stained with hematoxylin or carmine the former is seen to be an exceedingly dense network of very minute fibrils,} whereas the latter contains, in the meshes of a network of curved and twisted fibrils, real granules and particles of various sizes. The nucleus is situated in many instances in the transparent part, but next the membrana propria; in others it lies partly in the transparent, partly in the granular portion, and in still others it belongs almost entirely to the latter. See fig. 1, Plate XVIII. Other cells, especially those near the duct, z.e. the fine canal passing through the epidermis and formed by a single layer of flattened nucleated cells, are almost completely filled with spherical or elliptical or discoid globules of a 1 Speaking of the epithelial cells lining the glands of the cloaca of Triton, Leydig (l.c., p. 213) says, “They possess a vacuolated frothy aspect. After reagents and using high powers, it can be ascertained that this is due to atrellis- or network permeating the interior of the cell, that it origin- ates from the protoplasma surrounding the nucleus, and that the larger trabeculee start as it were in a radial direction from the nucleus while the finer ones lie in the periphery of the cell-wall.” ; “This peculiar structure of the cell may be placed side by side with what I communicated ten years ago of certain large nuclei of the same animal.” - . « . Ten years ago” would correspond to the year 1865—the above article having been evidently written in 1875—and the communi- cation was made in ‘ Vom Bau d. Thierischen Korpers,’ a work which I regret not to be able to procure. Leydig continues: “And I may expressly mention that this structure of the cell may have a much greater distribution; at any rate, I am able to see precisely the same structure in the coloured blood-corpuscles of the same amphibian species after acting upon them with Miiller’s fluid; also here a fine trelliswork passes radially from the nucleus to the periphery of the cell, and at first sight presents itself as ‘granulation.’” It appears from this that Leydig was the first to recognise the reticular structure of protoplasm and of the substance of coloured blood-corpuscles, having men- tioned it already in 1865, before Frommann 1867 and Heitzmann 1873. It is, however, important to add that Leydig, as appears further on (1. ¢., p. 227), regards this reticular structure merely as ‘‘a certain transforma- tion of the protoplasm in consequence of the appearance of numerous cavities.” The trabecular or spongy matter represents “remains of the original protoplasm attached to the cell-membrane,” 408 DR. E. KLEIN. fatty nature. In the fresh state they correspond in appear- ance to fat-globules, and when treated with alcohol and chloroform are, except a limiting outline, entirely dissolved. Hence, in sections treated with alcohol and oil of cloves, these cells appear filled with perfectly transparent, well-defined circles closely pressed against one another (see fig. 1, Plate XVIII). These are the cells which in the fresh state (on the warm stage) while moving are capable of ejecting the fat-globules, as stated above. It thus becomes intelligible how also in the living animal these cells, being situated nearest to the duct, are capable of at once ejecting on to the surface of the skin their fatty secretion. And indeed we find in sections many ducts filled with the same fatty matter. The question arises whether this ejection of the fat-globules represents the sole manner of “secretion,” or whether this process (viz. ‘‘secretion’’) is associated, as in the sebaceous glands of mammals, with the expulsion of fat-globules and the cell itself. I am inclined to think that both are possible ; under quiet, normal conditions, I presume secretion is carried out by the cells next the duct ejecting their contents. Under violent struggles, however, when all the muscles of the tail are in very active contraction, the continuous beautiful coat of unstriped muscle fibres—seen by Eberth in frogs, and especi- ally by Leydig in the glands of the cloaca of salamandrine as surrounding the gland-sac—by its contraction will be capable of effecting a discharge of the cells themselves next the duct. Ifa piece ef tail (while living) be thrown into a hardening fluid it is for some time actively moving, and the surface of the epidermis becomes covered with minute white spots. Sections prove that these are discharged gland-cells and their secretions lying at the mouth of the ducts. The facts that all cells lining these saccular glands show amceboid movement on the warm stage, further, the unequal size of these cells (some are many times bigger than others), and some of theth containing two nuclei, indicate that re- production is going on amongst them, in order that those that become lost may be replaced by others. Leydig states (I. c., p. 138) that the epidermis of all am- phibian animals, like that of all other vertebrates, consists of a stratum corneum and rete mucosum. A section through the skin (of the tail) of newt (Triton cristatus) shows that this is not the case, inasmuch as the epidermis does not contain anything of a stratum corneum, as generally understood, and also by Leydig. In a trans- GLANDULAR EPITHELIUM AND DIVISION OF NUCLEI. 409 verse section through tail of newt we notice that the epider- mis, whose thickness amounts to 0°081 to 0:094 mm., shows a deep stratum consisting of one or two layers of cells elon- gated vertically to the surface, their nucleus is generally oval ; then follow two to three layers of polyhedral cells, their nu- cleus is generally round, in some instances oval in a hori- zontal direction ; and, finally, one or two layers of flat cells, their nucleus being flattened horizontally and deeply stained in hematoxylin. The top layer is always very highly refrac- tive, and as such differs in a conspicuous manner from the transparent layers underneath. Some preparations show in some places two such layers of highly refractive cell plates, in others only one, and still inothers we see one such layer in the act of detaching itself from the layer underneath. The outlines of the cells, especially those of the middle strata are striated, numerous fine fibrils passing from the substance of one cell into that of its neighbours, prickle cells. In pre- parations obtained from bits of tail hardened in a + per cent. solution of chromic acid, these connecting fibrils are in many places of excessive length, the cells, probably through shrinking, having become separated from each other toa much greater extent than is ordinarily seen. And here these fibrils are distinctly seen to pass directly from the reticulated substance of one cell into that of its neighbours, as I de- scribed and figured it of the cells of stratified epithelium in a paper in the April number of this journal. Passingly I may mention the numerous migratory cells, with their folded and constricted nuclei, sometimes drawn out in fine filaments ; further, the branched connective-tissue cells with an oblong nucleus, and containing occasionally pigment granules, all these structures being found in the intercellular cement substance of the epidermis. The variability of the highly refractive top layer of cells, viz., whether one or two, finds its ready explanation in the fact easily noticed on observing newts”(kept in water) for several days, viz. that the cuticle is shed in form of a thin transparent membrane. By keeping several ani- mals in one vessel it is difficult to exactly estimate the rapidity and extent of this process of shedding, but if each animal be kept isolated, it can be observed much easier. The following table shows the exact rapidity with which four adult newts shed their cuticle while observed during May and beginning of June, the animals being kept separately in clear water :— 410 DR. E, KLEIN. Female, No.1. . May 1,.. 7.18.19. 23 . 27 . June? Female, No.2. . May 21.25.31. June 6.12. Male, No.1 . . May 2. 9.14. 20.25. 29 ~June3. MaleNovean: Mayle co, wane 1), 8". 12, The figures indicate the day when the cuticle is raised as a thin transparent film over the whole body of the animal ; a slight touch brings it down in large flakes, but with a little care it can be removed as a whole, that of the tail and toes included. The first appearance of the shedding in the above animals is noticed already after two or three days, the glistening surface of the body becoming more or less dis- tinctly cloudy. This gradually increases, and after a day or two we notice a thin, transparent membrane becoming raised over the head, dorsum, and abdomen, when viewed in profile in transmitted light. This rapidly increases, and we soon see the whole animal enveloped as it were in a bag formed by that thin membrane, and raised above the surface of the animal to a different extent in different parts. Thus, it is mostly raised on the head and extends gradually hence to- wards the posterior extremities. The “bag” is open corre- sponding to the oral cleft, and probably the water getting in at this opening gradually raises mechanically the bag from the surface of the animal while this is swimming about, head, of course, feremost. The cuticle, when shed, preserves the character of the surface of the different parts of the body, the part derived from the dorsum showing the uniform impressions of the “warts,” that from the abdomen showing a transverse arrange- ment of these impresssions, that from the tail and head being more or less smooth. The cuticle either shed or removed by means of a forceps can be at once placed into hemotoxylin, and after staining it—which it does readily—can be floated, as small segments, on to a glass slide and mounted in glycerine. Under the mieroscope the cuticle presents itself as a single layer of beautiful transparent squamous polygonal epithelial cells, each with an oval, or sometimes round, nucleus that takes the staining very well. Some cells—not many—pos- sess two nuclei. According to the nature of the surface of the part of the body from which the cuticle is derived, viz. whether smooth or with warts, we notice its surface either smooth, or groups of cells are raised into a smaller or larger convexity. 1 The cuticle of newt thus stained is a material well suited for class purposes, as it gives an abundance of permanent specimens of continuous masses of beautiful squamous epithelial cells. GLANDULAR EPITHELIUM AND DIVISION OF NUCLEI, 411 The thickness of the cells is about 0:004 mm., the breadth about 0:03 to 0:04 mm. The cell-substance is generally not deeply stained, and contains few pigment granules around the nucleus. As a rule, the cells forming the convex sections, 2.e. corresponding to the surface of the warts, are deeper stained than those between ; the cells of the cuticle corresponding to the front part of the head are also, as a rule, more deeply stained than those of the neck. Some of the cells contain one or more larger or smaller holes (vacuoles), probably signs of degeneration ; they were noticed in the superficial cells of other amphibia by F. E.Schultze and Eberth. The cells are separated by a very well marked, highly refractive linear interstitial substance, either straight or more or less curved and sinuous. The cells possessing a certain thickness, and their lateral margins not forming quite a vertical plan, but are more or less slanting one way or the other, it follows that when looking at the cuticle from the surface we see that the separating lines, viz. those marking the margins of the individual cells of one surface do not coincide with those of the other. In connection with this cuticle we notice numerous short tubes, some thin, others broad, opening with a small mouth between the cells. Their length is about 0°04 mm., and their breadth is about 0:018 or 0:027, according to whether they belong to the narrow or broad variety. These tubes are made up of a transparent membrane finely and indistinctly longitudinally striated, and showing a compressed nucleus at or about the opening. These structures represent, therefore, one or two flattened cells rolled into a tube. In some instances I can recognise the linear suture. I need hardly add that these tubes are the ducts, or part of them, of the numerous glands of the skin, shed simultaneously with the cuticle. The length of these tubes being less than half the thickness of the whole epidermis, even of hardened specimens, it follows that part only of the glandular ducts is shed with the superficial layer of the epidermis. In connection with these ducts there may be seen occasion- ally one, two, or three surrounding epithelial cells removed from the subjacent layer of the epidermis. There can be, therefore, no doubt that the most superficial layer of the epi- dermis, whether still belonging to this latter or already separated, is composed of nucleated squamous epithelial cells, not of non-nucleated horny ‘fcuticular excretions,” as maintained by Leydig (1. c.) for all amphibia. Seeing then that there exists in the adult newt a conti- 412 DR. E. KLEIN. nuous and rapid shedding of the superficial layer of the cells of the epidermis, it naturally follows that a corresponding continuous and rapid new formation of epithelial cells takes place, and accordingly I investigated the epidermis in sections, in order to find, as I expected to find, signs of division of cells and their nuclei. The adult newt being an animal . easily procured during the greater part of the year, and its ele- ments being considerably larger than most other vertebrates, easily accessible, would, therefore, be a good object for studying those exceedingly interesting phenomena accom- panying the division of nuclei, as first described by Strasburger, Biitschli, Mayzel, Eberth, Hertwig, Auerbach, Balfour, and especially very recently in the beautiful obser- vations of Flemming, Schleicher, and Peremeschko. My expectations were fully realised by the examination of the epidermis of the adult newt, and I will here describe the appearances presented by the dividing nuclei of the epider- mis very briefly, since my observations in many respects fully coincide with those of Flemming and Peremeschko, observed by the former in Salamandra maculosa and its embryo, by the latter in the embryo of Triton cristatus. Following the plan of Flemming (‘ Archiv f. mikro Anat.,’ Bnd. xvi, p. 363), I hardened my object in picric acid or chromic acid and stained it afterwards in hematoxylin, and I found it very good for the demonstration of the different forms of dividing nuclei. The picric acid I used is a mixture of two or three parts of a saturated solution and one part of water, the chromic acid is a + per cent. solution. Bits of tail —about ~ or 4 inch long—are placed in either of these fluids and kept there for seven to ten days, they are then placed for a short time (4 or 4+ hour) in spirit, em- bedded and used for cutting fine vertical sections. These are thoroughly washed in water, stained in very dilute hematoxylin and then prepared in the ordinary way for mounting and preserving in solution of Canada balsam. The sections prepared in picric acid are preferable to those in chromic acid, although the latter have many good points about them. The phenomena of division of nuclei to be observed in these specimens are confirmatory of the statements made by Flemming in his very exhaustive article, in which he minutely describes the different changes the intranuclear network undergoes during division, as observed by him in the living state and after reagents. In the same paper Flemming gives an-exhaustive and critical review of the observations and assertions on the same subject by his pre- GLANDULAR EPITHELIUM AND DIVISION OF NUCLEI, 413 decessors, and I can therefore omit detailed references to other observers. We notice in such a section that the nuclei of the two deeper layers of cells are oval, and placed vertically to the surface; they possess a sharp limiting membrane, and contain a uniform reticulum, intranuclear network, varying between the reticulum of minute fibrils to that of a spongy honeycombed structure. The interstitial substance of this reticulum is homogeneous and transparent in logwood. There is no trace of any nucleolus. Division of nuclei being limited to these two layers, we are justified in considering them as in a ripe state, and we have, therefore, here much additional evidence that the nucleolus is not a necessary feature in the structure of a nucleus, and that it is alto- gether absent in nuclei, that may be regarded as ripe and fully formed (see figs. 8 and 9, Plate XVIII). The nuclei of the middle strata of the epidermis show a more or less distinct reticulum, and in it larger or smaller accu- mulations—nucleoli; the interstitial substance is homo- geneous, but in many cases more or less stained in hema- toxylin. In all cases, however, we find the small, bright dots included in the network ; these, as stated by me on so many occasions, are fibrils of the reticulum viewed in optical section. Amongst the nuclei of the two deep layers of cells we notice some that are somewhat larger than the rest, and contain very beautiful, deeply stained fibrils, either twisted and coiled into a more or less dense convolution (Flemming), or arranged like a basket (Eberth), viz. most fibrils are peri- pheral, and have a transverse direction ; hence, the surface of the nucleus in the latter case shows a transverse striation. But in both instances, viz. the “convolution ” and the “ basket,” the fibrils are connected into a network (see figs. 1O—13, Pl. XVIIT). The membrane of the nuclei showing this arrange- ment is less marked than in the other nuclei of the ordi- nary kind, appearing not as a continuous structure, but more or less due to the close position of the fibrils. These forms are regarded by Flemming as the initial stages of the coming division of the nucleus. Ido not find anything that would be contrary to such an explanation. Like Flemming, I find all forms intermediary between the ordinary nucleus as above described and the enlarged nuclei with “‘convolutions” or basket-shaped arrangement of the intra- nuclear network. In some cases the “ convolutions” are very dense, and 41 4, DR. BE, KLEIN, hence many of the fibrils are seen endwise as bright dots or “granules.” This appearance is incorrectly interpreted by Mayzel, Eberth, and especially Schleicher and Pereme- schko, who describe the nuclei as at first containing “‘ oranules,” which gradually arrange themselves into fibrils. I am at one with Flemming in opposing such an interpre- tation, since I maintain, with him, that before the fibrils arrange themselves into “convolution ”’ and “ basket,” there is already a well-formed reticulum in the nucleus. Nuclei of this kind can be seen in the deepest and in the next following layer. Then we find nuclei somewhat larger, but without any limiting membrane whatever; they may be described with Flemming as containing deeply-stained filaments arranged in the shape of a “rosette ” or “ wreath ;” the filam ents are in different examples of different thickness; they form a loop at the periphery, and approach each other in the centre (see figs. 14, 17 and 18). Between the nuclei with “ con- volutions”” or “ basket ’’-shaped arrangement of filaments, and those in which the latter form a “ rosette’ or “ wreath,” we find many intermediary forms. See also Flemming, 1. c., p. 376, and the beautiful figures on Plate XVII, accompany- ing his paper. Further, we pass from these to large nuclei, also without any membrane, in which the deeply-stained fibrils are arranged like a single aster (“ Monaster’’), apparently termi- nating freely at the periphery, but connected into a central network. Mr. Balfour has also described and figured this form as the “stellate variety” of dividing nuclei of the developing ova of the embryo (this Journal, No. Ixxu, p. 395). Like Flemming, I also find the fibrils of this form, as a rule, much thicker than in any of the preceding ones (see fig. 19). Next, we trace these into nuclei without a membrane, in which the fibrils are similar in appearance to the preceding ones, but arranged as a double aster “ (Dyaster) ” (see figs. 20, 21, 22). The majority of the forms described as ‘‘ rosette” or “wreath,” and as “ monaster” and ‘dyaster,” are found amongst the deepest layer, but occasional!y we meet one or the other of them in the next following, or eyen the further layer; they are all very conspicuous on account of their size, and owing to this the cell itself is very much bulged out laterally. In the ‘ dyaster,” that I find in my specimens, the fibrils of one aster are connected with those of the other. The GLANDULAR EPITHELIUM AND DIVISION OF NUCLEI. 415 dyaster represents a more or less elliptical body, at the poles of which the fibrils are connected into a network; they pass from one pole to the other as isolated longitudinal fibrils. We have a form that coincides with the spindle of Strasburger, but in which the fibrils form a network at the poles. Flemming has figured them very beautifully on his Plates XVI and XVII. The axis, @. e. the line joining the poles of any ‘‘ dyaster,” lies in most instances parallel with the surface of the epi- dermis, and only in few instances have I seen it more or less vertical. This is, in so far, of interest, as it proves that in many instances the two daughter nuclei (derived from the division of the dyaster), and, consequently, also, the two daughter cells, do not lie above one another in a line vertical to the surface of the epidermis, but side by side. Then we find that the dyaster divides into two small separate monasters, the longitudinal fibrils running from one pole to the other of the dyaster dividing in the middle one by one. We have finally two small nuclei side by side, but separate, the fibrils of each possessing the arrangement of a monaster. I find, just like Flemming, who so exhaustively described them, that these daughter nuclei undergo the same changes as the mother nuclei did, but in a reverse order, viz. passing from the state of monaster into that of a “‘ rosette ” or “ wreath,” from this into that of a “ basket” or ‘“ convolution,” and, finally, into a nucleus containing a uniform spongy reti- culum. While the daughter nuclei undergo these changes, except the last, they are easily distinguishable from similar forms of mother nuclei, owing to the smallness of the former and their positions in couples (see figs. 22—25, Pl. XVIII). Just asis the case withmother nuclei in the stages of rosette, wreath, and monaster, so also the daughter nuclei of the ana- logous forms do not possess any membrane; in the “ con- volution ” and “ basket” of daughter nuclei the membrane is very indistinct, and is also here due to the close position of the fibrils. As has been mentioned above, the majority of daughter nuclei lie at first side by side, 7. e. in an axis parallel to the surface. But after the cell substance itself has become divided, the daughter nuclei gradually change their relative position, the (imaginary) axis joining them, rotating so as to assume a position vertical to the surface of the epidermis. The daughter nuclei enclosed in a still undivided cell 416 DR. E. KLEIN, generally belong to the deepest layer, but they soon become shifted into the next following stratum. A point of great importance is the relation of the fibrils of the nucleus in the different stages of division to the cell sub- stance itself. I have on two occasions (this Journal, July, 1878, and April, 1879) referred to a connection of the fibrils of the intranuclear network with the reticulum representing the protoplasm of the cell, and on carefully examining my specimens of dividing nuclei I find that also the fibrils of these are intimately connected with the cell substance. The forms mentioned as rosette or wreath, but especially as monaster, are those in which—the examination being greatly facilitated by the absence of any membrane—in many instances I can most positively see a direct connection between the fibrils of the nucleus and the reticulum repre- senting the cell substance. Such a connection will be found represented in figs. 14—19 of Plate XVIII. It is true the observation requires very favorable conditions, viz. the nucleus must be a large one, must be seen on its broad surface, the light must be good, the sections thin, and the power high. Zeiss’s new oil immersion, ;!; and + inch, have proved here invaluable. The fibrils of the nucleus taking the staining very deeply seem at first altogether distinct from the surrounding cell substance, which is either not at all or only slightly stained, but nevertheless, on careful inspection, it will be found that the fibrils, especially of the monaster, although they appear to terminate singly in the periphery and with a blunt extremity, do not so terminate but pass on, unstained, into the reticulum of the cell substance. The difference of the fibrils of the nucleus and the cell substance in their staining power is no doubt due to an essential chemical distinction, but this does not necessarily imply that the two substances cannot form an anatomical continuity. Nor, it seems to me, does the observation by Schleicher (‘ Archiv f. mikr. Anat.,’ Bd. xvi., p. 261) of the peculiar state of contractility— karyokinesis”’ —of the nucleus of cartilage cells preceding division, nor that by Peremeschko of similar appearances in the dividing nucleus of epithelial cells of embryo Triton, make sucha con- nection between cell substance and nucleus improbable. By the observations of Stricker (‘ Sitzungsber. d. k. Akad. d. Wiss.,’ Vienna, June, 1877) it is established that the nucleus of some colourless blood-corpuscles possesses con- tractility while within the cell as well as after separation 1 These two lenses, although of very great magnifying power, are never- tlicless marvellous in sharp definition. GLANDULAR EPITHELIUM AND DIVISION OF NUCLEL 417 from it, and it is likewise established by Stricker, that the nucleus of those cells is during life in direct anatomical continuity with the cell substance, and further that by the appearance of a membrane a central portion of the cell substance becomes temporarily differentiated as nucleus. I have also mentioned on a former page that the giant nuclei of the gland cells of newt show local contractions of their reticulum. ‘I'he connection of the fibrils of the dividing nucleus with the cell substance and the contractility of both, seems to me to explain also the peculiar appearances described by Auerbach as “ karyolitic figure”? and observed by many others (Flemming, Fol, Bitschli, Strasburger, O. Hertwig, and others) in dividing nuclei of ovum and other cells, viz. a radiar arrangement of fibrils of what corresponds to the cell substance towards the nucleus, when single as well as after division—in the former case as a single, in the latter as a double “ karyolytic figure.” We have to assume that, owing probably to contraction of the intranuclear network, the fibrils of the intracellular reticulum are drawn towards the former. Whether at the same time an exchange of the two substances takes place, or whether the nucleus alone takes in matter from the cell, it is difficult to decide ; both seem probable from theoretical considerations so thoroughly discussed by Auerbach, Strasburger, Biitschli, Flemming, and Schleicher. A point not less interesting is the question, whether the division of the nucleus takes place in all cells of the epi- dermis of adult newt after the same complicated manner as described in the preceding, or whether there is in addition another simpler mode, so often mentioned in normal and pathological histology as that of simple cleavage. Flemming proposes the term “‘indirect”’ multiplication of the nucleus for the former complex mode, and “ direct’? for the latter simple mode, and we shall accept these terms in the following description. Auerbach and Eberth accept such a direct mode of divi- sion, Flemming questions it, although he does not think it quite impossible. This last named author describes forms of nuclei which might be taken as indicative of simple cleav- age, viz. ordinary nuclei kidney-shaped and lobed, or beset with more or less deep constrictions; but he finds reasons to believe that’ these are only temporary appearances due probably to movement. As I mentioned on a former page the very rapid shedding of the superficial layer of the cells of the epidermis led 418 DR. E, KLEIN. me to examine the epidermis with reference to the pro- cess of division, and we have seen that division of nuclei occurs merely in the deepest or the next following layer. Considering that the superficial layer of cells is shed within five or six days (see the tables on a previous page), we should be justified in expecting to find very abundant division amongst the nuclei of the deeper layer. ‘This, however, is not the case by any means. True, some of the stages of indirect division described on a former page are, according to Flemming and Peremeschko’s direct observa- tions, only of very short duration, but I think I can show that all forms of nuclei indicating such divisions—from that of the “ convolution ” of the mother nucleus to the ‘‘ convolu- tion”? of the daughter nucleus—do not represent but a relatively small contingent, not sufficient to account for the copious new-formation of nuclei and cells that must be going on in order to defray such a loss of cells and nuclei as is represented by the shedding of the cuticle within five or six days. I have counted in several fields in a preparation prepared.with picric acid and stained with logwood, all the forms of nuclei indicating indirect division, and I found the following : The preparation is a vertical section through the tail of a female adult newt; the thickness of the section is such that the cells of the epidermis lie two deep. The counting was made with the objective K of Zeiss. The size of the field of the microscope under this lens on my stand comprises about 30 nuclei of the deepest layer of cells, 7. e. the layer next the corium, and as the section is two cells deep, it follows that we may take 60 nuclei as comprised in the deepest layer of one field. Of course this figure 60 is only approximately correct, since the section is not everywhere of equal thick- ness, and since the nuclei are not everywhere placed equally closely. But I should think the error in accepting that figure cannot be great. As I do not claim any degree of accuracy, we may accept that number as sufficiently ser- viceable. In Field 1, I count one ‘‘ wreath;” one divided, each daughter nucleus “‘monaster ;” one “ basket.” In Field 2, three “convolutions ;’ ** basket.” In Field 3, one “ wreath ;”’ one ‘ convolution.” In Field 4, one “ convolution ;” two “ baskets;” one divided, each daughter nucleus ‘‘ basket.” In Field 5, two “ convolutions.” In Field 6, one divided, each daughter nucleus “basket.” In Field 7, one ‘‘ dyaster.”’ 2 one divided, each daughter nucleus GLANDULAR EPITHELIUM AND DIVISION OF NUCLEI, 419 All these ‘* fields” follow each other consecutively, so that we may say that amongst about 840 nuclei (that is, counting the nuclei of the two lowest layers, each of these two deep), we find 17 only, indicative of indirect division. In another specimen (of the same tail), prepared in exactly the same manner, we find; In Field 1, two “wreaths ;” two ‘‘ monasters ;” five ‘‘ convolutions;” two “baskets.” In Field 2, two divided, each daughter nucleus ‘convolution ;” one “ mon- aster ;”’ one divided, each daughter nucleus “‘basket ;” two “ wreaths ;” } Bb] te} b] three “ convolutions ;” three ‘“ baskets.” Thus, in these two fields, corresponding, therefore, to about 240 nuclei we find 23 forms indicative of indirect division. In connection with this I have to add that I have taken great care not to omit any of those forms; this is to a cer- tain extent facilitated by the conspicuous appearance pre- sented by the nuclei of this kind. As I do not know at what rate the division of the nuclei takes place, and as the thickness of the epidermis is not con- stant in all places, I am not able to use in any, but a very approximate manner, the above numbers, and such as they are, they seem to me, on account of their smallness, to indicate that there must be another method of re- production of nuclei in addition to the indirect one. And we have only to examine carefully the deeper strata of the epidermis to convince ourselves of the presence of nuclei which appear to be in different stages of cleavage. They are oval nuclei, differing as regards their membrane and honeycomb reticulum in no way from the other nuclei of these layers. I have represented in figures 26—32, PI. XVIII, the most characteristic forms of nucleiin the various stages of cleavage. ‘They vary in numbers in different parts of a section, and appear to me to be more than merely con- stricted or lobed shapes, such as described by Flemming as being of a temporary nature. Figures 29, 30, and 31 seem to me quite convincing. I may state here that I have found very numerous nuclei, in the various stages of cleavage, also in the epithelium lining the neck of the duct of the cutaneous glands. It is quite possible that the nuclei undergoing the indirect division in the adult have inherited the power to do this from the ovum, the nuclei of which, as is now well known from numerous observations on different vertebrate and in- vertebrate animals, undergo the indirect mode of division ; it is probable, from Peremeschko’s observations, that in the 420 DR, BE, KLEIN. embryo Triton the nuclei of all, or nearly all, epithelial cells undergo the indirect division; but since it is equally pro- bable that in the adult only a relatively small number of nuclei possesses this property, it follows that many of them lose this power and degenerate in the manner of division, becoming degraded into nuclei that multiply after the more plebeic manner of simple cleavage. By doing this, nature evidently gains her end under great saving of energy, since the existence of these nuclei is only of short duration. As supporting the assumption that nuclei divide after the “direct” manner, viz. by cleavage, may be regarded those nuclei in which the fibrils have arranged themselves, as if those nuclei were going to divide in the indirect way, but for some reason or other did not succeed in doing so, but divided ultimately by cleavage. I refer to figs. 33, 34, and 39, which I have selected as the more characteristic forms ; fig. 33 represents a “ convolution,” 34 and 35 “ baskets” all undergoing the “ direct ’’ mode of division. A good object for demonstrating the different forms of nuclei while undergoing the indirect mode of division is the bladder of adult frog prepared with chloride of gold. The organ is filled ez se¢&w with chloride of gold (4 per cent.) until it is well distended; it is then ligatured at the neck, and placed in chloride of gold for about half an hour, then opened and exposed to the light in slightly acidulated water. Examining the inner surface of a small portion spread out on a slide and mounted in glycerin, we meet with many beautiful forms of ‘‘ convolutions,” “ monasters,” “‘wreaths,” ‘‘dyasters,” and couples of small daughter nuclei. The tail of tadpole prepared in chloride of gold (see ‘Handbook for the Physiolog. Laboratory,’ p.41) shows also, amongst the epithelium of both surfaces, forms of dividing nuclei, especially ‘“ baskets,’ “monasters,’ and “dyasters.’ Their number, however, is relatively small. The great majority of the nuclei present a uniform network of fibrils or rods. The nuclei of the epithelium of the bladder of frog are preferable to those of the tail of the tad- pole, being of a much larger size. P.S.—Since the printing of the foregoing I have received from my friend Professor Flemming, in Kiel, two of his preparations of embryo Salamander, and I see in them the most exquisite forms of nuclei dividing after the indirect mode, as figured by F. in his paper. HARLY DEVELOPMENT OF THE LACERTILIA. 42] On the Harty DeveLopMENT of the Lacertiia, together with some OBSERVATIONS on the Nature and Rewations of the Primitive Srreak. By F. M. Baxrour, M.A., F.RS., Fellow of Trinity College, Cambridge. (With Plate XIX.) Tix1 quite recently no observations were recorded on the early developmental changes of the reptilian ovum. Not long ago Professors Kupffer and Benecke published a preliminary note on the early development of Lacerta agilis and Emys Europea. I have myself also been able to make some observations on the embryo of Lacerta muralis. The number of my embryos has been somewhat limited, and most of those which I have had have been preserved in bichromate of potash, which has turned out a far from satisfactory hardening reagent. In spite of these diffi- culties I have been led on some points to very different results from those of the German investigators, and to results which are more in accordance with what we know of other Sauropsidan types. I commence with a short account of the results of Kupffer and Benecke. Segmentation takes place exactly as in birds, and the resulting blastoderm, which is thickened at its edge, spreads rapidly over the yolk. Shortly before the yolk is half enclosed a small embryonic shield (area pellucida)? makes its appearance in the centre of the blastoderm, which has, in the meantime, become divided into two layers. The upper of these is the epiblast, and the lower the hypoblast. The embryonic shield is mainly distin- guished from the remainder of the blastoderm bythe more columnar character of its constituent epiblast cells. It is somewhat pyri- form in shape, the narrower end corresponding with the future posterior end of the embryo. At the narrow end an invagina- tion takes place, which gives rise to an open sac, the blind end of which is directed forwards. The opening of this sac is regarded by the authors as the blastopore. A linear thickening of epi- blast arises in front of the blastopore, along the median line of which the medullary groove soon appears. In the caudal region the medullary folds spread out and enclose between them the blastopore, behind which they soon meet again. On the con- version of the medullary groove into a closed canal the blastopore becomes obliterated. The mesoblast grows out from the lip of the blastopore as four masses. Two of these are lateral: a third is anterior and median, and, although at first independent of the epiblast, soon attaches itself to it, and forms with it a kind of ‘are Die Erste Entwicklungsvorgainge am Hi der Reptilien,’ K6nigsberg, VOL, X1X.—NEW SER. EE 422 F. M. BALFOUR. axis-cord. A fourth mass applied itself to the walls of the sac formed by invagination. With reference to the very first developmental phenomena my observations are confined to two stages during the segmentation.! In the earliest of these the segmentation was about half completed, in the later one it was nearly over. My observations on these stages bear out generally the statements of Kupffer and Benecke. In the second of them the blastoderm was already imperfectly divided into two layers—a superficial epiblastic layer formed of a single row of cells, and a layer below this several rows deep. Below this layer fresh segments were obviously being added to the blastoderm frem the subjacent yolk. Between the second of these blastoderms and my next stage there is a considerable gap. The medullary plate is just established, and is marked by a shallow groove which becomes deeper in front. A section through the embryo is represented in Pl. XIX, Series a, fig. 1. In this figure there may be seen the thickened medullary plate with a shallow medullary groove, below which are two independent plates of mesoblast (me. p.), one on each side of the middle line, very imperfectly divided into somatopleuric and splanchnopleuric layers. Below the mesoblast is a continuous layer of hypoblast (dy.), which develops a rod-like thickening along the axial line (c4.). This rod becomes in the next stage the notochord. Although this embryo is not well preserved I feel very confident in asserting the continuity of the notochord with the hypoblast at this stage. At the hind end of the embryo is placed a thickened ridge of tissue which continues the embryonic axis. In this ridge ail the layers coalesce, and I therefore take it to be equivalent to the primitive streak of the avian blastoderm. It is somewhat triangular in shape, with the apex directed backward, the broad base placed in front. At the junction between the primitive streak and the blasto- derm is situated a passage, open at both extremities, leading from the upper surface of the blastoderm obliquely forwards to the lower. ‘The dorsal and anterior wall of this passage is formed of a distinct epithelial layer, continuous at its upper extremity with the epiblast, and at its lower with the notochordal plate, so that it forms a layer of cells connecting together the epiblast and hypo- blast. The hinder and lower wall of the passage is formed by the cells of the primitive streak, which only assume a columnar form near the dorsal opening of the passage (vide fig. 4). This passage is clearly the blind sac of Kupffer and Benecke, who, if I am not 1 For these two specimens, which were hardened in picric acid, I am indebted to Dr. Kleneinberg. EARLY DEVELOPMENT OF THE LACERTILIA. 423 mistaken, have overlooked its lower opening. As I hope to show in the sequel, it is also the equivalent of the neurenteric passage, which connects the neural and alimentary canals in the Icthyop- sida, and therefore represents the blastopore of Amphioxus Amphibians, &c. Series a, figs. 2, 3, 4, 5, illustrate the features of the passage and its relation to the embryo. Fig. 2 passes through the ventral opening of the passage. The notochordal plate (ch’.) is vaulted over the opening, and on the left side is continuous with the mesoblast as well as the hypoblast. Figs 3 and 4 are taken through the middle part of the passage (ze.), which is bounded above by a continuation of the notochordal plate, and below by the tissue of the primitive streak. The hypoblast (Ay.), in the middle line, is imperfectly fused with the mesoblast of the primitive streak, which is now continuous across the middle line. The medullary groove has disappeared, but the medullary plate (a p.) is quite distinct. In fig. 5 is seen the dorsal opening of the passage (we.). If a section behind this had been figured, as is done for the next series (B), 1t would have passed through the primitive streak, and, as in the chick, all the layers would have been fused together. The epiblast in the primitive streak completely coalesces with the mesoblast ; but the hypoblast, though attached to the other layers in the middle line, can always be traced as a distinct stratum. Fig. B is a surface view of my next oldest embryo. The medullary groove has become much deeper, especially in front. Behind it widens out to form a space equivalent to the sinus rhomboidalis of the embryo bird. The amnion forms a small fold covering over the cephalic extremity of the embryo, which is deeply embedded in the yolk. Some somites (protovertebre) were probably present, but this could not be made out in the opaque embryo. The woodcut (fig. 1) represents a diagrammatic longitudinal section through this embryo, and the sections belonging to Series B illustrate the features of the hind end of the embryo and of the primitive streak. Fic, 1.—Diagrammatie longitudinal section of an embryo of Lacetra. pp. Body cavity. am. Amnion. ne. Neurenteric canal, ch. Notochiprd hy. Hypoblast. ep. Hpiblast. pr. Primitive streak. 424, F. M. BALFOUR. As is shown in fig. 1, the notochord (ch.) has now throughout the region of the embryo become separated from the subjacent hypoblast, and the lateral plates of mesoblast are distinctly divided into somatic and splanchnic layers. The medullary groove is continued as a deepish groove up to the opening of the neuren- teric passage, which thus forms a perforation in the floor of the hinder end of the medullary groove (vide Series 8, figs. 2, 3, and 4). The passage itself is somewhat shorter than in the previous stage, and the whole of it is shown in a single section (fig. 4). This section must either have been taken somewhat obliquely, or else the passage have been exceptionally short in this embryo, since in an older embryo it could not all be seen in one section. . The front wall of the passage is continuous with the notochord, which for two sections or so in front remains attached to the hypo- blast (figs. 2 and 3). Behind the perforation in the floor of the medullary groove is placed the primitive streak (fig. 5), where all the layers become fused together, as in the earlier stage. Into this part a narrow diverticulum from the end of the medullary groove is continued for a very short distance (wide fig. 5, we.).% The general features of the stage will best be understood by an examination of the diagrammatic longitudinal section, represented in woodcut, fig. 1. In front is shown the amnion (am.), growing over the head of the embryo. The notochord (c/.) is seen as an independent cord for the greater part of the length of the embryo, but falls into the hypoblast shortly in front of the neurenteric passage. The neurenteric passage is shown at ve., and behind it is shown the primitive streak. In a still older stage, represented in surface view on Pl. XIX, fig. c, medullary folds have nearly met above, but have not yet united. The features of the passage from the neural groove to the s/° hypoblast are precisely the same,in the embryo just described, although the lumen of the passage has become somewhat narrower. There is still a short primitive streak behind the embryo. The neurenteric passage persists but a very short time after the complete closure of the medullary canal. It is in no way connected with the allantois, as conjectured by Kupffer and Benecke, but the allantois is formed, as I have satisfied myself by longitudinal sections of a later stage, in the manner already described by Dobrynin, Gasser, and Kolliker for the bird and mammal. The general results of Kupffer’s and Benecke’s observations, with the modifications introduced by my own observations, are as follows :—After the segmentation and the formation of the embryonic shield (area pellucida) the blastoderm becomes dis- & EARLY DEVELOPMENT OF THE LACERTILIA, 425 tinctly divided into epiblast and hypoblast.1.| At the hind end of the shield a somewhat triangular primitive streak is formed by the fusion of the epiblast and hypoblast with a number of cells between them, which are probably derived from the lower rows of the segmentation cells. At the front end of the streak a passage arises, open at both extremities, leading obliquely forwards through the epiblast to the space below the hypo- blast. The walls of the passage are formed of a layer of columnar cells continuous both with epiblast and hypoblast. In front of the primitive streak the body of the embryo becomes first differentiated by the formation of a medullary plate, and at the same time there grows out from the primitive streak a layer of mesoblast, which spreads out in all directions between the epiblast and hypoblast. In the axis of the embryo the mesoblast plate is stated by Kupffer and Benecke to be con- tinuous across the middle line, but this appears very improbable. In a slightly later stage the medullary plate becomes marked by a shallow groove, and the mesoblast of the embryo is then un- doubtedly constituted of two lateral plates, one on each side of the median line. In the median line the notochord arises as a ridge-like thickening of the hypoblast which becomes very soon quite separated from the hypoblast, except at the hind end, where it is continued into the front wall of the neurenteric pas- sage. It is interesting to notice the remarkable relation of the notochord to the walls of the neurenteric passage. More or less similar relations are also well marked in the case of the goose and the fowl (Gasser),? and support the conclusion deducible from the lower forms of vertebrata, that the notochord is essentially hypoblastic. The passage at the front end of the primitive streak forms the posterior boundary of the medullary plate, though the medullary groove is not at first continued back to it. The anterior wall of this passage connects together the medullary plate and the noto- chordal ridge of the hypoblast. In the succeeding stages the medullary groove becomes continued back to the opening of the passage, which then becomes enclosed in the medullary folds, and forms a true neurenteric passage. It becomes narrowed as the medullary folds finally unite to form the medullary canal, and eventually disappears. I conclude this paper with a concise statement of what appears fo me the probable nature of the much-disputed organ, the primitive streak, and of the arguments in support of my view. ' This appears to me to take place before the formation of the em- bryonic shield. ° Gasser, ‘ Der Primitivstreifen bei Vogelembryonen,’ Marburg, 1878. 426 F. M. BALFOUR, In a paper on the primitive streak in the ‘Quart. Journ. of Mic. Sci.,’ in 1873 (p. 280), I made the following statement with reference to this subject:—‘It is clear, therefore, that the primitive groove must be the rudiment of some ancestral feature. »+...-. Itis just possible that it is the last trace of that involution of the epiblast by which the hypoblast is formed in most of the lower animals.” At a later period, in July, 1876, after studying the develop- ment of Elasmobranch fishes, I enlarged the hypothesis in a re- view of the first part of Prof. Kolliker’s ‘ Entwicklungsgeschichte.’ The following is the passage in which I speak of it :! “Tn treating of the exact relation of the primitive groove to the formation of the embryo, Professor Kolliker gives it as his view that though the head of the embryo is formed independently of the primitive groove, and only secondarily unites with this, yet that the remainder of the body is without doubt derived from the primitive groove. With this conclusion we cannot agree, and the very descriptions of Professor Kolliker appear to us to demonstrate the untenable nature of his results. We believe that the front end of the primitive groove at first occu- pies the position eventually filled by about the third pair of protovertebre, but that as the protovertebre are successively formed, and the body of the embryo grows in length, the primi- tive groove is carried further and further back, so as always to be situated immediately behind the embryo. As Professor K6l- hiker himself has shown it may still be seen in this position even later than the fortieth hour of incubation. “Throughout the whole period of its existence it retains a character which at once distinguishes it in sections from the medullary groove. “Beneath it the epiblast and mesoblast are always fused, though they are always separate elsewhere ; this fact, which was originally shown by ourselves, has been very clearly brought out by Professor Kolliker’s observations. “The features of the primitive groove which throw special light on its meaning are the following :— “(1.) It does not enter directly into the formation of the embryo. ““(2.) The epiblast and mesoblast always become fused beneath it. *« (3.) It is situated immediately behind the embryo. “ Professor Kélliker does not enter into any speculations as to the meaning of the primitive groove, but the above-mentioned facts appear to us clearly to prove that the primitive groove is a ' «Journal of Anat. and Phys.,’ vol. x, pp. 790 and 791, Compare also my monograph on ‘ Elasmobranch Fishes,’ note on p. 68. EARLY DEVELOPMENT OF THE LACERTILIA. 427 rudimentary structure, the origin of which can only be com- pletely elucidated by a knowledge of the development of the Avian ancestors. “Tn comparing the blastoderm of a bird with that of any anamniotic vertebrate, we are met at the threshold of our inves- tigations by a remarkable difference between the two. Whereas in all the lower vertebrates the embryo is situated at the edge of the blastoderm, it is in birds and mammals situated in the centre. This difference of position at once suggests the view that the primitive groove may be in some way connected with the change of position in the blastoderm which the ancestors of birds must have undergone. If we carry our investigations amongst the lower vertebrates a little further, we find that the Elasmobranch embryo occupies at first the normal position at the edge of the blastoderm, but that in the course of develop- ment the blastoderm grows round the yolk far more slowly in the region of the embryo than elsewhere. Owing to this, the embryo becomes left in a bay, the two sides of which eventually meet and coalesce in a linear fashion immediately behind the em- bryo, thus removing the embryo from the edge of the blasto- derm and forming behind it a linear streak not unlike the primi- tive streak. We would suggest the hypothesis that the primitive groove is a rudiment which gives the last indication of a change made by the Avian ancestors in their position in the blastoderm, like that made by Elasmobranch embryos when removed from the edge of the blastoderm and placed ina central situation similar to that of the embryo bird. On this hypothesis the situation of the primitive groove immediately behind the embryo, as well as the fact of its not becoming converted into any embryonic organ would be explained. The central groove might probably also be viewed as the groove naturally left between the coalescing edges of the blastoderm. “ Would the fusion of epiblast and mesoblast also receive its ex- planation on this hypothesis? We are of opinion that it would. At the edge of the blastoderm which represents the blastopore mouth of Amphioxus all the layers become fused together in the anam- niotic vertebrates. So that if the primitive groove is in reality a rudiment of the coalesced edges of the blastoderm, we might naturally expect the layers to be fused there, and the difficulty presented by the present condition of the primitive groove would rather be that the hypoblast is not fused with the other layers than that the mesoblast is indissolubly united with the epi- blast. The fact that the hypoblast is not fused with the other layers does not appear to us to be fatal to our hypothesis, and in Mammalia, where the primitive and medullary grooves present pre- cisely the same relations as in birds, all three layers are, accord- 4.28 F. M. BALFOUR. ing to Hensen’s account, fused together. This, however, is denied by Kélliker, who states that in Mammals, as in Birds, only the epiblast and mesoblast fuse together. Our hypothesis as to the origin of the primitive groove appears to explain in a fairly satisfactory manner all the peculiarities of this very enigmatical organ; it also relieves us from the necessity of accepting Professor Kolliker’s explanation of the development of the mesoblast, though it does not, of course, render that explanation in any way untenable.” At a somewhat later period Rauber arrived at a more or less similar conclusion, which, however, he mixes up with a number of opinions from which I am compelled altogether to dissent.1 The general correctness of my view, as explained in my second quotation, appears to me completely established by Gasser’s beau- tiful researches on the early development of the chick and goose,” and by my own observations just recorded on the lizard. While at the same time the parallel between the blastopore of Elasmobranchii and of the Sauropsida, is rendered more com- plete by the discovery of the neurenteric passage in the latter group, which was first of all made by Gasser. The following paragraphs contain a detailed attempt to establish the above view by a careful comparison of the primitive streak and its adjuncts in the amniotic vertebrates with the blastopore in Elasmobranchii. In Elasmobranchii the blastopore consists of the following parts :—(1), a section at the end of the medullary plate, which becomes converted into the neurenteric canal;> (2), a section forming what may be called the yolk blastopore, which even- tually constitutes a linear streak connecting the embryo with the edge of the blastoderm (77de my monograph on Elasmobranch fishes, pp. 68 and 81). In order to establish my hypothesis on the nature of the primitive streak, it is necessary to find the representatives of both these parts in the primitive streak of the amniotic vertebrates. The first section ought to appear as a passage from the neural to the enteric side of the blastoderm at the posterior end of the medullary plate. At its front edge the epiblast and hypoblast should be continuous, as they are at the hind end of the embryo in Elasmobranchii, and, finally, the passage should, on the closure of the medullary groove, become converted into the newrenteric canal. All these conditions are exactly fulfilled by the opening at the front end of 1 © Primitivrinne u. Urmuxd,” ‘ Morphologisches Jahrbuch.,’ Band ii, p. 551. 2 Gasser, ‘ Der Primitivstreifen bei Vogelembryonen,’ Marburg, 1878. 3 I use this term for the canal connecting the neural and alimentary tract, which was first discovered by Kowalevsky. EARLY DEVELOPMENT OF THE LACERTILIA. 429 the primitive streak of the lizard (vide woodcut, fig. 1). In the chick there is at first no such opening, but, as I hope to show in a future paper, it is replaced by the epiblast and hypo- blast falling into one another at the front end of the primitive streak. At a later period, as has been shown by Gasser,! there is a distinct rudiment of the neurenteric canal in the chick, and a complete canal in the goose. Finally, in mammals, as has been shown by Schifer? for the guinea-pig, there is at the front end of the primitive streak a complete continuity between epiblast and hypoblast. The continuity of the epiblast and hypoblast at the hind end of the embryo in the bird and the mammal is a rudiment of the continuity of these layers at the dorsal lip of the blastopore in Klasmobranchii, Amphibia, &c. The seeond section of the blastopore in Elasmobranchii or yolk blastopore is, I believe, partly represented by the primitive streak. The yolk blastopore in Elasmobranchii is the part of the blastopore belong- ing to the yolk sac as opposed to that belonging to the embryo, and it is clear that the primitive streak cannot correspond to the whole of this, since the primitive streak is far removed from the edge of the blastoderm long before the yolk is completely enclosed. Leaving this out of consideration the primitive streak, in order that the above comparison may hold good, should satisfy the following conditions : 1. It should connect the embryo with the edge of the blasto- derm. 2. It should be constituted as if formed of the fused edges of the blastoderm. 3. The epiblast of it should eventually not form part of the medullary plate of the embryo, but be folded over on to the ventral side. The first of these conditions is only partially fulfilled, but, con- sidering the rudimentary condition of the whole structure, no great stress can, it seems to me, be laid on this fact. The second condition seems to me very completely satisfied. Where the two edges of the blastoderm become united we should expect to find a complete fusion of the layers such as takes place in the primitive streak ; and the fact that in the primitive streak the hypoblast does not so distinctly coalesce with the mesoblast as the mesoblast with the epiblast cannot be urged as a serious argument against me. The growth outwards of the mesoblast from the axis of the primitive streak is probably a remnant of the invagination of the 1 Loe. cit. * “A contribution to the history of the development in the Guinea-pig,” ‘Journal of Anat, and Phys.,’ vol. xi, pp. 332—336, 430 F, M, BALFOUR. hypoblast and mesoblast from the lip of the blastopore in Amphibia, &c. The groove in the primitive streak may with great plausibility be regarded as the indication of a depression which would natu- rally be found along the line where the thickened edges of the blastoderm became united. With reference to the third condition, I will make the following observations. The neurenteric canal, as it is placed at the extreme end of the embryo, must necessarily, with reference to the embryo, be the hindermost section of the blastopore, and therefore the part of the blastopore apparently behind this can only be so owing to the embryo not being folded off from the yolk sac; andas the yolk sac is in reality a specialised part of the ventral wall of the body, the yolk blastopore must also be situated on the ventral side of the embryo. Kolliker and other distinguished embryologists have believed that the epiblast of the whole of the primitive streak became part of the neural plate. If this view were correct, which is accepted even by Rauber, the hypothesis I am attempting to establish would fall to the ground. I have, however, no doubt that these em- bryologists are mistaken. The very careful observations of Gasser show that the part of the primitive streak adjoining the émbryo becomes converted into the tail-swelling, and that the posterior part is folded in on the ventral side of the embryo, and, losing its characteristic structure, forms part of the ventral wall of the body. On this point my own observations confirm those of Gasser. In the lizard the early appearance of the neurenteric canal at the front end of the primitive streak clearly shows that here also the primitive streak can take no share in forming the neural plate. The above considerations appear to me sufficient to establish my hypothesis with reference to the nature of the primitive streak, which has the merit of explaining, not only the structural peculiarities of the primitive streak, but also the otherwise inex- plicable position of the embryo of the amniotic vertebrates in the centre of the blastoderm. POINTS IN THE ANATOMY OF PERIPATUS CAPENSIS, 431 On Curtain Pornts im the ANATOMY of PERIPATUS CAPENSIS. By F. M. Batrovur, M.A., F.R.S.1 Tue discovery by Mr. Moseley* of a tracheal system in Peri- patus must be reckoned as one of the most interesting results obtained by the naturalists of the “Challenger.” The discovery clearly proves that the genus Peripatus, which is widely dis- tributed over the globe, is the persisting remnant of what was probably a large group of forms, from which the present tracheate Arthropoda are descended. ‘ The affinities of Peripatus render any further light on its anatomy a matter of some interest ; and through the kindness of Mr. Moseley I have had an opportunity of making investigations on some well preserved examples of Peripatus capensis, a few of the results of which I propose to lay before the Society. I shall confine my observations to three organs. (1) The seg- mental organs, (2) the nervous system, (3) the so-called fat bodies of Mr. Moseley. In all the segments of the body, with the exception of the first two or three postoral ones, there are present glandular bodies, apparently equivalent to the segmental organs of Annelids. These organs have not completely escaped the attention of pre- vious observers. The anterior of them were noticed by Grube,’ but their relations were not made out. By Saenger,* as I gather from Leuckart’s ‘ Bericht’ for the years 1868-9, these structures were also noticed, and they were interpreted as segmental organs. Their external openings were correctly identified. They are not mentioned by Moseley, and no notice of them is to be found in the text-books. The observations of Grube and Saenger seem, in fact, to have been completely forgotten. The organs are placed at the bases of the feet in two lateral divisions of the body-cavity shut off from the main central median division of the body-cavity by longitudinal septa of transverse muscles. Hach fully developed organ consists of three parts : i) A dilated vesicle opening externally at the base of a Toot. (2) A coiled glandular tube connected with this and subdi- vided again into several minor divisions. 1 From the ‘ Proceedings of the Cambridge Philosophical Society.’ > “On the Structure and Development of Peripatus Capensis,” ‘Phil. Trans.,’ vol. clxiv, 1874. > “ Bau von Perip, Edwardsii,” ‘ Archiv f. Anat. u. Phys.,’ 1853. * “Moskauer Naturforscher Sammlung,” ‘ Abth. Zool.,’ 1869. 432 F. M, BALFOUR. (3) A short terminal portion opening at one extremity into the coiled tube (2) and at the other, as I believe, into the body-cavity. This section becomes very conspicuous in stained preparations by the intensity with which the nuclei of its walls absorb the colour- ing matter. The segmental organs of Peripatus, though formed on a type of their own, more nearly resemble those of the Jieech than of any other form with which Iam acquainted. The annelidan affinities shown by their presence are of some interest. Around the seg- mental organs in the feet are peculiar cells richly supplied with trachez, which appear to me to be similar to the fat bodies in insects. There are two glandular bodies in the feet in addition to the segmental organs. The more obvious features of the nervous system have been fully made out by previous observers, who have shown that it consists of large paired supraesophageal ganglia connected with two widely separated ventral cords—stated by them not to be ganglionated. Grube describes the two cords as falling into one another behind the anus—a feature the presence of which is erroneously denied by Saenger. ‘The lateral cords are united by numerous (5 or 6 for each segment) transverse cords. The nervous system would appear at first sight to be very lowly organised, but the new points I believe myself to have made out, as well as certain previously known features in it, appear to me to show that this is not the case. The following is a summary of the fresh points I have observed in the nervous system : (1) Immediately underneath the cesophagus the cesophageal commissures dilate and form a pair of ganglia equivalent to the annelidan and arthropodan subcesophageal ganglia. These ganglia are closely approximated and united by 5 or 6 commissures. They give off large nerves to the oral papille. (2) The ventral nerve cords are covered on their ventral side by a thick ganglionic layer,! and at each pair of feet they dilate into a small but distinct ganglionic swelling. From each ganglionic swelling are given off a pair of large nerves” to the feet ; and the ganglionic swellings of the two cords are connected together by a pair of commissures containing ganglion cells. The other com- missures connecting the two cords together do not contain ganglion cells. The chief feature in which Peripatus was supposed to differ 1 This was known to Grube, loc. cit. 2 These nerves were noticed by Milne Edwards, but Grube failed to observe that they were much larger than the nerves given off between the feet. $ These commissures were perhaps observed by Saenger (loc. it.). POINTS IN THE ANATOMY OF PERIPATUS CAPENSIS. 433 from normal Arthropoda and Annelida, viz. the absence of ganglia on the ventral cords, does not really exist. In other par- ticulars, as in the amount of nerve cells in the ventral cords and the completeness of the commissural connections between the two cords, &c., the organisation of the nervous system of Peripatus ranks distinctly high. The nervous system lies within the circu- lar and longitudinal muscles, and is thus not in proximity with the skin. In this respect also Peripatus shows no signs of,a primi- tive condition of the nervous system. A median nerve is given off from the posterior border of the supracesophageal ganglion to the cesophagus, which probably forms a rudimentary sympathetic system. I believe also that I have found traces of a paired sympathetic system The organ doubtfully spoken of by Mr. Moseley as a fat body, and by Grube as a lateral canal, is in reality a glandular tube, lined by beautiful columnar cells containing secretion globules, which opens by means of a non-glandular duct into the mouth. It lies close above the ventral nerve cords in a lateral compartment of the body-cavity, and extends backwards for a varying distance. This organ may perhaps be best compared with the simple salivary gland of Julus. It is not to be confused with the slime glands of Mr. Moseley, which have their opening in the oral papille. IfI am correct in regarding it as homologous with the salivary glands so widely distributed amongst the Tracheata, its presence indicates a hitherto unnoticed arthropodan affinity in Peripatus. NOTES AND MEMORANDA. Chlorophyll in Turbellarian Worms and other Animals.— Mr. Patrick Geddes has recently investigated the physiology and histology of the small green Planarian Convoluta Schultzti, and communicated his results in a highly sugges- tive paper to the Royal Society (‘ Proceedings,’ No. 194). Mr. Geddes obtained these worms in large quantity at Roscoff, the zoological observatory of Prof. Lacaze Duthiers. He has.succeeded in obtaining from a number of them, enclosed in an inverted glass vessel and exposed to sun- light, a quantity of gas which on analysis (by means of pyrogallic acid) proved to contain from 43 to 52 per cent. of pure oxygen. ‘This is the first direct proof of the evo- lution of oxygen gas through the agency of the chlorophyll contained in the tissues of animals of so high an organisation as the Planarian worms; though it was from Euglena, an animal Flagellate that Priestley obtained oxygen gas, even before it was known to be given off by plants. The exact nature of the chlorophylloid substance has not been deter- mined by Mr. Geddes. It-has the general properties of the green colouring matter of vegetable tissues, but which of the constituents of that somewhat variable substance are present has not yet been determined. Leaving aside the unicellular organisms, we have at present knowledge of substances similar to leaf-green in the tissues of the Sponge Spongilla, of the Polyps Hydra, and Anthea cereus, of the Planarians Vortex viridis and Convoluta Schultz, of the Gephyrean Bonellia, of the Chetopod Cheetopterus and of the Crusta- cean Idotea. Of these cases only that of Spongilla and of Bonellia have been studied with special care as to their ab- sorption spectra, and it is to Mr. Sorby’s papers in vol. xv of this Journal that we must refer for a minute account of them. Mr. Sorby showed by spectroscopic evidence that the green matter of Spongilla contains the same con- stituents (though differing quantitatively) as do the leaves of green plants, namely, blue chlorophyll, yellow chlorophyll, orange xanthophyll, xanthophyll, yellow xanthophyll, and lichnoxanthine. In a later paper (this Journai, vol. xv, p. 166) he showed that the green colouring matter of Bonellia, though exceedingly close in spectrum and physical properties to the three species of chlorophyll distinguished by him NOTES AND MEMORANDA. 4.35 (* Proc. Roy. Soc.,’ vol xxv), viz. blue chlorophyll, yellow chlorophyll, and chlorofucine, is, nevertheless, distinct, and for it he proposed the name Bonelleine. The spectroscopy of the other cases of chlorophylloid substance in animals has not been worked out iz detail, though I have shown that the absorption spectrum of the green colour of Hydra, of Cheetopterus, and of Idotea, is similar in respect of its chief lines to that of the chlorophyll group. Besides the facts as to (1) solubility ; (2) fluorescence of the solution; (3) evanescence of the colour in sunlight; (4) position of the absorption bands; (5) optical and other properties of the products obtained by reagents, there are other highly-important classes of facts to be looked into in connection with the his- tory of the chlorophylloid substances of animals. These are (6) the form and distribution of the green-coloured substance in the tissues of the animal possessing it; and (7) the evi- dences of its physiological activity (whether or not identical with that established for the chlorophyll of plants). Mr. Geddes showed, so far as this last point is concerned, that large quantities of oxygen were liberated by the green Con- voluta Schultzw, and on the hypothesis that this was due to the breaking up of the CO, into O and CO under the in- fluence of chlorophyll in sunlight, proceeded to search for evidence of the formation in the tissues of the Convoluta of starch or similar substances. An analysis of the Convoluta en masse yielded evidence of the presence of ordinary vegetable starch in quantity. This, however, is not in itself a very striking fact. Sponges, devoid of chlorophyll, are known to contain in vacuoles of their constituent cells starch, so far as the blue reaction with iodine is evidence of the presence of that body,! whilst the glycogen reaction with iodine has been obtained from the tissues of a variety of animals (Tzenia, Lamellibranchs, &c.). What one would like to be able to adduce as evidence of the physiological activity of the chlorophylloid substance of ani- mals would be the appearance and disappearance of starch granules in close association with the green substance, and under such conditions as those established by Sachs in the case of the chlorophyll grains of higher plants. Unfortu- nately this is not possible in the case of Convoluta. Mr. " See Keller, ‘Zeitschr. wiss. Zool.’, Bd. xxx, p. 574, 1878. He ob- tained, in a certain number of cells of various sponges, a blue coloration with iodine. The starch appeared to be in solution, and contained in large vacuoles occupied by the solvent. Keller found it in Spongilla lacustris, in Reniera litoralis, Myzilla fasciculata, Geodia gigas, Tethya lyncurium, Suberites massa, Suberites flavus. He failed, on searching, to find it in any Calcispongise, in Halisarca, and in Chondrosia. 436 NOTES AND MEMORANDA. Geddes gives important observations referable to our sixth category, from which it appears that the green substance of Convoluta does not exist in the form of grains, nor of fine granules, but “is diffused throughout the whole protoplasm” of certain cells, which lie beneath the circular and longitu- dinal muscles. Thus, the green substance of Convoluta differs most markedly from that of the allied Vortex viridis, in which it occurs in the form of drops in the cells; equally it differs from that of Hydra viridis and of Spongilla, which occurs in the form of grains embedded in the protoplasm of cells, the grains having the form of concavo-convex discs in Spon- gilla. In Bonellia, too, and Chetopterus the green substance is granular; in Idotea it is diffused. Nevertheless, Mr. Geddes obtained evidence of the formation of fine granules of starch in the green cells of Convoluta by the application of iodine to fresh-teased preparations of the worm’s tissues. This we must regard as the most important part of the evi- dence which he is able to adduce in favour of the view that Convoluta Schultz is actually nourished by the activity of its chlorophyll—that it, in fact, feeds on carbonic-acid as a green plant does. It remains to be seen whether similar or even more con- clusive evidence of this kind can be obtained from the examination of such chlorophyllaceous animals as Hydra and Spongilla. Mr. Sorby, writing in 18765 in this Journal on Spongilla, said: ‘It would, I think, be well worthy of study to ascer- tain whether low animal forms which, like Spongilla, contain chlorophyll, have, when exposed to light, the power of de- composing carbonic acid, and supporting themselves, to some extent,as plants.... Imfso, they would be animals to some extent capable of plant-like growth, and would thus be the reverse of those plants which have lately attracted so much attention on account of their being able to partially support themselves by means of complex animal food, which they can digest and absorb like the most perfect classes of animals.” Mr. Geddes’s researches have established, in one case at least, what the mere fact of the presence of chlorophyll in animals had led naturalists to entertain as hypothesis. He remarks: “‘As the Drosera, Dionza, &c., which have attracted so much attention of late years, have received the striking name of carnivorous plants, these Planarians may not unfairly be called vegetating animals, for the one is the precise reciprocal of the other. Not only “does the Dionzxa imitate the carnivorous animal, and the Convoluta the ordi- nary green plant, but each tends to lose its own normal NOTES AND MEMORANDA. 497 character. The tiny root of the Drosera and the half- blanched leaves of Pinguicula are paralleled by the absence of a distinct alimentary canal and the abstemious habits of the Planarian.” It is worth while pointing out that a considerable difficulty in relation to the view that the green specimens of Hydra viridis and Spongilla fluviatilis possess a vegetative nutri- tion, is presented by the fact that side by side with the green specimens occur very abundant colourless specimens, which appear to be equally robust and healthy. Do these colourless examples possess a colourless modification of chlorophyll which decomposes carbonic acid? or is the capricious distri- bution of the green substance analogous to the capricious dis- tribution of Hemoglobin, which is present, for instance, in the blood of Planorbis whilst absent from that of its associate Linneus / In connection with this subject it is important to notice that Metschnikoff has shown that in Rhabdocel Planarians the individual cells of the euteric tract engulph food-par- ticles, and thus reduce the digestive processes of these worms to the stage presented by colonies of amceboid organ- isms devoid of a true enteron, whilst Balfour has suggested that the nutrition of the sponges is effected by the cells of the ectoderm and by those of the endoderm; not, therefore, by aid of a digestive cavity. Mereschkowsky (‘ Ann. and Mag. of Nat. Hist.,’? March, 1879) has adduced evidence in favour of a similar process, not only in Sponges but in Medusze, the latter of which he has observed not unfrequently to be devoid of stomach and buccal aperture.—E. Ray LANKESTER, A New Genus of Protista.—Prof. Sorokin, of Kasan, de- scribes under the name Gilotdium quadrifidum in Gegen- baur’s “Morph. Jahrb.,’ Bd. iv, p. 399, a new naked proto- plasmic organism devoid of nucleus, 03 mm. in diameter, with vacuolated endosarc and hyaline periphery, which gives rise to lamellar pseudopodia, and possesses a pulsating vacuole. It was discovered in an aquarium containing Oscillarie, Hormidia, &e. The specific name refers to its habit of multiplication by quadripartite division with- out encystation. Prof. Sorokin also observed the formation of a cyst around single individuals, which was not followed by division, but in many cases the organism escaped from the cyst by means of a small hole, which it appears to have the power of boriag in the test with which it has previously covered itself. “> 4 , VOL. XIX; FF PROCEEDINGS OF SOCIETIES. Dustin MicroscopicaLt CiuB. 21st November, 1878. Docidium hirsutum, Bailey, occurring in Scotland, exhibited.— Mr. Archer showed examples of Docidiwm hirsutum, Bailey, taken on the Deeside, in Scotland; it was very scanty indeed in the gathering, but Mr. Roy informed Mr. Archer that he had before encountered it. It seems to be scarcely happily named, as the roughnesses on the superficies partake, so to say, more of the cha- racter of elongate papille than of ‘“hairs;” but Bailey speaks of it as “ strongly hirsute,” possibly in allusion to the coarseness of these “ hairs ””—a point perhaps rendering the identification of the form the more certain, but still his figure, in that case, shows the roughnesses as rather fine. It is not a very pretty form ; the wall appears thick and somewhat opaque, and the green ‘contents not of a lively tint. In these countries, at least, it must be surely a very rare species. Section from an Enchondroma of Tibia, exhibited.—Mr. B. Wills Richardson exhibited two stained sections, one red, the other blue, taken with the freezing microtome, from an enchondroma that sprang from the head of the tibia of a young man. The tumour attained to a large size in a few months and amputation above the knee had to be performed. The case had a malignant history, death having occurred a year after the operation. The cells and their nuclei were large and there were one or two ossific centres in each section. Exhibition of Octaviania asterosperma, Vitt—Mr. Pim exhi- bited Octaviania asterosperma, Vitt. This, the first hypogeous fungus that Mr. Pim had met with, occurred in his garden at Monkstown, on a piece of old carpet that had been dug-in with manure. It appears to be but very sparingly distributed both in England and on the Continent, and is now, it is believed, recorded for the first time in Ireland. Section of Dolerite, containing the new mineral Hullite, Hard- man, exhibited.—Professor Hull, F.R.S., exhibited a thin section of the olivine dolerite of Carmoney Hill, near Belfast, containing the new mineral called ‘‘ Hullite,” by the discoverer, Mr. E. T. Hardman, who has given a description of it at the recent meet- ing of the British Association in Dublin (Section C). The mineral DUBLIN MICROSCOPICAL CLUB, 439 occurs in grains filling eavities and small fissures in the rock. It is black, glossy, and has a conchoidal fracture, resembling pitchstone, but the chemical analysis shows it has no connection with this mineral, as it belongs to the ferrugino-chloritic group. With a 2-inch object glass it appears translucent, of a rich brownish yellow to bronze colour, sometimes traversed by dark prism-like bars. It is structureless or reticulated, filling cavities and the narrow fissures between the other minerals, which con- sist chiefly of unaltered olivine-plagioclase, a little augite, and a few grains of titano-ferrite. The mineral does not polarise, but with a higher power (1-inch objective) shows evidences of a reni- form structure. The olivine in the rock is unusually fresh and polarises vividly. Section of Spine of Salmacis rarissima, Agassiz.—Mr. Mackin. tosh exhibited a cross-section of Salmacis rarissima, Agassiz, one of the Acanthopneustes group, which though apparently mono- cycline in its mode of growth is not truly so, inasmuch as the solid wedges which make up the greater part of the spine exhibit a series of expansions at regular intervals indicating periods of growth. Macro- and Microspores of Isoetes Morei, Moore, exhibited.—Dr. David Moore showed specimens of the macro- and microspores of his new species, Jsoefes More, just described and figured in the ‘ Journal of Botany,’ and contrasted the latter with those of the allied species Jsoetes setacea, a native of the Mediterranean district. December 19th, 1878. Neomeris, undescribed species, shown.—Dr. E.-Perceval Wright exhibited mounted specimens of a species of the genus Neomeris, collected in the Friendly Isles, by the late Professor Harvey. In the working collection of Dr. Harvey the species stood recorded under the manuscript name of VV. capitata ; from N. dwmetosa of Lamarck it differed in very many respects, and from NV. (Decais- nella) nitida of Harvey it differed, not only in being less calca- reous, but in the beautiful regular hexagonal shape of the cells, and by the apparently one-celled stipes. Section of Quartziferous Diorite of Quenast, shown.— Professor Hall, F.R.S., exhibited a section of quartziferous diorite of Quenast, kindly lent him by M. ’Abbé Reynard. In the crystal- line grains of the silica were to be seen, by the aid of a high magnifying power (S00 diameters), fluid cavities containing minute translucent cubes, inferred to be those of sodium chloride (or common salt), and about 753455th of an inch in size. In one of the cells exhibited the vacuum bubble was observed close beside the crystal. The ‘“‘diorite quartzifére” of Quenast is remarkable for containing these cubes, which have been also observed by Dr. Zirkel in the granite of Arran, in Scotland, and in other rocks. 44.0 PROCEEDINGS OF SOCIETIES, New form of Celospherium, inhabiting intercellular spaces of a flowering plant, shown.—Mr. Archer exhibited a preparation by Professor Alexander Dickson of the leaves of a warm-house plaut, containing in the spaces examples of a phycochromaceous alga, morphologically, if the term be allowable, falling under Nageli’s genus Ccelospherium. It seemed to differ from the ordinary pond species in the reddish-brown colour of the colonies, and in the elongate, not orbicular cells these seemingly seated in a proper cup-like, gelatinous support—the two together some- what like an acorn in its cup—this cup-like base sometimes appearing as if somewhat prolonged downwards, but not in so pronounced a manner as may sometimes be seen in the allied form, met with in pools, Gomphospheriaaponina, Kitz. Altogether the form would appear to be heretofore undetected—probably its unusual habitat may have something to say to that—instances of similar allied forms occurring in the tissues of flowering plants are, however, now not rare. If one should meet the present form in a pond it would at once strike the eye as unusual. Mr. Archer thought he might be justified in calling this alga Celospherium Dicksoni, after its discoverer. Section of Spine of Phyllacanthus imperialis,shown.— Mr. Mack- intosh showed a cross-section of the spine of Phyllacanthus ampertalis, Lam., taken near the apex. It presented a very regularly stellate appearance, due to the projection of a number of ridges on the surface, and had a very thick external crust. Crystals of Magnesian Phosphate from Urine, of unusually large size, shown.—Dr. Tichborne showed crystals of ammoniacal magnesian phosphate from urine, of remarkably large size, being the largest he had ever seen naturally deposited; some of them were 6 mm., and, being of a beautiful regularity, were particularly suitable for polarisation. 16th January, 1879. Section of Syenite, with imbedded slender prisms, considered to be disthene, shown.—Professor Hull, F.R.S., exhibited a thin section of a syenite (quartz, felspar, hornblende) from Slieve Gullion, containing long prisms of a greenish glistering mineral, considered to be disthene (kyanite), the analysis of which gives silica 36'8, alumina 63°2 (Dana). This mineral was formerly discovered by Professor R. 8S. Scott, in Donegal. With a magnifying power of about 225 diameters the grains of silica were seen to contain numerous fluid cells, together with long prisms abruptly truncated. Some of these prisms were also continued into the felspar, and, in comparison to their diameters, were of great length and perfectly straight. Though generally colourless, they sometimes presented shades of brown or umber. The mineral polarises vividly, and is supposed to be disthene. Olivine is also present. Cutis vera from Heel, stripped of Epithelium, shown.—Mr. B. Wills Richardson exhibited two blue-stained sections, each an inch DUBLIN MICROSCOPICAL CLUB. 4A] long, of the cutis vera (from the human heel), totally stripped of epithelium. The papille were thus perfectly exposed and in full relief. Sections of the heel were made with the freezing micro- tome last year, and he, being engaged with other matters, had to allow them to remain until recently, in glycerine and some Beale’s carmine stain. To his surprise, when he examined them he found that the epidermis had separated from all the sections, possibly from the action of the ammonia of the stain, which wasin excess. With some trouble he restained a few of them with anilin blue, two of which were those he exhibited. They were mounted in Farrant’s solution, an excellent medium for anilin blue stainings, as he fancied it preserved the colour. Pithophora Kewensis, transferred from Kew, and flourishing at Glasnevin, shown.—Dr. Moore showed a copious growth of Pithophora Kewensis, Wittr., in the normal healthy state, froma small supply sent from Kew in July, 1878, to Dr. E. P. Wright, and which Dr. Moore had placed in one of the tanks at Glas- nevin, where it seemingly was inclined to flourish. A probably new Cosmarium, shown —Mr. Archer showed exam- ples of what seemed to be either a new Cosmarium or a form of Cosm. hexalobum, Nordst., some from Scotland, prepared by Mr. Bisset ; others from County Wicklow, obtained in Glencree. These specimens at least were absolutely identical, one and the same thing in the most minute detail, and Mr. Archer thought would really prove to be distinct from Cosm. hewalobum, besides being apparently decidedly smaller. It is, here, at any rate, a very rare form. Eggs of Echinorhyncus, various stages, shown.—Dr. Macalister exhibited the eggs of EHhcinorhyncus pinguis, showing the early stages of the formation of the embryo of that species, the tri- laminar egg-envelope, and the two kinds of blastomeres, into which the yelk segments. The formation of a central cavity was also visible in some of the more mature embryos. Structure of the green normal leaves of Pinus monophylla.— Professor McNab exhibited transverse sections of the green nor- mal leaves of Pinus monophylla. Usually in Pinus the normal leaves are reduced to thin scales in whose axils the short shoots with the needle leaves are developed. Frequently, however, in P. monophylla, these normal leaves, instead of being, as they sometimes are, mere scales, become large green flattened struc- tures resembling the leaves of Abies. Such leaves, often with single needles or two needles in their axils, are frequent on young plants, on the newly formed shoots, both terminal and lateral. On transverse section these normal leaves are seen to be somewhat triangular, flattened above, but with a projecting midrib below. Both upper and under surfaces possess stomata. There are two resin canals in each leaf close to the epidermis of the under side, and about halfway between the rounded margin of the leaf and the projecting midrib. There is a single fibro-vascular bundle, surrounded by a distinctly marked sheath ; the hypoderm is well- 442 PROCEEDINGS OF SOCIETIES, developed. These normal leaves must not be confounded with the needle-leaves, which are produced in the axils of the larger or smaller normal leaves, either singly, in pairs, or in threes ; in young plants either singly or in pairs, in old plants usually in threes. The single needles have a large central fibro-vascular bundle and well-marked sheath, surrounding a quantity of tissue belonging to the fibro-yascular mass. The stomata are placed in rows all round the cylindrical leaf. There are two resin-canals, and abun- - dance of hypoderm is developed between the rows of stomata. The leaves in pairs are half-cylindrical, stomata on both surfaces, and with a small fibro-vascular bundle in a mass of tissue, sur- rounded by a circular sheath. The hypoderm is well developed, and there are two resin-canals in each needle. When in threes the needles are triangular, with a double fibro-vascular bundle and no resin-canals. The variation in the structure of the needles is remarkable, and the production of large green normal leaves seems to be a unique character, as yet quite overlooked by botanists. 20th February, 1879. The stated meeting of the Club appointed for the above even- ing did not take place owing to the recent sudden and lamented death, on 8rd inst., of one of the members, John Barker, M.D., F.R.C.8.1. 20th March, 1879. Fossil Calcareous Alge and remarks thereon.—Dr. E. Perceval Wright exhibited specimens of Cymopolia rosariwm, Lamr., and Polytrypa elongata, Defranc, side by side and called the attention of the Club to the very important memoir of M. Munier-Chalmas, “ Sur les Algues calcaires appartenant au groupe des Dasycladées Harv. et confodues avec les Foraminiféres,” which was published in the ‘Comptes rendus hebdomadaires of the French Academy of Science’ for October 29th, 1877, and which opened up quite a new or almost a new field of research, which has been followed up by the same author in a note presented last month to the Geological Society of France, “On the genus Ovulites.” Though regarded by some of the most eminent paleontologists as a monothalamic Foraminifer related to Lagena, the genus Ovulites is herein clearly demonstrated to be neither more nor less than an articulation of a siphonaceous alga having very close affinities to Penicillus. Ovulites margaritula is described by Messrs. Parker and Jones “asacommon Foraminifer of the ‘ Calcaire grossier.’ Shaped like an egg, and when full grown, about the size of a mustard- seed, it is one of the most elegant of the fossil forms. The Jarge terminal apertures, moreover, curiously impress upon the mind its resemblance to a ‘blown’ bird’s-egg. [Written in DUBLIN MICROSCOPICAL CLUB. 443 1860; nowadays birds’ eggs are not thus blown.] It is the largest of the monothalamous Foraminifera. As a species it appears to have been short-lived. Fully developed in the deposits of Hauteville and Grignon it breaks in at once in the Eocene period. It lingers as an attenuated form in the Miocene beds of San Domingo. A recent Ovulite has not been met with. Searcely another Foraminifer presents us with a similarly brief history—an undescribed form allied to Dactylopora affording almost the only parallel (namely, The term “ Batrachia,” is used in this paper in the restricted sense as equivalent to the Anurous Amphibia. VOL. XIX.—NEW SER. GG 450 W. B. SCOTT AND HENRY F. OSBORN. with the greatest care; and as the albumen is permeated by several membranes, it was found necessary to cut these with fine scissors before the embryo could be with safety extracted. Many hardening reagents were experimented with—osmic acid, bichromate of potash, Miiller’s fluid, &c., but the most satisfactory one proved to be Kleinenberg’s pieric acid, with which nearly all the embryos described in the following pages were prepared. In those cases where the entire egg was hardened without previously removing the albumen, the results were most unsatisfactory. Kleinen- berg’s heematoxylin was the staining fluid employed for the sections. A. This includes embryos intermediate in age between Gotte’s figs. 39 and 40, taf. ii. The blastospore is quite small, a narrow groove, the “ Rickenrinne,” running forward some distance from its anterior edge. The medullary folds do not as yet appear in surface views. The ovum is still almost perfectly spherical in shape. B (Unke, Taf. iii, figs. 40 and 41). At this stage the medullary folds become well developed and very plainly marked. As yet they are widely separated. The medullary plate is formed, but the groove which divides it into two parts does not reach far forwards of the middle ; or, any rate, if present anteriorly, is extremely faint. The ovum has elongated very slightly, but still appreciably. C (Taf. iii, fig. 42). The medullary folds now become still more pronounced, and begin to approach each other. The point of closest approximation is in the region which will eventually become the neck, and here is the first point of contact, just as it is in the Batrachia. The medullary plate is plainly divided throughout. The elongation of the embryo is not much more marked than it was in the previous stage. D (see Pl. XXI, fig. 16). Up to this stage no important external differences between ‘Triton and Bombinator are apparent, but now a number of points of divergence begin to be noticeable. The medullary folds have closed throughout the region of the trunk, but still remain open in the head. Posteriorly they separate to form a sinus rhomboidalis ; this does not seem to be merely a part of the canal which has not yet closed, but a genuine EARLY DEVELOPMENT OF THE COMMON NEWT. 451 dilatation. It is either absent or very transitory in Bombi- nator. As the folds enclose the blastopore, which remains open till a much later period, the sinus gives a communica- tion from the exterior to the alimentary canal. When the sinus closes there is still the communication between the neural and alimentary canals, which has now been observed in so many types (Amphioxus, Accipenser, Elasmobranchii, Bombinator, &c.). The elongation of the embryo becomes very decided, and one surface of it becomes nearly flat; in Bombinator this is the dorsal surface; in the Newt it is the ventral, so that the latter is curved over the yolk. This difference is due merely to the larger amount of food-yolk in the egg of the Urodele, and cannot be considered of any great morphological significance. The bearings of the increased quantity of food-yolk will be discussed further on. E. This stage includes embryos, perhaps not quite so far advanced as the one figured in Gotte’s Taf. iti, fig. 50. The closure of the medullary folds is now complete throughout, and the vesicles of the brain are obscurely marked. The cranial flexure is already decided, and the whole embryo is somewhat curved upon itself, causing the ventral surface to assume a concave outline (except posteriorly, where the large mass of yolk produces a bulge). A trace of the opening of the sinus is still apparent. F (Taf. i, fig. 52). The ventral curvature now becomes stronger, as does also the cranial flexure. The curvature is in an opposite direction to that taken by Bombinator. The vesicles of the brain are very distinct, and the optic vesicles which commenced in the last stage are now remarkably large, much more conspicuous than in the Bombinator of corresponding age. Another difference presents itself in the fact that in the latter the optic vesicle is an elongated oval, while in the former it is hemispherical. The rudiments of the fifth and seventh pairs of cranial nerves appear as buds from near the dorsal part of the hind brain, higher up than in Bombinator. A few protovertebre have been formed. Up to this time there has been little or no increase in absolute size, the changes in form being pro- duced by the elongation and narrowing of the embryo. G. In this stage the cranial flexure is carried further, and the head, as a whole, has taken a spherical shape, very differen 452 W. B. SCOTT AND HENRY F, OSBORN. from the shape assumed by the Batrachian head. The rudiments of the visceral arches appear, and the tail begins to bud out from the yolk sac as an unsegmented mass of mesoblast. The number of somites has increased. H (Taf. iii, fig. 53). The elongation of the embryo has now progressed to a very considerable extent. The cerebral hemispheres bud out as an unpaired rudiment from the forebrain. Four visceral arches and three clefts have been formed. The tail has elon- gated somewhat, and is still unsegmented. We have been unable to discover anything of the suckers or horny teeth found in the Batrachian larve. I (Taf. iti, fig. 54). (See also Pl. XXI, fig. 17). This stage exhibits a general advance in development, but the only new feature is the appearance of the involution for the mouth. This is transversely elongated, differing from the mouth involution of Bombinator. The head shews swellings, which correspond in position to those which Gotte has named, respectively, kidney swelling, lateral nerve, seventh and fifth nerves, auditory vesicle, and Gasserian gan- glion; but, owing to the fact that the curvature is in the opposite direction, these organs are separated by wider inter- vals than in Bombinator. We shall have occasion to refer to one or two later stages (x and Lt), which are marked by general increase in size, the formation of the lens, and the appearance of the external gills. Segmentation and Formation of the Layers. We have not succeeded in securing a complete series of specimens showing all the stages of segmentation, but from those which we have observed there can be little doubt that it proceeds very much in the same manner as in the Frog. Segmentation is asymmetrical, and this characteristic begins to appear at a very early period. The earliest stage we have seen shows two longitudinal furrows, which cut each other at right angles at the upper part of the egg, and passing down the sides, gradually fade and disappear before reaching the lower pole. The food-yolk even at this period preponderates in the lower part of the egg, and thus prevents the yolk- division taking place so rapidly as it does above. These furrows may be compared to two meridians on a globe; the next one (judging from the analogy of the Frog) represents the equatorial furrow in Amphioxus, but, for the reason above EARLY DEVELOPMENT OF THE COMMON NEWT. 453 stated, it is much nearer to the upper pole than_to the lower, and this gives at once the distinction of larger and smaller blastomeres. The smaller blastomeres grow round the ovum over the larger, and bear the same relation to them as they doin the Frog. The segmentation cavity appears early, and from the very first its roof is only one cell thick, just as in the case of the Lamprey. As we shall see later the epiblast is at first composed of one layer, and hence the roof of the cavity is covered by epiblast only. In the Elasmobranch Fishes the roof of the cavity is formed by lower layer cells also, and this Mr. Balfour explains by the increase in the quantity of food-yolk in the cells, compelling them to creep up the sides of the cavity. Although there is propor- tionately more food material in the Newt’s egg than in that of the Frog the increase is relatively small and does not affect the position of the cells. The only difference between the two at this stage consists in the fact that the roof of the cavity in the Frog is two or more cells thick, and in the Newt only one. In short, the ovum of the latter resembles the morula of Amphioxus with a large amount of food material stored away in its lower part. Judging from the descrip- tions of Calberla, it is in no way different from the ovum of Petromyzon of corresponding age. The floor of the segmen- ‘tation cavity, as in all ova which contain food-yolk, is formed by the upper layer of yolk-cells from which, eventually, the ventral epithelium of the alimentary canal is in part derived. The next step in development is, as in the Batrachians, a process of invagination, and, as in them, it is an unsym- metrical invagination. The disturbing cause is in both cases the presence of the food-yolk below. Owing to the fact that the food to be made available must be placed upon the ventral side of the body, the invagination must in this region take place very slowly or not at all. By this simple considera- tion Mr. Balfour explains the unsymmetrical gastrula of the higher Vertebrates. At the period when our study of the two lower layers proper begins, segmentation is complete; the lips of the blastopore are rapidly nearing each other ; the epiblast con- sists of a single layer of partly columnar, partly wedge- shaped, cells, and has already in great measure attained those characters which persist throughout several of the following stages. At the lip of the invagination (see Plate XX, fig. 2) there is a decided swelling produced, in part by a lengthening, in part by a reduplication of the cells, a histological change 4.5 4. W. B. SCOTT AND HENRY F, OSBORN. analogous to that which has been pointed out in the so-called embryonic rim in the Elasmobranchs.!. The cells have a radiated arrangement, losing as they are reflected inwards their columnar character and becoming more spindle-shaped. As they approach the inner side of the lip they are quadrate, then oblong, then columnar, their outer ends abutting against the inner ends of the long epiblast cells. As the sections pass into the lateral region of the embryo, this rela- tion is lost, and confluent with the forming hypoblast cells are the parent mesoblast cells. The latter may fairly be considered to arise actually from the point of invagination and not as a secondary splitting off from the hypoblast on either side. Two longitudinal sections of an embryo at this period have been figured in Plate XX, figs. 2 and 3. Fig. 2 represents a section passing through the median line, and those changes in the epiblast at the lip of the blastopore which have been just referred to, may be followed. The alimentary canal has not proceeded far forwards, but the cells of the upper yolk are plainly forming the future hypoblast cells. The segmen- tation cavity is being pressed downwards; the section is in the median line behind and out of the median line in front. The reverse is true of the succeeding section (fig. 3), which represents the growth of the mesoblast at the sides of the invagination and the actual forward progress of the alimen- tary canal in the middle line. It illustrates the position and advancing obliteration of the segmentation cavity. Compar- ing the two sections, a very fair idea can be formed of the advance of the embryo in the early part of the stage (a). The process at the sides of the median line in Triton is then homologous to that which Gotte? represents as occur- ring in the median line in Bombinator, a construction which aids him in carrying out his peculiar views of the development of the notochord from the mesoblast. Calberla,® on the contrary, describes as the immediate result of invagination, in Rana temporaria, the primary entoderm. ‘This does not split in the median line, while at the sides it splits soon after formation, to give rise to the lateral plates of mesoderm. A fuller notice of his views will be given later. 1 Vide Balfour, ‘ Elasmobranch Fishes,’ chap. ii, p. 43. : (tk Alexander Goette, ‘“‘ Entwickelungsgeschichte der Unke,” ‘ Atlas,’ Tafel. ii. 3 BH. Calberla, “Zur Entwickelung des Medullarrohres und der Chorda- dorsalis der par eallet und Petromyzonteu,” p. 261, ‘ Morphologischen Jahr- uch,’ 3, 1877. EARLY DEVELOPMENT OF THE COMMON NEWT, 455 Our sections do not wholly accord with the observations of either of the above, for if it is clear that the invagination gives rise in the median line to a single layer of cells, it is equally clear that at the sides it gives rise to a double layer, namely, of mesoblast as well as hypoblast. The process in Triton agrees then more closely with that occurring in the Elasmobranch Fishes,' where the lower layer cells, confluent with the reflected epiblast on either side of the axial line, form a layer of spherical cells above and co- lumnar cells below, and the former is ultimately separated off as the mesoblast proper, while in the axial line the lower layer cells give rise simply to a columnar layer. Now, turning to the transverse section of a Triton embryo Stage a (see Plate XX, fig. 4) we find that it adds still further probability to this view, for the relations of the layers fully accord with the above interpretation of the invagination. Now, as concerns the further growth of the mesoblast, it results from the foregoing conclusions concerning the hypo- blast that the mesoblast is never present across the axial line in the early stages. In transverse sections of Stage a it appears as two lateral plates extending on either side to a point just above the side limits of the alimentary canal. The layer where it is nearest the alimentary canal consists of small round cells, one or two deep, which can be readily dis- tinguished from the adjacent hypoblast. These are the cells which we have just referred to as having resulted from invagination, and we shall speak of them hereafter as the primary mesoblast cells. In conclusion, all the observations we have made favour the above interpretation, while none in any way disprove it. Thus, at once three important distinctions are established between the development of the layers at the point of invagina- tion in Triton and Bombinator, if we accept in full Dr. Gotte’s investigations of the latter. First: in Triton there is a decided thickening of the single layered epiblast as it approaches the point of invagination. In Bombinator there is none. Second: the resulting hypoblast in the axial line is in direct contact with the epiblast. There is no inter- vening mesoblast as in Bombinator. Third: the mesoblast is found in Triton as two lateral plates, and is not con- tinuous across the middle. These observations, coupled with those of Calberla, we think leave little doubt that Gotte has mistaken the upper hypo- blast cells for mesoblast, and thus at the start fallen into an * Fide ¥, M. Balfour, ‘ Elasmobranch Fishes,’ p. 49. 456 Ww. B. SCOTT AND HENRY F, OSBORN. error which involves some of his subsequent conclusions in doubt. Having thus briefly considered the origin of the two inner layers, as related to the phenomena of invagination, we shall return to the history of the epiblast from the beginning, and resume our discussion of the mesoblast and hypoblast in the subsequent pages. General Features of the Epiblast. When the epiblast can first properly be said to be formed, it consists of a single layer of very large quadrate cells, with large clear nuclei. Inthe next stage, when the invagination first commences, the cells have somewhat lengthened out, but are still very broad (Plate XX, fig. 1). When the in- vagination has progressed considerably, and the segmenta- tion cavity has been much narrowed, we find that the cells have assumed the condition which they retain for some time after this. They are long, narrow, and columnar; most of them can be traced through the layer from one surface to the other without any change of size, although here and there several may be seen which have a wedge-shape, and alternate arrangement with their neighbours. The nuclei, however, are arranged in two rows, like those of the Elasmo- branch epiblast. In general appearance, up to this time, the epiblast is more like that of Petromyzon than of any embryo which we have seen,! but the arrangement of the cells is somewhat more regular. For a short time, indeed, the appearance of the two is almost identical, but in the Newt the cells speedily become narrower, and more columnar in character, and the nuclei assume the alternate arrange- ment which is only faintly indicated in the Lamprey. During Stage A, when the medullary groove has begun to make its appearance, the middle line of the dorsal epiblast, exhibits a decided thinning to form the groove (Plate XX, fig. 4). But this grove is not at this period, nor do we find it afterwards, nearly so deep or so wide as it is in the Elas- mobranchs.” The next change of importance takes place during Stage B (Plate XX, fig. 5), when the medullary folds are well formed. ‘These folds are caused by the multiplication of cells of the epiblast, which here becomes much thickened. Although the folds are several cells thick they show no indica- tion of being separated into different layers. With the excep- 1 See a paper by Calberla, ‘ Morph. Jahrbuch,’ 1877, 3, taf. xii, fig. 7. 2 Balfour, loc. cit., plate iv, fig. 8 a. EARLY DEVELOPMENT OF THE COMMON NEWT, 457 tion of the medullary plate the remainder of the epiblast shows no especial change from the condition seen in the preceding stage. In the medullary plate, on each side of the middle line, is a low rounded ridge (Plate XX, fig. 5), which is formed by the increase in length of the epiblast cells, and perhaps partly also by the wedging in of the mesoblast along these two lines. The condition of the spinal cord at this period recalls the the condition of the same organ in the Batrachia of this age. For in the latter the nervous and epidermic layers fuse together into one indiscriminate mass, and do not separate again till much later. This separation takes place for the first time in Triton, not far from the age in which it reappears in the Batrachia. During Stage c sudden and rapid changes make their appearance. The medullary folds are now very prominent, and are composed of numerous elongated spindle- and wedge-shaped cells, while in many places the medullary plate shows a commencement of the same process (Plate XX, fig. 6). But as yet in neither of these regions are any distinct layers to be seen. The lateral epiblast is just beginning to separate into two layers ; the process commences immediately outside of the medullary folds, and spreads down the sides of the embryo, until it has been completed all around (fig. 6). Plate XXI, fig. 9, shows a drawing on a larger scale of the point where such changes are going on most actively. Even with the aid of this we have not thoroughly satisfied ourselves as to the exact manner in which these changes are accomplished. Three suppositions may be made with regard to it—(1) that the upper layer splits off from the lower by a process of cell division ; (2) that the wedge-shaped cells draw in their edges, and lying in alternate arrangement come to make two rows, one above the other; (3) that both of these have their share in the process. On the whole we rather incline to the. latter opinion. In favour of the alternate decrement of length is the fact that for some time preceding the separa- tion the nuclei of the cells are arranged in two alternate rows, very much as in the Elasmobranchs, while such an appearance as shown at the point a, fig. 9, looks as if it could only be cell division. Turning to Stage p (Plate XX, fig. 7), we find that in the trunk region the medullary canal is completely closed, and the division of the epiblast carried entirely around the embryo, giving us two well-marked layers. These are com- posed of quadrate, somewhat flattened cells, of nearly equal size in both layers. The cells composing the spinal cord 458 W. B, SCOTT AND HENRY F, OSBORN. are numerous, elongated, wedge- or spindle-shaped; but even yet there is no indication of distinct layers. As in the Bird, the Mammal, and the Elasmobranch Fish, the epithelium lining the spinal canal does not become dif- ferentiated till a considerably later period. As a whole the spinal cord is now a hollow cylinder with very thick walls and a very small lumen. It presents a transversely oval section, and is somewhat indented on its lower surface by the pressure arising from the notochord. The epiblast has met and coalesced glong the middle line above the canal, though a slight groove still shows the line of union. From this time forward the outer layer of the general epiblast becomes flatter and flatter, while the inner layer grows more columnar. But in those parts of the skin which cover the brain both layers are composed of very much flattened cells (Pl. X XI, fig. 13). The inner or mucous layer, when once formed, is the active layer, and from it alone such structures as the lens of the eye are derived. The primitive condition of the epiblast in Triton is an extremely interesting one, presenting in a somewhat un- expected manner great differences from that of the Frog. As is well known, in the latter animal the epiblast is double- layered from an extremely early period, the roof of the seg- mentation cavity being formed by two layers of cells, and by the time of invagination there is an outer stratum of a single row of flattened cells and an inner stratum of several rows of rounded cells, the epidermic and nervous layers of Stricker. ‘“‘ Both strata have a share in forming the general epiblast, and though eventually they partially fuse together, there can be little doubt that the horny layer of the adult epiblast, when such can be distinguished, is derived from the epi- dermic layer of the embryo, and the mucous layer of the epiblast from the embryonic nervous layer. Both layers of the epiblast assist in the formation of the cerebro-spinal nervous system, and they also at first fuse together, though the epidermic layer probably separates itself again as the central epithelium of the spinal canal.” (Balfour, loc. cit., p. 99.) All this is very different from what we see in Triton. At first the epiblast is of one layer, and so remains for a con- siderable time ; the mucous layer, when formed, consists of a single stratum of more or less columnar cells, and the epi- thelium of the spinal cord appears for the first time at a much later period. In short, the condition of the epiblast, except in the last respect, is more like that of Petromyzon than that EARLY DEVELOPMENT OF THE COMMON NEWT. 459 of the Batrachia. It is, as might be expected, intermediate between the two types in many ways. In the Lamprey the division into two layers does not occur until a comparatively late period, some time after the larva has been hatched, while in the Newt it occurs as early as Stage c. In the Frog it is found from the first. Another respect in which the Newt is intermediate is the histological character of the layers. The Elasmobranch Fishes in this respect present an inter- mediate condition between the Lamprey and the Newt. In them also the epiblast is primarily single; the first change consists in the part which will give rise to the central nervous system, becoming several cells thick, but presenting no distinction into two layers. Eventually, later than in the Newt, earlier than in the Lamprey, the epiblast divides into mucous and epidermic layers. Both layers seem to enter into the formation of the organs of sense, while in the Amphibians the sense organs are formed exclusively, or almost so from the mucous layer, and in the Lamprey they are derived from the epiblast before its division into the layers. These facts put us in a somewhat favorable position for the solution of the question as to whether the single- or double-layered epiblast is the primitive condition. We are decidedly of the opinion that the conclusion drawn by Mr. Bal- four on p. 100 of his book on the Elasmobranchs is the correct one, viz. that the single-layered epiblast is the more primitive condition. He was not aware at that time of the difference existing between the Frog and the Newt in this regard, and so attributed the double layer to the Amphibians generally. But, as we have seen, it is confined to the Batrachians, a much more restricted group, and is, perhaps, also found in Osseous Fishes, Besides these it is found in no other groups of the animal kingdom, and, as Mr. Balfour points out, it is more probable that a particular feature of development should be thrown back to an earlier period than for the distinction between the two layers to be absolutely lost, and then to reappear ata later stage. This d prior? consideration receives a great deal of support from the facts of the development of the Newt. By its aid we are enabled to arrange a series of steps of advancing differentiation of the epiblast from Amphi- oxus through the Marsipobranchs, the Elasmobranchs, and the Newt, to the Batrachians. The steps of this progression have been already stated, but it may be well to summarise them. (1.) Amphioxus has an epiblast consisting at first of short columnar cells in a single row. ‘These afterwards begin to flatten out, and in the adult are very much flattened, but never constitute more than a 4.60 W. B. SCOTT AND HENRY F. OSBORN. single row. The medullary plate is the only epiblastic development which consists of more than one row of cells. This fact alone is of considerable weight in the question we are considering ; and it should be borne in mind throughout the discussion that, in the most primitive vertebrate known, the epiblast is permanently single-layered. Into the peculiar method of the formation of the cerebro-spinal axis we need not enter. (2.) Inthe Lamprey the epiblast does not divide until very late; in fact, not before the embryo has for some time been hatched (see Calberla, loc. cit., p. 264). This change takes place, however, in the region of the spinal cord before that organ has been formed, just as 1s the case in Amphioxus. The development of the nervous axis presents some pecu- liarities of a secondary nature. The sense organs are formed from the undivided epiblast. (3.) The epiblast in the Elasmobranch Fishes separates into two layers much earlier than it does in the Lamprey, but still comparatively late in embryonic life, some time after the medullary canal has been completely closed, and several of the visceral clefts have appeared. According to Mr. Balfour it takes place at a stage slightly younger than K. The two layers are at first composed of flattened cells, but those of the inner stratum soon become columnar. ‘“‘ Both layers apparently enter into the formation of the organs of sense.” (4.) In Triton the epiblast, though at first single, divides into its two parts at a very early stage, some time before the closing of the medullary canal (Stage c). When once formed the mucous layer becomes the active one and enters almost exclusively into the formation of the sense organs. So far as we are aware this is the only case as yet known in which there is a primitively single epiblast dividing early and delegating all its activity toone layer. It shows an approximation to the state of things found in the Frog. (5.) In the Batrachia this is carried one step further and the two layers are distinguishable from the very first, even the roof of the segmentation cavity being double. The mucous or nervous layer, as in the Newt, enters alone into the formation of the organs of sense, &c. In short, almost the only difference in the matter of epiblast between the two classes of Amphibia lies in the é¢me of its division. Now, we are very far from asserting that these forms we have been considering represent the line of descent of the Batrachia; but we are decidedly of the opinion that they exhibit the steps of the process by which the epiblast of that group has reached its present complication. For EARLY DEVELOPMENT OF THE COMMON NEWT. 461 this reason we are forced to the conclusion that even the early condition of the epiblast in the Batrachia is a secondary modification, and that the primitive condition of the layer is single. As opposed to this conclusion may be adduced the fact that in the spinal cord of the Batrachia the two layers at first fuse together and at a later time reappear, as if the double- layered condition were a primary, the single-layered a secondary, and the reappearing double layer a tertiary stage in development. And further, that the first stage has been retained only in the Batrachia and (?) Osseous Fishes, and lost in other known vertebrates. But this appears unlikely, and standing entirely by itself, the above-mentioned fact cannot be considered to have any great value. The Hypoblast. We shall now continue the history of the hypoblast from Stage a onwards, until the development of the notochord. The embryo at this stage (see Pl. XX, fig. 4) is still spherical. In the section figured, which is in the anterior region of the embyro, the alimentary canal is broad and low, lined above by a deep single layer of columnar hypoblast cells. These are broader and longer than the epiblast cells above them, with nuclei of a spherical rather than oval shape. They are in contact with the epiblast broadly across the middle line, but at the sides, just below the two slight folds on either side of the medullary groove, the mesoblast begins to intervene as a single layer of small cells. Beneath these the hypoblast cells lose their columnar shape, and becoming more quadrate are gradually reflected around the sides of the alimentary canal, becoming continuous on the one hand with the quad- rate yolk cells lining the alimentary canal below, on the other with the cells bounding the great mass of yolk. This continuity has been carefully represented in Pl. XX, fig. 4. Where the invagination cells cease would be difficult to state, owing to the fact that the bending down at the sides is a gradual process partly dependent upon the growth of the mesoblast. The hypoblast can now be classed according to its develop- ment under two heads. (a.) The cells above the alimentary canal, which have arisen from invagination and are con- tinuous with the reflected epiblast at the blastopore. This we shall call the invagination hypoblast. (4.) Those cells lining the alimentary canal below and those immediately bounding the yolk elsewhere, which arise by histological 4.62 W. B. SCOTT AND HENRY F. OSBORN. changes in the yolk cells proper. We shall refer to this as the yolk hypoblast. The growth of the former class has been already con- sidered in full. The latter arises by a slow process of meta- morphosis in the peripheral yolk cells. The changes are not difficult to follow. The square yolk cells split as they approach the surface into long columnar or oblong cells, and at the same time a change takes place in the yolk spherules with which they are loaded, so that they show a greater avidity for the staining fluid. ‘The large spherical nuclei of the yolk cells give place to the characteristic oval nuclei of the hypoblast. These primitive hypoblast cells assume more regular proportions as development proceeds. In the split- ting off of the mesoblast which soon follows, fresh cells are constantly supplied from the yolk. A further notice of Calberla’s! views upon these points will perhaps not be out of place here. He considered the Lam- prey embryo immediately after invagination to consist of two layers, the primary entoderm and the ectoderm. The former divides everywhere, except across the axial line, into the secondary entoderm and the mesoderm. Across the axial line the primary entoderm remains intact. He does not admit that the mesoderm arises even in part by invagination ; but, still more important as it bears on the question under discussion, he does not include the outer yolk cells as part of the pri- mary entoderm. So what we shall consider hereafter as the lateral mesoblast, he concluded, was joint mesoblast and hypoblast, not allowing that the outer yolk cells formed a distinct layer. The comparison has been inserted because at this period of its history the Lamprey presents many points in common with the BiB .To resume the study of the hypoblast in Triton, it may | be considered in the latter part of Stage c as forming a con- tinuous layer around the yolk and completely enclosing the alimentary canal. By Stage Ba very decided change has taken place (see Pl. XX, fig. 5). The section is in the head region where the alimentary tract has now reached a con- siderable size. The hypoblast is now only in contact with the epiblast in the median line, although the connection is such a close one that the three or four cells, still adhering, im- pinge so closely as te form a decided indentation in the epiblast—a feature which has been previously noticed in the Elasmobranch Fishes. The middle cells have also elongated and narrowed considerably, while those at the sides remain shorter; this results in a rounded upper outline. Laterally, 1 Vide HK. Calberla, loc. cit., on ‘ Petromyzon planeri,’ EAKLY DEVELOPMENT OF THE COMMON NEWT. 463 they are still markedly continuous with the yolk hypoblast cells lining the alimentary canal and their lower margin arches upwards so as to form part of the lumen of the canal. This bending around of the hypoblast, which in Stage a was almost a straight line, into an arch of cells, must be partly attributed to a mechanical cause, viz. the rapid ingrowth of the mesoblast plates. Whatever the exact cause of this change it is well to note that no vital altera- tion has as yet taken place—the change is one merely of position. Elsewhere the hypoblast shows no new features. Inasmuch as the interest in the hypoblast chiefly centres around the development of the notochord we shall con- sider the history of that organ by itself and complete the hypoblast later. The Mesoblast. It is evident from transverse sections in the latter part of Stage A (see Pl. XX, fig. 4) that the lateral plates of meso- blast have already attained a considerable thickness. At the junction of the invagination with the yolk hypoblast they are three or four cells deep, thinning out rapidly at the sides. In the anterior sections they barely extend below the middle, while behind they meet as a single layer of cells at the bottom, thus encircling the hypoblast except in the axial line above. The lateral downward growth of the mesoblast in Triton is plainly not from the epiblast, for the epiblast has by this time formed a distinctly bounded single layer. There remain two modes in which it may 7%” great part arise, (a) from the hypoblast ; (b) independently of the hypoblast, from the yolk. This is of course excluding the mesoblast in the region of the alimentary canal which accompanies the process of invagina- tion. Ifwe consider, as we have reason to do from the analogy of the Frog, that the cells bounding the yolk form the primi- tive yolk hypoblast layer, we can only accept the former hypo- thesis. In the anterior section of Stage a the cells bound- ing the yolk below are as unquestionably hypoblastic as those bounding it above and at the sides. In other words, the hypoblast has formed as a distinct layer in contact with the epiblast below, before the mesoblast has appeared below at all. Moreover, at the sides, the down growth of the meso- blast is preceded plainly by a splitting off of the outer portion of the yolk hypoblast into large quadrate cells, and these in turn are seen in the process of subdivision. Although this growth seems to be at the expense of the hypoblast, it cannot be considered to arise altogether independently of the down- 464 WwW. B. SCOTT AND HENRY F. OSBORN. growth of the invagination plates by a process of cell division, for the mesoblast does not arise at separate points, capping the hypoblast, but in direct continuity with the invagination mesoblast. In the Elasmobranch Fishes, in which the origin of the mesoblast has been carefully observed, there is no doubt that this layer arises as two lateral masses, splitting off from the hypoblast at the same time that the latter arises as a distinct stratum from the lower layer cells. Here, however, the lateral plates do not form a continuous layer with the mesoblast which occasionally arises at the reflection of the epiblast at the sides, but are distinct from it. Calberla,! as previously stated, explains the growth of the mesoderm (mesoblast) in the Lamprey, as an early splitting of the outer portion of the primary endoterm. This view fully confirms our interpretation of the lateral growth in Triton. In Kowalevsky’s earlier researches upon Amphioxus he fell into the error of supposing the mesoblast of double origin, hypoblastic and epiblastic, an error which he cor- rected later? by attributing this layer to a constriction off from the hypoblast, which occurs subsequent to the forma- tion of the notochord. The simple invagination does not give rise to any but the two primitive layers. There can now be no doubt that the formation of the mesoblast is in all types a secondary phenomenon which is retarded in the simpler forms, and hastened in the more complex into an earlier period of development. To review the features noticed in Stage a. The meso- blast arises by invagination as two lateral plates, and is never found across the median line. Subsequent growth is partly by cell division of these plates; mostly, however, at the expense of the hypoblast. The most rapid development is posteriorly, both in respect to thickness and downward growth. There is no tendency to split into somatic and splanchnic layers. By Stage B the mesoblast shows a very marked progress. It is now thickest immediately below the medullary plates, and causes that upward curve in the out- line of the epiblast previously mentioned (Plate XX, fig. 5). At the same time the lateral plates have approached each other, bending the hypoblast downwards, so that now it is continuous with the epiblast only in the median line. The section figured is in the anterior part of the embryo near the head region. The cells appear larger than in the last stage, 1 EK. Calberla, loc. cit. * Vide A. Kowalevsky, ‘Archiv. fur Micros. Anatomie.’ Band 13, p. 191. EARLY DEVELOPMENT OF THE COMMON NEWT. 465 near the axial line they are crowded together irregularly, but at either side the splitting into two single-celled layers begins to be evident. ‘This splitting begins anteriorly and proceeds slowly backwards. In the posterior sections of the same embryo it is barely evident, although the cells show a tendency to arrange theinselves in two rows. Plate XX, fig. 6, represents a section from the trunk region during Stage c, and shows that the splitting of the mesoblast extends slowly backwards. In this region the layer is now thinner than it is forwards, although the reverse of this is true of Stage a, where the mesoblast is thickest posteriorly. The proximal cells now begin to arrange themselves radially around the vertebral portion of the future body cavity, closely im- pinging against the epiblast, and tending to grow in above the primitive notochord. The body cavity does not extend beyond the medullary folds in this embryo, for here the two rows of cells suddenly terminate in a single row bending around the sides. In other respects the mesobiast shows no new features until Stage D. Sections of an embryo, during the latter part of Stage p, show that the neural canal has completely closed. The section figured in Plate XX, fig. 7, is in the anterior trunk region, here the mesoblast appears as two great triangular muscle plates, expanding above so as to fill the space formed by the fusion of the medullary canal, and enclosing the large body cavity. The two layers now extend completely around the embryo, but have not separated except in the upper region. In Stage F the divi- sion into somites has begun. To conclude, there is one feature in the development of the mesoblast, which argues strongly for the fact that, meso- blastic invagination being begun, lateral growth sets in at once; that is, the cells formed by invagination are immedi- ately supplemented by those growing down at the sides, of hypoblastic (yolk cell) origin. As evidence of this we find the mesoblast of the posterior sections meeting in the median line below, before it even reaches the ventral region anteriorly. In this single respect, the mesoblast develops more rapidly behind than in front. Subsequent to the formation of the alimentary canal, the greater energy of the embryo is directed to the head region, and all following growth is from before backwards. This is true of the thickening of the lateral plates, of the splitting into two layers,of the formation of the body cavity, and of the subsequent division into somites. VOL. XIX.——NEW SER. H dH 466 W. B. SCOTT AND HENRY F, OSBORN. The Notochord. In our description of the hypoblast, we considered the layer as classed under two heads, the invagination hypoblast, and the yolk hypoblast; it is with the former that the development of the notochord is concerned. The cells lying during Stage B between the mesoblast plates may be con- sidered the primitive notochordal cells. The first indication of the growth of the notochord in Triton (see Plate XX, fig. 5), is the tendency of the cells to take a radiated arrangement. We may now at the out- set, point out three prominent features.- First, the hypo- blast consists of a single layer of columnar cells running from the epiblast above to the alimentary canal below. Second, these cells may be identified with the broad band of invagination cells which in Stage a were all in contact with the epiblast. They have been bent down by the ingrowth of the mesoblast above. Third, these cells are directly con- tinuous at the sides with the yolk hypoblast. In the Lamprey,! Petromyzon planeri, the relations of the hypoblast at this point to the epiblast and mesoblast are practically the same. There is the same close and broad contact with the epiblast, and the cells are of the same relative size. Here, as in Triton, the primary or invagina- tion cells are alone concerned in the origin of the notochord. In the Frog (Rana temporaria)’ the primitive condition of the notochord is a great cubical mass of small cells, con- fluent with the epiblast above, and with the mesoblast at the sides. These do not all enter into the formation of the notochord, however, for at the time this organ begins to be constricted off, the lower cells form a hypoblastic lining to the alimentary canal. Gd6tte’s account of the first appear- ance of the notochord in the Frog (Bombinator tgneus) differs widely, owing to the fact that he has mistaken the upper hypoblast cel ls for the mesoblast. In the Elasmobranch Fishes® the arrangement is analo- gous, for the whole layer with the exception of a thin line of cells over the alimentary canal, enters into the notochord. The cells are at no time so widely in contact with the epiblast as in Triton; so the change preceding the formation of the notochord consists, first, in the lengthening, and then splitting of the celis into two lines placed end toend. The lower line thus formed is, however, mostly absorbed in the ' Vide Hi. Calberla, loc. cit. * Vide K. Calberla, loc. cit., p. 260, 3 Vide Balfour, loc. cit., p. 93. ~ EARLY DEVELOPMENT OF THE COMMON NEWT. 467 formation of the organ, and is not, as in Rana temporaria, wholly expended in forming the upper layer of the alimen- tary canal. To return to Triton, it is well to notice here that the upper boundary of the alimentary canal is formed by the cells which will give rise to the notochord, and that the latter at this period actually contains part of the lumen of the canal. Following the notochord into the succeeding stage, we find no marked changes (Pl. XX, fig.6). The section taken from the middle region of the embryo presents much the same appearance. From this we infer that in common with the other organs, the notochord develops more rapidly for- wards, and that the backward development is a slow one, for in Stage c the notochord is but little more advanced in the middle region of the embryo than it is in the anterior region in the preceding stage. The primitive features pointed out above remain constant. Unfortunately there is a gap in our sections here, at least we have none by which we can trace the histological changes from the simple fold of hypoblast celis in Stage c, to the firm rod of radiating cells in the latter part of Stage D. There is no evidence of their splitting into two cells deep previous to this result as in the Lamprey and the Elasmo- branchs. The exact process beyond the ascertaining of this point is of little real importance. In Stage p (Pl. XX, fig. 7) the relations of this organ are not much altered, it still impinges against the epiblast above, and partly bounds the alimentary canal below, but the continuity with the hypoblast has been broken off, and the line of demarcation is plainly marked by the different character of the cells. The notochordal cells are subquadrate in shape, about twelve in number in a transverse section, and are arranged around a centre of their own. In other words, the notochord is now an independent body; at its sides below are the long narrow hypoblast cells which par- tially enclose it, and above are the mesoblast plates fully formed, which, however, show no tendency to sur- round it. The notochord is now larger than at any subsequent stage. In its formed or permanent condition, it persists as a close granular mass in which we can sometimes detect cell divi- sion, sometimes not. (See PJ. XXI, fig. 8; figs. 12 and 13.) In Stage u an ingrowth of hypoblast below, cuts off its connection with the alimentary canal. In a much later period, Stage m, it has a vacuolated appearance; a branching network of connective tissue supporting promi- 4.68 W. B, SCOTT AND HENRY F. OSBORN. nent nuclei, an appearance which has been noticed in many other forms (Pl. XX, fig. 15). This completes the interesting history of the development of the notochord. To summarise: The invagination hypo- blast cells are first continuous as a single layer, wholly across the median line; those farthest from the three central cells are gradually pushed down by the ingrowth of the mesoblast. There is no tendency to split below. They are further reflected around until the lateral cells meet, and the continuity with the hypoblast is broken. It still impinges against the epiblast above, and forms the upper boundary of the alimentary canal below. A comparison has already been instituted between the development of the notochord in Triton and its development in the Frog, the Lamprey, and the Elasmobranch Fishes. In important details the processes are very similar. To carry the comparison a step further, in Amphioxus the noto- chord is differentiated from the hypoblast before the meso- blast has become constricted off, and at the time that the medullary plate is closing in above. Hensen has demonstrated, beyond doubt, that the noto- chord is of hypoblastic origin in the Guinea-pig; and that it probably arises in the same way in the Rabbit. Quite recently,” Mr. Balfour has shown that it has a similar deriva- tion in the Lizard, Lacerta muralis. In several respects the notochord arises in a simpler manner in Triton than in any of those forms in which the process has been clearly followed out. In that: first, the cells do not reduplicate vertically, as in the Elasmobranchs and the Lamprey, previous to the formation of the organ; second, when the organ is completely formed, it still bounds the alimentary canal below, as in neither of the other forms nor in the Frog; third, no portion splits off subsequently to form the hypoblast layer bounding the canal above, this layer appears from the sides. It is difficult to judge from Kowalevsky’s description, whether the whole depth of the layer bounding the canal above is absorbed by the notochord, or whether the lower por- tion remains as an upper lining of the canal, and the upper portion alone enters into the notochord. If the latter is the case, the Newt presents the simplest notochordal develop- ment known. The evidence from all these forms points so strongly in one direction, as to amount almost to proof, that the study 1 Vide Kowalevsky, loc. cit. > Vide F. M. Balfour, this Journal, Vol. X1LX, p. 3, New Series. EARLY DEVELOPMENT OF THE COMMON NEWT. 469 of the more important types which have not as yet been observed, and the clearing up of the doubts which still envelop other types, will fix the derivation of the notochord from the hypoblast as a law, rather than as a feature posi- tive in some cases, and with an exceptional origin from the mesoblast in others. The Hypodlast. In Stage c the notochordal cells are continuous at the sides, with the layer of hypoblast lining the yolk (see PI. XX, fig. 6). In Stage p this continuity is completely broken, the layer appears as a long narrow row of cells, flattened against the sides of the notochord, but not enclos- ing it below. Elsewhere this layer shows no new features. In Stage £, however (see Pl. XXI, fig. 8), the cells have grown down and meet below, completely surrounding the alimentary canal and shutting it off from the notochord. This process is interesting, as it shows that, while the original upper lining is mainly absorbed by the notochord, the per- manent upper lining is formed from the yolk hypoblast cells, and that now almost the entire layer is formed of this secondary hypoblast, the bulk of the primary or invagina- tion hypoblast having gone to the notochord. The hypo- blast grows under the notochord, in much the same way in the Lamprey, but at a somewhat earlier stage. In most of the other forms there remains throughout, a thin layer of cells intervening between the notochord and the yolk. Body Cavity and Somites of the Head. As already mentioned, the growth of the mesoblast is from behind forward, and in Stage a (Pl. XX, fig. 4) we see that in the head region the mesoblastic plates do not meet ventrally. ‘They gradually thin out forwards and end near the blind termination of the alimentary canal. At this period the mesoblast is quite thick, and is composed of nu- merous cells of spherical shape, but exhibits no tendency to become divided into somatic and splanchnic layers. In Stage B, however, the cells have arranged themselves into two layers, and quite a cavity has appeared between them (Pl. XX, fig. 5). As yet this change is confined to the head, and so there is a cavity in the head on each side of the mid- dle line, contained between the somatic and splanchnic layers of the mesoblast. ‘These cavities, therefore, are parts of the pleuro-periteneal cavity, and when that is formed in the body, will be directly continuous with them. As in the 470 W. B. SCOTT AND HENRY F. OSBORN. Elasmobranch Fishes,! the cavity in the head is formed at @ period considerably before that at which it appears in the body. These two head cavities have no communication with each other, as the mesoblast in the head is in two separate masses. A longitudinal horizontal section (Pl. XXI, fig. 10) through an embryo slightly older than F shows this cavity (pp.) as an undivided slit bounded by columnar mesoblast cells. But when the first visceral cleft appears as an outgrowth from the hypoblast of the throat to join the external skin, this cavity is necessarily separated into two portions, one behind and one in front of the cleft. This cleft in the latest stages we have been able to observe never pierces the skin, but it lies close to it and so divides the me- soblast. The second cleft divides the cavity into three sec- tions, and each succeeding one adds a fresh segment to the number. Of course this number is not so great as it is in the Elasmobranch Fishes. The section in front of the first cleft presents some features which demand attention. It grows forward and becomes divided spontaneously into two portions, one of which lies close to the optic vesicle (Pl. X XI, fig. 11), and entirely in front of the mouth, while the second (2 pp.) is enclosed alto- gether in the mandibular arch. The first aortic arch (laa) runs between these two sections and somewhat dorsal to them. We have not been able to make any satisfactory observations upon their relation to the branches of the fifth nerve, but from their position it seems in every way probable that they have much the same relations as those de- scribed by Mr. Balfour in the Elasmobranch Fishes. The first division shows a small lumen surrounded by a layer of short columnar cells; in longitudinal vertical sections (Pl. XXL, fig. 11, 1 pp.), it has a somewhat oval shape; in trans- verse sections (fig. 13, py.) it has a transversally elongated shape, and the cavity in these sections is seen to be largest toward the middle line. During no period as late as Stage L could we find any trace of a ventral union between the ante- rior segments of each side, such as occurs in the Elasmo- branchs. It may, however, occur later, as during Stage L they approach very closely. The second segment (Pl. XXI, fig. 11, 2 pp.) is considerably smaller than the first, and has a very small lumen. Its cavity also is lined with columnar cells, and forms a narrow slit running parallel to the first visceral cleft. ‘The mandibular aortic arch lies just anterior to it instead of close to its inner side as in the Elasmobranchs. The other segments of the head cavity lie in the visceral ‘ Balfour, loc. cit., p. 86. EARLY DEVELOPMENT OF THE COMMON NEWT, 471 arches, and show narrow cavities lined by columnar epithe- lium (Pl. XXI, fig. 12, 3 pp). They present no features of especial importance. We have not followed out the subse- quent development of these segments, but in all probability their cells become transformed into muscle cells. In the foregoing description there will be observed a very close similarity to what has been described for the Elasmo- branchs ; in fact, with some minor exceptions, and the one important one of the non-communication of the first pair of segments, Mr. Balfour’s descriptions will apply equally well to our specimens. This is of the more interest, -for Triton in this respect is very much more like the Elasmo- branchs than it is like the Batrachians; a fact which is somewhat remarkable. In the Batrachians so carefully in- vestigated by Dr. Gitte,’ there appears to be no head cavity formed at any period. On the other hand, two series of segments, an inner and an outer series, become formed, and are believed by Dr. Gotte to correspond respectively to the vertebral and lateral plates of mesoblast which are developed in the trunk. The internal segments resemble the proto- vertebre in shape, but are smaller; their walls develop into muscular fibres and represent the anterior continuation of the dorsal muscles. The external segments are contained in the visceral arches. In the anterior division of the head (Gotte’s Vorderkopf) there is only one pair of segments, as the division of the segment in front of the first visceral cleft does not seem to occur ; the part contained in the mandibular arch is derived from the growth of the postero-lateral seg- ments. The most anterior segment of all gives rise, as in the Elasmobranchs, to the muscles of the eye. It is remarkable how very different all this is from the process observable in Triton. There are found in the pos- terior part of the head four segments which give rise to muscular fibres, as in Bombinator, and continue the dorsal muscle forwards. These may be equivalent to the four in- ternal segments of the head of Bombinator, but they have no ventral continuations. They are more to be compared with segmentsin the posterior part of the head of the Elasmobranchs. With regard to the latter, Mr. Balfour says, (p. 209), «All my efforts have hitherto failed to demonstrate any segmen- tation in the mesoblast of the head other than that indi- cated by the sections of the body-cavity before mentioned, but since these must be regarded as equivalent to muscle plates any further segmentation of mesoblast could not be anticipated ; to this statement the posterior part of the ' Unke, pp. 203-208, 216-229. . AD) ; 472 Ww. B.-SCOTT AND HENRY F, OSBORN. head forms an apparent exception. Not far behind the auditory involution, there are visible at the end of Period K a few longitudinal muscles, forming about three or four mus- cle plates, the ventral part of which is wanting. I have not the means of deciding whether they properly belong to the head or may not be a part of the trunk system of muscles which has to a certain extent overlapped the back of the head, but am inclined to accept the latter view.” The appearances here described are very much like those to be seen in Triton, and we are not in a position to pronounce any more decided judgment upon them, than upon those of the Elasmobranchs ; but taking into consideration Gdtte’s figures we are rather inclined to consider them the axial segments of which the plate containing the head cavity is the lateral part. The chief differences between the two types of Amphibians lie in the cavities themselves, and the number of segments in the anterior part of the head. Our researches do not, we regret to say, throw much new light upon that difficult morphological problem, the segmentation of the head. It is interesting to find that as in the Elasmobranchs there is one pre-oral segment, as might be expected to be the case if the head cavities afford any trustworthy guide to the number of head segments. Of course the number of postoral cavities is less than in the Elasmobranchs owing to the fewer gill clefts, but this isa feature which does not affect the question at issue. Of whatever value these facts in the development of the Newt are considered, we think that they favour the views expressed by Mr. Balfour in p. 216 of his book. For these head cavities, if of morphological importance, might be anticipated to be fairly constant in character. The Thyroid Body. Pl. X XI, fig. 12, represents the earliest condition of the thy- roid body which has fallen under our observation. In it we see that in the region of the mandibular arch there is a solid outgrowth of cells from the ventral wall of the alimen- tary cavity which has reached the inner layer of the epiblast. — The latter has at the point of contact risen up slightly from the external layer leaving a small triangular space between them. In the next stage (fig. 13), the inner layer of epi- blast has coalesced with the hypoblastic outgrowth and is discontinuous across the middle line. It is now difficult to determine where one layer begins and the other ends, so EARLY DEVELOPMENT OF THE COMMON NEWT. 473 complete is their fusion. ‘The external layer is never inter- rupted. Fig. 14 presents a rounded thickening of the fused mass, which is the next step in development. The latest stage we have (somewhat later than m) shows the gland separated from the epiblast (Pl. X XJ, fig. 15) which is now continuous across the middle line, but still connected with the ventral wall of the esophagus by a cord of cells. The thyroid is now a solid cylindrical rod of considerable length, ending posteriorly near the ventral aorta ; the section shows an aortic arch (1 aa) cut through longitudinally. The gland consists of an outer or cortical layer of columnar cells arranged radially, and an inner small kernel of rounded cells. As yet there is no trace of a lumen, or any division into lobules. Further than this we have not ‘been able to follow its development, but have no reason to suppose that it presents any great peculiarities. On the whole the thyroid body of the Newt corresponds quite closely in position and mode of development to the same body in the Elasmobranch Fishes; but there are some points of difference to which we should like to call par- ticular attention. (1.) In the latter the diverticulum of the hypoblast is hollow in front and solid behind at first. and only subsequently becomes solid throughout, while in Triten we have not been able to discover any stage which shows a hollow outgrowth. ‘The solidity, however, does not occur from any confused mass of cells, but from the fact that the two sides of the diverticulum are pressed closely together (Pl. XXI, figs. 12 and 13). Ofcourse it is very possible that we have missed a stage in which the outgrowth was hollow ; but if that is the case that condition must be a very tran- sitory one. The difference is only one of detail in any case. (2.) Of much more importance is the fact that in the Elas- mobranchs there is never found any indication of continuity between the hypoblast and epiblast, which at this period is still single layered. But the diverticulum is pressed very closely against the epiblast, presenting just the appearance of the first visceral cleft which does not perforate the skin.’ (We do not wish to intimate by this comparison an opinion that the thyroid is a modified visceral cleft, because all diver- ticula from the throat to the external skin must look more or less alike.) The account given by Dr. Gotte? of the development of the thyroid in Bombinator is still more like our account than is that given by Mr. Balfour of the Elasmobranchs. 1 Balfour, loc. cit., Plate XIV, fig. 5a, p. 228-5. > Loe. cit., p. 667, ATA WwW. B. SCOTT AND HENRY F, OSBORN. In Bombinator the thyroid “is formed from a pit of the hypoblast, which persists as the remains of an early depres- sion of the hypoblast behind the mandibular arch, produced by a fusion of the epiblast and hypoblast” (Taf. vii, fig. 127- 130, and Taf. xiii, xv, xvi, figs. 292 and 293.) At first it is connected anteriorly with the median division line which bisects that arch; after the disappearance of this the rudi- ment of the thyroid appears as a funnel-shaped diverticulum of the hypoblast and is free below. The fusion between thetwo layers, which in Triton persists for a considerable period and is seen throughout the length of the gland, here is confined to the anterior end, and remains only a short time. W. Miiller, in his account of the development of the thy- roid body! in Rana temporaria, does not give any figures or descriptions leading us to suppose that he has observed this continuity of the layers. We must confess that we ourselves are very much puzzled by the fusion of the epiblast and hypoblast at this point, and are unable to give any morphological explanation of its meaning. Is it not just possible that it may represent some shifting in the position of the mouth ? but if so, we shall be obliged to abandon, for this form at least, the homology of the thyroid body with the endostyle of the Ascidians. We mention it with the hope of directing the attention of some morphologist, who will clear the matter up, to this curious and unexplained feature. It may be of use to give a brief summary of the points which we have endeavoured to establish in this paper, before passing on to consider to what general conclusions these points lead us, if established. 1. As to external features, we have failed to find in Triton the suckers and horny teeth with which the Batrachian larva is furnished. 2, Segmentation proceeds in a manner much like that of the Frog, but the roof of the segmentation cavity is from the very first only one cell thick. 3. An unsymmetrical invagination, like that of the Frog and Lamprey, takes place, giving rise to one layer in the middle line, the hypoblast, and two at the sides, hypoblast and mesoblast. The invagination mesoblast is supplemented by other cells, which split off from the yolk hypoblast. These two lateral and disconnected masses of mesoblast are, we consider, the homologues of the paired hypoblastic divers ticula in Amphioxus. 4. The epzblast is at first composed of a single layer of 1 Jenaische, ‘ Zeitschrift,’ 1871, pp. 435-439. EARLY DEVELOPMENT OF THE COMMON NEWT, 475 columnar cells, which early separate into two rows, and of the two layers thus formed the inner becomes the active one, entering exclusively into the formation of the sense organs. In the spinal cord and brain the division into two layers does not take place till very much later. 5. The hypoblast is of two kinds, the invaginated and that which arises from the metamorphosed yolk-cells. 6. The notochord is of hypoblastic origin, and takes up the entire dorsal wall of the alimentary tract (except in the head) in its formation, fresh hypoblast growing from the sides below it. It becomes well formed and cylindrical in shape before any cell division takes place in it. 7. The body-cavity extends into the head, appearing in this region first. The head mesoblast becomes split into somites, which have the same relations and number (except so far as modified by the reduction of the visceral clefts) as in the Elasmobranchs, but do not seem to communicate below. 8. The thyroid body is.formed by an outgrowth from the alimentary canal, the walls of which become continuous with the mucous layer of the epiblast ; the continuity of the horny layer is not interrupted. Conclusion. If the statements in this paper prove to be well founded, they will give us some data for judging of the relationships of the two groups of Amphibia to each other, and to some lower types. The marked divergences from the Batrachian type which the Newt shows us point to the conclusion that the Urodeles and Batrachians have been separated for a very long period. And it is interesting to observe that, in those cases where the divergence is other than a mere matter of detail, it leads towards the Lamprey, and through that to Amphioxus. The opinion seems to be gaining ground that some such form as the Lamprey is the point toward which the Amphibia, the Elasmobranch, Ganoid, and Dipnoic fishes converge, and the more these types are investigated the better established appears this view. As yet, however, we are not in a position to pronounce upon it with even an approximation to certainty. The observations brought forward in this paper tend strongly, we think, in this direction, and we hope that future investigations upon the Amphibia, the Ganoids, and especially the Dipnoi, will soon put the matter to a crucial test. In conclusion, we must express our very sincere thanks to Mr. F. M. Balfour for his never-failing kindness and assist- ance to us while engaged in this work, 4.76 PROFESSOR E, RAY LANKESTER, The Structure of HatipuHyseMA TumAnowtczir. By E. Ray Lanxester, F.R.S. (With Plate XXII.) A REMARKABLE dispute has been carried on during the past year concerning a minute marine organism which forms a tubular case in shape like a “ cornucopia,” scarcely so large as a letter “y’”’ as printed on this page. These little tubes were first described by Dr. Bowerbank (in 1864, ‘ British Spongiade,’ Ray Society), and were considered by him to be the skeletons of a very simple kind of sponge, to which he gave the name Halipbysema. ‘Two species were described by that author, viz. H. Tumanowiczi and A. ramulosum. Mr. Carter, in 1870 (Ann. and Mag. Nat. Hist.,’ p. 309) brought forward Foner for considering these little tubes as the work of quite another group of organisms, viz. the Foraminifera, and described what he considered as a closely allied form under the name “ Sguamulina scopula” In 1877 Professor Ernst Haeckel published in the ‘ Jenaische Zeitschrift’ an account of Haliphysema, in which he recog- nised five species; with this genus he associated a new one, Gastrophysema, into which he placed the * Sguwamulina scopula”’ of Carter, and a new species G. dithalamium. The soft parts of the Haliphysema of Bowerbank and of Carter’s similar organism had never been described before Professor Haeckel’s memoir on the subject. Haliphysema was simply known as a funnel-like shell of minute size, the substance of the shell being made up of particles foreign. to the organism itself, namely, grains of quartz, spicules of sponges,—and any other such material. Thére was nothing in the structure of the tests of these organisms to forbid their association with the arenaceous Foraminifera or similar building forms of Protozoa. On the other hand, it was possible that they were the work of a sponge, a polyp, or even of a worm. Professor Haeckel gave a most minute and fully illustrated description, not only of the test of Haliphysema and Gastrophysema, but also of their soft living substance. His memoir is illustrated by three plates, and on these plates are figured, with ideal symmetry and precision, the appearance of these forms as seen when longitudinally divided in the living state. Professor Haeckel described Haliphysema and Gastrophysema as hollow mouth-bearing sacs, built of two layers of cells—-an outer “syncytium ” the ectoderm—-and an inner closely set lining of flagellate “collared-cells,” similar tothose found in the ciliate chambers STRUCTURE OF HALIPHYSEMA TUMANOWICZII. 477 of sponges. Further, he described and figured a number of egg-like bodies as adhering to the endoderm and formed by a modification of its cells. These were regarded as ova. Excepting for the absence of pores in the body-wall, the structure thus described corresponded very closely with that of the simplest examples of the Porifera or Sponges. In consideration of their wanting the pores characteristic of Sponges, Professor Haeckel proposed to place the genus Haliphysema of Bowerbank and his own new genus Gas- trophysema in a new great group of Ceelenteric animals, to which he gave the name “‘ Physemaria.” The Physemaria were stated to represent the simplest two-cell-layered forms of life from which all the Metazoa (or Enterozoa) have been derived. As such the Physemaria have been admitted into text-books (e.g. Gegenbaur’s ‘Grundriss’),and have formed the subject of many a discourse when the principles of phylogeny and the germ-layer theory have been expounded to zoological students. ; Quite recently a doubt has been raised as to whether the ‘‘Physemaria”’ as a group have any existence at all. We are, in fact, asked to believe that there are two sets of organisms exactly alike in the details of their external struc- ture, viz. the cornucopia-like tube with its disc-like base and its constituent spicules, &c., but differing from one another in the structure of their soft parts—the one being Proto- zoa, the other sponge-like multicellular Ceelenterates. The matter has been brought to this pass by a series of papers in the ‘Annals and Mag. of Nat. History,’ con- tributed during the past year by Mr. Carter, the Rev. A. M. Norman and Mr. Savile Kent, and the difficulty of the position will be in no way diminished by the observations which I have myself made and am about to record. Mr. Carter, the original discoverer of Haeckel’s Gastrophysema scopula, protests that the chambered nature of the shell of his little organism, and the extrusion of protoplasm in the form of pseudopodia from broken but living specimens, proves them to be Foraminifera and not Ccelentera. At the same time Mr. Carter is not able to state from observa- tion that his specimens are devoid of an axial cavity lined by flagellate collar-cells. Mr. Norman, on the other hand, after examining Mr. Carter’s specimens of Gastrophysema (= Squamulina) scopula, and comparing them with Dr. Bowerbank’s type- specimens of Haliphysema, and with other specimens and supposed diverse species of that genus, comes to the con- A78 PROFESSOR E. RAY LANKESTER. clusion that al] these forms, Gastrophysema and Haliphy- sema, are but variations of one species, necessarily referable to the original Haliphysema Tumanowicz. At the same time Mr. Norman has no observations to offer relative to the internal structure of the soft living animal, and accepts (as all zoologists would gladly do at this moment) Professor Haeckel’s description as correct. Accordingly Mr. Norman refers Haliphysema to the Sponges. In July, 1878, however, the ‘Annals’ contained a very important paper by Mr. Saville Kent. Whilst other zoologists had settled down to a belief in the Physemaria, Mr. Kent had not rested content till he obtained living specimens of these forms. These he procured in abundance at Jersey, and was now able to offer some most astonishing observa- tions on Haliphysema. He figured in a drawing, which must be accepted as an accurate representation of fact, a specimen of the tube of Haliphysema, from which was issuing an abundant reticular protoplasm, spreading its filaments far beyond the tube, even to a distance of five times its greatest diameter (‘Annals and Mag. Nat. History,’ ser. v, volii, pl. v). This drawing represents, Mr. Kent tells us, what he saw of a living specimen examined intact on the field of the microscope. The conclusion which Mr. Kent drew from this obserya- tion was perfectly legitimate. He concluded that he had before him a Reticularian Rhizopod. Further, he had no reason to doubt, especially after Mr. Norman’s discussion of the subject, that the tube from which the protoplasm issued was that of Haliphysema (alias Squamulina, alias Gastro- physema). Accordingly, Haliphysema was shown not to be a two-cell-layered organism, but an arenaceous Foraminifer, one of Dr. Carpenter’s Lituolida. At the same time Mr. Kent is careful to point out that, should there be organisms, as represented by Professor Haeckel, corresponding to the forms identified by himself (Mr. Kent) with Haliphysema, and having internal cavities lined with collar-bearing flagellate cells, their sponge nature would be unquestionable, and we should have in them merely remarkable isomorphs or external facsimiles of the Foraminiferal type. Being deeply interested in this controversy, and not knowing whom to credit nor how to explain discrepancies, ‘doubting very much the ‘‘isomorph” theory, I applied to Mr. Saville Kent for living specimens of his Haliphysema Tumanowiczt. With my request he most courteously complied, and sent STRUCTURE OF HALIPHYSEMA TUMANOWICZII. 479 from Jersey, not only a quantity of living specimens, but subsequently others, carefully treated by reagents on the spot aecording to my directions. I may confess, without offence to Mr. Kent, that I was intent upon discovering in his Haliphysema evidence of the syncytium and collar-bearing flagellate cells described by Haeckel, which, I thought it possible, might have escaped his observation. My inquiries were made on both living and preserved specimens, and have led to the discovery of a very interesting structure, which might at first sight be taken to indicate that the organism was built up of many cells, and was similar to a sponge. The structure, as described below, is, however, essentially that of the Protozoa, and leaves no doubt whatever in my mind that Haliphysema is to be referred to that group. Whether there are isomorphs of Haliphysema constituting the group “ Physemaria,” as suggested by Mr. Kent, and as also asserted by Dr. R. Hertwig, of Jena, in Hoffman’s and Schwalbe’s ‘ Jahresbericht,’ vol. vii, second part, is a matter which is clearly out of the field of discussion. It is certainly most desirable that these “isomorphs” should be produced, as I earnestly hope that they will soon be, by my friend Profesor Haeckel, or else that some kind of explanation should be offered to remove the present puzzling antagonism of the statements which have been made in regard to Haliphysema and Gastrophysema, by Professor Haeckel on the one side, and by English observers on the other. 1. Condition of the material studied.icThe specimens forwarded to me were in two conditions: firstly, several living specimens sent in a large vessel of sea water; secondly, Specimens preserved in Jersey by Mr. Kent by placing them first in a large quantity—half a litre—of one sixth per cent. solution of chromic acid, from which, after a lapse of twenty-four hours, they were removed to strong alcohol. %. External testi—In Pl. XXII, fig. 1,1 have given a drawing of the external test of a small specimen, magnified 135 times linear. The specimens sent to me were very varied in form, some much more elongated than that figured ; others with a more globose anterior region (like Gastro- physema) ; others exhibiting a nodose series of enlargements (polythalamous). The character and direction of the’ spicules and fragments of spicules used to form the test was not the same in all. The first specimens which I received closely resembled the Haliphysema figured by Haeckel in 480 PROFESSOR E. RAY LANKESTER, the ‘Jen. Zeitschrift,’ but none were so perfectly sym- metrical and uniform in the disposition of the spicules. It is, however, important to state that the forwardly-pointing spicules, giving the organism a brush-like appearance, are very nearly as abundant in some of the Jersey specimens as in Professor Haeckel’s figure. The form which I have drawn was selected as being the commonest in the gathering sent to me. There are certain very striking points of identity between the Jersey specimens and Professor Haeckel’s figure. The first is the possession of a large disc-like or rather a hemispherical base, which gives support to a narrow stalk, comparable to the stem of a wine glass. The second is the composition of the test from sponge spicules, among which those of Reniera and Esperia predominate, associated with which are spicules of Calcispongie, fragments of the spines of Crustacea, and granules of quartz. It is obvious enough that a composite test of this kind is liable to vary in its components almost indefinitely, according to the material existing in its locality. No pores or fenestrze are visible in the walls of the test, excepting anteriorly, where there is a considerable aperture in or deficiency of the test. 3. The contents of the test.—It is difficult to ‘obtain from a fresh specimen of Haliphysema satisfactory evidence of the nature of the living substance which it encloses. Mr. Kent was fortunate enough to observe reticular protoplasm ex- truded from his specimens. ‘Those which I received did not exhibit this phenomenon, owing, no doubt, to the fact that they had been affected by the journey. It was, however, possible, by carefully teazing the fresh specimens with needles, either in salt water or in osmic acid, to obtain frag- ments of a finely granular protoplasm interspersed among the broken-up spicules of the test. These fragments of protoplasm exhibited very usually one or sometimes three or four vesicular nuclei, which could readily be stained with picro-carmine. ‘These nuclei were identical with those drawn in Pl. XXII, fig. 10. The most successful method of separating the test from the contained soft matter I found to be the following :— Specimens which had been placed when quite fresh in chromic acid (4th per cent.), and, subsequently, in alcohol, were treated successively with absolute alcohol, oil of cloves, and Canada balsam, either with or without previous staining by hematoxylin. ‘The whole specimen was mounted in bal- sam, and the covering glass then gently pressed, and moved STRUCTURE OF HALIPHYSEMA TUMANOWICZII. 481 in such a way as to crack the test and roll away its frag- ments from the soft kernel within. In this way I succeeded in obtaining several more or less complete “ cores’’ or “ ker- nels,” such as that figured in Pl. XXII, fig. 2. These were sufficiently transparent to admit of their exa- mination by the highest powers of the microscope, and by teazing stained specimens it was easy to obtain complete evidence of their structure. The “core” of Haliphysema—I speak of the Jersey specimens, not of Professor Haeckel’s—is a continuous mass of protoplasm, exhibiting no central cavity, and devoid of “ cell-structure.” On its surface this core is fluted and moulded to the shape of the adjoining spicule-fragments which form the test (see Pl. XXII, figs. 2 and 117). There appears to be no differentiation of a ‘cortical substance” on the surface of the core, though the protoplasm is more free from granules here than it is deeply. The nuclet.—Scattered in the protoplasm are an immense number of vesicular bodies averaging +.!,,;th inch in dia- meter and of very constant size. ‘These vesicular bodies stain deeply; their walls are thick and their contents finely granular or else hyaline. The wall of the vesicles stains much more deeply than their contents. In the living state these vesicular bodies are spherical in form; after the action of chromic acid or of alcohol they exhibit various conditions of collapse and shrinking; some of these are drawn in fig. 10. In teazed chromic-acid specimens the vesicles are readily isolated, frequently leaving a “‘ bed ”’ or space in the protoplasm from which they have been disinterred. The term “ vesicular nuclei” may be applied to these bodies which certainly constitute the most obvious structural feature of the soft substance of Haliphysema. We have not to go far to find their parallel amongst the Protozoa. Though they differ in the fact that they are very abundant, and in their sharp emargination, from the nuclei recently discovered in Foraminifera by F. E. Schulze and Hertwig, yet it seems most probable that they are only an elaborated condition of such nuclei. In abundance and sharpness of outline they are paralleled or even surpassed by the vesicular nuclei of Pelomyxa, and it is also a conclusion admitting of little doubt that the peculiar oat-shaped cor- puscles of Labyrinthula and Chlamydomyxa are further examples of the existence of very numerous sharply-defined nuclei existing in an organism which is, nevertheless, uni- cellular. The vesicular nuclei which are now figured as character- VOL, X1X.—NEW SER. 1a 482 PROFESSOR E. RAY LANKESTER, istic of Haliphysema occur in all probability in the other Arenaceous Foraminifera, and in other members of the group also. Dr. Carpenter figures in his classical monograph of the group, published by the Ray Society, certain vesicular bodies from Orbitolites, which correspond in size and general character with the vesicular nuclei of Haliphysema. It is, however, possible that the bodies found in Orbitolites are, as Mr. Moseley’ has suggested, parasitic unicellular Alge. Those of Haliphysema are certainly not parasitic, but integral parts of the organism in which they occur. In the fresh state they are colourless, whilst Mr. Moseley states that the corpuscles of Orbitolites are green when fresh (probably coloured by chlorophyll), and compares them with the yellow “cells ” of Radiolaria, which have been supposed by Cienkowski to be parasitic. Egg-like bodies.—The vesicular nuclei are most abundant in the basal portion of the core of Haliphysema. Ante- riorly they are much diminished in number, and here I found in several specimens that the protoplasm was seg- mented into bodies of much larger size than the vesicular nuclei, varying from the ;3,,th to the =4,th of an inch in diameter. These bodies correspond very closely with the “eggs” figured by Haeckel in his “ isomorph ” of Hali- physema. The smallest of them (fig. 6) are devoid of nucleus, and the constituent protoplasm appears to be vacuolated. In the larger specimens the outline of the corpuscle is well defined, but there is nothing like a wall or capsular inyest- ‘ment. The protoplasm has the rather coarsely granular character seen in egg-cells so usually, and a central nucleus is after some care to be made out. I obtained these bodies most satisfactorily for observation by teazing preserved specimens of the Haliphysema. One which I have figured is seen to be undergoing transverse fission. The formation of such egg-like germs within the general protoplasm of a unicellular Protozoon is entirely in accord with what is known as to the reproductive process in such organisms. There are numerous observations of long standing (see Car- penter’s ‘ Foraminifera ’) which indicate such a formation of nucleated germs within the substance of the shell-bearing Reticularia, whilst the most recent observations on the Radiolaria confirm the earlier observation of a similar pro- cess in those allied forms. The body substance in general.—The vesicular nuclei and the egg-like corpuscles are embedded in a finely granular 1 «Notes of a Naturalist on the Challenger,’ p. 293. STRUCTURE OF HALIPHYSEMA TUMANOWICZII. 483 protoplasm, which, when teazed and examined in small pieces, has the appearance of being built up by a meshwork of fine fibrille, or, to put it in another way, appears to con- sist of denser substance, honeycombed by very small ‘“vacuoles”’ or spaces of less dense substance. Here and there are denser granules and small corpuscles, smaller and less emarginated than the vesicular nuclei. In no part of the body substance is there evidence of any axial cavity comparable to the enteron of higher animals, nor the slightest trace of a breaking up of the protoplasm into areas or units corresponding to cells, with the exception of the egg-like bodies of the anterior region. The external protoplasm.—In the specimens preserved in chromic acid, though no expanded networks of protoplasm, such as that seen by Mr. Kent in living examples, can be observed, having as a matter of course been retracted and shrunk during the disturbance preliminary to the action of the preserving fluid, yet in all my specimens knob-like masses of the protoplasm could be observed here and there on the surface of the unbroken tubes. The prettiest examples are those in which the protoplasm has been killed and preserved whilst crawling along the surface of one of the projecting spicules of the tube. In fig. 1 such knobs of protoplasm are seen, and in fig. 3 a camera lucida drawing is given of a spicule projecting well forward from the test of a Haliphysema, having on its surface a quantity of stream- ing (or rather what was streaming) protoplasm. An impor- tant fact is exhibited by this specimen, namely, that the vesicular nuclei pass out of the test and stream with the protoplasm over the surface of the spicules, and probably on to the network which is formed beyond in the living condi- tion. One of the vesicular nuclei is seen in fig. 3 2. From the preceding account it appears that the structure of Haliphysema is not quite so simple as that which has been supposed to characterise the body-substance of the Lituolida. It seems to me very possible that we shall even- tually find among the larger members of the varied groups of organisms classed as “ Foraminifera ” as high a structural differentiation as that exhibited by any of the naked fresh- water forms of Gymnomyxa (Rhizopoda) such as Pelomyxa, Chlamydomyxa, and Actinosphzrium. Possibly, when means are taken to overcome the difficulties of observation pre- sented by their opaque and resisting shells, the larger “‘ Foraminifera’ may prove not only to be nucleated but to be as highly organised (though not in the same way) as the Radiolaria. 48 4. PROFESSOR E, RAY LANKESTER. LITHAMGBA DISCUS, nov. gen. et sp., one of the GYMNOMYXA. By E. Ray Lanxesrer, F.R.S. (With Plate XXIII.) I 1ncLUDE. under the division Gymnomyxa all those Pro- tozoa or Homoblastic animals which expose, ina naked state, to the medium in which they live, the living protoplasm of their body-substance, in the form of those lobose, filamen- tous, or reticulate processes known as pseudopodia. The group is the complement of the Corticata, in which a perma- nent differentiation of the surface of the body-substance has been effected, necessitating either parasitic nutrition (Gregarine) or the specialization of an ingestive orifice (the Ciliate, Flagellate, and Suctorial Infusoria). The Gymno- myxa thus include, together with the Radiolaria and others, all those forms known as Rhizopoda, whether provided with nucleus or devoid of that structure. In examining a gathering from a pond near Birmingham, forwarded to me in April last by Mr. Bolton of that town, I observed six specimens of an organism belonging to the group of the Gymnomyxa, apparently hitherto undescribed. The organism in question is related to the Amcebe, having the coarse, lobose pseudopodia characteristic of that genus. At the same time the protoplasm of which it consists is vacuolated in a remarkable way not observed in Ameba, and moreover, numerous peculiar concretions are embedded in its substance, which are not precisely like anything known in Ameeba. The actual form of the processes of the body- substance or pseudopodia extruded by the present form is also not identical with that of the pseudopodia of the com- moner Ameebe, such as A. princeps or A. radiosa, but rather resembles the hernia-like extrusions of the protoplasm ex- hibited by that very remarkable example of the freshwater Gymnomyxa, Pelomyza, described a few years since by Professor Greef, a form which I have had the good fortune to find also in this country. The new Protozoon I propose to call Lrthameba discus, the generic name having reference to its characterstic con- cretions, and the specific name to the form which it assumes when in a quiescent condition. I am not able to furnish any particulars as to the life- history of Lithameba discus, but it appears to me that the details of its structure are sufficiently interesting to merit publication. Form of the body.—In Plate XXIII, fig. 1, a specimen is LITHAMG@BA DISCUS. 4.85 represented as seen in the living condition, quiescent. It consists of a discoid mass of protoplasm the ;4,th of an inch in diameter. The concretions.—The periphery of the disc is clear and colourless, towards the centre a dark greyish appearance is observed, owing to the large number of rounded concretions of a highly refringent substance which are embedded in the protoplasm. Most of these concretions are of minute size, with a tendency toa reniform shape. Two much larger concretions are seen, the larger of which measured the -1;th inch in length. The substance of which these concretions are formed was not determined. It resists the action of dilute acetic acid and of dilute caustic potash, but is dissolved by strong hydrochloric acid. In fig. 8 one of these concretions is represented from another specimen isolated. The nucleus.—A single nucleus (7), of large size, measuring =i,th inch in longest diameter is present. It has an irregular block-like form and a very obvious and definite structure. It is enclosed in a well-differentiated membrane, which can be separated from it by the action of reagents (fig. 5). Its substance appears to be built up by a number of minute, closely-set granules, which are angular and set side by side in acementing substance. ‘There is no specialised nucleolus, nor are nucleolar fibrille to be observed. Food matters.—Besides the concretions and the nucleus the protoplasm contains a quantity of food débris (ff), con- sisting of a frustule of the Diatom Navicula, and the carapace of a Rotifer and other matters. Contractile vacuole.—The centre of the disc is occupied by a very large vacuole (cv), containing a clear liquid, and having, both above and below, excessively thin walls. The vacuole measures ;1,th inch in diameter. Continued ob- servation showed this vacuole to be contractile, and that its contents are discharged periodically to the exterior. Vacuolar structure of the protoplasm.—In focussing the upper wall of the vacuole I first became aware of the ex- cessively fine reticulate or vacuolar structure which charac- terises the protoplasm of the whole body. This differentiation of the protoplasm can be detected all round the margin of the disc also, and, in fact, wherever the protoplasm is sufficiently free from concretions or food matter to allow of proper illumination and inspection. This vacuolar structure, as seen under a No. 10 immersion objective after treatment of a specimen of Lithamceba with osmic acid, followed by picro-carmine, is represented in fig. 4. 486 PROFESSOR E. RAY LANKESTER. The staining with picro-carmine did not affect the concre- tions, but was taken very strongly by the whole contents of the nuclear cyst. The cuticle.—Iodine was applied to one specimen, in order to ascertain the presence or absence of starch. No starch was found, but the iodine brought out a very remarkable structure on the surface of the organism, which certainly must be held to indicate the existence of a cuticular pellicle. The structure in question consisted of exceedingly fine granules (fig. 7), which, when a portion of the margin of the body was focussed, so as to give an optical section, had the appearance represented in fig. 6. The regular disc- like form of Lithamceba and the peculiar character of its hernia-like pseudopodia are quite in accordance with the existence of a cuticular pellicle, which must be inferred from the punctate structure rendered evident by iodine. The cuticle of Lzthameba is not a highly-developed one, like those of Amphizonella, or of Amphitrema, which leave portions of the body unprotected, whence the naked proto- plasm can be extruded, but it is of a delicate and easily ruptured consistency, bursting, as it were, sometimes at one point, sometimes at another, in order to allow the con- tained protoplasm nakedly to expose itself in a hernia-like excrescence. Pseudopodia.—The hernia-like pseudopodia of the same specimen as that drawn in fig. 1 are seen in fig. 2, the or- ganism being represented in a state of activity. The extrusion of these masses seems to begin with a minute rupture of the cuticle. Through the orifice thus produced the fluid pro- toplasm exudes in a spherical form, and as it increases in quantity the rupture of the cuticle is increased, whilst con- cretions from the more central portion of the disc-like body flow into the enlarging lobe. With great rapidity the whole extrusion now appears to fuse once more with the disc, and a new rupture and extrusion takes place at another point of the margin. A new cuticular pellicle must be formed very rapidly on the surface of the hernia-like extrusions of protoplasm. I did not observe in Lethameba any filamentous or elongated pseudopodia, such as are known to accompany hernia-like pseudopodia in Pelomyza. Contractions of the vacuole—During the movements of the specimen (fig. 1, fig. 2) the large central vacuole was seen to burst and discharge a portion of its contents to the exterior but it did not entirely collapse. Its walls fell together in such a way as to produce two smaller vacuoles, STRUCTURE OF THE VERTEBRATE SPERMATOZOON, 437 together of less capacity than the first vacuole. These slowly increased in size, and after a time fused together to form one large vacuole, precisely like that from which they were derived. Lithameba discus is thus seen to be a uninucleate form with contractile vacuole. In the vacuolar differentiation of its protoplasm, its concretions, and hernia-like pseudo- podia, it presents affinity with the multinucleate Pelomyxa, which has crystalline bodies in place of concretions, and no contractile vacuole. In the structure of its nucleus and delicate cuticle Lithameba is unlike any other form, whilst the combination of characters which it presents entitles it to a very distinct position amongst the Amceboid Gymnomyxa. The concretions appear to be, very probably, only a larger form of the refringent granules which are present in great quantity in the protoplasm of the common large Ameebe. On the Srructure of the VERTEBRATE SPERMATOZOON. By HeneaGe Gisses, M.B. (With Plate XXIV.) In making an examination into the structure of the spermatozoa of Vertebrate animals those of the Amphibia, such as the Zriton cristatus aid Salamandra maculata, from their large size, afford the best examples. Taking then the living spermatozoon of either of these animals in the fresh condition just removed from the body we find the following appearances, shown in figs, land 2, of Salamandra maculata, and fig. 3, of Triton cristatus. Fig. 1 was drawn from a specimen of Salamandra maculata, mounted in a 3 per cent. solution of sodium chlorate. Fig. 2, also in the same solution, under a lower power. Fig. 3, spermatozoon of Triton cristatus, had been placed in a solution of chromate of ammonium and then mounted in glycerin. From these illustrations it will be seen that the spermato- zoon consists of (a) a long-pointed head, at the base of which is (6) an elliptical structure joining the head to (c) a long filiform body; (d) a fine filament, much longer than the body, is connected with this latter by (e) a homogeneous membrane. 488 HENEAGE GIBBES., The head as it appears in the fresh specimen has a different refractive power to the rest of the organism, and with a high power appears to be a light green colour ; there is also a central line running up it, from which it appears to be hollow. The elliptical structure at the base of the head connects it with the long thread-like body, and the filament seems to spring from it. Whilst the spermatozoon is living this filament is in con- stant motion; at first this is so quick that it is difficult to see it, but as its vitality becomes impaired the motion gets slower, and it is then easily perceived to be a continuous waving from side to side. When the connecting membrane is thrown into folds as the motion gets slower it is readily seen with a high power, but it is only visible in the fresh specimen, and disappears entirely on the application of glycerin. This moving filament forms a most beautiful object under a moderately high power; it can be seen with Crouch’s + or Zeiss’ D, but with Powell and Lealand’s + immersion on the new formula, it is seen to perfection. The constant wavy motion gives one the idea that a fine thread is being constantly poured out from the base of the head, and it is difficult at first to realise what the motion is. After a large number of experiments with reagents, I found that after placing the spermatozoon in a 5 per cent. solution of chromate of ammonium the body and filament can be stained with one reagent, while the head would take another. This is best shown by staining the spermatozoon first deeply with hematoxylin, when it will be found that the body and filament show the colour well, but the head scarcely at all, and staining it then in a weak solution of aniline blue ; if it be not left in this fluid too long the head will be found a bright blue, while the body and filament remain coloured with the hematoxylin. I have always found THAT THE ELLIPTICAL STRUCTURE uniting the head and body REMAINED OF THE SAME COLOUR AS THE BODY AND FILAMENT. It isa difficult thing to do this double staining well, since a slight mistake in the time of immersion or in the strength of the solution alters the result of the whole experiment, and although I have had numberless failures, I have succeeded in so many instances that Iam confident the substance of which the head ts com- posed shows a different chemical reaction to the rest of the organism. With regard to the existence of a homogeneous membrane STRUCTURE OF THE VERTEBRATE SPERMATOZOON. 489 connecting the filament to the body, this membrane at first seemed doubtful, and the filament appeared to be un- connected with the body ; but with a high power the mem- brane can be recognised in the fresh state, and it will invariably he found that when the spermatozoon is curved, as it frequently is, and often lying in a double curve, the filament will always be found placed at a certain distance from the convexity of each curve; this distance varies a little in individual cases. If, while examining a specimen in salt solution or distilled water, gentle pressure with the point of a needle be applied to the cover-glass so as to cause a slight vibration in the fluid, the filament will be seen to move to and fro but can never be forced further from the body than its natural distance, unless it has in any way been subjected to sufficient force to rupture the membrane, in which case it may be seen lying quite away from the organism to which it belongs. ‘This seldom happens, and never when the experiment is care- fully done. This would not be the case if the filament were free. In the spermatozoa of Triton cristatus and also Salaman- dra maculata, prepared with a 5 part. solution of chromate of ammonium, and stained in picro-carmine, this membrane is not easily seen, and the filament appears as if free of the body, and twisted more or less like a spiral round the latter. This appearance was originally described by Dr. Klein in this Journal, and its more minute examination was the primary object of my inquiry, which I carried on under his direction. Leydig (‘ Lehrbuch der Histologie’) describes and figures (p. 493) the spermatozoon of Salaman- drine as if possessed of a narrow undulating membrane attached to its body. I next proceeded to examine some of the Mammalian spermatozoa to see if they possessed the filament just de- scribed, and in every instance I have found it. I have examined spermatozoa of horse, dog, bull, cat, rabbit, and guinea-pig, and in every case the above filament was found to exist. The structure of the spermatozoon, as is well known, is in these instances slightly different from that of the sperma- tozoon of Amphibian animals. The long-pointed head is wanting, and the long filament does not seem to extend so far as in the Amphibia, but the Mammalian spermatozoon being so very mnch smaller it is very difficult to make out the filament in its whole extent. I have seen it best in the 490 HENEAGE GIBBES, spermatozoon of the horse, as shown in Fig. 4, and of that of the guinea-pig, Fig. 5. In these spermatozoa there is an intermediate part between the head and tail, and on it the filament is seen plainly, but beyond this it is very indistinct. In Reptilia I have only as yet examined the spermatozoon of the green lizard and slow worm, and in both of these I have found the filament, but very indistinct, and requiring a high magnifying power. The speramatozoon of Lacerta viridis in the fresh state has a very peculiar appearance. The part corresponding to the elliptical body in the Amphibia is envelopedin a gelatinous mass somewhat resembling a leucocyte; it keeps in con- stant motion fora long time, and it is almost impossible to see any other part of it until it loses its vitality; the gela- tinous mass keeps changing its shape as it moves with a quick jerky motion. After a number of experiments in staining the sperma- tozoa of Mammals with several dyes, I found it almost impossible to obtain any such definite results as in the case of the larger spermatozoa of the Amphibia, and it occurred to me to try to attain the same result, viz. to show differences in chemical constitution of the different parts of the sperma- tozoon, by observing the effect produced by different acids and alkalies of varying strengths. I obtained the most striking result with a solution of chloride of sodium, varying from 4 to 5 per cent; with this reagent I found that the head gradually dissolved away, together with the membrane connecting the filament to the body. In Figs. 6, 7, 8, and 9 the effect of the chloride of sodium is shown Taking a solution of 3 per cent. strength at the end of twenty-four hours, the head will be found in different stages of disintegration; some heads are not affected in the least, others are partially dissolved, while still others have become so faint as scarcely to be discerned. After another twenty- four hours, quite one half of the head will have altogether disappeared, but at the same time some heads will remain almost untouched. The same result may be arrived at in a much shorter time by using a stronger solution. It will be seen, by referring to Figs. 7 and 8, that the elliptical structure, the long filament, and the body, remain intact. In the spermatozoon of ZL. viredis, the gelatinous mass a STRUCTURE OF THE VERTEBRATE SPERMATOZOON, 491 enveloping the head becomes also dissolved. In the guinea- pig the large flat head disappears, and that part only re- mains which is seen as a dark band when the head is en profile, as in c and p in Fig. 5. The action of Sode Bicarb. is somewhat different; in about forty-eight hours the head becomes transformed into a mass of minute globules, as shown in Fig. 10, and aftera time these disappear. From the foregoing experiments I am justified in con- cluding— Ist. That the head of the spermatozoon is enclosed ina sheath, which is a continuation of the membrane which surrounds the filament, and connects it to the body, acting, in fact, the part of a mesentery. 2ndly. That the substance of the head is quite distinct in its composition from the elliptical structure, the filament, and the long body, and that it is readily acted upon by alkalies; these reagents have no effect, however, on the other part excepting the membranous sheath. 3rdly. That this elliptical structure has its analogue in the Mammalian spermatozoon ; in the one case the head is drawn out as a long pointed process, in the other it is of a globular form and surrounds the elliptical structure. 4thly. That the motive power lies, in a great measure, in the filament and the membrane attaching it to the body. In my next paper I propose to enter into the structure of the human spermatozoon and that of some of the in- vertebrata. NOTES AND MEMORANDA. New Record of Zoological Literature.—We would call the attention of naturalists to the following notice. “‘ The Zoolo- gical Station at Naples has undertaken the publication of a new ‘ Zoological Record,’ in which equal attention will be paid to all departments of zoology. A large staff of zoologists of various nationalities will act as recorders under the editor- ship of Professor J. V. Carus, of Leipzig; and the first volume, dealing with the literature of the current year, will appear in 1880. All those engaged in zoological work on any group of the animal kingdom, are invited to send copies of their papers to Professor J. V. Carus, Leipzig, Querstrasse 30, and to write on the address ‘* For the Jahresbericht.” Papers so sent will be distributed by Professor Carus amongst the recorders, and after being abstracted for the ‘ Record,’ will be deposited in the Library of the Zoclogical Station at Naples.—AntTon Donen.” Mr. Bolton’s Agency for the Supply of Microscopie Or- ganisms.—Mr. Bolton, of 17, Ann Street, Birmingham, has supplied to me once a week by post, during the past year, a tube containing in a living state new or interesting forms of Protozoa, Entomostraca, Rotifera, &c. Every naturalist within a day’s post of Birmingham should subscribe a guinea to Mr. Bolton’s agency, and ensure the weekly receipt of one of his most interesting tubes. Mr. Bolton has sent out during the past year most of the more impor- tant forms of Rotifera, such as Hydatina senta, Lacinularia socialis, Conochilus volvox, Melicerta and Cicistes, Stepha- noceras and Floscularia, &c. One form sent by him, viz. the Rhinops vitrea, of Dr. Hudson, is especially worthy of mention. Large Amcebe and the commoner Ciliate Infusoria have been supplied by Mr. Bolton in abundance. Amongst rarer Ciliata supplied by him we may mention Trachelius ovum and Zoothamnium arbuscula. The work which Mr. Bolton is doing is not, however, limited to the distribution of forms already known; he has made some important addi- NOTES AND MEMORANDA, 493 tions to the British Fauna, for which he deserves the warmest support and encouragement of zoologists. About three months ago I received from him a tube containing speci- mens of an Entomostracon which he was unable to identify, rightly considering it new to this country. The form proved to be the beautiful Leptodora hyalina of Lilljeborg. A few days later another tube was sent by him, containing a species which I identified as the Hyalodaphnia Kahlber- gensis of Schodler. ‘These two very fine Entomostraca were obtained by Mr. Bolton from a deep reservoir at Olton. Besides these I have to thank Mr. Bolton for the new Pro- tozoon Lithameba discus, described in the present number of the Journal. Last autumn, from the same source, I received an abundant supply of one of those very interesting spiculate Heliozoa, which my colleague, Mr. Archer, of Dublin, was the first to make known to zoologists. The specimens forwarded by Mr. Bolton proved to be the Raphi- diophrys pallida, a species named by Prof. F. Eilhard Schulze, and assigned by him to Archer’s genus. Mr. Bolton has also during the year supplied me with the finest specimens of Hydra fusca which I have seen, with Volvox, Uroglena, and other similar forms. A few marine organisms have been distributed by him, namely, the interesting disc-like larvee of the Polyzoon Alcyonidium, and the delicate polyp Lucernaria auricula—K. Ray LANKESTER. ¢ aati wi eabye ii ix a 5 TATE sae ati Lo y ab onl han ae eed Rotiiee (ipl . oy : awe abl»: \Qanuley ) aA or ,. ie F. OTS ee hs a ert Beri (tun Ae) Me licaeaa7 ; “ pti By Benihs tgs atl a tae iar? a4 nati ich cate ae Pu a ee ; ' ann PE 1 ne. § Biyi i,» aii t ha i 7 ij Gt rid | * de ee i _ . aw lm i p | : fy ‘ - a , 2 i , ie | : =) 7. oo A ve As bow tee rey ere ~~ . Pep ex. TO JOURNAL. VOL. XIX, NEW SERIES. Bacteria in beetroot sugar, 116 Balfour (F. M.), on the early develop- ment of the Lacertilia, aud on the nature of the primitive streak, 421 »» on Head Kidney in chick, 1 », on morphology of Spongida, 103 », on Peripatus capensis, 431 Blood, microphytes found in, by T. R. Lewis, 356 Bolton (Thomas), his agency for sup- ply of microscopic organisms, 492 Brady on Reticularian Rhizopoda of the Challenger, 20, 261 Brain of the cockroach, by E. T Newton, 340 Butschli on flagellate Infusoria, 63 Capitellide, Hisig, on, 115 Carpenter (P. H.), on apical and oral systems of Hchinodermata, 176 Cells and nuclei, by Klein, 125, 404. Chlorophyll in Turbellarian worms, 434 Cockroach, brain of, by E. T. New- ton, 340 Dublin Microscopical Club, 120, 438 Earthworm, the development of the, by Nicolas Kleinenberg, 206 Echinodermata, apical and oral sys- tems of, by P. H. Carpenter, 176 Flagellate organisms in blood of rats, by Timothy Lewis, 109 Flagellate infusoria, Butschli on, 63 Gibbes on Spermatozoa, 487 Haliphysema, the structure of, by E. Ray Lankester, 473 Head-kidney in the embryo chick, by Balfour and Sedgwick, 1 Klein, on nuclei in skin of newt, and on glandular epithelium, 404 Klein on the structure of cells and nuclei, 125, 404 Kleinenberg on the development of the Earthworm, 206 Lacertilia, early development of, by F. M. Balfour, 421 Lankester (HE. Ray) on Lithameba discus, nov. gen. et. sp., 484 », on the structure of Haliphy- sema, 47 Lewis on Flagellate organisms in the blood of healthy rats, 109 Lewis (T. R.), on microphytes found in blood, 356 », onthe nematoid Hematozoa of man, 245 Lithameeba discus, by E. Ray Lan- kester, 484: 496 Marshall (A. Milnes) on the mor- phology of the vertebrate olfactory organ, 261 Microphytes found in blood, by T. R. Lewis, 356 Nematoid Heematozoa of man, by T. R. Lewis, 245 ' Newt, early development of the, by Scott and Osborn, 449 », nuclei in skin of, by E. Klein, 404 . Newton (EK. T.), on brain of cock- roach, 340 Nuclei in skin of newt, by E. Klein, 404 Olfactory orgau, morphology of the vertebrate, by A. Milnes Marshall, 261 INDEX. Osborn and Scott on the early devel- opment of the common newt, 449 Peripatus capensis, Balfour on, 431 Primitive streak, on nature of, by F. M. Balfour, 421 Protista, a new genus of, 437 Record of zoological literature, 492 Reticularian Rhizopda of Challenger, Brady on, 20, 261 Scott and Osborn on the early de- — velopment of the common newt, 449 : Sedgwick on Head Kidney in chick, 1 Spermatozoa, Gibbes on, 487 Spongida, morphology of, by Balfour, 103 Turbellarian worms, chlorophyll in, 43.4 PRINTED BY J. E. ADLARD, BARTHOLOMEW CLOSE. BOE. w del. 7 F.M.Balfour & A Sedgwick JOURNAL OF MICROSCOPICAL SCIENCE. DESCRIPTION OF PLATES I, IL Illustrating Messrs. Balfour and Sedgwick’s paper “On the Existence of a Head-Kidney in the Embryo Chick, and on Certain Points in the Development of the Millerian Duct.” Comerite List or RereRENCE LETTERS. ao. Aorta. c.v. Cardinal vein. g/. Glomerulus. gr,. First groove of head-kidney. gr,. Second groove of head-kidney. gr3. Third groove of head-kidney. g.e. Germinal epithelium. mr.6. Malpighian body. me. Mesentery. m.d. Mivlerian duct. 7,. First ridge of head-kidney. 7. Second ridge of head-kidney. .r,. Third ridge of head-kidney. W. d. Wolffian duct. #2. Fold in germinal epithelium, EXPLANATION OF PLATE I. Srertzs A.—Sections through the head-kidney at our second stage. Zeiss, 2, ocul. 8 (reduced one third). - The second and third grooves are represented with the ridge connecting them, and the red of cells running backwards for a short distance. No. 1.—Section through the second groove. No. 2.—Section through the ridge connecting the second and third grooves. No. 3.—Section passing through the same ridge at a point nearer the third groove. Nos. 4, 5, 6.—Sections through the third groove. No. 7.—Section through the point where the third groove passes inte the solid rod of cells. No. 8.—Section through the rod when quite separated from the germinal epithelium. No. 9. Section very near the termination of the rod. No. 10.—Last section in which any trace of the rod is seen. Srries B.—Sections passing through the head-kidney at our third stage. Zeiss, c, ocul. 2. Our figures are representations of the following sections of the series, section 1 being the first which passes through the anterior groove of the head-kidney. Nai ie 4 - SecTion 3./No. 8 : . SeEcrion 13. 93° Ns 5 “ An Wess co A : aie tad oe i : o Bol ray 4 LO : : ay pers : = : Gone ye. Le : ; San eat - : Suilsaw de : : rae a ee eee is 4 ON a, | ah : : See = : ; ; i, Tae a ee ; : sae Os The Miullerian duct extends through eleven more sections. The first groove (gr,.) extends to No. 3. The second groove (gr, ) extends from No. 4 to No. 7. The third groove ((gr3.) extends from No. 11 to No. 13. The first ridge (7,.) extends from No. 2 to No.5. The second ridge (7..) extends from No. 8 to No. 11. The third ridge (75.) extends from No. 13 backwards through twelve sections, when it terminates by a pointed extremity. Fic. C.—Section through the ridge connecting the second and third grooves of the head-kidney of an embryo slightly younger than that from which Series B. was taken. Zeiss, c, ocul. 3 (reduced one-third). The fold of the germinal epithelium, which gives rise to a deep groove (x.) external to the head-kidney is well marked. SERIES G.—Sections through the rod of cells constituting the termina- tion of the Miillerian duct at a stage in which the head-kiduey is still present. Zeiss, c, ocul. 2. = 3 abe SEL betes —————— Fig: i....x100 ee S Po ey \e oe eg "8 Sos, eT eo pry gerkeaons em aennee me Fig. + sien oy as "GED, we ep ee Stay i (g2Zs2. , es ae LTT i ae Se ee mep Esse Ps oe $3332) (603256 %005, grals 234° eS Sas 6" —o8ee (Szeesi Seg eos Ss oe Mor Eourn! VAHANSIA HE ¥. Huth, Lith? Edin? i JOURNAL OF MICROSCOPICAL SCIENCE. DESCRIPTION OF PLATE XIX, Illustrating Mr. F. M. Balfour’s paper on the “ Early Development of the Lacertilia, together with some Observations on the Nature and Relation of the Pri- mitive Streak.” Complete List of Reference Letters. m.g. Medullary groove. me. p. Mesoplastic plate. ep. Epiblast. hy. Hypoblast. eh’. Notochordal thickening of hypoblast. ch. Noto- chord. ze. Neurenteric canal (blastopore). pr. Primitive streak. am. Amnion. Series A.—Sections through an embryo shortly after the formation of the medullary groove. x 120.' Fie, 1.—Section through the trunk of the embryo. Fics. 2—5.—Sections through the neurenteric canal. Fic. B.--Surface view of a somewhat older embryo than that from which Series Ais taken. x 30. Serres B.—Sections through the embryo represented in Fig. zB. x 120. Fic. 1.—Section through the trunk of the embryo. Figs. 2, 3.—Sections through the hind end of the medullary groove. Fie. 4.—Section through the neurenteric canal. Fie. 5.—Section through the primitive streak. Fic. c.—Surface view of a somewhat older embryo than that represented in Fig. B. x 30. 1 The spaces between the layers in these sections are due to the action of the hardening reagent. = —————— = = = = = --- = 7 ” wap . f t = ‘ \ _ 2s —_ Ped at PUSISIRE RT + Meh ip LS} ‘3 mend Q oN ol ' s ae, 6% Ove 2 Ope £ a ose OF aise” 18 HT AS = - Vs hy! aah Fe hi i% ne ul EN di aN oe A $ 9 RSE in ; Keer eso z an 4 oe” Series Il, Fig. 7. i i x ANN W.B.S & HF 0. del ¥. Huth, Lith? Edin ee ee ee eee a te a DOM OE! oO ) p Soins ANE Bae NEE SNR OAS PURDON QS He 20 Ba i me Cerancd SSS ee x M Sak 0 r meen aie, y IIS Cie: Fei wide Sertes HL, ZE = BS - = a a Neo een ca goes) eae Scone Sal ae ee SES WBS &HEO del JOURNAL OF MICROSCOPICAL SCIENCE. EXPLANATION OF PLATES XX AND XXI. Illustrating the Memoir on some Points in the Early Development of the Common Newt (Zriton teniatus), by W. B. Scott, B.A., and Henry F. Osborn, B.A. With the exception of fig. 1 the following figures were drawn with a Zeiss’ A objective. In figs. 2, 3, 4, 5, a No. 2 (Zeiss) eyepiece was used, and for figs. 6 and 7 a No. 3 eyepiece. EXPLANATION OF PLATE XX. List oF REFERENCES. ep. Epiblast. ey’. Inner layer of epiblast. —y&. Yolk. hy. Hypo- blast. iz. dy. Invagination hypoblast. —_y. Ay. Yolk hypoblast. i. Mesoblast. sp. Splanchnopleure. so. Somatopleure. al, Alimen- tary canal. ac. Neural canal. ch. Notochord. mg. Medullary groove. mf. Medullary folds. Fic. 1.—Longitudinal section of an embryo at time of commencement of invagination. Hartnack No.7 obj., eyepiece 3. It shows one of the earliest stages of the epiblast. Fic. 2.—Represents a longitudinal section of a Triton embryo (probably cristatus) in the early part of Stage a. At the opening of the blastopore the section is in the median line. It slants off forwards, however, to one side, and therefore out of the region of the alimentary canal. It shows the formation of the invagination-hypoblast and the confused mass of cells arising from the reflection of the epiblast. Fic. 3.—A section of the same embryo. It may be considered the re- verse of the last. At the blastopore it is at one side of the median line, while anteriorly it is directly in the median line. This obliquity explains the apparent upgrowth of yolk-cells in the centre. Putting this and the previous section together, a fair idea may be obtained of the actual relation of the layers at this period. It illustrates the formation of mesoblast by invagination, and the obliteration of the segmentation cavity by the advance of the alimentary canal, The blastopore has been artificially widened, Fic, 4.—An anterior transverse section of an embryo, at Stage a, slightly more advanced than the previous one. It shows the shallow medullary groove, the lateral plates of mesoblast extending half way down the sides, KEK EXPLANATION OF PLATE XX—Continued. also the invagination-hypoblast above: the alimentary canal continuous at the sides with the yolk hypoblast. Fic. 5.—A transverse section through the head region of an embryo of Stage B. It shows the splitting of the mesoblast and the formation of the medullary plate and notochord. Fic. 6.—A transverse section through the trunk region of an embryo at Stage c, showing a slightly more advanced development than the last. Fic. 7.—Represents a transverse section through the anterior trunk region late in Stage D. EXPLANATION OF PLATE XXI. List oF REFERENCES. op. Optic vesicle. pp. Head cavities (numbered in order 1, 2, &c.) ve. Visceral clefts. aa. Aortic arches and auditory vesicles. eb. Ex- ternal branchia. mb, Mid brain. hé. Hind brain. th. Thyroid body. al. Alimentary canal. ep. Outer layer of epiblast. ep’. Inner layer of ditto. Zeiss: A, obj. oc. No. 2, exeept for figs. 9, 16, and 17. Fie. 8.—Another transverse section in the middle region. This section is cut obliquely, so that the lateral and vertebral plates of mesoblast do not appear continuous with the mesoblast lining the sides of the embryo; it gives therefore at first sight a false impression. Fic. 9.—Hnlarged view of the lateral epiblast of fig. 6. Zeiss D, ocul. 3. a. One point of cell division. Fic. 10.—Horizontal longitudinal section through the head of an embryo of Stage Fr. The section is slightly oblique, and hence unsymmetrical. It shows the unsegmented head cavity. Fic. 11. Vertical longitudinal section through the head of an embryo of Stage k, showing the relations of the head cavities, aortic arches, and gill clefts ; it is taken too much at the side to show the thyroid. Fic. 12.—Transverse section through head of an embryo of Stage 1. Fic. 13.—Transverse section of head of embryo very slightly older than the preceding figure. Fic. 14.—Section through the same embryo as fig. 12, but considerably further forwards. Fic. 15.—Transverse section through the head of an embryo of about Stage M. Fic. 16.—Hxternal drawing of an embryo of Stage pv. s. 7. Sinus rhomboidalis. Fic. 17..-External drawing of an embryo of Stage 1. o. Oral inyo- lution. Scale for Figs 1 & i Thousandths of an inch. Fig. hi a0e®@ iz & a e Seale for Fig? 3 to Il. Thousandths of an inch. E Ray Lankester, ad nat. del. F. Huth, Lith? Edin*® VAS Ee Savas. JOURNAL OF MICROSCOPICAL SCIENCE. DESCRIPTION OF PLATE XXII, Illustrating Professor Ray Lankester’s Memoir “ On the Structure of Haliphysema.” Fie. l—Haliphysema Tumanowiczii, Bowerbank, drawn from a spe- cimen, placed while living in weak chromie acid (1th per cent.), and subse- quently preserved in strqng alcohol. p/. Streaming protoplasm investing re spicula. esp. Spicules derived from Esperia. vez. Spicules derived from eniera. Fic. 2.—Protoplasmic core of a similar specimen, obtained by gently crushing the test. The core as drawn is a restoration of a specimen broken into three pieces. It is somewhat flat/ened, and therefore widened by pressure. Anteriorly the egg-like bodies are seen embedded in the solid protoplasm. The surface of the core is grooved or ribbed by the longitudinally placed spicules forming the test. N.B.—Figs. 1 and 2 are magnified 135 times linear. Fic. 3.—A spicule of the test (derived from a Reniera) showing invest- ment of streaming protoplasm. 7. One of the vesicular nuclei. From a specimen preserved in chromic acid followed by alcohol. Fic. 4.—Egg-like body ; from a similarly preserved specimen teazed. Fic. 5.—Vacuolated protoplasm and large and small corpuscles ; from a similar specimen. Fic. 6.—Hgg-like bodies from a similar specimen ; one is in the process of transverse fission. Fic. 7.—Portion of the protoplasm showing the wall of cavities in which egg-like bodies were embedded. Fic. 8.—Corpuscle similar to those of fig. 5. Fic. 9.—Vacuolated, reticular protoplasm, with a number of the cha- racteristic vesicular nuclei: embedded. From a chromic-acid-alcohol specimen, teazed. Fic. 10.—Vesicular nuclei of Haliphysema, showing various forms of collapse due to the action of reagents. a, J. Still spherical. c. Invagi- nated hemisphere. d. False appearance of transverse septum and fission. e. Lateral view of @. Fic, 11.—Portion of the core of a specimen hardened in + per cent. chromic acid, followed by alcohol, then stained with hematoxylin, mounted in oil of cloves and Canada balsam, and carefully crushed whilst in the last- named medium. ‘The vesicular nuclei, darkly stained, are seen besides smaller corpuscles. c. Cavity from which a vesicular nucleus has been removed. 7. Ridges fitting into the interstices of the test. : N.B.—Figs. 3 to 11 represent the objects of 280 times the natural size, inear, bie. Aes ie f ieee au Sera barr, PUR ART Bip mi Print {f Ne aa cy * ’ i.e ’ a. , ya ter Z ; ! Rah 7 -_ t m4 ao > hay. 7 } cae * if ‘ = — ae 4 | oe a ae = Sig vant i a ms, 2 4 Sea (: e ° ard Worn Deo 0 RO . a> + ree ion oe hie ey fh +h OPpaLR vee ee Pe area Sera iii cipal eae ae qi nh ; if ae Hernbed itn ht bi AUTOS atte ES ay: ite; ens Sire: sais! smn ean PAN rear Ny a "6 Toh death ta al Fits | THY if) i), Sip a titss TSA OF utils aft} Gi 5) tl a Fe. REIS) OG 4 (( SHO RP ny JORGOLY STAC TU are RAT CR eal ae aioe al sal Fae Mines ie “VES ie mae de fe) CAT WG ae key hom Shani ia c. Hany isierse es jek Ou ee an Se: eae BAB Fes tay: hid Star Mth Lan’ TOR Rola era} TN P Donate ciel) ath any io) AT bie. a ‘onde ie Are Mee, “oth a. ehereee antl a han 1ORTO Ea mae) alk yal) it} ¥ KS 1 we may 't . te) JRA ma , i Salt eel Vilas f areaibe sie FAY Sh aP iF Wy Gerhy ¥ rary eens 2 ph ta > MAS Lr FA BEET) % Tat: tame c an Dee Sea ‘oe is ; j ‘ FP DIOE ES Le, TAM eles 04 ST OR SUT LE 3 Joie Pak : ’ 4 (a Oath tel if ad UP at Lith ary % ud Seng ere MAG? atu kd @ 4 ‘OLSai asian iy . ti + hie A eieT hype DAT VPS, PIPER Tes WEY Bee Es Pay iv i% ary ‘1 aha slyschiti yy a at yt ; = 3G) yh UP Re oR Ee are a! hl Meee Nope Voie «ly ; iif ord Seg Air Pio va q Bea JP UT ue Rane agg Bk sf dot viebiat wena Anrareio irl. Wi Pet ‘wainte i , 73 \ fades ue a MI \ : en te ceeeptnl nhl af me os Al) ee a TC DT tie | 4 ight Mie Fibs Vet eat Hasty (tee Tay May es ay th (iin taste | one NaLatG i Mires ber Hihiaia Ua Hise Meat ug ron ita We He ape. fork ny Uf inde We Ti Gee, Ae hihi 10 2 ae 4 ‘ hay Wes wie talons nay aye) atl i . ) y Waly ary Te) ’ inhale 9 Py DOPAP alt ha eT mee ald (aoiqde thee Oe a bulk th : . J ; AS s int og ee Meer Fourns Vedi us Ye, 2 ¥F. Huth, Lith® Edin™ E.Ray Lankester ad nat del LITHAM @BA. JOURNAL OF MICROSCOPICAL SCIENCE. EXPLANATION OF PLATE XXIII, Illustrating Professor Ray Lankester’s ‘ Description of Lithameba discus, nov. gen. et sp., one of the Gym- nomyxa.” Fic 1.—Lithameba discus at rest; magnified about 350 dinmeters. x. nucleus ; conc. concretions ; f. food matters; cv. contractile vacuole. Fic. 2.—The same specimen actively extruding pseudopodia. Fic. 3.—Another specimen (less magnified) killed by iodine solution. Fic. 4.—The vacuolar structure of the protoplasm, as seen under No. 10 immersion lens, in a specimen treated with osmic acid and picro-carmine. Fic. 5.—The angular nucleus and its investing membrane after the action of dilute acetic acid. Fic. 6.—The granular cuticle in optical section, after the action of iodine solution, Fic. 7.—The granular cuticle, surface view, after the action of iodine solution. Fic. 8.<-A concretion isolated. oi ' - un ro ra a wat 1 Ta elit ideas Spins eee hh) Te b, 3 bf as , Th : t by ay FO ie Cy AAs a we has a) i» Pit: ae ‘a . Pees Pe ae o 7 i; Na Tra " « Bees ebay NLM Een aa ree Ls ae ms hy a ; te bt i _ Le Ae Oh a is ; 5) vy iz Ry Fj 7 5 +2e es Ma TODROU TN oe aN ie: hee tO. KORA AIS be a Date pest eit Ue chyna Mibbadon} wed haat ie omy) ant ta ety nee da Oe Te Aa Phen | q rt ’ ‘en rau i er Taeiryitt: ed aed bagi S WET 46 VAS t att A seal f SOMAZ Qikhisttiad =n 7 valida bw \ 730 arte Bhynobiaiogy + BUMS 25. Youbs noneheY "ee ofa hovlwlon supakcad byt A Shadlagem a oly charac ee. o> ealipedt: aye: Amaia yn hane a) 39 sad ort a ee De ’ etree acc lit dmavaiies.d “a r bwlisk cau ba ‘ak aa eat rely acpi: ‘nel ee Pig ait whiina Sane Kite + WORSE + ere yy ih fixe 4 th, a LA pose wen) Dee Re eile 403 wale beat sees, 1ivy2 Aim imines loyt toes witht rey ; tS eI i Mion Sourni Vol HUE, WS Fi, XXIV Zeiss F 5% Chromate of ammoniam Triton cristatus. Mounted in Glycerine. ee Horse. i6 immers. Fresh im Glycerine. Upper part of Filament _ in motion. Guinea Pig. Fresh in Glyce. is P.& L.imm. S.Maculata. Zeiss F. 2% Na.Cl. S.Maculata. Fresh P &lis imm: x 950 Salamandra Maculata. $% NaCl P&L. imm: 24 hours. Fig. 10. | \ Salamandra Maculata, i2 oil imm: enlarged 2,5% Soda Bicarb. > 48 hours. H. Gibbs, del ’ ; F Huth, Lith? Edin® JOURNAL OF MICROSCOPICAL SCIENCE. DESCRIPTION OF PLATE XXIV, Illustrating Mr. Gibbes’ Memoir on the “ Structure of the Vertebrate Spermatozoon,” Fie. 1.—S. maculata. Fresh. Drawn with Powell and Lealand’s zzimm. x 950. Fic. 2.—8. maculata. Fresh. Drawn with Powell and Lealand’s ¢ new formula imm. ; upper part of filament was in motion at the time. Fie, 3.—Zriton cristatus. Prepared in 5 per cent. chronic ammonium, and mounted in glycerin. Drawn with Ziess’ F. Fic. 4.—Spermatozoon of horse, fresh mounted in glycerin. Drawn with Powell and Laland’s +, immersion. x 950. Fie, 5.—Spermatozoon of guiuea-pig, fresh mounted in glycerin. Drawn with +; immersion. x 950. Fic. 6.—Spermatozoon of Salamandra maculata, mounted in a solution of chloride of sodium 3 per cent., and drawn, after having been mounted forty-eight hours, with Zeiss’ F. Fic. 7.—Spermatozoon of Triton cristatus, taken fresh and mounted in 3 per cent. solution of chloride of sodium, and drawn with Powell and Lealand’s 7, dry, after being mounted four weeks. _ Fies. § and 9.—Spermatozoon of S. maculata, taken fresh and mounted in 3 per cent. salt solution, Drawn with Powell and Lealand’s + immer- sion. In Fig.8 the head and membrane have altogether disappeared, while in Fig. 9 they are scarcely touched. Fic. 10.—Spermatozoon of §. maculata after immersion in a 5 per cent. solution of Sod Bicarb. for forty-eight hours. Drawn with ?, of immersion. oid) ty Bate. Bit ie Ody ie HY +h Pe. 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