NORMENTAFELN ZUR ENTWICKLUNGSGESCHICHTE DER WIRBELTIERE. IN VERBINDUNG MIT Dr. Bles - Glasgow , Dr. Boeke- Helder, Holland, Prof. Dr. Brächet - Brüssel , Prof. Dr. B. Dean - Columbia University, New York, U. S. A., Dr. H. FUCHS-Strassburg, Dr. GLAESNER-vStrassburg, Prof. Dr. O. GROSSER-Wien, Prof. Dr. B. HENNEBERG-Giessen, Prof. Dr. HuBRECHT-Utrecht, Prof. J. Graham KERR-Glasgow, Prof. Dr. KOPSCH- Berlin, Dr. THILO KRUMBACH-Breslau, Prof. Dr. LUBOSCH-Jena, Prof. Dr. P. MARTIN-Gi essen, Dr. Nier.strasz- Utrecht, Prof. Dr. C. S. MiNOT-Boston, U. S. A., Prof. MiTSUKURl-Tokio, Prof. Dr. NiCOLAS-Paris, Prof. Dr. Peter- Greifswald, Prof. REIGHARD-Ann Arbor, U. S. A., Dr. SAKURAi-Fukuoka, Japan, Dr. ScAMMON-Harvard Medical School, Boston, U. S. A., Prof. Dr. Semon- Prinz -Ludwigshöhe bei München, Prof. Dr. Sobotta- Würzburg, Prof. Dr. SOULIE-Toulouse, Prof. Dr. TANDLER-Wien, Dr. TAYLOR-Philadelphia, U. S. A., Prof. Dr. TOURNEUX- Toulouse, Dr. VOELKER-Prag, Prof. WHITMAN-Chikago, U. S. A. HERAUSGEGEBEN VON Prof. Dr. F. KEIBEL, LL. D. (Harvard), FREIBURG I. BR. ZEHNTES HEFT. NORMAL PLATES OF THE DEVELOPMENT OF LEPIDOSlßEN PARADOXA AND PROTOPTERUS ANNECTENS. ' BY J. GRAHAM KERR UNIVERSITY OF GLASGOW. WITH 1 PIGURE IN" THE TEXT. AND 3 PLATES. JENA, VERLAG VON GUSTAV FISCHER. 1909. Verlag tou Grnstay Fischei' in Jena. Normentafeln zur Entwickelungsgeschichte der Wirbeltiere, in Ver- liiiuluiig (iiit Dr. Bles-Glab^gow, Di-. B oeke- Hehler, Holland, l'rof. Dr. Bracliet- Brüssel, Prof. Dr. B. D ean - Columbia University, New York, U.S.A., Prof. Dr. H. Fuchs-Strassburg, Dr. Glaesner-Strassburg, Prof, Dr. 0. Grosser- Wien, Prof. Dr. B. H enneberg - Giessen, Prof. Dr. Hubrecht- Utrecht. Prof. J. Graham Korr -Glasgow, Prof. Dr. Kop seh- Berlin, Dr. Thilo Krumbach- Breslau, Prof. Dr. Lub osch-.Iena, IVof. Dr. P. Marti n -Glossen, Dr. Nier- straß - Utrecht, Prof. Dr. C. S. 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GROSSER-Wien, Prof. Dr. B. HENNEBERG-Giessen, Prof. Dr. HuBRECHT-Utrecht, Prof. J. Graham KERR-Glasgow, Prof. Dr. KOPSCH- Berlin, Dr. Thilo KRUMBACH-Breslau, Prof. Dr. LUBOSCH-Jena, Prof. Dr. P. MARTIN-Giessen, Dr. Nierstrasz- Utrecht, Prof. Dr. C. S. MiNOT-Boston, U. S. A., Prof. MiTSUKURl-Tokio, Prof. Dr. NiCOLAS-Paris, Prof. Dr. Peter- Greifswald, Prof. REIGHAPUJ-Ann Arbor, U. S. A., Dr. SAKURAI-Fukuoka, Japan, Dr. ScAMMON-Harvard Medical School, Boston, U. S. A., Prof. Dr. Semon - Prinz - Ludwigshöhe bei München, Prof. Dr. SOBOTTA- Würzburg, Prof. Dr. SOULIE-Toulouse, Prof. Dr. Tandler- Wien, Dr. TAYLOR-Philadelphia, U. S. A., Prof. Dr. TOURNEUX- Toulouse, Dr. VOELKER-Prag, Prof. WniTMAN-Chikago, U. S. A. HERAUSGEGEBEN VON Prof. Dr. F. KEIBEL», LL. D. (Harvard), FREIBURG 1. BR. ZEHNTES HEFT. NOMAL PLATES OF THE DEVELOPMENT OF LEPIDOSIREN PARADOXA AND PROTOPTEßUS ANNECTENS. BY J. GRAHAM KERR UNIVERSITY OF GLASGOW. WITH 1 FIGURE IN THE TEXT. AND 3 PLATES. JENA, VERLAG VON GUSTAV FISCHER. 1909. A.lle Rechte vorbehalten. Contents. page Introduction l General Sketch of the Course of Development in Lepidosiren and Protoptnrtis ... 2 External features 2 The skin 3 Nervous System 3 Peripheral nerves 4 Olfactory organ 4 Eye 4 Otocyst 5 Skin sense organs 5 PiNKUs' Organ 5 Pituitary body 5 Alimentary canal 5 Buccal cavity 5 Visceral clefts r 6 Lung 6 Thyroid and thymus 6 Digestive tract 7 Liver 7 Pancreas 7 Coelomic organs 7 Splanchnocoele 8 Myotomes 8 Nephridial System 8 Archinephric ducts 9 Mesonephros lO Genital ducts lO Gonads lo Organs of the mesenchyme n Skeleton ii Tables 12 Conclusion 20 Literature 27 31829 Introduction. In selecting the various "stages" which were to form the basis of my work upon the development of Lepidosiren and Frotopterus I realized from the beginning the importance of making my series of "stages" agree as closely as possible with the series of stages defined by Semon in his classical work on Ceratodus. In would clearly have greatly facilitated the comparison of data obtained from the investigation of the development of the Monopneumona and Dipneumona and therefore have added to the value of these data if the developmental history could have been divided into exactiy corresponding stages. A little investigation was sufficient to make clear the impossibility of arranging any such corresponding series of stages and I was therefore compelled to make my selection of stages of Lepidosiren quite independent of those selected by Semon for Ceratodus. In defining the stages of Frotopterus I have endeavoured to make them correspond in number with those oi Lepidosiren but even here it will be seen that the agreement between the stages of Lepidosiren and Frotopterus, although the two genera are so closely allied, is only of a comparatively rough kind, and I have had to make the descriptive tables quite independent. The figures reproduced in the three plates cover the developmental history of the two genera fairly completely up to stage 36, except that in the case of Frotopterus the early stages of segmentation have not yet been observed. I have not thought it advisable to include figures of stages subsequent to 36, when the adult form is being assumed, as their inclusion in the plates available would have necessitated the reduction in size of the earlier and more important figures. For the figures of the various stages I am indebted to the high artistic skill combined with con- scientious care of Mr. A. K. Maxwell. They have been drawn throughout under my close supervision and I can vouch for their accuracy. The necessary section cutting has been carried out with his usual skill and care by Mr. P. Jamieson. The data given in the Tables are to be taken as referring to the specimens figured. In most cases several, in some cases numerous, specimens belonging to the same stage according to their external features have been investigated by sections and in the few cases where it has seemed necessary to include data derived from such other specimens such data are enclosed between brackets. Such necessity has arisen in various cases where particular points can be determined with greater accuracy in sections cut in different planes from those in which the specimen figured had been cut or prepared by ditferent embedding or staining methods. Seeing that the present part of the "Normentafeln" deals with forms so little familiär to embryologists generally I have thought it advisable to preface the Tables with a short sketch of the general development of the two forms in question. Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. X. A Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. General Sketch of the Course of Development in Lepidoslren and Protopterus. External features. {Lepidosiren, Graham Kerr, 1900a; Protopterus, Budgett, 1901.) The egg of Lepidosiren (6,5—7 ^'^) and that of Protopterus (3,5—4 mm) undergo a complete but unequal segmentation. In Lepidosiren the first two furrows are meridional and they are succeeded by a series of four vertical furrows. These are liable to Variation and individual furrows may become actually latitudinal. In the case of Protopterus the early phases in segmentation have not yet been observed. Segmentation results in the formation of a blastula with a large segmentation cavity, roofed in by two layers of micromeres and overlying the heavily yolked macromeres which form the lower part of the egg. Gastrulation begins with the appearance of a latitudinal furrow (usually formed at first of a linear series of small depressions) about 8-10" below the equator of the egg and at first extending through it may be 120" of longitude. The central part of this groove deepens to form the archenteron while its terminal parts flatten out and disappear so that by the time the blastopore is completed (the whole mass of macromeres being now covered in) it forms a short latitudinal opening-crescentic in shape and concave towards the dorsal side owing probably to the more active backgrowth of the central part of the dorsal lip as compared with its two ends. M • At a varying period about this time (stages 13—15) a slight flattening %DI> in front of the blastopore marks out the position of the medullary plate and by stage 16 definite medullary folds can be seen. For a short period — about stage 18 — varying with different eggs — the folds can be seen to be continuous with one another behind the blastopore or anus (cf. Text-fig. l). In the egg of stage 18 figured the bind end of the embryo has Flg. I. Lepidosiren paradoxa. Stage l6+. X 8V2. View of specimen showing already proceeded too far in its development to show this feature. continuity of medullary folds behind t^, , j j . -i • ^ ■ ^^ ■ -n j^ i j • i.u ,, -^ ihe head and tau project more prommently m Protojnerus and m the latter the body of the embryo extends round a considerably greater angular extent of the egg, the tips of the head and tail coming nearly into contact with one another at stage 25 in Protopterus while they remain widely separated in Lepidosiren. Conspicuous features in these stages are the cement organ — a crescentic structure on the ventral side — and the external gill rudiments situated on visceral arches III— VI. About stage 23 in Lepidosiren a vascular network is seen over the surface of the yolk, its cavities filled with colourless blood there being for some time after its appearance no haemoglobin present. About the time of hatching (stage 27) the larva has a somewhat tadpole-like shape the hinder tail- like region of the trunk being flexed ventrally. In Protopterus a larger proportion of the yolk is con- centrated in the anterior swoUen part which as a consequence bulges more prominently and the rudiments of various organs — external gills and eyes — are also seen to be relatively larger than in Lepidosiren. Within a short space of time after hatching (stage 28) the trunk becomes straightened out and the pinnae of the external gills appear as two rows of little knobs on their external surface. The myotomes are seen to be growing actively in dorsiventral direction. About stage 30 active growth becomes apparent in the postcloacal or true caudal region which up tili this time has been insignificant in size. Tlie limbs make their appearance about stage 31 the pectoral Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. ■! limb being identical in appearance with the externa! gill rudiments of earlier stages and being at first directly posterior to the external gills as if forming a member of the same series of organs. During the later stages of development the most conspicuous features are the rapid growth of the true tail region, the rapid growth in the head region in front of the main mass of yolk, and the spreading downwards of the myotomes in the lateral wall of the body. With the increase in size of the head region the cement organ becomes carried forwards on its ventral side so as eventually to lie well in front of the opercular opening. The cement organ reaches a great size and forms a very conspicuous feature in the young Lepidosiren of stages 32 — 34. After this atrophy gradually overtakes it and by stage 36 it has completely vanished. The external gills reach their maximum about stages 32 — 34 in ProfojHerus, rather later (stage 34, 35) in Lepidosiren. Thereafter reduction takes place, rapidly in Lepidosiren, very slowly in Protopterus where vestiges of the three external gills frequently still persist in sexually nature individuals. In Lepidosiren there takes place at stage 36 what may be called metamorphosis the external gills undergoing rapid atrophy, the cement organ disappearing, the colouration of the young animal becoming much darker and the habits more lively. Whether there is a similar concentration of developmental change in the case of Protopterus is not evident. The skin. (Graham Kerr, 1901 d.) Up to stage 32 — 35 in Lepidosiren the ectoderm retains its two-layered condition. Thereafter the deep layer cells begin to multiply and the ectoderm gradually assumes the many layered condition of the adult. At about the stage mentioned isolated cells begin to assume a clear glandulär character — the forerunners of the great unicellular glands with which the adult epidermis is crowded, and flask glands begin to appear as solid downgrowths of ectoderm which. develop a cavity secondarily. Chromatophores which are already present in the mesenchyme show their strongly heliotropic tendencies by wandering towards the surface of the body, crowding together immediately beneath the ectoderm and many of them wandering in between the ectoderm cells from about stage 25 onwards. A remarkable local development of ectodermal gland cells goes to form the cement organ which is so conspicuous a feature of the young Protopterus or Lepidosiren. Forming at its first appearance a long crescentic structure spreading across the ventral side of the body, it becomes later on shortened from side to side and is borne in the case of Lepidosiren on a conspicuous cushion-like structure. The glandulär part of the cement organ arises as a thickening of the deep layer of the ectoderm, the cells of which become tall and columnar, while the superficial layer soon breaks down so as to expose the ends of the gland cells. The atrophy of the organ takes place in the usual way, the glandulär epithelium becoming penetrated by vascular loops and invaded by crowds of leucocytes. Nervous system. (Graham Kerr, 1901 d.) The ectoderm over the whole archenteric region shows as early as stage 13 its deep layer slightly thickened its cells being somewhat columnar forming a wide medullary plate. Later on the axial part of this medullary plate shows active cell multiplication so that a deep solid keel is formed out of which the central nervous System develops. In both Lepidosiren and Protopterus the definitive cavity of the central nervous system appears as a secondary excavation in the at first solid rudiment. As the front end the rudiment becomes enlarged to form the brain ; it soon shows a segmentation into primary forebrain and rhombencephalon. It is not until a much later period that the primitive forebrain shows signs of division into thalamencephalon and mesencephalon. The hemispheres when they appear arise as paired and quite I* . Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. independent bulgings outwards of the wall of the primitive forebrain. During the later stages of development the hemispheres grow rapidly though it is not tili much later than the last stage figured that they approach the extraordinary size and complexity (Elliot Smith, 1908) characteristic of the adult. As regards details of brain development it is to be noted that the pineal body is simple. There is no obvious indication of a parapineal body, and there is at no time any trace of eyelike structure. There is a well marked paraphysis closely resembling that of Urodeles and the velum is clearly paired in origin. Peripheral nerves. (Graham Kerr, 1904.) Leindosiren with its large cell elements is a very favourable object for studying the development of nerve trunks. Already in stage 24 i. e. while the myotome is still in close contact with the spinal cord the motor trunk can be seen as a naked bridge of soft granulär protoplasm continuous at its outer end with the substance of the myotome and at its inner end with that of the spinal cord. As development goes on this protoplasmic bridge becomes fibrillated — neurofibrils appearing in its substance — it becomes drawn out in length as the myotome recedes from the spinal cord with the growth of the trunk and heavily yolked masses of mesenchymatous protoplasm aggregate round the nerve and spreading along it form the primary sheath. Olfactory organ. (Graham Kerr, 1901 d, 1909.) The olfactory organ (in Protopterus) makes its appearance as seen in external view as a rounded dimple on each side of the under surface of the head some little distance in front of the line of junction of the yolky buccal rudiment with the ectoderm. This dimple becomes gradually elongated to form a groove which passes outwards and backwards. When the lips begin to grow out the whole of the olfactory grooves become enclosed within the Upper lip, the hinder end of the groove soon becoming hidden as the lower jaw grows forwards. The olfactory groove assumes a dumb-bell shape dilated at either end and reduced to a narrow slit in the inter- vening portion. By the fusion of the edges of the slit-like portion the two dilated ends become separated off as the anterior and posterior nares. While the openings of the olfactory organ develop in the manner above described it is to be noted that the cavity in the inferior of the organ takes its origin as a secondarily arising split in the at first solid rudiment derived from a thickening of the deep layer of the ectoderm. In the later stages of development of the olfactory organ a conspicuous feature is formed by a rounded diverticulum of its lateral wall corre- sponding closely with the similar structure occurring in the embryo Urodele and possibly homologous with the organ of Jacobson of amniotic vertebrates. Eye. (Graham Kerr, 1901 d.) The optic "outgrowth" of the brain is at first solid as is the thalamencephalon at this stage. A cavity develops secondarily in the optic outgrowth and becomes continuous with that which has meanwhile appeared in the thalamencephalon. The lens develops as a solid ingrowth of the deep layer of the ecto- derm in which a cavity soon appears secondarily. There is a wide choroid fissure which however closes very soon, and which is restricted to the optic cup. From the size of the individual elements Lepidosiren IS a very favourable object for studying the development of the visual cells. The main features in the development of the rods have been described and iigured in an earlier paper (1901 d). Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. 5 Otocyst. The otocyst rudiment becomes apparent about stage 20 as a down growth of the deep layer of the ectoderm. A split is apparent almost from the first and this soon widens out to form a rounded cavity. In the subsequent development of the otocyst the chief point of interest seenis to be that the recessus endo- lymphaticus appears to develop in Frotopteras and Lepidosiren as in Ceraiodus (Semon) quite independently of the original connexion of the otocyst with the outer ectoderm. The endolymphatic outgrowth develops considerably mesiad and posterior to the isthmus which forms the last connexion between otocyst and skin. Skin sense organs. The System of lateral line organs makes its appearance early in development {Lepidosiren, stage 27) as a thickening of the deep layer of the ectoderm on each side anteriorly. This thickening spreads out along the paths marking the adult distribution and becomes divided up into the individual sense organ rudiments. These are at first arranged segmentally in the trunk region. In Lepidosiren the organs retain their primitive superficial position while in Protopterus they become in the head region eventually sunk beneath the surface in tubulär Channels. PINKUS' organ. Agar (1906b) has described how the ectodermal outer end of the spiracular cleft becomes converted into the sensory organ of Pinkus. Pituitary body. (Graham Kerr, 1901 d.) The development of the pituitary body takes place after the normal Amphibian manner. Arising as a wedge shaped ingrowth from the ectoderm about stage 23, the inner end becomes enlarged and develops a cavity as a secondary split. About the same time as the split appears the organ loses its connexion with the skin through its undilated portion undergoing atrophy. Alimentary canal. (Graham Kerr, 1909.) The differentiation of the alimentary canal out of the primitive mass of yolk may be said to begin about stage 23 with the modelling of its anterior region caused by the precocious development of meso- dermal tissues which foreshadows the development of heart and pericardium. In this way the region of the foregut becomes marked off from the midgut which serves as the great storehouse of yolk and which no doubt on this account is much retarded in its differentiation. Buccal cavity. The main part of the buccal cavity is developed as a secondary excavation in the originally solid yolkladen anterior part of the enteric rudiment developed from the macromeres. The outer part of the buccal rudiment becomes converted into the epithelial lining of the buccal cavity. Examination of celloidin sections shows that there is no actual ingrowth of ectoderm along the surface of the buccal rudiment. This mode of development of the buccal lining is no doubt secondary but it is of interest as emphasizing the possibility of grave error in using embryological evidence for deciding as to the morphological nature of Organs which develop in proximity to the boundary region between two germinal layers. Were the two Dipnoans now under discussion and certain Urodeles the only vertebrates whose embryology had been f. ■ Nonnentafeln zur Entwicklungsgeschichte der Wirbeltiere. worked out we might conclude that the vertebrate teeth were originally organs of the endoderm ! Apart frotn their origin the teeth of Lepidosiren are of interest in comparison with those of Ceratodus in as much as here the primitive condition in which the teeth have not yet fused to form the characteristic dental masses of the adults of existing Dipnoans and which is so beautifully recapitulated in the development of Ceratodus is completely slurred over. The tongue is a "primary tongue" exactly similar to that of the embryos of Urodeles though in this case there is no gland field developed in front of its roots as is the case in the Aniphihia. The sohd rudiment from which the main part of the buccal cavity is developed by secondary excavation comes in contact with the skin of the ventral surface of the head along a transverse line in front of the outer ends of which the olfactory dimples appear. About stage 34 this area on the ventral side of the head containing the olfactory rudiments becomes enclosed by the lower lip growing forwards while the Upper Hp appears as a ridge enclosing it in front. By the increased development of these lip rudiments the olfactory openings come to be included in the front part of the definitive buccal cavity. Visceral clefts. Six visceral clefts are laid down in the embryo as solid yolk laden rudiments. The fate of the first (Hyomandibular) has been described by Agar (1906b). It never develops any lumen except at its inner end. It loses its connexion with the skin and, later on, with the pharynx also and eventually its presence is betrayed only by the peculiar Pinkus' organ derived from its outer epiblastic end. Clefts II — VI become perforated though eventually in Lepidosiren II becomes closed, leaving the four clefts which persist in the adult. In Lepidosiren the clefts at no time develop regulär respiratory lamellae as in most fishes. Their walls grow out into irregulär rounded respiratory processes which vary greatly in their extent of development in different individuals. Lung. (Graham Kerr, 1906, igo8, 1909.) The lung arises as a rounded knob about stage 32 projecting downwards in the middle line from the lower side of the still solid pharynx close to its bind end i. e. on a level with cleft VI. The Oesophagus which is already clearly modelled out of the solid mass of yolky endoderm slopes obliquely tailwards, ventralwards and towards the left side. The lung rudiment grows backwards in the median plane, sloping slightly dorsalwards, the Oesophagus being bent well out of its way to the left side. Along the dorsal side of the main mass of yolk a way is as it were prepared for the backwardly growing lung by the formation of a kind of valley along which the lung grows. Later on this valley flattens out and disappears. Already soon after its appearance the lung rudiment becomes bilobed and the two lobes grow backwards as the lungs of the adult. Like so many other organs the lung is quite solid at first and only later on develops a cavity in its interior. Thyroid and thymus. The thyroid arises from a solid yolk laden rudiment of at first considerable anteroposterior extent which becomes gradually nipped off from the pharynx from behind forwards. The development of the thymus has been described by Bryce (1905) for Lepidosiren. The main thymus buds are derived from the walls of clefts III and IV while abortive buds arise from clefts II and V. There is a well marked postbranchial body on the left side developed as a solid projection from the pharyngeal rudiment close to the ventral end of cleft VI. Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. y Digestive tract. (Graham Kerr, 1909.) The comparatively undifferentiated stomach arises from the hinder part of the foregut. The yolk- laden region behind this becomes gradually converted by a process of modelling — associated with the ingrowth of mesenchyme into the solid yolk along a spiral line — into the spirally coiled mid-gut. As the difterentiation of the mid-gut proceeds the swollen character of its anterior portion containing the main mass of yolk becomes less and less pronounced until at stage 36 the thickest and yolkiest part of the mid- gut is some distance back in the second turn of the spiral. Later (stage 37) the intestine forms in external appearance a straight cylinder the turns of the spirally coiled endodermal tube being now ensheathed in a thick cylindrical wall of connective tissue. By this stage the rectum is slightly dilated and dorsal to it passes forvvards the elongated finger shaped rudiment of the cloacal caecum (see p. 10). Liver. The liver is in its early stages an outgrowth of the alimentary rudiment anteriorly, becoming distinguishable (about stage 31) by its yolk assuming a fine grained character. An ingrowth of vascular mesoderm cuts off the liver rudiment except for the narrow stalk by which it remains continuous with the gut wall. The liver rudiment rapidly increases in bulk particularly in anteroposterior diameter and it soon loses its at first symmetrical shape and mesial position becoming rotated round so as to lie on the right side of the stomach. Pancreas. The dorsal pancreas makes its appearance about stage 32 as a rounded yolk-laden projection from the gut wall dorsally and to the left of the middle line and situated about the level of the posterior nephrostome in Protopterus, rather farther back in Lepidosiren. In Lepidosiren the rudiment, even in early stages, forms a hollow diverticulum of the gut wall while in Protopterus it is solid except for a small irregulär closed lumen. A little after the appearance of the dorsal pancreas, a pair of ventral rudiments develop, one on each side of the bile duct opening. These latter meet and fuse dorsal to the bile duct and then the dorsal pancreas fuses with the right ventral so as to produce the single pancreatic complex of the adult. By stage 35 the pancreas is penetrated by a network of blood vessels and is becoming histologically differentiated. The most noteworthy feature in the later development of the pancreas is that at no period does it come to project conspicuously beyond the general outline of the gut wall : it remains throughout life concealed within the mesodermal sheath of the gut. This led to its existence being ignored up to the date of Parker's paper upon the structure of the adult Protopterus. Coelomic organs. The mesoderm and notochord are represented in early stages (stage 12) by the medium sized blastomeres with medium sized yolk granules which occupy the space between the dorsal wall of the archenteron and the medullary plate, thinning out towards either side and eventually passing laterally without any break into the large blastomeres. This common rudiment of mesoderm and notochord becomes marked off from the endoderm except at its outer edge by a distinct split, while later on (ca. stage 14) another split appears on each side which demarcates the lateral mesoderm rudiment from the median chordal rudiment. Segmentation of the mesoderm on each side begins about stage 17, while the lateral unsegmented mesoderm continues to extend by delamination from the large-yolked cells of the definitive o Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. entoderm. The lateral plates meet ventrally under the head about stage 23 but in the trunk region not tili much later. Splanchnocoele. The splanchnocoele becomes patent first in the pericardiac region, the at first paired pericardiac cavities soon becoming fused. The main part of the splanchnocoele develops by a Splitting process of the lateral mesoderm spreading back from the pericardium and downwards from nephrocoeles and myocoeles. In addition to the original communication between pericardium and the main splanchnocoele (pericardio- peritoneal canals) there arises by Splitting a secondary more ventral communication. The pericardio- peritoneal canals and the ventral communication become obliterated about stage 34—35 tlie latter a little later than the former. Myotomes. (Graham Kerr, 1904.) In the early development of the myotomes there are two features of special interest and importance. There is first the fact that the myoblasts of the inner wall of the myotome are for a time in the form ot large neuromyoepithelial cells of the most diagrammatic looking kind — the cell being continued at its inner end into a tail-like process — the motor nerve rudiment. The second feature of interest is that the Dipnoans in question show beyond any possible doubt the development of muscle fibres from the external wall of the myotome. The comparative certainty of observations of this in Lepidosiren is due to the fact that the outer ends of the myoblasts of the inner wall of the myotome form a very characteristic broad clear zone which demarcates in the most obvious way the inner wall from the outer wall. A relatively considerable proportion of the substance of the definitive myotome owes its origin to the outer wall. Details as to the fate of the anterior myotomes, the musculature of the limbs etc. will be found in Agar (1907). A detail of general morphological interest is the double origin of the constrictor pharyngis (Wiedersheim) a typical "splanchnic" muscle in which as Agar has shown the dorsal part is actually myotomic in origin. Nephridial System. The earliest indications of the kidney System make their appearance about stage 17 in the form of a slight swelling of the mesoderm, producing a faint elevation of the dorsal surface of the embryo on either side. The nephric rudiment so indicated gradually spreads backwards and about stage 22 a well marked difference in size becomes apparent between the swoUen headward end of the rudiment which is destined to become the functional pronephros, and the slender hinder portion which forms the pronephric duct. About stage 24 the ducts are seen to have extended right to the cloacal region. As regards the details of structure in the earliest stages of development of the pronephros I do not feel yet in a position to speak with any confidence owing to the extreme liability of error in investigating the heavily yolk laden tissues. The pronephric rudiment in early stages forms a solid compact mass of mesoderm which as seen in transverse sections forms a somewhat ellipsoidal mass projecting laterally from the nephrotome between the ectoderm and the somatic mesoderm. Appearances point to the nephridial rudiment being formed in the first instance by a series of nephrotomal outgrowths like those described by Brauer for Amphihia, but solid instead of hoUow. As many as eight of these segmental tubule rudiments are apparent in some Lepidosiren series stretching from myotome II backwards i). Except for these early stages which until the technical difficulties in the way of their investigation have been completely overcome I) Traces of at least one tubule may appear in front of this. Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. g must remain somewhat doubtful, the general course of development of the pronephros is fairly clear. About stage 21 the coelomic cavity makes its appearance in the" nephrotome and rapidly extends out into the hitherto solid tubule rudiment, and later on back into the archinephric duct. Of the series of nephrotomes which go to compose the pronephric rudiment on each side only two normally proceed with their development to form functional pronephric tubules, the fully developed pronephros being characterized like that of Ceratodus, Polypterus and many Urodeles by its having two functional tubules. In both Lepidosiren and Protopterus the pronephric tubules which become functional appear to be those corresponding with myotomes II and IV. As an occasional Variation three tubules may be developed (II, III, and IV). In those nephrotomes which develop functional tubules the nephrotome itself goes on developing, its cavity becoming widely patent to form a pronephric Chamber. In enibryos with three tubules there is seen to be a corresonding series of three pronephric Chambers lying one behind the other and at first without any open communication between successive Chambers. Later on the pronephric Chambers on each side become confluent so that there is now a single Chamber stretching through the region occupied by myotomes II, III and IV. The floor of the pronephric Chamber becomes pushed upwards about stage 24 by a blood sinus which expands beneath it opposite each nephrostome to form a dorne -shaped swelling, the rudiment of the glomerulus. These originally separate glomerular rudiments soon fuse so that each Compound pronephric Chamber contains a single elongated glomus. By differential growth of the wall of the pronephric Chamber the glomus has its point of attachment gradually shifted mediad and dorsad so that by stage 30 it Springs from the dorsomedial angle of the Chamber i. e. from close to the now median dorsal aorta. As will have been gathered the pronephric Chambers or Chamber are at first in perfect continuity with the splanchnocoele which spreads outwards from them. Later on as the pronephros becomes greatly enlarged it bulges prominently across the splanchnocoele towards the mesial plane and eventually about stage 32 it comes in contact and fuses with the mesodermal sheath of the alimentary canal. In this way the glomus comes to be enclosed in a secondary pronephric Chamber which however remains in free communication with the splanchnocoele at its hinder end. The glomus becomes firmly slung diagonally across this Chamber by its tip undergoing fusion with the mesodermal capsule of the pronephros upon the ventrolateral side of the Chamber posteriorly. To return to the pronephros itself. From about stage 26 onwards the pronephros increases rapidly in size owing to the rapid growth in length of the anterior end of the archinephric duct and also — though to a much less extent — of the tubules. The anterior part of the archinephric duct increases so rapidly in length that it becomes greatly convoluted. This marked increase in length of the anterior part of the duct is accompanied by great dilatation of its cavity and thinning of its walls. These phenomena may be correlated with the fact that the cloacal opening becomes closed about the time of hatching and, there being no allantoic or other urinary reservoir posteriorly, the urinary fluid driven out through the still active pronephric tubules has perforce to accumulate in the pronephric duct and causes great distension as it does so. As is well known a similar effect appears to be brought about in some Amphihia by an occlusion of the archinephric duct (Marshall and Bles). Rapid degeneration of the pronephros now sets in. Its walls assume a waxy appearance, atrophy takes place and by about stage 36 it has practically disappeared although the archinephric duct can still be traced forwards for some distance in front of the mesonephros. Archinephric ducts. The question as to how the archinephric duct extends backwards is one to which it is very difficult to find a certain answer. In a perfectly preserved embryo both ectoderm and mesoderm are fitted Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. X. 2 jQ Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. closely round the archinephric duct. A slight amount of contraction is sufficient to cause the formation of fine chinks between the structures named and it seems a matter of chance whether the duct is left attached to the ectoderm or to the mesoderm or on the other hand is left lying freely between the two layers. No great weight can therefore be given to the fact that the hind end of the duct is attached to one layer or to the other in deciding which layer the duct is originally derived from. There remains the histological character of the duct rudiment and this is clearly mesodermal: the cells forming it being laden with large coarsely granulär yolk. This character indicates that the duct is of mesodermal origin. It is in regard to the further question — whether the hind end of the duct grows back freely by its own growth activity — that the chief difficulty arises. The presence of an occasional mitotic figure in the duct rudiment does not necessarily mean that the duct rudiment is doing anything more than merely keeping pace with the general growth of the tissues. If the duct is growing backwards by its own activity all probability points to the growth activity being localised at its hinder end as it is hardly conceivable that the duct can slide bodily backwards between the cells which closely invest it. That there is no such growth activity at the tip of the duct is indicated by the coarsely granulär character of the yolk contained in it, because the active metabolism associated with active growth is invariably accompanied b}' the breaking down of the yolk into a finely granulär form so as to be readily assimilable. The probability therefore is that the backgrowth of the duct is effected by delamination from the somatic mesoderm. Junction with the cloaca takes place about stage 24 — 25 {Lejiidosiren). Up tili about stage 35 {Lepidosiren) the ducts open separately on either side of the cloaca but about this period their cloacal ends are found to be continued backwards into a common portion. About stage 36 (Lepidosiren) the region common to the two ducts begins to bulge forwards in front and the projecting part grows actively and forms by stage 37 a long tubulär cloacal caecum. With further growth of the animal the caecum becomes wider and gradually assuines the rounded form characteristic of the adult. Mesonephros. The mesonephric tubules arise as at first solid rudiments, arranged roughly segmentally and not showing at any period continuity with the myotomes. In Protopterus they begin about segment 14 but in occasional specimens nuclear condensations have been seen in Segments anterior to this (as far forward as the hinder limit of the pronephros) which may possibly represent vestigial tubules. The definitive tubule rudiments become obvious about stage 30. They are at first quite solid and are independent of the duct. Each rudiment assumes a C-shape, a split develops in its interior and its outer end undergoes fusion with the wall of the archinephric duct, the cavity of the tubule and that of the duct soon (stage 31 Lepidosiren) becoming continuous. The free end of the tubule now becomes dilated to form the Malpighian bod}' (stage 32 Lepidosiren) and after a time (stage 35 Lepidosiren) the glomerulus is formed by a pushing in of the wall of the Malpighian cavity. Genital ducts. The development of the genitorenal connections of the male and of the oviduct in the female has not yet been worked out. In stage 37 {Lepidosiren) the oviducal funnel is present. It passes back into a solid MüUerian duct rudiment which at its hind end appears to die away amongst the mesenchyme. Gonads. The development of the gonads has not yet been worked out. In stage 38 {Lepidosiren) a cylindrical Strand of gonad with large spherical nuclei rieh in chromatin is clearly visible ventral to the mesonephros. Normal Platcs of the Development of Lepidosiren paradoxa and Protopterus annectens. II Org^ans of the mesenchyme. As investigation of these organs is not yet nearly complete I-shall content myself with referring only very briefly to some of the more important skeletal features which have been determined. Skeleton. It will be recalled that the notochord arises from the axial portion of the mass of medium sized blastomeres lying dorsal to the archenteron. By stage 14 in Lepidosiren the mesoderm has become marked off on each side by a split, the notochordal rudiment now forming a ridge like projection of the archenteric roof. About stage 16 the chorda becomes split off from the thin layer of endoderm beneath it which per- sists as the enteric roof. By about stage 23 the notochord has become cylindrical and a delicate primary sheath is formed on its surface. As Agar (igo6 a) has shown, the front end of the notochord degenerates leaving the sheath anteriorly filled with mesenchyme. Later on as the chordal cells increase in size as they become vacuolated the notochord pushes its way forward again into the sheath, occupying the position of the original front end which had degenerated and disappeared. About stage 32 the secondary sheath makes its appearance. It rapidly increa.ses in thickness and about stage 36 (Lepidosiren) begins to be colonized by Immigrant amoeboid cartilage cells from the arcualia, becoming eventually converted into a continuous cylinder of cartilage. It is to be noted that the intracranial part of the secondary notochordal sheath be- comes colonized by cartilage cells from the parachordals in precisely similar fashion. In the head region the trabeculae appear first. The quadrate region of the mandibular arch is from the first continuous with the trabeculae. A faint rudiment of the palatopterygoid outgrowth appears but soon disappears again (Agar). The Suspension of the jaw apparatus is entirely by means of the upper end of the mandibular arch (proto- stylic, Graham Kerr, 1907 b i) ; or autostylic — Gregory, 1904 — condition). The chondrocranium shows progressive development towards the adult condition without signs of retrogression. Bone first makes its appearance about stage 32 — 34 in Lepidosiren in the form of thin sheaths investing the base of the skull (parasphenoid) the pectoral girdle and hyoid arch, on the inner face of the lower jaw (splenial) and along the side of the head from the quadrate forwards ("palatopterygoid" bone). By stage 37 all of the individual bones of the adult skull have developed. 1) I was unaware at the time of Gregory's paper of 1904, which renders my note in great part unnecessary. ?* 12 Normentafeln zur Entwicklungsgeschichte der Wirbeltiere, Tables. Lejridosiren Stage External features Segmentation cavity Invagination Archenteron Dorsal wall of archenteron External form 2 First meridional furrow. 3 Second meridional furrow. 4 First four vertical furrows. 7 Egg com- pletely seg- mented. Hardly any chinks between blasto- meres. 9 Late seg- mentation. Appears as a larger chink amongst the blastomeres. n Fully developed. Becomestraversed iDy spongework of macromeres about stage 12.) Continuous latitu- dinal groove which may reach 120" in length. 13 Practically obliter- ated. Reduced to a few chinks. Blastopore reduced in length : crescen- tic slit concave dorsally. 135 " in length. (In other specimens of same ex- ternal appearance 103 ", 105'', 106", 120", 140".) Inner end rounded with continuous cuticle. Composed of large-yolked cells. Roof cells large yolked agreeing in character with rest of endoderm, not with ectodenn. 14 Much shorter. Large yolk cells almost completely hidden. (Mesoderm split off firom endoderm except at outer edge: also separated by a split from the notochordal rudiment.) 16 Beginning to be enclosed by meduUary folds. (Mesoderm and notochord distinct.) i8 Branchial eminence appears. (Pronephric swelling appears 17.) Reduced to short slit-like opening. 225". 20 MeduUary folds have completely met. Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. 13 jKiratloxa. Metotic mesoderm segments Nervous System Eye Otocyst Visceral clefts Urogenital System Stage Mesoderm not yet segmented. Mesoderm segments (about 7) faintly dis- cernible with central coelomic cavity be- ginning to appear. About 12? Myocoeles present widely open. Deep layer of ectoderm of medullary plate decidedly thickened and beginning to be more than one cell thick. (Very slight longitudinal de- pression along centre of me- dullary plate. The latter has grown down into a distinct keel by multiplication of its deep layer cells in the region of the mesial plane.) Medullary folds distinct. Me- dullary keel well developed. Medullary folds have met along middle of trunk region. Neural rudiment still solid. Solid optic rudiment. Begins as down- growth of deep layer of ectoderm, 13 14 16 18 (3 solid rudi- ments [Agar].) Pronephric swelling oppo- site anterior segments. 20 14 Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. Stage External features Cement organ Metotic Segments Nervous System Eye Otocyst Nose 21 Optic rudi- Still solid. (Rudiment with in- (Rudiment ap- ments visible. dications of a splitiparent with ih- in its interior.) dications of * split.) 23 Head and tail Cement organ About 24. Central canal now Split dilated to (Split dilated to form definite folds becoming rudiment as (Sclerotome ap- extensive, dilated form definite ca- distinct. Bran- slight thicken- pears.) in rhombencepha- vity. cavity.) chial eminence ing of deep lon and extending becoming seg- layer of ecto- through about ''/j mented. derm. of the length of the neural rudi- ment. (24. Motor nerve trunks apparent as protoplasmic bridges.) 25 Tail fold be- Cement organ About 47. Transverse fold of Retina becoming Widely ex- Paired thick coming more clearly visible Inner wall of myo- brain floor appears thickened. (Lens panded thin- downsrowth of prominent than in a external tome of flattened in front of rhomb- thickening begins walled sac still: deep layer of head. External view crescentic cells stretching encephalon. to appear in ecto- connected by ectoderm with gill rudiments with longitu- throughout myo- (Nerve fibres ap- derm.) stalk with ecto- radiating ar- appear as knob- dinal groove. tome. (Sclerotome pear in spinal cord derm. rangement of like projections Superficialecto- spreading up inter- and motor trunks.) columnar cells: from visceral derm breaking nal to myotome.) (26. Hemisphere their inner ends arches UI-VI. down. rudiments as slight bulgings outwards of side walls of thalam- encephalon.) clear of yolk. Cavity repre- sented by traces of split. 27 Hatching. (First About 55. (Sheath mes- (Otocyst still Hatching. spontaneous Contractile fibres enchyme begins connected with movements in inner walls of to collect near ectoderm. about two days myotome. motor trunks. Ductus endo- previous.) Hemispheres present as lateral bulgings of wall of primary fore- brain.) lymphaticus be- ginning to sprout out.) 28 Hind part of About 59. Lens rudiment as Otocyst still Cavity as a Three trunk straigh- distinct thickening connected with slight split, closed. Super- day larva. tened out and of deep layer of ectoderm. growing ra- ectoderm. Retina Ductus endo- ficial layer of pidly. much thickened. lymphaticus as s ight pro- ectoderm con- tinuous over jection quite rudiment. separate from connection with ectoderm. Normal Plates of the Development of Lepidosiren paradoxa arid Protopterus annectens. 15 Hypophysis Enteron NotochorJ Visceral clefts Splanchno- coele Urogenital System Heart and Vessels Stage Foregut becoming folded off from rast of endoderm by j small Space devel oping beneath its anterior end. (Separated from endoderm, circular in transverse section , cells flat and plate-like. Primary sheath lias appeared.) (Ingrowth just cora- mencing.) Foregut well folded off from rest of endoderm. (Six solid cleft ru diments. Last two not yet completely fused with ecto derm.) Anus closed. Anus closed. Six solid cleft rudi ments. 21 (Pronephric tubules developing; pro- nephric Chambers not continuous; duct does not reach cloaca.) 23 Spacious pericardiac cavity, two halves fused except be hind. Pronephros with two funnels. Pronephric Chambers continuous. (Glomerulus still in two segmental pieces ) Archinephric ducts are open into cloaca. Heart rudiment with a few cor- puscles free in lumen. Vessels of external gills also apparent and with a few corpuscles. 25 Cleft rudiments solid. (Glomus no longer segmented.) Archi- nephric duct tortuous towards its front end. (Dorsal aorta, as solid heavily 3'olked rudiment.) Archinephric duct coiled in region of pronephros. Dorsal aorta with lumen and scat- tered corpuscles 27 28 i6 Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. Stage Length External features Chondral skeleton Bony skeleton Nervous System Integument Eye Otocyst Nose Hypo- physis Mouth 30 Ten day larva. 19 mm Growth of post- anal region coramencing. External gills becomingraised up ona common base. Mouth in- dicated by groove. 31 Thirteen day larva. (12-15 daj's.) 20 mm Median fin fold much increased in size. Appear ance of limbs andofopercular fold. Scattered chromatophores on dorsal side of head and an- terior trunk region. 32 Twenty four day larva. 24 mm Operculum growing back- wards. Cement organ pro- minent. Acti- vely functional. Chromato- phores scat- tered over whole dorsal surface. Hemispheres growing for- ward but not yet reaching an terior limit of forebrain. Posterior root ganglia devel oped. Rudiments of epidermal sense organs present. (Dermis be- ginning to appear.) Pineal rudiment and paraphysis developed. Hemispheres project beyond the limit of the primary fore- brain. Trabe- culae. Mandibu- lar and hyoid arches. Para- sphenoid Lens still solid thickening of deep layer of ectoderm. Slight traces of pigment ap- pearing in po- sterior wall of optic cup. Endo- lymphatic outgrowth has ap- peared mediodor- sally. Oto- cyst has lost its con- nexion with ectoderm Pigment present in hind wall of optic cup. Lens detached from ectoderm. Hind wall thickened. Chromato- phores in ectoderm. Rods not yet developed. Narrow ca- vity has de- veloped. With distinct lumen. Curves round tip of in- fundi- bulum. Cavity well marked dC' finite closed. Dimple vis' ible on ex' ternal sur- face. Outer cells of solid buc- cal rudiment begin totake on an ecto- derm-like character. Slit-like aperture along ven- tral side of olfactory organ. Solid. Faint indications of tooth germs. Lumina in buccal rudi- ment but not continuous. Tooth germs well devel- oped. (Ap- pearance of enamel cap.) Normal Platcs of the Development of Lepidosiren paradoxa and Protopterus annectens. 17 Digestive tract and liver Pancreas Visceral clefts Thyroid Post- branchial l)odies Lung Urogenital System Haart and vessels Myotomes Splanchno- coele Stage Gut rudiment solid except in neigh- bourhood of open ings of archineph- nc ducts. Anus closed. Liver rudi ment split off from main mass of yolk. Postanal gut he- Coming reduced Liver distinguished from main yolk by fine grained yolk Traversed by rieh network of blood vessels. (Gut lumen only in cloacal region.) Postanal gut dis' appeared. Buccal lumen de veloped but not yet open to exterior. Extends back into pharynx but not to glottis. In midgut lumen between pylorus and liver, then solid nearly to cloacal region. Small lumen roun- ded in section and varying in thick- ness developed for Short distance in front of cloaca. Spiral groove developed slightly at hina end. Shai- low dorsal Valley along midgut in which the lungs lie Solid. In form of solid projec- tion of pharyn- geal floor. Attachment of pro- nephric glomerulus now medio-dorsal. (Mesonephric tubule ruaiments make their appea- rance.) Heart a simple curved tube: contractile fi- brils in mj'ocar- dium. Dorsal aortadilatedbut not yet quite circular in sec tion. (29+. Six aortic arches devel oped.) (Eye muscles in- dicated by conden- sations of mes- enchyme. Agar.) Solid. Solid, still con nected by narrow neckwith buccal rudiment in front of root of tongue- (Yolky rudiment on left side pro- jecting forwards from side of pha- ryngeal floor ven tral to aortic arches VI and V.) Rudi- ment solid in front : with split like ca- vity be- hind : bicuspid posterior ly; left pointpro- jecting farther back than right. Yolky pro jection from dorsal side of gut rudi- ment to left of midline and just be- hindopening of foregut into midgut. Wide cavity which opens into gut lumen. No clefts perforate. Cleft II almost perforate. Yolky rudiment on left side. Iso- lated from Pha- rynx. Blood vessels begin- ning to penetrate Lumen appearinj as split in some mesonephric tubule rudiments. Most still solid. Some becoming fused with archinephric duct at outer end, Anterior end of archinephric duct and pronephric tubules much distended. (31 +, Agar. Pro- nephrocoeles open to pericardium by pericardio-peri- toneal ducts : about 26 tubule rudi- ments.) Blood red. (Mandibular and hyoidean aortic arches reduced.) 31 +. Posterior cardinals be- ginning to fuse Lung rudiment well de- veloped withwide lumen reaching to glottis double except at its Iront end. Two pronephro stomes: archi- nephric duct much dilated in front. (Secondary pro- nephric Chamber open behind into splanchnocoele.) Some mesonephric tubules have devel oped a lumen, open into archinephric duct at one end and are slightly dilated at the other to form the rudi- ment of the Mal- pighian body. Outer wall be- ginning to thicken and to develop con- tractilefibrils. Inner wall myoblasts converted almost entirely into fibrils. Mesenchyme be- ginning to wander in between myo- tomes. (Lateral plates not yet met in trunk: split in anterior Segments. Cavity con- tinued as pericardio- peritoneal ducts into pericardium. Agar.) Heart still tubu- lär. (Rieh vitelline network cover- ing ventral and lateral a.spects of gut. Drains anteriorly into large irregulär subintestinal vein which passes into liver. Right anterior Cardinal in front much larger than left.) (31 + Pro- 31 nephric Chamber open to peri- cardium by pericardio- peritoneal ducts. Ven- tral com- munication between pericardium and main splanchno- coele in ad- dition to pericardio- peritoneal ducts. Agar.) Normentafeln zur Entwicklungsgeschichto der Wirbeltiere. X. i8 Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. Stage Length External features Chondral skeleton Bony skeleton Nervous System Integument Eye Otocyst Nose Hypo- physis Pineal body Mouth 34 30 mm. Darklycoloured Floor and side "Palatoptery- Para- Ectoderm Lens Ductus endo- Lips of Open. Twenty seven except ventral wallsof cranium goid" extending physis be- still mostly nearly lymphaticus nasal open- side of trunk cartilaginous. back to Quad- coming two-layered fills cup : with swoUen ing have day larva. which is still Lower jaw, rate. Splenial reduced. except in small end in con- fused except without pig- hyoid, occipital present on Sheath of head region. amount tact with ,at ends so as ment. Cement arch and rib also inner side of motor of mes- hindbrain to separate Organ about cartilaginous. Meckel's carti-l trunks enchyme. roof later- anterior and maximum. Skeleton offore- limb marked out by conden- sation of nuclei. läge. Pectoral girdle commen- cing to be ensheathed in bone. much attenu- ated. ally. Semi- circular ca- nals formed. Thickened maculae in floor. posterior nares. Ex- ternal diver- ticulum pre- sent. 35 ca. 36 mm. External gills at (Arcualia pre- Hyoid Commen- (Commen- Rods Thirty day larva. maximum de- sent.) Chorda ensheathed in cing in- cing devel- develop- velopment. cells becoming bone. growth of opment of ing. Cement organ vacuolar. lateral unicellular much reduced. plexus glands.) Pelvic limbs into ven- much increased tricle. in length. 36 ca. 41 mm. Metamorphosis. Olfactory cap- Fronto- Ductus endo- Forty Pigment advan- sule cartilag- parietalia lymphaticus day larva. ces to ventral inous. Secon- not yet devel- with end side. Atrophy dary sheath of oped. divided into of external gills. notochord be- lobes. Pigment much coming coloni- denser. zed by Im- migrant cells from arcualia. Neural spines develo- ped, continuous anteriorly with arcualia. Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. 19 Teeth Teeth calcified. Bony trabe- ciilae at their bases. Digestive tract and liver Pancreas Well devel- oped but still CO' vered by buccal epithe- lium. Projec- ting into buccal cavitybut covered by epi- thelial sheath. Oesophagus solid behind glottis. Pharynx with lumen in middle (but solid laterally) reaching back to widel)' open glottis. Lumen rounded in region of stomach — extending into midgut for short distance. Solid back to near cloacal region. Pharynx with wide lumen though still unsplit at edge. Oesophagus with small discontin- uous lamina. In stomach large con- tinuous lumen opening into wide irregulär lumen of midgut which Stretches back for some distance but not yet continuous with cloacal cavity. Intestine deeply incised by spiral ingrowth of mes- enchyme. Liver greatly in- creased in size extending back dorsal to gut on right side. Gall bladder showing on surface ven- trally. Liver and stomach have been rotated so that liver lies now to the right of the stomach which is con- sequently visible from the ventral side. Liver growing rapidly backwards. Oesophageal lumen still dis- continuous. Ventral rudi- ments present. Pancreas much lobedand tubulär in places. In some parts the cellshave assumed the defi- nitive character of pan creas cells and are func- tional. Visceral clefts II widely open. III closed still by thin mem brane. IV, V, VI solid. Inter- pene- trated by intrusive connec- tive tissue with blood vessels. Clefts II, III IV, V, VI open, VI by very nar- row chink Clefts II— VI open. (In other spe- cimens of this stage II is becoming closed.) Thyroid Highly vascular follicles, well devel- oped. Post- branchial bodies Isolated. Nearly free from yolk. Pene- trated by blood vessels. Thymus Thymus bud of cleft III devel- oped. Glottis open, Thymus bud in- creased in size. (Rudi- ment on cleft II. Bryce.) Yolk gone. Pene- trated by blood vessels. Main thymus bud divi- ded into lobes. Bud also present from cleft IV. Lung Functional Extends back about '/j distance from glottis to cloaca. Walls thin and mem- branous and widely di- lated except close to hind end where growing actively. Urogenital System Three pro- nephrostomes on right; two on left. (Normally two on each side.) Heart and vessels Pronephro- stomes still open. Meso- nephric tubules much elongated forming com- pact gland. Glomeruli fully developed. Archinephric ducts opening into cloaca in- dependently on each side. Reaches back as far ashinderend of Spiral part of gut. Pronephros very degenerate and shrunken. Pronephric Chambers re- duced to small anteriorly pro- jecting diverti- cula of splanchnocoele, on the walls of which traces of the degenerate nephrostomes are still visible. Archinephric ducts unite posteriorly and common por- tion is dilated bulging slightly forwards as rudiment of cloacal caecum. Ventri- cular sponge- work present. Myo- tomes Outer wall thick, many layers of muscle cylinders. Splancfano- cocle Ventral com- muni- cation between pericar- diac coe- lom and main splanch- nocoele. Pericar- liac coC' lom shut off from main splanch- nocoele. Stage 34 35 36 3* 20 Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. Frotojtterus Stage VII IX XI XIII XIV XVI XVIII XX XXI XXIII External features Completely segmen- ted. Advanced segmen- tation. Segmentation cavity Chinks between blastomeres. Large segmen- tation cavity with thin 2- layered roof. At its maxi- mum. Almost obliter- ated reduced to chinks be- tween blasto- meres. Invagination Faint swellings in position of external giUs and pronephros. Medullary folds fused. Pronephric swelling more elongated. Optic outgrowths indicated by slight bulging of surface. Head region pro- jecting more distinctly above general surface. Branchial eminence becoming segmented Tip of head projecting markedly: tail end beginning to project. T-shaped pronephros with duct slightly cur- ved. Duct does not yet reach hind end? Long longitu- dinal groove. Slightly con- cave towards dorsal side. Patch of macro meres still ex- posed. Short crescentic blastopore. Macromeres completely covered in. Blastopore short latitudinal slit. Archenteron Shallow slit just begin ning to bend dorsalwards at its inner end. Rounded at its inner end. 165" (in other specimens of same stage down to 65"). 135" 255" Dorsal wall of archenteron Cement Organ Metotic mesoderm Segments 290° Mesoderm rudi- ment on each side marked off by its more rounded cells from the more compact enteric roof and noto- chordal rudi- ment. Notochord not yet split off from endoderm. About seven. Nervous System Rudiment present as slight ticke- ning of deep layerofecto- derm. About 10. Anterior 2 with widely open myo- coeles. About 17. Myocoeles developed anteriorly. 24. Inner wall cells flat- tened, plat- like. (Deep layer of ectoderm columnar in medullary plate region.) Medullary folds make their appear- ance. Me- dullary keel well devel- oped. Thick solid rudiment of brain and spinal cord. Medullary folds have met except posteriorly where they diverge to Surround blastopore. Solid. Lumen defi- nite in spinal cord and narrow split forming in brain. Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. 21 annectens. Eye Otocyst Enteron Notochord Visceral cleft Splanchno- coele Urogenital System Stage 1 VII IX XI XUI XIV XVI ' xvm (Slight solid projection.) Downgrowth of deep layer of ectoderm. XX Optic rudiment solid. Stretches through 305°. Notochord cells be- coming flattened. Faint indication of primary sheath. Chorda still con- tinuous with endo- derm anteriorly. XXI Optic rudiment with narrow lumen. Inner wall very slight- ly thickened. Otocyst with definite roun- ded cavity sur- rounded by thick wall. Foregut begin- ning to be mar- ked off by de- velopment of a small Space ven- tral to it. Chorda cells flat- tened platelike. Three solid rudiments of clefts I-III; common rudi- ment of IV, V and VI. Paired pericar- diac cavities present. Solid proneph- ric rudiment with two tubu- les. Nephro- coele beginning to form opposite first tubule. XXIII 22 Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. Stage Length External features Cement organ Metotic Segments Chondral skeleton Nervous System. Integument Eye Otocyst Nose XXV Head and tail Present as About 29. Cavity of Anterior Otocystwith Slight thicken- folds projecting thickening Myocoeles central ner- (retinal) wall widedefinite ing of deep markedly so as of deep patent. Myo- vous System of rudiment cavity. layer of ecto- nearly to meet. layer of blasts flat developed. slightly derm. Anus hidden by ectoderm : yolky cells Primary fore thickened. tail fold. superficial stretching brain mar- Cement organ layer gone whole length ked off. visible as long from surface of myotome. crescenticstruc- over gland. ture. XXVII Larva tadpole- 38. Brain sUght- Retina much Still con- Solid ingrowth Hatching. shaped with hind part of ly more ad- thickened tinuous with of deep layer vanced than not involu- ectoderm by of ectoderm. trunk flexed fig. B (stage 28)inLepido- ted. (Lens narrow isth- ventrally. Ex- not yet appa- mus. (In ternal gills pro- siren Gra- rent.) other speci- ecting marked- ham Kerr, mens of this y. Dorsal ridge 1901 d. stage the of body con- ductus endo- taining myo- Ij'mphaticus tomes much is visible as more pro- a small out- minent. growth from otocyst dor- sally.) XXVIII Hind end of Lens rudi- Otocyst still Olfactory rudi- During first day of larval body nearly ment as in contact ment as much straight. Pinnae yolky thicke- with ecto- thickened deep of external gill ning of deep derm. layer of ecto- life. appearing as double series of small knobs on their external side. layer of ecto- derm. Retina cells long co- lumnar, free from yolk at their ends towardslens. derm: distal ends of colum- nar cells be- coming free from yolk. Superficial layer of ecto- derm still con- tinuous over rudiment. XXIX A little Median fin fold Hemi- Ectoderm Lens yolky Otocyst still Thickening of About over more devel- spheres not two-layered. thickening in contact deep layer of end of 9 mm. oped. No vet reaching level of an- of deep layer with ecto- ectoderm. first day larval appreciable in- of ectoderm. derm. Duc- Distal ends of crease of post- terior limit Inner ends tus endo- cells becoming life. anal region. of primary fore brain. of retinal cells begin- ning to be freed from yolk. lymphaticus as wide out- growth from mediodorsal wall much posterior to point where in contact with ecto- derm. free from yolk. Superficial layer of ecto- derm still con- tinuous over olfactor}' rudi- ments. XXXI II mm. Pinnae of ex- Notochord Hemi- Ectoderm Lens with Isolated Open to ex- Two day ternal gills elon- with thin spheres have two-layered. rounded from skin. terior. Super- larva. gated. Postanal primary nearly reached level Ulmen. In- ficial ectoderm region in- sheath. trusive mes- broken down creasing in of anterior enchyme in over opening. length. limit of pri- mary fore brain. Para- physis pre- sent. Hind brain roof thin and mem- branous. optic cup. Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. 23 Hypo- physis Enteron Noto- chord Moutli Digestive tract and Liver Visceral cleft Lung Urogenital System Heart and Vessels Mye- lomes Splanchno- coele Stage Foregut Noto- Cleft rudi- Two tubules First trace of heart Pericardiac XXV longer chord ments pre- and duct with visible asinvoluted cavities owing to ex- of flat sent but not distinct lumen. thickcning of ven- fused. tension back yolky easily distin- tral walls of peri- lieneath it of cells. Pri- guishable cardium contain- pericardium. ma ry from inter- ing rudiment of 1 sheatli vening mes- endocardium. distinct. enchyme. Simple Anus open. Six solid Two pronephric Main vessels laid XXVII wedge- Pharynx so- rudiments. tubules. (In one down also network shaped. lid. Lumen from this back. Di- lated behind case 3 tubules opposite Seg- ments 2, 3 and 4. Duct showing beginning of of vessels devel- oped in parts on surface with distinct flattened pericardium. endothelium. Large coilinganterior- masses of spherical ly. Lumen ex- cells on surface of tends to cloaca.) yolk-young corpus- cles spherical and füll of yolk. Dorsal aorta dilated in places but cavity not continuous. Becom- Pharynx so- Cleft rudi- (Anterior end of Dorsal aorta di- xxvm ing con- lid. Small ments solid. archinephric lated with fluid but stricted lumen back duct elongating very few corpus- oflf. from this. Anus open. and becoming coiled. Two tubules forming T-piece.) cles in it. At tip of Gut solid ex- Still solid. Anterior end Dorsal aorta with Contrac- Cavity of XXIX infundi- cept be- of duct be- wide lumen cir- tile fibrüs pericardium bulum : tween coming coiled. cular in section. along extendsback solid. cloacal opening and opening of archinephric ducts. Post- anal gut large solid. Glomus at- tached to floor of pronephric Chamber to- wards its mesial side. Heart S-shaped tube bifurcating at each end. " dorsal and ven- tral sur- faces of myo- blasts. for some distance on each side (pericardio- peritoneal ducts). Lateral plate unsplit in trunk. Buccal Ahmen tary Cleft rudi- Not yet Two nephro- Corpuscles laden Contrac- Pronephric XXXI rudiment canal solid ment still apparent. stomes. with yolk. tile fibrils Chamber still solid. except in cloacal region, with traces of cavity here and there elsewhere. solid. Rudiments of mesonephric tubules. have appeared in myo- blasts. continuous with peri- cardium by pericardio- peritoneal ducts. 24 Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. Stage Length Externa! features Chondral skeleton Bony skeleton Nervous System Integu- ment Eye Otocyst Nose Hypo- physis Pineal body Mouth XXXII Four day larva. 14 mm. XXXIV 7 day larva. 16 mm. XXXV 9 day larva. 19 mm. XXXVI Cloacal opening lateral. Postanal region much elongated. Median fin fold ditto. First rudi- ments of limbs visible in externa! Front part of trunk shrinking re- latively. Limbs now project free- ly. Oper- cular fold distinct. Anterior part of trunk now only slightly bul- ging. Pec- tora! linib extends back beyond ex- terna! gills. Bulging of anterior part of trunk region has disappeared. Cement Or- gan has dis- appeared. Limbs and tail long and slender. Median fin fold very prominent. Limb axis marked out by nuclear conden- sation. Mandibular and hyoid arch, pec- tora! girdle, baseof skull, auditory cap- sule. Occipita! arch in con- tact dorsally with audi- tory capsule. Branchia! arches l — 4 present. Neural spines con- tinuous vyith arches. Secondary sheath of notochord not yet in- vaded by cartilage cells. Herai- spheres pro- ject for- wards beyond level of anterior end of pri- mary fore brain. Pineal organ developed. (Chromato- phores present on dorsal side of head.) Hind wall of lens vesicle much thicke- ned. Pig- ment present in pigment layer of re- tina. Mes- enchyme in optic cup highly vascular. Canals be- ginning to bulge. Macu- lar thicke- nings ap- pearing. (Rods developing in centre of retina.) Bony trabe- culae at tooth bases spreading along jaws and in region of para- splenoid. Commen- cing in- growth of lateral plexus into ventricles of hemi- spheres. Thin para- sphenoid la- mella. Palato- pterygoid. Bone ensheathing hyoid occi- pita! rib and on inner side of Meckel's cartilage. Also on ven- tral face of lower end of pectora! girdle. Flask gland rudiments. Chromato- phores. Rods developed. Endo- lymphatic ducts pass dorsalwards towards midline over hind brain roof. Out- growths fore- shadowedby slight bul- gings ? Canals for- med. Endo- lymphatic ducts reach dorsal mid- line and Short out- growths are developed on them. Slit-like opening. Externa! diver- ticulum present. Wide lumen. (Isolated : lying postero- dorsal to hyoid arch.) Solid. Tooth germs apparent. Lumen devel- oped back into pharynx but not free- ly open to ex- terior al- though slight süt present. Lip fold pro- jects down on each side enclosing ex- terna! naris. Lower jaw beginning to grow for- wards. Free!}' open. Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. 25 Teeth Digestive tract and Pancreas Visceral clefts Thyroid Post- branchial bodies Thymus Lung Urogenital System Heart and vessels Myo- tomes Splanchno- coele Stage Endoderm solid ex- cept in region of cloaca. Liver rudi- mentgrow- ing for- wards be- neath peri- cardium. Tooth gernis with cal- careous matter. Liver rudi- ment with fine yolk. Round yolky projection containing small lumen in its centre. Attached to gut dorsally by narrow stalk at level of hinder pro- nephrostome to left of me- sial plane and projecting to- wards right. Dorsal pan- creatic rudi- ment with thick yolky wall and large definite cavity. Ventral rudi- ments solid. All solid. Solid yolky rudi- ment. Heavily yol- ked solid rudiment arising from floor of pharynx, stretching from root of cleft VI for- wards to cleft V on left side. Solid. (Connec- tion with pharynx reduced to slender cord or broken through.) Bodies of teeth well devel- oped. Pharyn- geal lumen not yet contmuous in front of glottis. Be- hind glottis for some distance nearly so- lid. Liver with rieh vascular network. Wide bile duct. Pancreas compact penetrated by vascu- lar network, undergoing histological differentiation Three rudi- ments fused together. Cleft I solid except for PiNKUS' organ. Re moved from skin. Still in connection with pharynx. II and III open, IV nearly perforate; V and VI solid. Isolated, vascular. Still solid, yolky, con- nected with pharynx bya narrow neck. Projects for- wards and downwards from is attachment, in contact with hind wallofaortic arch VI. No longer yolky. Pene- trated by blood vessels. Buds pre- sent at dorsal ends of clefts II and (lar- ger) ni. Rounded projection from mid ventral sur- face of pharynx Stretches back along- side oeso- phageal rudiment: small closed cavity for- med by cyto- lysis in centre. No bilobing. Wide lumen but no glot- tis pharynx being solid at this level. (Lung rudi- ment distinctly bi- lobed, ex tendingback short distance be- hind pO' sterior nephro- stome.) Glottis open Lungs with thin vascular wallsextend ing back nearly half the distance from glottis to cloaca Meson ephric ments. rudi- (Archinephric ducts much coiled anteriorly. About 12 mesonephric rudiments.) Vitelline network of vessels over sur- face of yolk. (Right posterior cardinal 1 arger than left in front. Right and len con- nected by cross Channels.) (Right posterior Cardinal larger and ana- stomo- sing with left.) Pronephric cham- ber posterior to main mass of pro- nephriccoils. Much connective tissue between coils: also in glomerulus. Nephrostomes still open with flagella though walls de- generating. An- terior nephrostome opens mto pro- nephric Chamber at extreme front end. Posterior back near hind end of glome- rulus. (Archi- nephric ducts unite close to opening into cloaca.) Myo- tomes have not yet met ventrally in trunk Teeth project into buc cal cavity but are covered by epi- thelial sheath. II— V per- forate (IV barely per- forate). Illverywide. PiNKUs' Or- gan isolated from pharynx. Thyroid isolated secreting. Open sponge work with blood vessels in meshes. Pancreas much larger lying in dorsal groove of gut Forms mass of branched sec- retory tubes with fine lumen, separ- ated by con- spicuous con- nective tissue containing blood vessels, Normentafeln zur Kntwicklungsgeschichte der Wirbeltiere. X. Bud from cleft II small. That of UI much enlarged. Extend back rather more than half way to cloaca. Peri- cardiac coelom isolated from main splanch- nocoele and from pro- nephric Chamber. XXXII XXXIV Peri- cardiac coelom isolated from main splanch- nocoele and from pro- nephric Chamber. XXXV XXXVI 25 Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. Conclusion. In comparing together the Normentafeln of the three Dipnoi it will be seen at once how the close affinity between Lepidosiren and Protopterus is brought out clearly in their developmental features. Their whole course of development — segmentation, gastrulation, the modelling of the body of the embryo, the characters of the larvae with their external gills and cement organ, and the internal details of development so far as known — alike attest the naturalness of the group Dipneumona. Just as striking are the differences which mark off the developmental phenomena of Lepidosiren and Protopterus from those of Ceratodus. In the latter the segmentation departs less from the equal holoblastic type, the external features of gastrulation approach more near to those of the typical amphibian, and striking differences are to be seen in the early larval stages. There is an absence of the tadpole shaped stage so characteristic of Lepidosiren and Protopterus due to the fact that the yolk is in Ceratodus distributed more equally along the length of the midgut rudiment. And with the absence of concentration of the yolk towards the headward end of the midgut it is seen that the whole head region in Ceratodus proceeds more rapidly in its development, while in Protopterus and Lepidosiren it is caused to lag behind in comparison. Apart from such general differences, the numerous differences in details of structure are enough to make it piain that a deep cleft separates the monopneumona from the dipneumona although in my opinion there still exists aniple reason for retaining them as subdivisions of a single group. Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. 27 List of Papers dealing with the Morphology of the Dipnoi published during the years 1900—1909. For the sake of convenience I have endeavoured to include in the following list all papers (excluding mere Referats) dealing with the Ontogeny of the Dipnoi even though included in Semon's Bibliography. In compiling the list I have had the valuable assistance of Dr. R. H. Traquair F. R. S. who has most kindly furnished the necessary palaeontological references and to whom I have much pleasure in offering my acknowledgments and grateful thanks. 1906a Agar, W. E., The development of the Skull and Visceral arches in Lepidosiren and Protopterus. Trans. R. See. Edinb., XLV, p. 49—64. 1906b Agar, W. E., The spiracular gill cleft in Lepidosiren and Frotopterus. Anat. Anzeiger, XXVIII, p. 298 — 304. 1907 Agar, W. E., The development of the anterior mesoderm and paired fins with their nerves in Lepidosiren and Frotopterus. Trans, ß. Soc. Edinb., XLV, p. 611—639. 1908 Agar, W. E., On the appearance of Vascular Filaments on the Pectoral Fin of Lepidosiren paradoxa. Anat. Anzeiger, XXXIII, p. 27—30. 1904 Bing, R., and Bueckiiardt, R., Das Zentralnervensystem von Ceratodus forsteri. Anat. Anzeiger, XXV, p. 588 — 599. 1905 Bing, R., and Burckhardt, R., Das Zentralnervensystem von Ceratodus forsteri. Semon's Zoologische Forschungs- reisen, I, p. 509 — 660. 19()3 Blunt.schli, H., Eisenhämatoxylin- und BiONDi-Präparate der Leber von Ceratodus forsteri und Acipenser ruthenus. Verh. anat. Ges., XVII, p. 198, 199. 1904 Bluntschli, H., Der feinere Bau der Leber von Ceratodus forsteri, zugleich ein Beitrag zur vergleichenden Histologie der Fischleber. Semon's Zoologische Forschungsreisen, I, p. 333 — 375. 1900a BouLENGBR, G. A., Exhibition of one of the type specimens of a new species of Frotopterus from the Congo. Proc. Zool. Soc. London, 1900, p. 775. 1900b BouLENGER, G. A., Blateriaux pour la Faune du Congo. {Frotopterus dolloi.) Ann. Mus. Congo, Ser. 1, Zool., I, p. 129—164. 1901 BouLBNGER, G. A., On a small Collection of Fishes from Lake Victoria made by order of Sir H. H. Johnston, K. C. B. Proc. Zool. Soc. London, 1901, II, p. 158. 1902 BouLENGEE, G. A., Second Account of the Fishes collected by Dr. W. J. An.sorgb in the Niger Delta. Proc. Zool. Soc. London, 1902, II, p. 325. 1901 Braus, H., Die Muskeln und Nerven der Ceratodus-V\osse. Semon's Zoologische Forschungsreisen, I, p. 139—300. 1904 Braus, H., Tatsächliches aus der Entwicklung des Extremitätenskelettes bei den niedersten Formen. Zugleich ein Beitrag zur Entwicklungsgeschichte des Skelettes der Pinnae und der Visceralbogen. Haeckel's Fest- schrift, p. 377—435. 1904 Bridge, T. W., "Fishes" in "Cambridge Natural History", VII, p. 139—537. 1900 Brindley, H. H., Note on some Abnormalities of the Limbs and Tail of Dipnoan Fishes. Proc. Camb. Phil. Soc, X, p. 325—327. 1905 Broman, L, Ueber die Entwicklung der Mesenterien, der Leberligamente und der Leberform bei den Lungfischen. Semon's Zoologische Forschungsreisen, I, p. 585 — 640. 1903 Bryce, T. H., The dividing Cells of tlie Embryo of Lepidosiren. Journ. Anat. PhysioL, XXXVIII, p. 70. 1904 Bryce, T. H., The Histology of the Blood of the Larva of Lepidosiren paradoxa. Pt. I. Structure of the Resting and Dividing Corpuscles. Trans. R. Soc. Edinb., XLI, p. 291 — 310. 2g Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. 19(J5 Beyce T. H., The Histology of the Blood of the Larva of Lepidosiren paradoxa. Pt. II. Haematogenesis. Trans. R. Sog. Edinb., XLI, p. 435—467. (Ab.str. Laucet, CLXVII, p. 406.j 1905 Bryce, T. H., Note on the developmeut of the Thymus gland in Lepidosiren paradoxa. Journ. Anat. Physiol., XL, p. 91—99. 19Ul BuDGETT, J. S., On the Breeding Habits of some West Afncan Fishes, with an Account of the Exteriial Features in the Development of Protopterus annectens and a Description of the Larva of Polypterus lapradei. Trans. Zool. Soc. London, XVI, p. 115 — 136. (Abstr. in Zool. Centralbl., IX, p. 93—95.) 1905 BcECKHAEDT, E., Das Zentralnervensystem von Cerntodus forsteri. C. R. Congr. Internat. Zool. Berne, p. 314 — 315. 1901 Dean, Bashford, Palaeontological Notes. Mem. New York Acad. Sei., II, p. 87 — 123. 1903 Dean, Bashfoed, Obituary Notice of a Lung-Fish. Populär Science Monthly, p. 33 — 39. 1904 Dean, Bashfoed, Still another Memoir on P.alaeospondylus. Science, (2) XIX, p. 425, 426. 1906 Dean, Ba.shfoed, Notes on the living speeimens of tbe Australian Lung-Fish, Ceratodus forsteri, in the Zoological Society's Collection. Proc. Zool. Soc. London, 1906, I, p. 168—178. 1907 Dean, Bashford, Dr. Eastman's Recent Papers on the Kinship of Arthrodires. Science, (2) XXVI, p. 46 — 50. 1908 Dean, Bashford, Studies on Fosisil Fishes during the year 1907. Science, (2) XXVII, p. 201 — 205. 1909 Dean, Bashford, Studies on Fossil Fishes (Sharks, Chimaeroids and Arthrodires). Mem. Aij.er. Mus. Nat. Hist., IX, p. 5. 1906 DoLLO, L., Sur quelques points d'ethologie paleontologiques relatifs aux Poissons. Bull. Soc. beige de Geologie, de Paleontologie et d'Hydrologie (Bruxelles), XX. 1907 DoLLO, L., "Les Ptychodontes sont des Arthrodires". Bull. Soc. beige de Geologie, de Paleontologie et d'Hydro- logie (Bruxelles), XXI. 1901 Eastman, C. R., Review of Bashford Dean's "Palaeontological Notes". Amer. Naturalist, XXXV, p. 418 — 420. 1902 Eastman, C. R., Some hitherto unpublished observations of Orestes St. John on Palaeozoic Fishes. Amer. Naturalist, XXXVI, No. 428. 1903 Eastman, C. R., Carboniferous Fishes from the Central Western States. Bull. Mus. Comp. Zool. Harvard, XXXIX, p. 188. 1904 Eastman, C. R., A peculiar modification amougst Permian Dipnoans. Amer. Naturalist, XXXVII, p. 493 — 495. 1906a Eastman, C. R., Structure and Relations of Mylostoma. Bull. Mus. Comp. Zool. Harvard, L, p. 1—30. 1906b Eastman, C. R., Dipnoan Affinities of Arthrodires. Amer. Journ. Science, (4) XXI, p. 131 — 143. 1907a Eastman, C. R, Mylostomid Dentition. Bull. Mus. Comp. Zool. Harvard, L, p. 211 — 228. 1907b Eastman, C. R., The Devonic Fishes of the New York Formation. New York State Education Department, N. Y. State Museum, Albany. 1908 Eastman, C. R., The Devoniau Fishes of Iowa. Iowa Geol. Survey, XVIII, p. 29 — 344. 1906 Etheeidge, R., The Cranial Buckler of a Dipnoan Fish, probably Ganorhynclius, from the Devoniau Beds of the Murrumbidgee River, New South Wales. Rec. Austral. Mus., VI, p. 129 — 132. 1904 Fraas, E., Ceratodus priscus E. Fraas aus dem Hauptbuntsandstein. Ber. Oberrhein. Geol. Ver., XXXVII, p. 30 — 32. 1904a Füebringer, K., Beiträge zur Morphologie des Skelettes der Dipnoer, uebst Bemerkungen über Pleuracanthiden, Holocephalen und Squaliden. Semon's Zoologische Forschungsreisen, I, p. 423 — 510. 1904b Fürbeingee, K., Notiz über einige Beobachtungen am Dipnoerkopf. Anat. Anzeiger, XXIV, p. 405 — 408. 1906 Giacomini, Ercolb, Sulle capsule surrenali e sul simpatico dei Dipnoi. Ricerche in Protopterus annectens. Note prelim. Rend. Accad. Lincei (5), XV, 1. sem., p. 394—398. 1904 Goeppert, E., Der Kehlkopf von Protopterus annectens (Owen). Anatomische Untersuchung. Haeckel's Fest- schrift, p. 115 — 132. 1903 Goodrich, E. S., On the Dermal Fin-rays of Fishes. Quart. Journ. Micr. Sei., XLVII, p. 465 — 522. 1907 Goodrich, E. S., On the Scales of Fish, Living and Extinct, and their Imjjortance in Classification. Proc. Zool. Soc. London, p. 751 — 774. 1909 Goodrich, E. S., Vertebrata Craniata (First Fascicle, Cyclostomes and Fishes) in "Treatise on Zoology", edited b}' Sir Ray Lankbster, K. C. B., London. 1904 Gregory, E. H., The Relations of the Anterior Visceral Arches to the Cranium. Biol. Bulletin, VII, p. 55 — 69. 1905 Gregory, E. H., Die Entwicklung der Kopf höhlen uud des Kopfmesoderms bei Ceratodus forsteri. Semon's Zoologische Forschungsreisen, I, p. 640, 661. 1906 GiiEiL, A., Ueber die Entstehung der Kiemenderivate von Ceratodus. Anat. Anzeiger, Erg.-Heft, p. 115 — 131. 1908 Greil, A., Entwicklungsgeschichte des Kopfes und des Blutgefäßs5'stems von Ceratodus forsteri. Erster Teil. Gesamtentwicklung bis zum Beginn der Blutzirkulation. Semon's Zoologische Forschungsreisen, I ,p. 661 — 934: 1901 Halkett, A., An African Dipnoid Fish (Protopterus annectens). Ottawa Naturalist, XIV, p. 184—187. 1904 Haug, E., Sur le Faune de couches t\ Ceratodus du Djoua, pres Timassänine (Sahara). C. R. Acad. Science, CXXXVIII, p. 1.529-1531. Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. 20 l'JOi Hosen, Das Sehorgan von Frotoptenis annectens. Arch. miki-. Anat., LXIV, p. 99 — 110. 1900 V. HuBNK, F., Rhynchotus emiyratus v. Huenb. Centralbl. f. Mineral., p. 178. 19()5a HussAKoi'', L., Notes on the Devonian Placoderm Dinichthys intermedius Nkwis. Bull. Amer. Mus. Nat. Hist., XXI, Art. IV, p. 27—36. 19()öb HüsSAKOK, L., On the structui-e of two impeil'ectl}' knovvn DinicLthyids. Bull. Amer. Mus. Nat. Hist. XXI Art. XXV, p. 409—418. 1906 HussAKOP, L., Studies on the Arthrodira. Mem. Amer. Mus. Nat. Hist., IX, p. 103 — 154. 1908a HiissAKoF, L., Catalogue of the Type and Pigured Speciinens of Fossil Vertebrata in the American Museum of Natural History. Part I. Fishes. Bull. Amer. Mus. Nat. Hist., June 1908. 190Sb HüssAKOF, L., Review of Eastman's "Devonic Fishes of the New York Formations". Science, (2) XXVIII, p. 311—313. 1909 HussAKOF, L., The Systematic Relationship of certain American Arthrodires. Bull. Amer. Mus. Nat. Hist. XXVI, Art. XX, p. 263-272. 1902 Jabkel, 0., Ueber Coccosteus und die Beurteilung der Placodermen. Sitzungsber. Gesellsch. naturf. Freunde Berlin, p. 103—105. 1903a Jaekel, O., Ueber die Organisation und systematische Stellung der Asterolepideu. Zeitschr. deutsch, geolog. Gesellsch., Mai-Protokoll, LV, p. 41 — 60. 1903b Jaekel, 0., Ueber die Epiphyse und Hypophyse. Sitzungsber. Gesellsch. naturf. Freunde Berlin, p. 27 — 58. 1904 Jaekel, 0., Neue Wirbeltierfunde im Oberdevon von Wildungen. September -Protokoll der deutschen geol. Gesellsch., LVI, p. 159—164. 1906a Jaekel, 0., Ueber die Mundbildung der Wirbeltiere. Sitzungsber. Gesellsch. naturf. Freunde Berlin, p. 7 — 32. 1906b Jaekel, 0., Einige Beiträge zur Morphologie der ältesten Wirbeltiere. Sitzungsber. Gesellsch. naturf. Freunde Berlin, p. 180, 189. 1906c Jaekel, 0., Neue Wirbeltierfunde aus dem Devon von Wildungen. Sitzungsber. Gesellsch. naturf. Freunde Berlin, p. 73—85. 1907 Jaekel, 0., Ueber Phoüdosteus nov. gen., die Mundbiklung und die Körperform der Placodermen. Sitzungsber. Gesellsch. naturf. Freunde Berlin, p. 3 — 19. 19u5a Kellicott, W. E., The Development of the Vascular System of Ceraiodus. Anat. Anzeiger, XXVI, p. 200 — 208. (Correction p. 400.) 1905b Kellicott, W. E., The development of the vascular and respiratory Systems of Ceratodus. Blem. New York Acad., II, p. 135—249. 1897a Kekr, J. Graham, Remarks upon bis recent Expedition to Paraguay in quest of Lepidosiren. Proc. Zool. Soc. London, p. 921—923. 1897b Kerr, J. Graham, The Lepidosiren of South America. Nat. Science, XII, p. 3. 1897c Kerr, J. Graham, On the Development of Lepidosiren. Proc. Zool. Soc. London, p. 921. 1898a Kerr, J. Graham, On the dry season habits of Lepidosiren. Letter from R. J. Hont. Proc. Zool. Soc. London, 1898, p. 41—44. 1898b Kerr, J. Graham, Exhibition of Lepidosiren and accompanying Teleosts. Proc. Zool. Soc. London, p. 492. 1899a Kerr, J. Graham, The External Features in the Development of Lepidosiren paradoxa Fitz. Proc. Roj'. Soc, LXV, p. 160, 161 (also in Zool. Anzeiger, XXII). 1899b Kerr, J. Graham, Development of Lepidosiren. Abstr. Nat. Science, XIV, p. 432, 433. 190()a Kerr, J. Graham, The External Features in the Development of Lepidosiren paradoxa Fitz. Phil. Trans. Roj\ Soc, B CXCII, p. 299—330. 1900b Kerr, J. Graham, Note on Hypotheses as to the Origin of the paired Limbs of Vertebrates. Proc. Camb. Phil. Soc, X, p. 227—235. 1900c Kerr, J. Graham, The Zoologieal Position of Palaeospondylus Traqüair. Proc. Camb. Phil. Soc, X, p. 298 and 299. 1901a Kerr, J. Graham, The Development of Lepidosiren paradoxa. Pt. II. With a Note upon Corresponding Stages in the Development of Protopterus annectens. Quart. Journ. Micr. Soieuce, (2) XLV, p. 1 — 40. (Abstr. in Zool. Centralbl, IX, p. 143—146.) 1901b Kerr, J. Graham, On the male Genito-urinary Organs of Lepidosiren and Protopterus. Proc. Zool. Soc. London, 1901, p. 484—498. (Abstr. in Zool. Anzeiger, XXV, p. 30—31.) 1901c Kehr, J. Graham, The Genito-urinary Organs of Dipuoau Fishes. Proc. Camb. Phil. Soc, XII, p. 329 — 333. 1901d Kerr, J. Graham, The Development of Lepidosiren paradoxa. Pt. III. Development of the Skin and its Derivatives. Quart. Journ. Micr. Science, XLVI, p. 417 — 459. 1901e Kerr, J. Gi;aham, The Origin of the Paired Limbs of Vertebrates. Rep. Brit. Association for the Advancement of Scit-nce, 1901. (Abstr. in Nature, LXIV, p. 588—589.) Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. 1902 Kbrr, J. Graham, The Early Development of Muscles and Motor Nerves in Lepidosiren. Rep. Brit. Association for the Advancement of Science, p. 655 — 657. 1904 Kerb, J. Graham, On some Points in the Early Development of Motor Nerve trunks and Myotomes in Lepidosiren paradoxa (Fitz.). Trans. Roy. Soc. Edinb., XLI, p. 119—127. 1906 Kebr, J. Graham, The Embryology of certain of the Lower Fishes, and its Bearing upon Vertebrate Morphology. Proc. Roy. Phys. Soc. Edinb., XVI, p. 191 — 215. 1907a Kehr, J. Graham, Note on the Cause of Disappearance of the Fifth Aortic Arch in Air-breathing Vertebrates. Proc. Roy. Phys. Soc. Edinb., XVII, p. 167, 168. 1907b Kerr, J. Graham, Note on the Autostylic Skull of Vertebrates. Proc. Roy. Phys. Soc. Edinb., XVII, p. 169. 1908 Kerr, J. Graham, Note on ^wira-bladder and Lungs. Proc. Roy. Phj'S. Soc. Edinb., XVII, p. 170—174. 1909 Keer, J. Graham, Development of the Alimentary Canal and its Appendages in Lepidosiren and Protopterus. Quart. Journ. Hier. Science. (In the Press.) 1906 Merciai, G., Lepidosiren paradoxa Fitz. Riv. Ital. Sc. nat. Siena, XXVI, p. 59—61. 1902 Moore, J. E. S., The Tanganyika Problem, London 1902, p. 152. (Fig. of Protopterus aethiopicus.) 1906 Murray, J. A., Zahl und Größenverhältnisse der Chromosomen bei Lepidosiren paradoxa Fitz. Anat. Anzeiger, XXIX, p. 203—208. 1903 Neumayb, L., Die Entwicklung des Darmkanales von Ceratodus forsteri. Verb. anat. Ges., XVII, p. 139 — 142. 1904 Neumayb, L., Recherches sur le developpement du foie du pancreas et de la rate chez Ceratodus forsteri. C. R. Ass. Anat. Sess. VI, p. 73—77. 1904 Neumaver, L., Die Entwicklung des Darmkanales, von Lunge, Leber, Milz und Pankreas bei Ceratodus forsteri. Semon's Zoologische Forschungsreisen, I, p. 377 — 422. 1904 Sabatier, A. , Sur les mains scapulaires et pelviennes des Poissons holocephales et chez les Dipneustes. C. R. Acad. Science, CXXXVIII, p. 249—252. 1905 Sarasin, f., Exhibit of Protopterus annectens which had just left its burrow. Arch. Science Nat., XX, p. 594, 595. 1904 Schulz, W. A., Ueberblick über die Geschichte der Auffindung von Lepidosiren paradoxa Fitz. Verh. k. k. zool.-bot. Ges. Wien, LIII, p. 588—591. 1893a Semon, R., Verbreitung, Lebensweise und Fortpflanzung des Ceratodus forsteri. Semon's Zoologische Forschung- reisen, I, p. 11 — 28. 1893b Semon, R., Die äußere Entwicklung des Ceratodus forsteri. Ibidem, I, p. 29 — 50. 1895 Semon, R., Vermeintliche "äußere" Kiemen bei Cerfflto^MS-Embryonen. Anat. Anzeiger, X, p. 332 — 333. 1896 Semon, R., Im australischen Busch und an den Küsten des Korallenmeeres, Leipzig 1896. 1898 Semon, R., Die Entwickelung der paarigen Flossen des Ceratodus forsteri. Semon's Zoologische Forschungsreisen, I, p. 59—111. 1899a Semon, R., Weitere Beiträge zur Physiologie der Dipnoerflossen, auf Grund neuer, von Mr. Arthur Thompson an gefangenen Exemplaren von Ceratodus angestellten Beobachtungen. Zool. Anzeiger, XXII, p. 294 — 300. 1899b Semon, R. , Ueber die Entwicklung der Zahngebilde der Dipnoer. Sitzungsber. d. Ges. f. Morphologie und Physiologie in München, XV, p. 75 — 85. 1901a Semon, R., Die Zahnentwicklung des Ceratodus forsteri. Semon's Zoologische Forschungsreisen, I, p. 113 — 135. 1901b Semon, R., Die Furchung und Entwicklung der Keimblätter bei Ceratodus forsteri. Ibidem, I, p. 301 — 332. (Abstr. in Zool. Centralbl., VIII, p. 781—782.) 1901c Semon, R., Zur Entwicklungsgeschichte des Urogenitalsystems der Dipnoer. Zool. Anzeiger, XXIV, p. 131 — 135. 1901d Semon, R., Die „ektodermale Mediannaht" des Ceratodus forsteri. Arch. f. Entwickl.-Mech., XI, p. 310 — 320. (Abstr. in Zool. Centralbl., VIII, p. 781—782.) 1901e Semon, R., Ueber das Verwandtschaftsverhältnis der Dipnoer und Amphibien. Zool. Anzeiger, XXIV, p. 180 — 188' (Abstr. in Journ. Roy. Micr. Soc, 1901, p. 409.) 1901f Semon, R., Normentafel zur Entwicklungsgeschichte des Ceratodus forsteri. Keibbl, Normentafeln zur Ent- wicklungsgeschichte der Wirbeltiere, Heft 3. 1902 Sewektzofp, A. N., Zur Entwicklungsgeschichte des Ceratodus forsteri. Anat. Anzeiger, XXI, p. 593 — 608. 1908 Smith, G. Elliot, The Cerebral Cortex in Lepidosiren, with comparative Notes on the Interpretation of certain Features of the Forebrain in other Vertebrates. Anat. Anzeiger, XXXIII, p. 513—540. 1903 Sollas, W. J. and I. B. J., An Account of the Devonian Fish Palaeospondylus gunni Traquair. Phil. Trans. Roy. Soc, B CXLVI, p. 267—294. (Abstr. in Proc Roy. Soc, LXXII, p. 98, 99.) 1904 Spengbl, J. W., Ueber Schwimmblasen, Lungen und Kiementaschen der Wirbeltiere. Zool. Jahrbücher, Suppl. VIT, p. 727—749. 1905 Tagliani, G., Le fibre de Mauthner nel midollo spinale dei Vertebrati inferiori (anamni). ArcJi. Zool. Ital., II, p. 385—438. Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. -jj 1900 Traquaiu, R. H., Presidential Address to the Zoological Section. Rep. Brit. Association ior the Advancement of Science, 1900. 1903a Traquair, R. H., Od the Diatribution of Fossil Fish-remains in the Carboniferous Rocks of the Edinburgh District. Trans. Roy. Soc. Edinb., XL, p. 687 — 707. 1903b Traquair, R. H., The Lower Devonian Fishes of Gemünden. Trans. Roy. Soc. Edinb., XL, p. 723—739. 1908 Traquair, R. H., On Fossil Fish-remains from the Old Red Sandstone of Shetland. Trans. Roy. Soc. Edinb. XLVI, p. 321—329. 1908 Whitbaves, J. F., Illustrations of the Fossil Fishes of the Devonian Rocks of Canada. Pt. III, Supplementary Notes. Trans. Roy. Soc. Canada, 3. Series, 1907 — 1908, p. 245—275. 1903 WiBDERSHEiM, R., Ueber den Kehlkopf der Ganoiden und Dipnoer. Anat. Anzeiger, XXII p. 522 535. 1904a WiBDERSHEiM, R., Ueber das Vorkommen eines Kehlkopfes bei Ganoiden und Dipnoern, sowie über die Phylogenie der Lunge. Zool. Jahrbücher, Suppl. VII, p. 1 — 66. 1904b WiBDERSHEiM, R., Nachträgliche Bemerkungen zu meinem Aufsatz über den Kehlkopf der Ganoiden und Dipnoer. Anat. Anzeiger, XXIV, p. 651—652. 1901a Wilson, Gre(4g, The First Foundation of the Lung of Ceraiodus. (Preliminary Notice.) Proc. Roy. Phys. Soc. Edinb., XIV, p. 319—321. (Abstr. in Journ. Roy. Micr. Soc, 1901, p. 510—511.) 1901b Wilson, Gregg, Embryonic Excretory Organs of Ceratodus. (Preliminary Notice.) Ibidem, p. 321 — 323. (Abstr. in Journ. Roy. Micr. Soc, p. 510 — 511.) 1906a Wood WARD, A. S., On a Tooth of Ceratodus and a Dinosaurian Claw from the Lower Jurassic of Victoria Australia. Ann. Mag. Nat. Eist, XVIII, p. 1—3. 1906b Woodward, A. S., On a Carboniferous Fish Fauna from the Mansfield District, Victoria. Mem. Nat. Mus. Melbourne, I, p. 1 — 32. Frommannsche Buchdruckerei (Hermann Pohle) In Jena. — 55Q5 Normeiital'eln z l'.iilvMckluii^s*.d.Wirbelthicre,Hcrt X Taf. I , A K' Maxwell de: Nünnoiilareln/ljilwioklun^sJ.il.Vv'irbellhiiirc.llofl X Tal' U. Proloplorus iiiinciii'ns AK Maxwell (ifl \':r\ V (iuslav Fisrhpr .Ici Ulli Ans! ■. AG)!;;!-!!^™ Noriiiciitarfliiz.Eii(wickluii;5.s^.(l.Wirl)L'lll[iere.Hefl ,X. Taf.ni. A.K.Kame!l Jf! V-^il V Gustav Fischer, Verla svonG 11 8 1 a T Fischer in Jena. Handbuch der vergleichenden und experimentellen Entwickeliings- lehre der Wirbeltiere. Bearbeitet von IVof. Dr. Barfurtli, Hostocic. l'rof. Dr. Braun, lleiilelbcrg u. v. a., lierausgogelicn von Prof. Dr. Oslfar Hcrtwisr. Drei Bände (vollständig). 190(). In Lieferungen begann das Werk 19(0 zu er- scheinen. Preis : 135 Mark, geb. l.öO Mark. Bd. I, Teil 1, I. Hälfte: 0. 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Von J. Weise, Rerlin-Niederschöuhausen. — D. Di])tera (I.). 1. Ghironomidae. Von Prof. Dr. J. Kieffer, Bitsoh. Mit 15 Figuren im Text. 2. Asilidae. Von Prof. Dr. Fr. Hermann, Erlangen. 3. Dolicho])odidae. Von B. Licht^vardt, Charlottenburg. 4. Antbumyidae. Von Prof. P. Stein. 5. Diptera pniiipara (lliiipoboscidae). Von Dr. med. P. Speiser. Mit 1 F'igur im Text, 6. Simuliidae, Bonibyliidae, Euipididae, Syrjihidae, Tachinidae, Muscidae, Phyco- droniidae, Borboridae, Trypetidae, Ephydridae, Drosphilidao, Geomyzidae, Agroniy- zidae, Gonopidae. Von Prof. Mario ISezzi, Torino. Mit 6 l'iguren im Text. Lehrbuch der Entwicklungsgeschichte des Menschen und der Wirbel- tiere. von Dr. Oskar Hertwig, 0.0. Prof., Geh.-Uat, Direktor des anatomisch- biologischen Instituts in Berlin. Achte umgearbeitete und erweiterte Auflage. Mit 623 Abbildungen im Text. 1906. Preis: 13 Mark, geb. 15 Mark. Natur und Kultur, Heft 5, Dezember 1906 : . . . Die Brauchbarkeit und den Wert des grossartig angelegten Werkes beweist schon die für ein solches Buch ungewöhnlich hohe Auflagenzahl. Die vorliegende achte Auflage trägt natürlich allen Foi tschritten auf dem Gebiete der Entwicklungs- geschichte Rechnung. . . . Das Buch ist in erster Linie für Aerzte und Studierende der Medizin und Naturwissenschaften bestimmt. Weiter dürfte es besonders dem Lehrer für Naturkunde an den höheren Schulen als Nachschlagebuch willkommen sein. Das Werk ist eine ganz hervorragende Leistung deutscher Gelehrsamkeit und deutschen Fleisses und ein Meisterstück verständlicher Darstellung schwieriger Materie. Die Morphologie der Missbildungen des Menschen und der Tiere. Em Lehrbuch für ilorphologen, Physiologen, praktische Aerzte und Studierende. Von Dr. El'Ilst ScllWalbc. a. o. Professor der allgemeinen Pathologie und pathol. Anatomie an der Universität Heidelberg. 1. Teil: Allgemeine Missbildnngs- lehre (Teratologie). Eine Einführung in das Studium der abnormen Entwicklung. Mit 1 Tafel und 165 Abbildungen im Text. 1900. Preis: 6 Mark. II. Teil: Die Doppelbildungen. Mit 2 Tafeln und 394 z. T. farbigen Abbildungen im Text. 1907. Preis: 11 Mark. Deutsche Med. Wochenschrift, No. 38 v. 19. Sept. 1907: Der reiche Inhalt des Werkes berechtigt den Verfasser, in der Vorrede das Werk ein „Lehr- und Handbuch" zu nennen. Als solches wird es zweifello.s, wie der erste Teil, jedem Interessenten reiche Dienste leisten und gewiss viel benutzt werden. III. Teil: Die Einzelmissbildungen. 1. Lieferung enthaltend: I. Abteilung: M issb il d ung eil der äusseren Form. Bearbeitet von E. Schwalbe, F. Kermauner. 2. Abteilung: Missbildungen der einzelnen Organe und Organsysteme. 1. Kapitel. Bearbeitet von E. von Ili|)pel. Preis: 6 Mark. i''miiiuiaiiu8die liuchdruckeroi (Uoruiaun Pühlo) in Jena. — 3696 mm