August 24, 1905] 



NA TURE 



401 



and Colonies 23, Italy 11, America 3, and other 

 countries 16. The largest contributors to the pro- 

 ceedings of the congress, however, were the Germans ; 

 out of a total of 117 communications, 32 were made 

 by them, 31 by the French, 18 by the British, 15 by 

 the Swiss, 8 by Italians, 5 by Swedes, and 2 by 

 Americans. 



From every point of view the congress was a suc- 

 cess. Anatomy is peculiarly susceptible of inter- 

 national treatment, the subjects for description and 

 discussion being concrete and capable of direct demon- 

 stration. The language difificulty certainly hindered 

 a free discussion on more than one occasion ; for in- 

 stance, on the second day, a speaker, after 

 giving his communication in French, listened 

 most attentively to a vigorous criticism in 

 German, and, bowing profoundly, replied, " Je ne 

 comprends pas I'allemand." With an agenda list 

 overloaded with 117 communications, there was a 

 grave risk of disorganisation. Thanks to the com- 

 plete arrangements made by the committee of organi- 

 sation, presided over by Prof. A. Eternod, of Geneva, 

 and to the perfect arrangement of business by the pre- 

 sident of the secretariat. Prof, von Bardeleben, the 

 proceedings of the congress made an even and steady 

 progress. The success of the congress must also be 

 ascribed to Prof. Nicholas, of Nancy, secretary of the 

 French society ; English members were indebted to 

 Prof. Symington, president of the British society, 

 and to Dr. Christopher Addison, its secretary. Each 

 day's work was divided into two parts; the morning 

 was devoted to papers, ten minutes being allowed for 

 each communication, and three minutes to any mem- 

 ber who wished to criticise ; the afternoon was set 

 aside for exhibition of new specimens and demonstra- 

 tions of the material on which the communications of 

 the morning were based, and this was by far the 

 most instructive and profitable part of the day's work. 

 The Swiss cow-bell, employed by the president of 

 each day's proceedings (for the president of each 

 society acted in turn as chainnan) to warn the speaker 

 that he had reached the limit of his allotted time, 

 bound the members of the congress by a common 

 sense of humour and materially aided the success of 

 the meeting. In spite of the entente coriia\e, the 

 British anatomists associated more closely with the 

 German than with the French members of the con- 

 gress — an association determined, for the greater 

 part, by the fact that the Germans were the superior 

 linguists. 



With so extensive a programme, it is impossible in 

 a report such as this to do more than note the more 

 outstanding communications. Making every allow- 

 ance for prejudice of race, the first place, both in im- 

 portance of results and excellence of technique, must 

 be assigned to the contributions made by Prof. J. T. 

 Wilson, of Sydney University, who placed before the 

 congress the results of a prolonged investigation into 

 the developmental history of ornithorhynchus 

 made by his colleague and collaborator, J. P. 

 Hill, and by himself. With the material now 

 at their command they will be able to write a 

 full and precise account of the development of 

 the monotremes and throw a great deal of light on 

 mammalian morphology. The photograph of an 

 ornithorhynchus ^g,s^, in the eight blastomere stage, 

 was shown. Most remarkable of all were the 

 specimens and photographs showing the early de- 

 velopmental phases of the central nervous S3'stem. 

 The medullars' plates, instead of folding over at an 

 early date to form the neural tube as in mammals 

 generally, remain exposed on the surface of the 

 embryo and thus give a superb opportunity of study- 

 ing the processes of segmentation and differentiation 



NO. 1869, VOL. 72] 



of the central nervous system. The cephalic part of 

 the central nervous system is seen at first not to be 

 differentiated into three parts, viz., hind-, mid-, and 

 fore-brain, but into two, a hind part, or archen- 

 cephalon, and a fore part, or deuterencephalon, under 

 which the notochord terminates. The archencephalon 

 shows four or five sharply demarcated neuromeres in 

 front of the neuromere connected vwith the facial 

 nerve (prefacial neuromeres), but Prof. Wilson de- 

 tects in some of them traces of a subdivision. There 

 are three post-facial neuromeres. By using em- 

 bryos of Perameles and Dasyurus to supply blanks 

 in the ornithorhs'nchus series, Wilson and Hill were 

 able to show that the neural crest forms at first a 

 continuous hem on the lateral margins of the medul- 

 lary plates. That part of the neural crest correspond- 

 ing to the prefacial neuromeres undergoes, relatively 

 to the rest of the neural system, an enormous growth 

 forming a plate of cells which was mistaken by 

 Selenka in other marsupial embryos for a mass of 

 mesoblast. The neural crest connected with the 

 facial segment forms the acoustic ganglion ; that 

 with the post-facial neuromeres the glosso-vagal 

 ganglion, the rest of the crest becoming differen- 

 tiated into spinal ganglia. 



It is within the memory of even the younger 

 zoologists that ornithorhynchus was regarded at one 

 time as a toothless mammal ; then came the dis- 

 covery by Poulton and by Stewart that teeth were 

 present but remained embedded in the gums. Prof. 

 Wilson was able to demonstrate in his series of em- 

 bryos the presence of two dentitions — the develop- 

 ment and absorption of a milk dentition and the 

 formation of a permanent dentition — that discovered 

 by Poulton and Stewart. Thus ornithorhynchus, so 

 far as its dentition is concerned, takes its place with 

 diphyodont mammals. Further, it was shown that 

 each cusp of the permanent molars is preceded by 

 a separate milk tooth — a powerful argument in 

 favour of the evolution of molar teeth by the con- 

 crescence of single-cusped teeth. Photographs were 

 exhibited of a reconstructed model of the skull of a 

 fcetal ornithorhynchus which shows many aberrant 

 and puzzling features. Other contributions to the 

 embryology of monotremes were made by Prof. 

 Keibel, of Freiburg (models showing the develop- 

 ment of the urogenital apparatus of echidna), and 

 to the embryology of marsupials by Dr. Fiir 

 Bresslau, of Strassburg (preparations showing the 

 development of the pouch of Didelpliys marsupialis). 



Two papers on the agenda list, one by Prof, von 

 Bardeleben, of Jena, entitled, " Die Homologie des 

 Unterkiefers in der Wi/beltierreihe," the other by 

 Prof. Gaupp, of Freiburg, " Die Nicht-Homologie 

 des Unterkiefers in der Wirbeltierreihe," brought 

 again into prominence that much-debated problem — 

 the origin and nature of the mammalian lower jaw. 

 Bardeleben maintained that the lower jaw of a 

 mammal was stricth' the same structure as that of a 

 reptile, and produced, as evidence of his contention, 

 mandibles of marsupials and of human foetuses in 

 which there could be traced lines somewhat similar 

 to the sutural lines to be seen in the reptilian 

 mandible. Prof. Gaupp 's paper was a clear and 

 vigorous denial of Bardeleben 's contentions. In 

 Gaupp's opinion the temporo-maxillary joint of 

 mammals was a new joint formed between the 

 coronoid process of the reptilian jaw and the 

 squamosal, and quite different from the mandibulo- 

 quadrate joint of reptiles. His conclusions were 

 largely based on a consideration of the relationship 

 of muscles and nerves to these joints. The new 

 mammalian joint was formed in the insertion of the 

 pterygoideus externus, the end tendon of which be- 



