Makch 9, 1900.] 



SCIENCE. 



367 



He was also the first to give a satisfactory 

 interpretation to a characteristic structure 

 of thegastrulation of the meroblastic types, 

 the primitive streak. An especially i-e- 

 markable feature of von Kupffer's work was 

 that he made his interpretation of the in- 

 vaginate character of the early gastrula of 

 a meroblastic type in his study of the tel- 

 eost — a form in which the appearance of 

 the infolding process is so diiSeult to observe 

 that his early results were for thirty years 

 discredited — and it is only recently that the 

 ' prostoma ' in these forms is again described 

 (Sumner). It was his earliest paper on 

 teleostean development, by the way (Ref. 

 No. 6, II.), which describes' Kupfier's ves- 

 icle,' which in the m3.tters of its homology 

 and function has since been an unusually 

 fruitful theme for controversy. We may note 

 in passing thatvon Kupifer believed that the 

 region of the prostoma was (as he also in- 

 terpreted the primitive streak of amniotes) 

 the only region of gastrulation in the bony- 

 fish, that he failed to determine the invag- 

 inate character of the germ ring, and that 

 he interpreted the early embryo as equiva- 

 lent to the primitive streak, and not there- 

 fore to the actual embryo. 



In connection with Kuplfer's work on the 

 development of the teleosts it should be 

 mentioned that it is he who deserves the 

 credit for the view that the cells of the 

 blastoderm are the progenitors of the peri- 

 blast nuclei, and that they also give rise to 

 the tissue cells of the embryo, questions of 

 great theoretical importance. His work on 

 the development of the herring, undertaken 

 in the interest of the Commission for the In- 

 vestigation of the Fisheries of the German 

 Ocean, is a further memorable contribution 

 to the biology of fishes. Here for the 

 first time in any extended embryological 

 memoir photo-micrographs were introduced 

 as plates. 



Only a tithe of von Kupffer's publications 

 relate to the development of mammals. 



His most noteworthy paper deals with the 

 question of the ' inversion of the germ 

 layers' which had been described in a ro- 

 dents, a condition which appeared to be an 

 extraordinary contradiction to the usual 

 mode of origin of the germ layers. By 

 means of a series of stages of the field- 

 mouse he showed conclusively, however, 

 that this 'inversion' was only apparent : dur- 

 ing early growth the embryonic area bowed 

 downward to the ventral side of the ovum, 

 so that the flattened gut came to be ap- 

 posed to the surface while the central ner- 

 vous system was left to develop within the 

 cavity of the ovum. 



The philosophy of the vertebrate head 

 has furnished the fruitful theme of von 

 Kupffer's studies during the past ten years. 

 And his memoirs (three of the series have 

 thus far appeared) upon this subject are, I 

 think, regarded generally as his magnum 

 opus. His endeavor in these memoirs is to 

 demonstrate by ontogenetic conditions in 

 the lowest craniotes the mode of origin, 

 phylogenetic, of the structures of the ver- 

 tebrate head — brain, cranial nerves, sense 

 organs, mouth region, muscles and skele- 

 ton. The plan of this series accordingly 

 recalls somewhat that of Dohrn in his 

 ' Urgeschichte der Wirbeltiere,' although 

 the views of their authors are usually 

 widely at variance. Von Kupffer derives 

 the ground plan of the conditions of the 

 vertebrate head from that in the proto- 

 chordates while Dohrn, for a long time, at 

 least, has been the strong supporter of the 

 famous annelid theory. Certain it is that 

 the results of von Kupffer are welcomed by 

 the warmest interest even by those whose 

 faith in the great value of developmental 

 characters as tests of phylogeny has been 

 severely shaken. And all will admit he 

 has already been able to clear up a num- 

 ber of doubtful points in cranial problems : 

 thus, to mention but an instance or two of 

 the general value of his work, it is now 



