xxx vni 



serial duties was soon extended to Comparative Anatomy and Zoo- 

 logy. After seven years' agreeable and successful labour in Dorpat, 

 Rathke was recalled to his native country to succeed his distinguished 

 friend Von Baer, whom we still happily number among our Foreign 

 Members, as Professor of Anatomy and Zoology in Konigsberg, 

 where he continued till the time of his death. 



The chosen task of Rathke' s scientific life was the investigation of 

 the laws of formation of the animal body ; and he soon perceived 

 that the solution of the great questions involved was to be sought 

 for not only in the examination of the mature structure, but also, 

 and indeed with the best promise of success, in the study of the body 

 in its embryo state, and in tracing its several parts through their 

 successive phases of development up to their final condition. Zoo- 

 tomy and the study of embryonic development were in his hands 

 mutually elucidative in determining the morphological equivalence 

 of apparently dissimilar forms ; and, in this way, passing from the 

 one course of investigation to the other as the object of inquiry 

 demanded, and labouring unremittingly as well as successfully, 

 Rathke has earned a foremost place among those who have advanced 

 the science of Animal Morphology. 



Rathke' s earliest researches were directed to the anatomy and 

 development of Amphibia and Fishes. The most notable results 

 were his various papers on the internal structure, in many ways so 

 remarkable, of the Cyclostomes, and his monography on the deve- 

 lopment of the Blennius viviparus, the first thorough history of 

 the embryogeny of a fish that had then appeared. 



He next applied himself to the difficult problem of tracing the 

 development of the genital system in the series of vertebrated ani- 

 mals, following out the metamorphoses of the Wolffian body in 

 reptiles, birds, and mammals, and investigating its relation to the 

 sexual organs. With the results of these inquiries appeared the 

 account of his researches on the development of the respiratory appa- 

 ratus, and the announcement of his well-known and important dis- 

 covery that the embryos of all vertebrata have at a certain period 

 the rudiments of a branchial system in form of arches and apertures, 

 although without formation of real gills in the higher classes. 



These extensive labours having been accomplished, and Von Baer's 

 celebrated work on animal development having in the mean time 



