JOURNAL OF THE COLLEGE OF SCIENCE, IMPERIAL UNIVERSITY 

 TOKYO, JAPAN. 



VOL. XVII., ARTICLE 3. 



Contributions to the Embryology of Amphibia :— 



The Mode of Blastopore Closure and the 



Position of the Embryonic Body. 



By 

 Sakujiro Ikeda. 



With Plates I— IV. 



Although the earlier phases of the amphibian development 

 have been studied within reeent years by many able investigators 

 such as Pflüger ('83), Roux ('88a), O. Hertwig ('92, '95/?), 

 O. Schulze ('88&.c), Morgan and Tsuda f93&), Kopsch ('90), 

 Assheton ('94«) and Eycleshymer ('98), it is a remarkable 

 fact that some of the most fundamental points are still far from 

 being settled. Above all, the questions : (1) in what manner the 

 blastopore is closed, and (2) on what portion of the egg-surface, 

 the fundamental parts of the embryonic body are formed, have 

 been answered by many different writers in as many different 

 ways. The opinions held in regard to them can, however, be 

 classified into three categories : — 



