Observations and Experiments on the 

 Ctenophore Egg. 



III. Experiments on Germinal Localization of 

 the Egg of Be roc ovata. 



By 



Nsiohide Yatsu. 



CHUN'S isolation experiments on the egg of Encliaris multicornis 

 carried on in the summer of 1877 and described fifteen years later 

 ('92 p. 104) had given Driesch and Morgan ('95) an impetus to 

 study more fully the development of isolated blastomercs and egg- 

 fragments of Bero'c ovata. Their study was followed by FlSCHEL'S 

 clear analytical investigation on the germinal localization of the same 

 animal ('97, '98 and '03Ì. ZlEGLER ('98) incidentally carried 011 

 similar experiments while studying the mode of cleavage of the Beroc 

 egg after operation. These works, it seemed to me, were so satis- 

 factorily carried out that we do not need any further experiment 

 along this line of study. Yet when I repeated at Naples the investi- 

 gations of the above authors in somewhat extensive ways, some new 

 data were obtained, which embody the present paper. 



Of many eggs operated upon in forty different ways 216 reached 

 two-day embryos, 1 at which time they were examined and sketched. 

 The numbers of comb-plates were recorded in each case for the pur- 

 pose of future comparison. Instead of giving the results of individual 

 series of experiments I shall only describe those which will serve as 

 a supplement to FisCHEl.'s thoroughgoing investigations. 



I Incidentally it may be of interest to note that in two-day embryos there is no 

 co-ordination in the movement of comb-plates, each performing its flickering motion of its 

 own rhythm. 



