GERMINAL LOCALIZATION IX THE EGG OF CEREBRATULUS. 



also because it has not a little bearing on further experiments ; 

 should this have been otherwise, all the following experiments 

 would have been unreliable, because unfertilized eggs of various 

 periods after release were used indiscriminately. 



Series B. Removal Experiment performed before 

 and after Fertilization. 



Eggs were cut in two obliquely after 

 fertilization, when the first polocyte 

 was formed and the fragments with the 

 polocyte were reared (Fig. 3). This series 

 of experiments was undertaken in order 

 to ascertain if there was any progress in 

 germinal localization during the period 

 extending from the entrance of the sper- 

 Diaoram showino- the niatozoon up to the formation of the first 



operation in Series B, polocyte. Nearly half of the number of 



the part removed beino; .-, , , ^. ^ 



® eggs thus operated on died, owing pro- 



ntiTjClit3(.l« 



bably to the fact that the germ-nuclei 

 had been separated, and that each of them failed to develop by 

 itself I succeeded, however, in rearing nineteen fragments into 

 pilidia. Of these nine were defective. If this result be com- 

 pared with that of Series A, one will at once notice that the 

 defective pilidia increased considerably when the operation was 

 done after entrance of the spermatozoon. This may indicate 

 that localization is established more definitely through the in- 

 fluence of the spermatozoon. This, however, as I stated in my 

 previous paper, is not, in ordinary cases, dissociated from the 

 phenomenon accompanying the dissolution of the germinal vesicle, 

 since the spermatozoon may enter an unmatured egg. 



Fig. 



