4 AtlT. 10. — N. YATSU : 



111 comparing the above result with Zeleny's we still find 

 discordance between them. He made the same experiment upon 

 the egg of C. mm'ginahis and found out that in every case there 

 was more or less deviation from the normal mode of cleavage 

 ('04, pp. OÜ12 and 306). It may, therefore, be concluded that in 

 the Neapolitan species tiie cleavage factor is established much 

 earlier than iii C. lacieus. 



As I have already referred to in my previous paper ('08), the 

 above experiment clearly shows that the spindle may be moved 

 about in the egg to its definite position before the karyokinesis 

 reaches the telophase or perhaps the late anaphase, when the diastem 

 is formed. As to the fixation of the position of the spindle, the 

 importance of diastem formation cannot be too much overestimated. 

 It should here be remarked that the establishment of the diastem 

 and that of the cleavage factor are not one and the same thing, but 

 the former is evidently a result of the latter. 



II. Experiment B (C lacteus). 



A portion of cytoplasm was cut off along different j)lanes 

 from one of the blastomeres^ before the completion of the first 

 cleavage, care being taken not to injure or remove the nucleus. 

 I have ten cases to report. All divided unequally from the 

 beginning, and the subsequent cleavage was irregular. Two out of 

 ten, however, cleaved fairly normally owing probably to the fact 

 that the injury was not great enough to cause a considerable 

 disturbance of the cleavage factors. 



1 Strictly speaking, tlie term blastomere should not be employeil lefoie the comple- 

 tion of first cleavage, yet the meaning here will be quite clear. 



