SOME EXPERIMENTS ON CELL-DIVISION. 



271 



ing blaslomcres are of equal size. The result is, however, different when 

 the operation is performed in a later stage as we shall see below. 



Cases A, G and H. The eggs were cut vertically, in an anaphases, 

 parallel to the division plane. The cleavage furrows were formed along 

 the normal planes and the blastomcres were of different sizes one the 

 normal size and the other smaller (Figs. 1, 15-18). 



Case I. A portion of a blastomere of the two-cell stage was cut at 

 an anaphese of the second cleavage (Fig. 19). The operated blastomere 

 divided unequally, the result being three of the normal size and one smal- 

 ler (Fig. 20). 



From this it will be seen that in a later stage of a karyokinesis i. c, in 

 the anaphase and telophase the future cleavage plane is definitely fixed 



10 20 



Fig. 15. Egg form which a portion is cut off at the anaphase. Fig. 16. The same divid- 

 ing. Fig. 17. Egg from which a portion is cut off at the anaphase. Fig. IS. The same 

 dividing. Fig. ig. Egg from which a portion is cut off at the beginning of the stcond cleavage. 

 (11.35 P.M.) Fig. 20. The same at 11.45 P.M. All the drawings Xigo. 



