CELL-DIVISION 







Fig. 33. — Stages in the first cleavage-cycle of the egg of Arbacia. (Drawn by 

 Mrs. L. G. Hugueley from author's preparations). 



(Fig. 331?). As the variously shaped chromosomes are 

 converted into lightly stained spheres (Fig. 33)), they 

 are at the inner border of the now no longer spherical 

 centrospheres; the wide-flung astral rays are losing defi- 

 nition. When the chromosomes within the centro- 

 spheres begin to fuse, centrospheres and asters are on 

 the wane (Fig. 33g). A moment later the egg elongates 

 (Fig. 33A); cleavage quickly follows (Fig. 331, j, k) to give 

 rise to two spheres. 



For the sake of simplicity and in order that the reader 

 may not be confused, I omit at this place a description of 

 the evanescent changes in the hyaline plasma-layer. 

 Indeed, the figures that I have given here do not show 

 the layer. A structure concerning which biologists are at 

 odds, because of lack of knowledge, ought be set off" from 



263 



