THE CELLULAR BASIS 119 



it is sometimes possible to see that each bead- 

 like chromomere divides through its middle. 

 The daughter chromosomes then separate and 

 move to opposite poles of the spindle, where 

 they form the daughter nuclei, and at the same 

 time the cell body begins to divide by a con- 

 striction which pinches the cell in two in the 

 plane which passes through the equator of the 

 spindle (Figs. 5, 24 F, 26 B). Finally the 

 daughter nuclei grow in size by the absorp- 

 tion of achromatin from the cell body and the 

 substance of the chromosomes is again scat- 

 tered through the achromatin in the form 

 of threads and granules and thus the daughter 

 nuclei come back to a "resting" stage similar 

 to that with which the division began, thus 

 completing the "division cycle" of the cell. 



During the whole division cycle it is possi- 

 ble in a few instances to distinguish the chro- 

 mosomes of the egg from those of the sperm, 

 and in every instance where this can be done 

 it is perfectly clear that these chromosomes do 

 not fuse together nor lose their identity, but 

 that every chromosome splits lengthwise and 

 its halves separate and go into the two daugh- 



