Centrosome in Enucleated Egg-Fragfnents. 



297 



cytasters have arisen. At the center of the cytasters there is always 

 a Httle accumulation of centroplasm; in Fig. 9c this has enlarged a 

 good deal. The ray system around the centroplasm is exactly 

 the same as that of the normal asters. Many rays extend quite 

 far into the yolk region. A few stronger rays go through the 

 centroplasm and reach the center, while most of them start from 

 the periphery of the centroplasm. No marked archiplasmic dif- 

 ferentiation can be 



pa 



w 



detected, but there is 

 a little difference in 

 the nature of rays be- 

 tween the part of rays 

 running through the 

 yolk layer and that 

 within the central 

 portion of the cytaster 

 free from yolk gran- 

 ules. This relation is 

 clearly seen in Fig. 6. 

 At the center of the 

 cytaster are always 

 found a few dark 

 granules of various 

 sizes. In small cytas- 

 ters, where there is 

 very little centro- 

 plasm, the granules 

 are crowded together 



/TTip-c Qo anrl ob^ 9" ^"'^ ^' Cytasters from the section shovVn in Fig. 6, more 



„,i M • .1 hiehlv enlarged. Oc, cytaster with enlarged centrosome and several 



while m case the cen- •..,.. ,. ^ 



, • 1 1 centnoles in it, snowmg mtermediate stage between the cytasters 



troplasm is enlarged 9^ and fe, and the one shown in Fig. 7. 



the granules are found 



farther apart from one another. In no case I was able to find 



at the center either a single granule or the granule at the division 



stage. 



In the section represented in Fig. 7 only one large cytaster 

 occupies the central part of the fragment and the centroplasm 

 is of enormous size with many dark granules. The rays are 

 comparatively short and not very straight. They intercross one 

 another, giving a felt-like layer. 



Fig. V (X2284). 



