Centrosome in Enucleated Egg-Fragments. 



295 





.N. 



throughout the cytoplasm, as is shown in Fig. 6, corresponding 

 to the pieces studied in Hving state. (Fig. 2a, 3, 4 and 5a.) In one 

 of the fragments as many as twelve cytasters were found. In 

 case a few cytasters are produced they have a tendency to come 

 together near the center of the fragment. Another point to be 

 noted is that the larger the number of cytasters in a fragment 

 the smaller the aster. The central portion of the fragment stains 

 lighter than the outer. Besides fine yolk granules large ones of 

 various sizes are found. The latter kind of granules is more 

 thickly disposed near the periphery than the center. 



b. In one fragment a 



single aster is found near ^5 



the center with an en- 

 larged centrosome. (Fig. 

 7.) The general charac- 

 ter of the cytoplasm is the 

 same as those of the four 

 fragments described un- 

 der a. 



c. In three fragments 

 I found a group of cytas- 

 ters in a central clear area. 

 This type occurs more 

 frequently than any other, 

 as I learned from the 

 study of living fragments. 

 Fig. 8 is a section through 

 the same fragment repre- 

 sented in Fig. if. The 

 entire cytoplasm is 

 packed with large yolk 

 granules, which look as if ,; 



they were crowded together by the central accumulation of hyalo- 

 plasm. They stain very dariy>nd re^is(t^ e?itraction by the iron- 

 alum solution for a considerable length of time. In fact, when 

 these granules become dark blue both the rays and centrioles 

 are found completely decolorized. At the center there is a large 

 clear area of almost the size of the germinal vesicle. In it some 

 two or three dozens of cytasters are seen, most of them being 

 situated near the periphery. Each aster bulges out a little toward 



t:. 



'•'■/■'■■> 



^ 



fes*;^^^'* 



Fig. Ill (X913). 



6, Section of an enucleated fragment, in which several 

 cytasters have been produced^ by CaCl2 solution; four 

 cytasters are seen in' the sectioh; the centrioles of the two 

 cvtasters are in the next section. 



