566 VEEA DANCHAKOFF 



of the nuclear vesicle of the immature egg has now become a 

 part of the cytoplasm. The nucleus of a mature egg does not 

 contain definite structures aside from occasional chromatic gran- 

 ules; its stroma is lightly acidophilic and only under the highest 

 magnifications presents a lightly granular structure. The cyto- 

 plasm still contains more or less numerous mitochondria, which 

 do not appear very distinct in my preparations. 



But quite new morphological structures have appeared in the 

 cytoplasm of the mature egg cell. These are somewhat large, 

 spherical accumulations of a very intensely basophilic and re- 

 fractory substance. They are very different in their size and 

 number. There is, however, a somewhat definite relation be- 

 tween their number, size, and distribution; if they are small, 

 they are numerous and more or less uniformly distributed 

 through the cytoplasm; if they are larger, they are few and 

 irregularly placed. 



The ' spherical accumulations of the basophilic substance are 

 chiefly found in the cytoplasm, yet sometimes one or two smaller 

 accumulations of similar basophilic substances are observed 

 within the nucleus. These usually appear in the form of small 

 granules closely flattened against the nuclear membrane in the 

 form of discs (fig. 2). 



Since both in normal fertilization and in artificial partheno- 

 genesis an important function seems to be assigned to the baso- 

 philic accumulations in the cytoplasm, it may be permitted to 

 cite a paper of Schaxel, dealing with analogous structures. Study- 

 ing the maturation processes in the sea urchin eggs, Schaxel con- 

 siders the chromatin filaments in the nucleus as derived from 

 the chromosomes. According to him, they condense later into 

 nucleoli and finally join all together in one large nucelolus. This 

 cell organ is, for Schaxel, a center of assimilation and emission 

 of chromatin. The emission of chromatin by the nucleus is 

 effected without conspicuous accumulations at the nucleus mem- 

 brane, the chromatin being swiftly transported by currents. 

 Lack of chromatin stagnation makes the process of emission of 

 chromatin by the nucleus imperceptible and easily overlooked. 

 The nucleolus appears after the emission of chromatin as an 



