568 VERA DANCHAKOFF 



form a single mass which elongates, assumes a fibrillar structure, 

 and finally divides. 



Scattered chromatin is very frequently found in the cytoplasm 

 of protozoa. Givago states, that the sexual development in the 

 microsporidia consists in chromidiogamia in all definitely known 

 cases. Here the nuclei of copulating individuals lose their out- 

 lines, the nuclear chromatin is transformed into chromidia and 

 the copulation of the nuclear substance takes place at the time, 

 when it is scattered in the cytoplasm. 



Again after the union of the gametes, Popoff finds, that the 

 nuclear substances transfuse into the cytoplasm, accumulate 

 around the nucleus and are transformed into a chromidial net. 

 According to Popoff, Svarchevsky and Elpatievsky this chromi- 

 dial net gives rise to the nuclei of the gametes and also to the 

 nuclei of the Shisogonic descendents of Arcella. A description 

 of diffuse scattering of chromatin substance in the cytoplasm of 

 the protozoa is recalled by the names of Schaudinn and Hertwig. 

 Some of the figures of Dobell's paper, which represent the de- 

 velopment of Adelae ovata exactly correspond to some of my 

 preparations of parthenogenetic eggs in the prophase of the first 

 cleavage. 



This analogy between the structure of unicellular organisms, 

 during their multiplication, and that of multicellular organisms 

 in the unicellular stage may offer some further suggestion. The 

 students of protozoa identify the chromidial nets and the chro- 

 matin granules scattered in the cytoplasm with true nuclear 

 chromatin. They seem to be justified in doing that, the nu- 

 cleus- of the protozoa usually losing its individuality; yet the 

 nucleus in the egg cell of the sea urchin, on the contrary, retains 

 its outlines, while the cytoplasm contains the described chro- 

 matic accumulations. Therefore, great caution is required in 

 the interpretation of the chromatic accumulations found in the 

 cytoplasm of sea urchin eggs. 



