THE GERM-CELL CYCLE 



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later are always segregated in a particular blastomere until the 

 sixteen-cell stage is reached. By this time the nurse cells have 

 disintegrated into a mass of granules which become scattered 

 throughout the cytoplasm of one cell, the primordial germ cell. 

 No recent morphological investigations of Nematodes have 



Fig. 3. — Diagram illustrating the segregation of the primordial germ cell in copepods. 



The egg contains a group of granules (ectosomes) which are gradually localised in one cell (g), the primordial 

 germ cell. The descendants of the primordial germ cell (g) are apparently all provided with an equal 

 amount of ectosomes. (After Haecker and Amma.) 



added materially to our knowledge of the early history of the 

 germ cells in this group, but the experimental results of Boveri 

 (15) and Hogue(i6) are of much interest. Studies of dispermic 

 and centrifuged eggs have proved that the chromatin-diminution 

 process in Ascaris eggs is not controlled by the nucleus, but by 

 the other egg contents. It follows from this that the origin of 

 the primordial germ cell, which always arises from the cell with 

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