THE GERM-CELL CYCLE 



273 



absence of germ cells within them is supposed to be due to the 

 failure to obtain cells with material from the "nucleolo," i.e. 

 germ cells. 



The segregation of the germ cells in hymenopterous insects, 



o 



H 



Fig. 2. — Diagrams illustrating the germ-cell cycle in Miastor. 



A-E, stages in the formation of the primordial germ cell (g). F-M, stages in the history of the 

 primordial germ cells. A, mature egg with cleavage nucleus and polar-plasm (p). B, two-cell stage. 

 C, four-cell stage. D, eight-cell stage. C, = chromatin left behind in the cytoplasm after mitosis. 

 E, fifteen cell stage. C 2 = cast-out chromatin after second diminution process. F, single primordial 

 germ cell. G, two o5gonia. H, four oogonia. I, eight oogonia in a single group. J, eight oogonia 

 in two rows of four each. K, an ovary with eight oogonia. L, an ovary with sixteen oogonia. 

 M, fully developed ovary with thirty-two oogonia. (After Kahle and Hegner.) 



as just described, does not differ materially from that observed 

 in many other insects, as we shall see later, but there are 

 several points that need to be reinvestigated, particularly the 

 distribution of the cells containing " nucleolar " material, the 

 formation of the " sexless " larvae, and the origin of the "nucleolo.' 



