176 GERM-CELL CYCLE IN ANIMALS 
Meyer (1895) extended the study of chromatin- 
diminution to other species of Ascaris. In A. lum- 
bricoides no diminution takes place until the four- 
cell stage; then three of the nuclei become deprived 
of part of their chromatin. A diminution of this 
JN \ 
Joe Wed 
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Fic. 52.— Ascaris. Diagram showing segregation of primordial germ 
cell. EH=egg; Pi, Po, P3=stem cells; P,= primordial germ cell. 
Circles represent somatic cells. (From Boveri, 1910.) 
sort had been described by Boveri as a variation in 
the process observed in A. megalocephala. In A. 
rubicunda the differentiation of the cleavage cells 
seems to resemble A. megalocephala more than it 
does A. lumbricoides. Only late cleavage stages 
of A. labiata were obtained by Meyer, but there is 
