GERM-CELL CYCLE IN ANIMALS 



hence the spermatozoa simply initiate development. 

 The chromosome cycle of Rhabditis nigrovenosa has 

 been studied by Boveri (1911) and Schleip (1911). 



PHYLLOXERA CAKYMCAULJS 



o 



t! O 



tfrma/ eS Iftngeft 



O 



O 



o 



O 



eaa 



FIG. 72. Chromosome cycle in Phylloxera carycecaulis. (From Mor- 

 gan's Heredity and Sex, published by the Columbia University Press.) 



