26d 



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). 



rHYLLOXERA CARYJECAULJS 



ToO*^ 7*^ctU ^ ^^ (^ 



0<fmw of ifin^eU ^»t%. 



• o 





o 



C^j 



<:::? 



O 



o 





Fig. 72. — Chromosome cycle in Phylloxera carycBcaulis. (From Mor- 

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



