268 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 CARYECAULIS 
Fotar Plate @@eo 
O/;@ @/0 ont X yi 
rete nts ||| LTO) eset 
7 Ogee Os? % Coy 
| | 
sro foals A/S tag map: 
omega (: 68) BS 
“99 NZ a 
Oe 
pee ee Z 
a 0 Si 
Fic. 72.— Chromosome cycle in Phylloxrera caryeca © s Mor- 
gan’s Heredity and Sex, published by the Columbia University Press.) 
