210 GERM-CELL CYCLE IN ANIMALS 
Regarding the differentiation of the germ cells in 
hermaphrodites then we may recognize two principal 
views: (1) that there is some material within the 
cell which initiates specialization, or (2) that differ- 
entiation is due to general or local causes outside 
of the germ cells. The former is favored by Elpatiew- 
sky (1909, 1910) from studies on Sagitta and by 
Demoll (1912) from studies on Helix. The second 
view is more widely advocated. The conclusions 
derived by Kuschakewitsch (1910) and Champy 
(1913) on amphibians, and of Ancel (1903) and 
Buresch (1911) on Helix agree in their essential fea- 
tures. All of these investigators maintain that the 
sex cells pass through an indifferent stage and are 
differentiated into odcytes or spermatocytes because 
of influences external to themselves. Buresch and 
Champy also believe that even in the fully developed 
germ glands of the adult these primitive cells are 
present. The causes of their differentiation, how- 
ever, have not been definitely determined. 
