GERM CELLS OF HERMAPHRODITES 195 



One of the problems connected with hermaphrodit- 

 ism that has caused a great amount of discussion is 

 whether the dioecious or the monoecious condition 

 is the more primitive. The majority of zoologists 

 are inclined to consider the hermaphroditic condition 

 more primitive, but a number of careful investigators 

 have decided in favor of gonochorism. Among these 

 are Delage (1884), F. Muller (1885), Pelseener (1894), 

 Montgomery (1895, 1906), and Caullery (1913). 



Very little is known regarding the segregation and 

 early history of the germ cells of hermaphrodites. 

 The principal results have been obtained from studies 

 on Sagitta by Elpatiewsky (1909), Stevens (19106), 

 and Buchner (1910a, 19106), and on Helix by Ancel 

 (1903), Buresch (1911), and Demoll (1912). Boveri 

 (1911), Schleip (1911), and Kruger (1912) have made 

 some interesting discoveries on the chromosome 

 cycle in nematodes, and likewise Zarnik (1911) on 

 pteropod mollusks. To this list we may add such 

 investigations as those of King (1910), Kuschake- 

 witsch (1910), and Champy (1913), on amphibians. 



The segregation of the germ cells in Sagitta was 

 described and figured in Chapter VI (Fig. 54) . Here 

 the first division of the primordial germ cell is probably 

 differential ; one daughter cell becomes the ancestor 

 of all the ova, the other of all the spermatozoa in the 

 hermaphroditic adult. None of the three investi- 

 gators who have studied this subject in Sagitta have 

 been able to discover with certainty any visible differ- 

 ences between the first two germ cells, but Elpatiew- 

 sky thinks the peculiar cytoplasmic inclusion, called 



