HERMAPHRODITISM IN EURYCEA BISLINEATA. 365 



Bouin ('oi) and Dustin ('07) for other species of Amphibia 

 (mainly Anura), and Okkelberg ('21) for the brook lamprey, but 

 also a complete bridging over of the gap between the early de- 

 velopmental phenomena and the seasonal sexual phenomena of 

 adult life. 



With regard to the bearing which occasional hermaphroditism 

 such as this has upon its regular occurrence in certain species of 

 animals, and upon the significance of the phenomenon in general, 

 two opposing views are held. One of these, as set forth by Don- 

 caster ('14), regards hermaphroditism not as a primitive but as a 

 purely secondary condition. This opinion is based mainly on the 

 fact that the hermaphroditic species of animals are, for the most 

 part, highly specialized ones. Sporadic hermaphroditism is thus 

 considered an example of variation along this same direction. 



The other view is that which has recently found so vigorous a 

 supporter in Jordan ('22), that hermaphroditism, at least in the 

 vertebrate group, is a primitive character. Jordan points out " the 

 abundant evidence of a normal hermaphroditic condition either 

 adult or juvenile, among lower vertebrates (e.g., tunicates, cyclo- 

 stomes, probably some Amphibia)," and that "the early gonads 

 with their primordial germ cells appear identical." This view of 

 the primitive character of hermaphroditism naturally goes hand 

 in hand with the theory that sex determination is a matter of dif- 

 ferential metabolism and that forms in which sex determination 

 has become bound up in the chromosomes represent a higher stage 

 in metabolic control of the developing organism. 



Jordan points out the peculiar interest presented by the case of 

 amphibians in this connection, since most investigators have 

 failed to find any evidence of a sex chromosome in this group, al- 

 though King ('12) describes it for Nee turns maculatus, Levy 

 ('15) for Rana csculenta, and Swingle ('17) for Rana pipiens. 

 In a later paper, however, Swingle ('21) questions the correctness 

 of his own earlier identification of an accessory chromosome in 

 Rana pipiens and suggests the strong probability that Levy may 

 also have been mistaken. 



Jordan makes the suggestion that the Amphibia may consti- 

 tute a group in which the evolution of the sex chromosome as a 

 separate element can be traced, and in which also a general ten- 



