DEVELOPMENT OF THE EGG OF CLAVA LEPTOSTVLA. 213 



////// rnbnun, has been able to show that in this form spermaries 

 arise first on the mesenteries and that ova appear later, when the 

 production of sperm acini ceases. "The ova grow enormously 

 with the final result that the mass becomes entirely female, con- 

 sisting, usually of two or three large ova. flattened on their sides 

 against one another and occupying the whole area of the former 

 testes." 



Hermaphroditism is also known among Scyphomedusae, Wright 

 having described in some detail the chief features in the case of 

 Chrysaora liyoscclla. He says, " Large individuals are herma- 

 phroditic, but smaller ones are found which are unisexual, the 

 male or female element being suppressed. Small Chrysaoras 

 (about four inches in diameter), have no ovarian bands in their 

 pouches, which only contain masses of the grape -like bodies 

 (testes), and tentacles before mentioned." 



This would seem to imply that here again we have protandrous 

 hermaphroditism, the spermaries developing first, and later the 

 ovaries. Incidentally, it may be observed in passing, that this 

 author in his account of the development of the eggs of this 

 medusa was much impressed with the absence of any germinal 

 vesicle. "The ova of Clirysaora liyoscclla do not present, at any 

 stage, a trace of the germinal vesicle, objects which are so 

 readily detected in the ova of other polypoid Zoophytes." 



Haeckel ('79), who has also studied the development of the 

 medusa, was able to confirm Wright's account as to hermaphro- 

 ditism. " In Uebereinstimmung mit letzteren habe ich gefunden, 

 dass junge Chrysaoren rein mannlich vorkommen, solche mittle- 

 ren Alters meisters Hermaphroditen sind, und endlich ganz alte 

 Thiere meisters nur weiblich sind, oft noch mit Ueberresten 

 mannlicher Organe." 



So far as I have been able to discern in the case of Clava, there 

 is no evidence to indicate the operation of either of these oscil- 

 lating phases of sexualism. I have specimens taken at all times 

 of the breeding season and have found no tendency toward the 

 one or the other. I am rather disposed to regard it as an 

 expression of a mutative impulse, in response to which in other 

 forms, such as those already cited, these interesting features 

 became established. 



