Artificial Parthenogenesis in Frogs 275 



starfish and some annelids by gentle agitation, in the egg of 

 the frog it can be done by puncturing the surface layer. 

 Future experiments will decide whether or not the leucocytes 

 play the role of the second factor which Bataillon ascribes to 

 them. 



Loeb and Bancroft tried to ascertain the sex of the par- 

 thenogenetic frog and tadpole which they obtained. The 



Fig. 76 Fig. 77 



Pigs. 76 and 77.— Parthenogenetic frog and parthenogenetic tadpole (nat- 

 ural size). 



gonads contained eggs in both cases. This at first sight might 

 I x.i_... x_ ;., j:..4.„ i-j^g^^ jjQ^jj -^yere females, but the problem is 



compiiuaieu uy wie lact found by Pfluger, and recently worked 

 out by Kuschakewitsch,! ^j^^t very often in the early stages the 

 gonads of a frog may contain eggs which afterward degenerate. 

 Such "intermediates" may develop into males. 



The gonads of the parthenogenfetic frog obtained by Loeb 

 and Bancroft agreed with Kuschakewitsch's description of 

 an "intermediate" which is in the process of developing into a 

 male. 



' Kuschakewitsch, Festschrift f. Richard Hertwig, Bd. II. p. 145, 1910. 



