354 



THE AMEBIC AX NATURALIST 



[Vol. LIV 



Probably the larval sexual cycle just mentioned is an 

 interesting example of a "carrying over" in ontogeny 

 of an earlier phylogenetic condition when the Salientia 

 were sexually mature and normally reproduced as larvae. 

 It is interesting to note in this connection that male 

 anuran larvae whose period of metamorphosis is indefi- 

 nitely postponed, as for example by thyroid extirpation, 

 readily mature sexually, in so far as the production of 

 ripe spermatozoa is concerned. 



The male germ cells, unlike those of the female, do not 

 undergo growth, except in relatively rare instances to 

 be described later, and consequently do not fill up the 

 lumen of the gonad. This lumen later is obliterated by 

 the migration into the gonads of cells from the mesentery 

 and possibly from the cortical substance of the adrenal 

 gland. From this ingrowth the testicular interstitium 

 and rete apparatus develops. The efferent tubules at 

 the time of metamorphosis form a connection with the 

 mesonephros. The true sex cords of the testis arise as 

 proliferations of the germinal epithelium, and not as 

 so often claimed for amphibia, as ingrowths from the 

 mesonephros. 



This phenomenon of precocious ripening of the male 

 germ cells of Bana catesbiana larvae undoubtedly occurs 

 in other Anura, though is not carried so far as in the bull- 

 frog. The figures of Kuschakewitsch and Witschi show 

 clearly that this condition exists in Bana esculenta and 

 Bana temporaria. Indeed, it seems more than likely that 

 these writers have mistaken male frog larvte whose germ 

 cells were in early pseudo-reduction stages, for hermaph- 

 rodites and females. The so-called sexually indifferent 

 or sexually intermediate forms of the Pfliiger-Hertwig 

 school are very probably male animals whose germ cells 

 show precocious ripening as far as the pachytene stage. 

 This is plainly evident from their photographs, drawings 

 and descriptions. This probable misinterpretation of the 

 cytological data accounts for the transformation of such 

 so-called hermaphrodites into male animals, so minutely 

 described by these investigators. Using the chief cri- 



