356 THE AMERICAN NATURALIST [Vol. LI V 



disappearance, they are similar in every way to the cells 

 of Bidder's organ. Their follicles are derived from sur- 

 rounding peritoneal or stroma cells. These follicles are 

 commonly observed surrounding isolated spermatogonia. 

 In certain male gonads a few cells grow to the size of 

 oocytes, and possess yolk nuclei. The presence of yolk, 

 however, is no sex criterion for the male germ cells of 

 many animals form yolk as for instance Ascaris, and the 

 apyrene spermatozoa of certain Prosobranchs, and the 

 degenerating cells of the frog. 



The larval spermatocytes of the first maturation cycle 

 are in many instances of enormous proportions, scarcely 

 smaller than many organs of Bidder cells near the end of 

 their cycle. It is not impossible that there may be a 

 genetic relation between these two types of testicular ele- 

 ments. This question is reserved for further discussion 

 in a later paper. 



The writer is of the opinion that these "oocytes" are 

 of the same nature as the cells of Bidder's organ in Bufo. 

 It might be suggested as a possibility worthy of consid- 

 eration, that in male animals such cells may be of true 

 male character, but owing to the precocious sexual cycle, 

 itself a vestige of a primitive phylogenetic condition 

 when the Anura were sexually mature in the larval form, 

 a few of the germ cells are unable to complete their cycle, 

 and simply grow to an abnormal size, thus assuming the 

 unspecialized character associated with oocytes. These 

 cells degenerate during the second larval maturation 

 cycle when normal sex products are produced. It is 

 rather significant that the whole first larval sexual cycle 

 is abortive in almost every feature. For instance the 

 spermatocytes are abnormally large, the tetrads equally 

 so, the first maturation division never proceeds past the 

 anaphase, the centrosomes fragment, form polyasters, 

 and sometimes axial filaments. Entire cysts of perfectly 

 formed spermatocytes go to pieces in the very act of divi- 

 sion, and most of the germinal elements show marked 

 evidences of a deep seated protoplasmic disorganization. 



In view of these facts it is possible that the cells of 



