GERM CELLS OF ANURANS 279 
study of the serm cells of Rana pipiens the writer arrived at 
essentially the same conclusions, and only after a study of the 
germ-cell cycle of the bullfrog was it possible to unravel the puzzle. 
The writer does not believe that females transform into males or 
vice versa, nor that tadpoles develop solely as females during early 
stages. A correct interpretation is possible only by comparing 
the bullfrog tadpole with other forms. In the germ-cell cycle of 
the larvae of most species of anurans, for example, forms like Rana 
pipiens with short periods of larval life, the precocity of the mat- 
uration cycle is apparently very marked and evanescent, hence it 
is more obscure and difficult to interpret than that of the bullfrog. 
But perhaps the most remarkable example of precocity of the 
larval germ-cell cycle is presented by Bufo. In the toad the 
early maturation phenomena of the germ cells, i.e., leptotenej 
amphitene, and pachytene stages, appear in extremely young 
larvae, about two weeks after hatching and are confined chiefly 
to the anterior end of the male and female gonads, i.e., that por- 
tion which develops into the organ of Bidder. The ripening pro- 
cess does not go beyond the pachytene stage apparently before the 
cells become senescent. The question whether or not Bidder's 
organ is or is not a rudimentary hermaphrodite gland is reserved 
for discussion in another paper. A very brief and curtailed 
sketch of the writer's view of this structure in the toad and the 
so-called hermaphroditism of the Anura will be found in the 
American Naturahst for July-August, 1920. 
There appears to be some sort of correlation in anurans 
between length of larval fife and stage in development to which 
the ripening of the germ cells is carried before degeneration. 
The whole problem of sex development and sex differentiation of 
anuran larvae needs reinvestigation in the light of these obser- 
vations on the bullfrog tadpole. 
7. Significance of degeneration of sexual elements derived from 
primordial germ cells 
It is with considerable reluctance that the writer touches upon 
this particular phase of the problem in this paper, which is to be 
regarded as a cytological introduction to a more extensive report 
