SPERMATOGENESIS IN THE ALBINO RAT 165 



I have made only a slight study of the Sertoli cells of the rat, 

 but think there are certain differentiating characters not yet 

 described which appear in the early history of the cells, and which 

 I hope to discuss at length in another paper that will deal more 

 fully with the problem of origin and differentiation. No such 

 distinguishing body as the rod which has been described in man 

 by Montgomery ('11) and Winiwarter ('12), and in the cat by 

 Hague ('16), appears in the cytoplasm of the Sertoli cells of the 

 rat, so far as I can see, nor has any been noted by other workers. 

 In the young testes I find only cells of type A present, and am 

 inclined to think with Winiwarter (man) that the Sertoli cells 

 develop from these, their develoi)ment being controlled by the 

 factors which control growth. 



Regaud ('01) describes degenerating spermatogonia, especially 

 numerous in one stage of the spermatogenic wave. Duesberg 

 ('08) reports that he finds nothing of the kind. I have found 

 in nearly every individual cells such as Regaud describes as 

 degenerating spermatogonia, but they are not confined to any 

 particular phase of the wave. They occur most commonly in 

 rats which are not up to par for some reason not yet fully deter- 

 mined. These cells, as Regaud states and figures, possess a 

 spherical nucleus in which are some chromatic bodies, either 

 spherical or elliptical, of variable size and number. These 

 masses, Regaud states, fuse and gradually disintegrate. Con- 

 trary to Regaud, neither Duesberg nor I find any evidence of 

 amitosis. 



In concluding this discussion, I shall call attention to the con- 

 clusions of Popoff ('09) and Swift ('16) on the development of the 

 sex cells. Popoff finds from his studies in vertebrates that the 

 germinative epithelium early differentiates two kinds of cells, the 

 'male ovule' and the follicle cells. With the lower vertebrates 

 (fishes and amphibians), the male ovules develop into sex cells, 

 the follicle cells into the cells of Sertoli. The male ovules of 

 Scyllium show no signs at all of degeneration. In amphibians 

 and reptiles some male ovules degenerate. With the higher 

 vertebrates (birds and mammals), all the male ovules of the 

 first generations disappear, leaving only one kind of cell, which 



