SPERMATOGENESIS IN THE ALBINO RAT 161 



syncytium that persists into the adult stage. Later ('01) he 

 concludes that the Sertoli cells spring from an early type of cell 

 which he calls 'stem spermatogonia.' These stem spermatogonia 

 have previously fused to form a syncytium which persists in the 

 adult tubule as long as spermatogenesis continues. Neither 

 Schoenfeld (bull) nor Duesberg (rat) agree with this interpreta- 

 tion. Schoenfeld concluded that both the Sertoli cells and the 

 spermatogonia arose from the indifferent cells. Duesberg omits 

 consideration of the Sertoli cells, but regards these indifferent 

 cells as spermatogonia of one type. These divide and produce a 

 second type of spermatogonia (my type B), and these in turn hy 

 division produce the spermatocytes. This type B cell had been 

 called by Lenhossek ('98) krustenartige and by Regaud croutel- 

 leuses cells. 



In my figures cell type A corresponds with the indifferent or 

 poussiereux (granular) cell, while type B corresponds with the 

 croutelleux (crusty or flaky) cell. It has been noted above that 

 these cells have been regarded as two kinds of spermatogonia. 

 The evidence which I present from the young tissue (figs. 2 to 9), 

 in connection with other evidence which I cite later, leads me 

 to think that there is only one type of spermatogonium, and that 

 this flaky cell (type B) is a first spermatocyte cell in its earliest 

 history, representing the reorganization of the chromatin from 

 the telophase condition of the last spermatogonial division of 

 this cell. Its confusion with spermatogonia may have arisen 

 from the fact that it appears in the adult testis next to the limiting 

 membrane, even to such an extent that in some cross-sections of 

 tubules no other kind of cell can be seen there, and in longitudinal 

 sections a considerable length may be occupied by these cells, 

 frequently to the exclusion of all others. My interpretation of 

 such aggregations of this particular type of cell is that they are 

 the product of a number of actively dividing spermatogonia 

 (type A) in their particular phase of the spermatogenic wave. 

 If successive sections of such regions are examined it is found 

 that Sertoli cells and cell type A are present also in some sections, 

 the latter perhaps in small numbers. 



JOURNAL OF MORPHOLOQT, VOL. 31, NO. 1 



