130 GERM-CELL CYCLE IN ANIMALS 
claim that they arise from cells other than germ cells ; 
these writers have been called by Waldeyer (1906) 
“dualists.” An equal number of authorities be- 
lieve that both Sertoli cells and spermatogonia 
Fie. 41.— Stages in the formation of the Sertoli cell in man. <A. Sper- 
matogonium containing granular inclusion (X) from which “ Sertoli 
cell determinant’”’ may arise. B. Antepenultimate spermatogonium 
showing rod (R) and idiozome (I). C. Division of rod. D. A Ser- 
toli cell containing a divided rod (R) and two rodlets (rz). HE. Ser- 
toli cell with crystalloid of Charcot and lipoid granules; at lower 
right corner a spermatogonium with crystalloid of Lubarsch. (A-—D, 
from Montgomery, 1911; E, from von Winiwarter, 1912.) 
originate from primordial germ cells; these are the 
**monists.” 
The researches of Montgomery and von Wini- 
warter have decided the question, at least so far as 
man is concerned, in favor of the monists. Mont- 
gomery’s results are diagrammatically shown in 
Fig. 42. Of thirty antepenultimate spermatogonia 
examined, twenty-three contained each a rod-shaped 
structure (Fig. 41, B, R) and it seems probable 
that this peculiar body, which is identified by von 
Winiwarter with the “cristalloide de Lubarsch” 
(Lubarsch, 1896), is present in every cell of this 
