No. 2.] THE OOGENESIS OF BUFO LENTIGINOSUS. 421 
the germinal vesicle into the cell body, and he also is inclined 
to the opinion that nucleus takes part in the formation of 
yolk. “One might suppose that granules from the germinal 
vesicle serve as starting points, centers of attraction or stim- 
ulation as it were, while the cytoplasm perhaps through the 
mediation of the yolk-nuclei, elaborates and supplies he 
requisite deutoplasmic material out of nutritive elements fur- 
nished it by the follicle cells.”’ 
Since it is seemingly impossible to harmonize these various 
observations regarding the yolk-nuclei and the yolk in the 
egg of amphibians, it can only be supposed, if these observa- 
tions are correct, that the processes by which yolk is formed 
differ in various species. ‘The details of these processes must, 
therefore, be worked out for each species separately, since 
there is no apparent similarity between them even in closely 
related forms. 
In the egg of Bufo it is possible to trace the anlage of 
the yolk-nuclei back to the primordial germ-cells. As I have 
already stated, there is present in the cytoplasm of these 
cells a small, round, apparently homogeneous body which is 
sometimes, though not invariably, separated from the cyto- 
plasm by a clear area (Fig. 8, V). This body colors very 
intensely with iron hematoxylin, and it always takes the saf- 
ranin when sections are stained with safranin and gentian vio- 
let or with safranin and Lichtgriin. In preparations stained 
with Delafield’s hematoxylin and orange G. this body is 
hardly discernible, since it takes the orange stain as does also 
the cytoplasm. Judging from its staining reactions this body 
is not chromatin; neither is it a centrosome, since the same 
section of the cell may show both of these structures (Fig. 
7). I have not been able to determine the origin of this body 
owing to the fact that in very young tadpoles the large yolk 
plaques in the primodial germ-cells obscure the other cyto- 
plasmic structures, while in older tadpoles, when the yolk is 
beginning to be absorbed, the small yolk granules show the 
same staining reactions as this body and therefore cannot be 
distinguished from it. Not until the tadpole is at least thir- 
