No. 2.] THE OOGENESIS OF BUFO LENTIGINOSUS. 429 
of these bodies. I have never found any evidence that would 
support such an assumption. Since these vitelline bodies are 
formed some distance from the yolk-nuclei and are at first 
nearly uniform in size, it would seem as if they must be new 
secretion products of the cytoplasm. ‘There is the possibility, 
however, that they are derived either from the few vitelline 
bodies that were left over after the formation of the yolk- 
nuclei or from the granular substance of which the yolk-nuclei 
are composed. The vitelline bodies increase very rapidly in 
number and in size, and many of them give rise to small granu- 
lar yolk-nuclei, similar to those shown in Fig. 46, which al- 
Ways remain at the outer surface of the egg (Fig. 54). 
While the new formation of vitelline bodies is taking place 
at the egg periphery, the ring of yolk-nuclei is gradually mov- 
ing towards the centre of the egg and at the stage of Fig. 54 
it closely encircles the germinal vesicle. In many cases yolk- 
nuclei seem to come in actual contact with the nuclear mem- 
brane. Whether there is a fusion between these bodies and 
the substance of the germinal vesicle, as Jordan is inclined to 
believe, I am not able to state. There is no noticeable. in- 
crease in the size of the nucleus or any unusual change in the 
nuclear structure as one might expect to be the case were a 
considerable quantity of substance taken at this time into the 
germinal vesicle. .After reaching the germinal vesicle the 
circle of yolk-nuclei stains less intensely and gradually dis- 
appears (Fig. 56). I am inclined to the opinion that their 
substance is dissolved in situ to take part later in the forma- 
tion of the yolk spherules in this region of the egg. This 
view agrees substantially with that advanced in 1859 by 
Thompson and since advocated by Jordan. 
As a rule the yolk-nuclei that are first formed have moved 
close to the germinal vesicle by the time that new yolk-nuclei 
are to be found at the periphery of the egg, and there is a 
cytoplasmic zone between them which is free from vitelline 
bodies or yolk-nuclei (Fig. 54). In exceptional cases, as 
shown in Fig. 53, the formation of the peripheral vitelline 
bodies and yolk-nuclei takes place even before the older yolk- 
