430 KING. [Vou XIX. 
nuclei have become arranged in the form of a ring, and the 
only portion of the cytoplasm which does not contain these 
structures is that surrounding the germinal vesicle. As these 
cases are found so infrequently I have not been able to de- 
termine whether the yolk-nuclei later become arranged as 
in Fig. 54, or whether all of them remain at the periphery of 
the egg to take part in the formation of the yolk there. 
In Bufo, as in other amphibians according to the investiga- 
tions of Vogt, Goette, Schultze, Born, Iwakawa, Jordan, and 
Dubnisson, yolk spherules first appear in the outer regions 
of the cytoplasm and usually simultaneously in different parts 
of the egg. There are apparently two methods by which the 
first yolk spherules may be formed in the egg of Bufo. Both 
of these methods sometimes take place in the same egg; 
whether this is true for all eggs Iam unable to say. The yolk 
develops so rapidly that it is difficult to follow the processes 
of its formation in any detail. 
Soon after the stage of development shown in Fig. 54 a 
varying number of small, oval bodies appear in the peripheral 
yolk-nuclei (Fig. 56). These bodies, which stain somewhat 
less intensely than the vitelline bodies, are yolk spherules which 
are being formed, evidently, from the substance of the yolk- 
nuclei. As the yolk spherules increase in number the granular 
yolk-nuclei fade away and they have completely disappeared 
by the time that the yolk forms a continuous layer around the 
periphery of the egg. 
In some cases certain of the vitelline bodies at the periphery 
of the egg grow very large (Fig. 55). The outlines of these 
bodies become irregular (Fig. 52, a), and subsequently they 
break into from two to four rounded, homogeneous pieces 
(Fig. 52, b) which in turn divide into smaller bodies (Fig. 52, 
c-e). As a result of the repeated division of the one vitelline 
body there is formed a mass of small oval bodies (Fig. 52, f) 
which are of the same size and shape as the small yolk spher- 
ules, although at first they stain more deeply than the yolk 
spherules and can therefore readily be distinguished from 
them. Later these bodies stain less intensely and seem to pass 
