Nor 2,1 DEVELOPMENT OF BIDDER’S ORGAN. 451 
in the cytoplasm which at first have the shape and size of the 
yolk-nuclei (Fig. 29). Later these spaces are united and the 
cytoplasm then contains several large vacuoles (Fig. 27). In 
cases in which the cytoplasm contains only a few large yolk- 
nuclei instead of a number of small ones (Fig. 18), these 
masses become sharply marked off from the cytoplasm when 
degenerative changes begin and they stain much more in- 
tensely than before. The appearance of these bodies thus be- 
comes so very different from that of the yolk-nuclei shown in 
Fig. 19 that it might be thought that they were not yolk-nuclei 
but the products of a fatty degeneration of the cytoplasm. In 
order to determine this point definitely several cells appearing 
much like that shown in Fig. 18 were drawn with the aid of 
a camera lucida and the preparations containing them were 
then put in ether where they remained for about two weeks. 
At the end of this time the slides were remounted and the 
same cells were again drawn. The irregular granular masses 
had not been affected in any way by the ether and they were 
just as large and conspicuous as before. These bodies cannot, 
therefore, be products of a fatty degeneration of the cytoplasm 
or they would have been dissolved by the ether. Soon after the 
stage of Fig. 18 these masses dissolve in situ and several large 
vacuoles are formed in the cytoplasm which later become 
connected as in Fig. 27. 
Knappe maintains that there are four ways by which the 
rudimentary eggs in Bidder’s organ disintegrate: (1) through 
the penetration into the cytoplasm of follicle cells which ab- 
sorb the egg substance; (2) through the development of pig- 
ment in the cytoplasm which seems to bring about a gradual 
collapse of the egg; (3) through the invasion of the cytoplasm 
by both follicle cells and blood capillaries; (4) through pig- 
ment formation combined with the penetration of blood capil- 
laries into the egg. To these Ognew, from his study of 
Bidder’s organ in Bufo vulgaris, adds a fifth method—a pecu- 
liar process in which the follicle membrane between two ad- 
jacent odcytes disappears leaving a space which grows in 
breadth and finally becomes a large spherical vacuole which is 
