No. 2.] DEVELOPMENT OF BIDDER’S ORGAN. 443 
their effects on the latest development of the cells of Bidder’s 
organ are far reaching since, after the stage of Fig. 8, the 
nuclei of these cells appear, as a rule, very different from the 
nuclei of the same size in the ovarian ova. The development 
of the ova in Bidder’s organ is similar to that of the germ- 
cells in the ovary only until the synizesis stage. During the 
time that the chromatin forms a contracted mass in the centre 
of the nucleus changes occur which check normal development 
and eventually bring about a degeneration of the cells. Just 
what these changes are it is impossible to determine. A com- 
parison of the early post-synizesis stages in the cells of Bid- 
der’s organ with similar stages in the ovarian ova indicates 
that during the contraction period in the cells of Bidder’s 
organ the chromatin does not become arranged in a normal 
manner, since in later stages there is no separation of the 
chromatin that is normally used for the chromosomes from 
the chromatin that has other uses in the cell, as is the case 
in the ovarian ova. The turning point in the development of 
the ova in Bidder’s organ is, therefore, the synizesis stage. 
Since normal development is not possible beyond this period, 
except in rare instances, it is evident that the causes which 
bring about the degenerative processes in the cells of Bidder’s 
organ manifest themselves during synizesis and that they act 
in such a way as to prevent a normal arrangement of the 
chromatin granules. Since the amount of chromatin in the 
nucleus is apparently not affected by these changes it must 
be that it is the arrangement of the chromatin granules that is 
the important thing in synizesis. The fact that the cells of Bid- 
der’s organ show degenerative changes and divide by ami- 
tosis soon after synizesis strengthens my belief that synizesis 
in the egg of Bufo is a means by which the chromatin which 
bears the hereditary qualities is separated from the chromatin 
which has other uses in the cell. This separation is not ef- 
fected during the synizesis stage in the ova of Bidder’s organ, 
consequently these cells are not capable of developing into 
functional eggs. 
Since Bidder’s organ develops much more rapidly than the 
sex-gland, it is possible, perhaps, that the rapid growth of the 
