GERM CELLS OF ANURANS 259 
During late stages of diakinesis the cells in many cases become 
greatly enlarged and in many instances are of giant proportions 
(figs. 64, 67, 112). The increase in volume may affect either nu- 
cleus or cytoplasm or both. It is rather common in my material 
to find over one-half or two-thirds of a nucleus in a single section 
because of the size, and it may be added that my material was sec- 
tioned at a thickness of 8 to 10 ^u. These large spermatocytes 
of the larvae resemble those of urodeles more than adult anurans. 
It is an interesting and suggestive fact that near the period of 
metamorphosis the elongated, more or less ribbon-Hke testis be- 
comes transformed into a very small typically shaped frog tes- 
tis. The shortening process may require a considerable time, 
though the writer is inclined to doubt this on account of the 
absence of transition stages. The shortening progresses from 
posterior to anterior and may amount to as much as 1 mm. 
Figure 35 is a section through gland from a newly metamorphosed 
animal; figure 34 a gland of the second season (before meta- 
morphosis) ; figure 33 a section of a gland of a first season larva. 
Examination of the small, fully formed testes (full formed 
except for the efferent or rete apparatus) of recently metamor- 
phosed animals reveals some interesting size differences of the cellss 
compared with those of the gonads of young larvae of the first 
season. The cellular elements of the small gonads are more nearly 
like those of the adult, and it is rare to find the giant spermatocytes 
of the type figured in plates 7 to 13. The primary spermatogonia 
are of about equal size with those of the younger tadpoles, the 
chief differences are in the spermatocytes and diplotene and 
pachytene nuclei. These small testes first appear in tadpoles 
measuring 120 mm. or more from snout to tip of tail. Such ani- 
mals are about a year and a half old or perhaps somewhat younger 
and are due to metamorphose the following summer. The hind 
legs are on the average about 25 to 30 mm. ; the fore hmbs are not 
visible. Now, oddly enough, some of the male animals are 
mature, in so far as the possession of ripe spermatozoa is con- 
cerned. And, as we shall shortly see, this character marks off 
this type of gland from those of the first-season larvae. As was 
stated before, the bullfrog tadpole passes approximately two 
