er 
show very clearly that there is no period during the season of in- 
activity at which spermatogonia are absent, or even of extreme rarity. 
Erzotnp (91) and after him LoıseL (02) have shown that the 
testis of Passer (Fringilla) is reduced greatly in weight during the 
winter. This is due to a reduction of the seminiferous tubules to one 
tenth of their former diameter and to a fraction of their functional length. 
I have found from numerous measurements that the seminiferous 
tubules of Chrysemys suffer in the winter an average reduction to four 
tenths of their diameter during the periods of sexual activity. There 
results from this, a certain concentration of tissues, which is no doubt 
of importance in allowing a distribution of the spermatogonia to neigh- 
boring parts of the seminiferous tubules devoid of them when sexual 
activity ensues in the early spring. 
Quite diverse views have been held regarding the nature and fate 
of the sex-cells. WALDEYER ’70, BALBIANI ’79, Bourn ’90, LOISEL 702, 
and others have considered them to be female elements doomed to 
degeneration in the testis. BALBIANI ’79 held a curious view of their 
significance in the testes of the Elasmobranchs and Amphibians. He 
found them to be sourrounded by follicle cells .of peritoneal origin, 
each of which became elongated and entered into a vague copulation 
with a cell cut off from the sex-cell (primordial ovum). As a result 
of this process, the follicle cells rapidly divided and formed a large 
number of spermatogonia. 
MIHALKOVICS ’85 claims that in embryos of Lacerta agilis of 
12—14 mm length, the sex-cells (große Geschlechtszellen) are found 
to have almost wholly disappeared from the peritoneum. According 
to his view, they have migrated into the stroma, to give rise by re- 
peated division to a blastema which will eventually be organized into 
sex-cords, while the oögonia arise by differentiation of cells of the 
germinal epithelium. 
Braun ’77, Roucet ’79, Nusspaum ’80, HOFFMANN ’86, ’89, ’92, 
EIGENMANN ’92 and ’96, and many others. have called attention to 
the remarkably close resemblance between oögonia and spermatogonia 
during embryonic stages. I can fully substantiate this in Chrysemis, 
not only as regards the embryonic stages, but in adult life as well. 
Summary. 
1. The sex-cells of Chrysemys are first observed in the hypoblast 
at the edge of the area pellucida, in a zone extending on each side 
from a point opposite the anterior portion of the pronephrous, to a 
point behind the embryo. 
