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occurred simultaneously in the sex-gland anlage, between the splanchnic 
mesoderm and endoderm, in the endoderm, and even in the germinal 
wall itself. While he thought it possible that they migrate into the 
sex gland anlage, he could not decide whether they do so, or whether 
they degenerate in situ. 
I have found in Chrysemys that many of the sex-cells never mi- 
grate out of the endoderm, but remain there, some of them persisting 
for a long period. I found numbers of them in the colon of a young 
turtle killed three months after hatching. How much longer they may 
persist, I am unable to say. EIGENMANN (’92 and ’96), BEARD (00 
—’04), and others have made similar observations among the fishes. 
These facts may lend some support to BEARD’s (00) hypothesis to 
account for the origin of dermoid cysts, although they constitute but 
a Short advance in one line of work which future investigation should 
undertake, in order to test it. A number of sex-cells pass dorsad 
above the root of the mesentery until they come to lie in the loose 
mesenchyme immediately beneath the aorta, and often slightly to either 
side in the anlagen of the adrenal bodies. It would seem very un- 
likely that they should contribute to the formation of the latter. Their 
fate has not been determined, but it is certain that they persist in 
these regions until after the sex glands have begun to form. Those 
sex-cells which find their way to the sex gland anlagen, pass into the 
peritoneum which soon after begins to form the sex-cords as outlined 
in a previous paper — ALLEN (05). We shall speak of them as being 
imbedded in the peritoneum, not as a part of it. 
EIGENMANN (96), BEARD (’00—’04), Woops (’03), and Bönı (704) 
have determined by actual counting that during these early stages and 
up to about the end of the period of migration there 1s no multipli- 
cation of sex-cells. Nusspaum (80), WHEELER (99), and others have 
held the same view, based on the abscence of any evidence of cell 
division. I am, for the same reason, inclined to share this view. 
In Chrysemys, so soon as the sex-cells have finished migrating, 
they begin to undergo important changes. The nucleus, instead of 
possessing one nucleolus as in earlier stages, usually contains two. The - 
chromatin has a much coarser appearance, the chromatin granules 
being larger and far more clearly defined than in the earlier stages. 
A centrosphere is to be found in most cells. In many primitive sex- 
cells, the yolk spherules are wholly absent, while in most, they show 
reduction in size and number. Throughout all succeeding stages until 
alter sex-differentiation has become clearly evident — total length 
18 mm, carapace length 11 mm — these yolk spherules may still be 
