SEX-CELLS OF AMIA AND LEPIDOSTEUS 21 
76. Of these all were in the sex-gland anlagen except three; one 
of which occurred in the gut-entoderm and two in the parietal 
peritoneum. I am inclined to consider it unlikely for these mis- 
placed sex-cells to reach the sex-glands. One is struck, however, 
with the great difference in the relative number of misplaced sex- 
cells in Amia as compared with Lepidosteus. This may be 
apparent rather than real, owing to the possibility that in Amia 
large numbers of them may have failed to migrate from the ento- 
derm into the mesoderm during early stages. Owing to the diffi- 
culty of certainly distinguishing sex-cells in the entoderm from or- 
dinary entoderm cells, it was quite impossible to make any count 
of those left behind in migration. All but avery few, however, that 
reach the mesoderm succeed, as we have seen, in reaching the sex- 
gland anlagen. A considerable number of cells seen in the ento- 
derm in later stages contain small yolk spherules and show other 
points of resemblance to sex-cells. In this stage the mesentery 
has become quite lengthened and the coelome very large. The 
sex-cells have penetrated into the root of the mesentery, fig. 
20. 
The sex-cells, with rare exceptions, still contain large quanti- 
ties of yolk material. In these exceptional cases a finely granular 
appearance gives at least the suggestion of small unstained yolk 
spherules. The yolk appears in the shape of particles varying 
in size from small granules up to large lemon-shaped pieces quite 
as large as those with which the cells of the yolk entoderm are 
so completely filled. 
Amia 11.4 mm., total length. The sex-cells are fairly numerous 
over a region 1.85 mm. in length, beginning at a point 0.06 mm. 
back of the yolk stalk and ending at a point 0.85 mm. cranial 
to the cloaca. Two isolated sex-cells are found caudad to the 
point named, one of them occurring very close to the cloaca. 
Their total number in this embryo is eighty-two. The sex-cells 
have much the same characteristics as in the previous stage. 
This stage is marked by a decided increase in the length of the 
mesentery and by a decrease in the size of the yolk-sac, which is 
now but 0.7 mm. in diameter and is greatly hollowed out to 
form a portion of the intestinal wall. 
