136 DELLA DRIPS 
of the structure. Several smaller ones are present in the central con- 
nective-tissue core. There are several sinuses about the periphery 
lined with endothelium which appear to contain lymph. The lutea 
cells themselves have increased in size. Many more have taken on an 
oval shape and are lying with their long axes perpendicular to the 
capsule. The same red granules are still present in the protoplasm. 
These do not seem to be quite as numerous in the cells, which fact is 
in part due, no doubt, to the increased size of the latter. The granules 
are now found scattered throughout the protoplasm, the clear zone 
about the periphery of the cell having disappeared. The granules 
show more difference in size than formerly, but they are still all spher- 
ical. The nuclei have not changed. In a few cells there is a clear 
space in the protoplasm on one side of the nucleus. 
Microscopic observations of the right ovary. Fixative, formalin 
zenker. Stain, hematoxylin and eosin. There are seven corpora lutea 
which make this ovary larger than the other one. Beside these bodies, 
this ovary contains approximately five good-sized, growing follicles 
about 0.4mm.x 0.4mm. Four follicles nearly the same size are under- 
going atretic changes and there are about twenty small follicles, some 
of which are degenerating. Around the edge of the ovary are a few 
primordial ova. Through the medullary portion are some small 
groups of interstitial cells. They are not nearly as conspicuous as 
they were earlier in pregnancy (fig. 14). 
Experiment 355-16 (spermophile 375). Captured May 20, 1916. 
Both ovaries were removed May 22, 1916. Weight, 128 grams. 
Gross observations. The fetuses in the uterus are 1.5 cm. in length. 
Microscopic observations of the right ovary. Fixative, acetic osmic 
bichromate. Stain, acid fuchsin and methyl green. There are six 
corpora lutea in the right ovary, measuring about 0.8 mm. x 0.9 mm. in 
diameter. Something is.noted in the luteal structures in this ovary which 
has not been seen before, namely, that there are present in the cells close 
to the periphery some osmic-stained droplets. The size of the corpus 
luteum and the size of the individual cells are about the same as that 
of spermophile 331. There is a slight increase in the number* of red 
granules in the cells. The clear space next to the nucleus is present 
in many more cells. The osmic-stained droplets are located at the 
periphery of the cell. They are very large compared with the red 
granules. They vary somewhat in size, but not in shape; all are 
spherical. Of course, in sections fixed with formalin zenker and stained 
with the various stains which were used, these lipoid droplets appeared 
as vacuoles. But they could be easily recognized by their correspond- 
ing size and location in the cells. For convenience, these droplets 
will be called lipoid droplets, because they certainly are a lipoid prod- 
uct. They do not appear in the luteal cells before the fetus is about 
1.5 cm. in length or about fourteen days old, that is, until the period 
of pregnancy is half over. These droplets make up the ‘lutein’ of the 
corpus luteum. which has been described for many years and which 
has given the corpus luteum its name. 
