THE OVARY OF THE SPERMOPHILE © 137 
When the lipoid droplets appear in the cells, the period of the red 
granules is waning. The latter seem to reach their crisis of abundance 
when the fetus measures about 8 mm. in length. But the granules are 
still very abundant in the cells until the lipoid droplets begin to appear. . 
From this time on, the former grow fewer and fewer and the latter 
increase in number, as will be shown, until they, too, reach a crisis of 
abundance and then decline. 
Experiment 363-16 Garenonhale 383). Captured and _ sacrificed 
May 24, 1916. Weight 140 grams. 
Gross observations. The animal was in labor when killed. The 
uterus still contains two live fetuses, four having already been born. 
The crown-rump measurement of a fetus is from 4 to 5 em. 
Microscopic observations of the left ovary. Fixative, acetic osmic 
bichromate. Stain, acid fuchsin and methyl green. The luteal struc- 
tures in the ovaries of this animal show some changes over those pre- 
viously described (fig. 18). There are four of them. They have 
increased slightly in size, measuring 0.9 mm. x 0.9 mm. and the indi- 
vidual cells have increased correspondingly. Still more noticeable 
than their increase in size is the regularity of their oval form and the 
uniformity with which all their axes point in a radial direction. This 
seems to be due to an increased amount of connective-tissue frame- 
work, which, from the first, has seemed to govern the position and 
shape of the cells. The increase of connective-tissue framework has 
been accompanied by an increase in the size of the blood-vessels and 
capillaries. In the luteal cells (fig. 27) the red granules have decreased 
still more than in the cells last described, and this is very general 
throughout the structure. The lipoid droplets are much more numer- 
ous in all the cells. In fact, it seems hard to tell which is the predom- 
inant product of the cells, the red granules or the black droplets. The 
nuclei of these cells are slightly larger than the ones of the preceding 
,description. Otherwise, they are the same. Most writers have agreed 
“that degeneration of the corpus luteum begins about the time of birth. 
None is in evidence here. Several writers have stated that the prin- 
cipal reason for their belief was the entrance into the cells of osmic 
staining droplets which they considered to be evidences of fatty degen- 
eration in the cells. It would not seem from the nuclear character- 
istics of the cell nor from the color, shape, and the regular size of the 
droplets, that they could be fatty degeneration products, especially 
when compared with the true fatty degeneration which occurs much 
later in the life history of the corpus luteum and which will be described 
accordingly. 
Microscopic observations of the right ovary. Fixative, formalin 
zenker. Stain, hematoxylin and eosin. There are two corpora lutea 
in this ovary. A striking feature is the number of good-sized atretic 
follicles. There are at least twelve. This seems to be a noticeable 
feature of other ovaries about this same time. In fact, the follicles 
which were growing when ovulation took place, evidently go on and 
develop if there are not too many corpora lutea in the ovary, but as 
