THE OVARY OF THE SPERMOPHILE 141 
Microscopic observations of the left ovary. Fixative, acetic osmic ® 
bichromate. Stain, acid fuchsin and methyl green. The left ovary 
shows three luteal stuctures (fig. 16). The largest measures 0.8 mm. 
x 0.8mm. No red granules or lipoid droplets are discernible. The 
greenish-gray granular protoplasm is everywhere filled with various 
sized fat droplets. In some cells these fat droplets are so large that 
they occupy nearly the whole cell, squeezing the degenerated nucleus 
out to one side of the cell (fig. 29). The nuclei are so degenerated, 
no. chromatin strands or nucleolus are recognizable as such. What 
is left of the nucleus takes the acid fuchsin rather than the methyl 
green stain—so it is red. All the blood-vessels and capillaries are 
markedly dilated. There is a marked increase of connective tissue 
throughout the body. The thin capsule of connective tissue which 
before surrounded the luteal structure seems to have disappeared in 
places, making it appear as if the connective tissue of the body were 
continuous with that of the ovary around it. This connective-tissue 
invasion is evidently another factor in the disappearance of the corpus 
luteum. Three factors, then, are associated with the disappearance of 
the corpora lutea in the ovaries, cellular degeneration, vascular dilata- 
tion, and connective-tissue Invasion. 
A word may be added concerning the changes in the ovary 
outside the luteal bodies. There were in this organ six or seven 
good-sized, normal, growing follicles and four and five atretic 
ones. The most noticeable feature is the number of small 
hyalinized follicles. This is a noticeable feature of all the 
ovaries of this date which contain old corpora lutea. It would 
appear that as long as there are still luteal bodies in the ovary, 
there is very little growth in the follicles. There are a few 
primordial ova. The interstitial cells are not recognizable as 
such. By September 1 the corpora have disappeared from the 
ovaries and the organs again have assumed the appearance 
described for September 15. 
There are occasional exceptions to the normal cycle. An 
ovary of spermophile 462, sacrificed October 30, 1916, was 
found with a little structure in it which appeared in every way 
to be a young corpus luteum. The cells contained red granules. 
Perhaps impregnation had occurred in the fall. This instance is 
mentioned because one function of the corpus luteum in spermo- 
philes has been suggested by it. What keeps the follicles from 
becoming mature and ovulation from taking place at other 
times in the year from the spring? Evidently, the corpora 
