THE OVARY OF THE SPERMOPHILE 135 
Experiment 264-16 (spermophile 302). Captured May 1, 1916, and 
sacrificed the same day. 
Gross observations. This animal is definitely pregnant, the fetuses 
measuring 7 mm. in length. The blood-vessels going to the uterus 
and the ovary are very much congested. They stand out sharply, 
showing plainly the blood supply to the two organs. The blood supply 
to the ovary is practically separate from that to the uterus, there being 
only one small anastomosing branch close to the ovary. There are 
what look like corpora lutea in the ovaries, but they cannot be counted 
with any certainty. They resemble little reddish-pink cysts sticking 
out from the surface of the ovary. Naturally, from the size of the 
fetuses, the corpora lutea in these ovaries are older than those of sper- 
mophile 328. 
Microscopic observations of the left ovary. Fixative, acetic osmic 
bichromate. Stain, acid fuchsin and methyl green. There are four 
luteal structures in this ovary. They show some changes over the 
younger ones previously described. They are slightly larger, measur- 
ing about 0.7 mm. x0.8mm. The luteal cells have become larger and 
more regular in shape. Many more have assumed an oval form and 
all seem to be approaching this. They seem to be tending toward a 
radial arrangement also. This is being effected evidently by the ar- 
rangement of the connective-tissue strands. The latter are running 
from the capsule to the central core of blood, which is almost organ- 
ized. The system of capillaries and blood-vessels is even more com- 
plex than that of the luteal body of spermophile 328. In the luteal 
cells themselves the red granules have increased in number and vary 
slightly in size. They occupy the same position in the cell. The 
nuclei of all the cells are larger and contain one or two large bright 
nucleoli with numbers of very fine chromatin strands. 
Experiment 296-16 (spermophile 331). Captured and _ sacrificed 
May 6, 1916. Weight, 146 grams. 
Gross observations. The fetuses in the uterus are 1 ecm. in length, 
which lead us to expect to find changes in the corpora lutea of the 
ovaries. 
Microscopie observations of the left ovary. Fixative, acetic osmic 
bichromate. Stain, acid fuchsin and methyl green. The size ofthe 
luteal structures has increased. There are two in this ovary, one 
measuring 0.9 mm. x 0.9 mm., and the other, 1 em. x 0.8 mm. The 
most noticeable feature of this later luteal body is the absence of any 
blood in the center. Instead, there is a core of connective tissue. The 
size of this connective-tissue core depends evidently on the amount of 
hemorrhagic material there is to organize. In some bodies the core is 
much larger than in others. Very perceptible strands of connective 
tissue run from this central mass to the capsule, enclosing columns of 
luteal cells. Gross strands have developed also so that connective- 
tissue strands seem to be enveloping each cell. There is a complete 
capillary network following the arrangement of the strands of connec- 
tive tissue. Good-sized blood-vessels are located about the periphery 
