The Generative Organs 17 



fact in relation to the persistence of the true corpus luteum 

 during pregnancy is a well marked tendency to abortion when 

 the ovaries are removed from a pregnant female, or the corpus 

 luteum is forced out of the ovary by crushing or otherwise. 



The size and form of the ovaries differ greatly according to 

 species, age and individual and even the two glands in the same 

 animal are not ordinarily alike and may vary greatly in size. 



The ovary of the mare is much the largest seen in the domes- 

 tic animals, reniform, very dense owing to its thick tunica albu- 

 ginea, with a smooth surface which is elevated here and there in 

 many cases by the presence near the surface of cystic Graafian 

 follicles. It attains its maximum size at the age of two or three 

 years and begins to atrophy at ten to fifteen years, to finally 

 become very small as age advances. The ovary of the young 

 mare is usually 3^^ to 4 inches in its greatest diameter and weighs 

 about 4 ounces, while, in the aged, it may shrink to ij^ inches 

 in its greatest diameter and its weight to J4 ounce. 



The ovary of the cow is much smaller, being about one inch 

 in its greatest diameter, weighing but ^ to ^ ounce ; it is ob- 

 long in form, more regular in outline and its tunica albuginea is 

 less dense. 



The ovary of the sow is very large comparatively and the 

 numerous ovisacs appear prominently on its surface to such an 

 extent that the most superficial of them stand out entirely be- 

 yond the general ovarian line in such a manner that they are 

 attached to the body of the organ by a somewhat constricted 

 neck. 



The ovary of the cat is very small, oblong, with pointed ex- 

 tremities and of a bright scarlet color with the ovisacs standing 

 out thickly over the surface in a way to suggest a mulberry. 



The ovary of the bitch is very small, dark livid in color, even 

 in outline, and, unlike that of other domestic animals, is com- 

 pletely enveloped in the pavillion of the oviduct, except for a 

 minute oblong opening of so small size that the ovary cannot be 

 exposed to plain view through it. 



Forming in the fetus, beneath and on either side of the 

 notochord just posterior to the kidney, and above the perito- 

 neum, the ovary descends into the peritoneal cavity, carrying 

 with it the peritoneum, which thus forms a double layer behind 

 2 



