60 Sir Everard Home on corpora lutea. 
parts so much, that when full grown, and even when there 
are several in the same ovarium, that body is not much en- 
creased beyond its natural size. 
The structure of the corpus luteum is of a very particular 
kind, and is not distinctly seen in small animals, or in those that 
have numerous litters; but in the cow, which has commonly 
only one calf at a birth, the corpus luteum is so large, that 
when it is magnified, the structure can be made out; it is a 
mass of thin convolutions, bearing a greater resemblance to 
those of the brain than of any other organ. Its form is an 
irregular oval with a central cavity, and in some animals its 
substance is of a bright orange colour when first exposed ; 
all these appearances are most accurately displayed in the an- 
nexed drawings of it in the cow. [Plate VII. fig. 2,3.3 Corpora 
lutea are found to make their appearance in the ovaria at the 
age of puberty, and continue to succeed each other as the 
young are produced, till the period arrives when breeding 
no longer goes on. [Plate III. fig. 7; Plate IV. fig. 6 ; 
Plate IX. fig. 6.3 
As the object of the present paper is to draw conclusions from 
the appearances that are represented in the annexed drawings, 
in proof of corpora lutea being the structures in which the 
ova are formed ; of their being produced previous to, and 
independent of sexual intercourse; and when they have ful- 
filled their office of forming ova, being afterwards removed 
by absorption, whether the ova are impregnated or not; I 
shall not take up the time of the Society longer than in de- 
tailing a number of facts, which indeed will be doing little 
more than giving a catalogue raisonnbe of Mr. Bauer’s 
drawings, which put these facts upon record. That corpora 
