
IN MAN AND OTHER MAMMALIA. 349 
epithelium cells, in consequence of which large and small masses of the latter 
become imbedded more and more in the stroma of the ovary. The imbedded 
cells present a variety. Some of them, by simple increase in size, grow into 
ova, viz., primordial ova, while others keep to their original size, and by 
numerous divisions, at least as it appears to me, produce still smaller cells, viz., 
the follicular epithelial cells. A genetical distinction between primordial ova 
and follicular epithelial cells has consequently no existence. The germ epi- 
thelium is the common source of both. The first origin of eggs cannot be looked 
for in the ovary, but dates much farther back, even to the beginning of 
embryonic life. 
The tubes of VaLenTIN and Priiicer can lay claim only to a secondary 
importance, and are not essential for the egg and follicle formation; the greater 
part of the follicles have undoubtedly an earlier existence, long before these 
tubes are formed.” 
In the following description of my observations on the development of 
the ova and structure of the ovary, I shall in the first place state what I have 
seen in the foetal calf, then describe the ovary in young kittens, afterwards 
give an account of what I have observed in the human ovary, make some 
general observations on the development of the membrana granulosa in adult 
ovaries, and conclude with a few remarks on the structure of the ovum. 
The drawings in illustration of this paper are all original, and have been 
carefully prepared, by the aid of the camera lucida, from microscopic prepara- 
tions in my possession. 
THE OVARY OF THE CALF, 
If thin sections are made through the ovary of a fcetal calf of about nine 
inches in length, the followmg appearances may be recognised in them. A 
section of such an ovary presents for examination two parts,—an external 
cortical or parenchymatous part (fig. 1, a), and an internal fibro-vascular part 
(6,6). The latter is directly continuous with the peduncle or stalk to which 
the ovary is attached at the hilum (¢,c). On the surface of the peduncle, above 
and below, is a layer of epithelium (d, d) directly continued from the peritoneal 
epithelium towards the ovary; and when the layer is detached from the stalk or 
peduncle, and examined under high powers of the microscope, it is found to con- 
sist of small corpuscles, with large, clearly-defined, oval-shaped nuclei (fig. 2, ¢). 
Many of the nuclei contain granular matter in their interior. Each nucieus 
presents a sharply defined wall. In their largest diameter the nuclei measure 
about =-oth of an inch. The protoplasm round each nucleus is very clear and 
transparent. Between the nuclei are seen delicate lines, indicating apparently 
the surfaces of contact of the contiguous corpuscles. The clear substance 
round some of the nuclei is so small in quantity that the nuclei are almost in 
VOL. XXVII. PART III. 4Y 
