IN MAN AND OTHER MAMMATIA. 347 
the germinal vesicles originate surrounded by a diffuse protoplasm, that forms 
a more definite investment for each as they become more deeply situated with 
the tube. Thereupon a number of the cells become conspicuous by their more 
vigorous growth, whilst the rest remain unaltered, and form the epithelial lining 
of the tubes. The larger cells, which are primordial eggs, occupy the axis of 
the tube. 
These subsequently increase in number by fission and budding, the pro- 
ducts constituting the definite eggs that for a time remain connected with one 
another in the interior of the tubes in the form of a chain, by processes of pro- 
toplasm, constituting the “egg chains” of Pricer. The membrana propria 
outside the epithelial lining of the tubes sends in processes between the indi- 
vidual eggs, in consequence of which the latter are gradually separated from 
each other along with a portion of the tubular epithelium; the latter forms 
the epithelial lining of the Graafian follicles in this way produced. Pricer, 
in one of his figures (plate ii. fig. 1), has represented a connection existing 
between his tubes and the superficial columnar epithelium, and has frequently 
remarked that the contents of the egy tubes must proceed from the ovarial epi- 
thelium, which he always considers to be a serous epithelium. 
The most important work published within the last few years on the deve- 
lopment of the ova and ovary is that by W. WALDEYER, entitled “ Eierstock 
und Ei.” (Leipzig, 1870). 
According to WaLDEYER, the first appearance of the ovary consists of a 
thickened germ epithelium investing a small outgrowth rich in cells, which 
projects from the interstitial tissue of the Wolffian body on its median side. 
The thickened epithelium investing this outgrowth gradually forms the rudi- 
ments of the Graafian follicles and ova, and of the subsequently appearing 
epithelium of the ovary, whilst the outgrowth itself is destined to furnish the 
vascular stroma of the ovary. 
In the embryo of fowls, WALDEYER states, the interesting observation may 
be made as early as the fourth day of incubation, that some among the germ 
epithelial cells have become conspicuous by their round form, their size, and 
the size of the nucleus they contain. We may conclude, from the regular 
arrangement of these structures and the constancy of their position, that they 
represent the youngest primordial ova, which thus, even during embryonic life, 
are formed by a simple process of growth from the epithelial cells of the germ 
organ. The further development of the ovaries depends on a peculiar mode of 
growth of the superficial epithelium on the one hand and of the vascularised 
stroma on the other. Certain more or less delicate processes of the connective 
_ tissue now shoot forth from the stroma, whilst coincidently the epithelium 
imcreases by the continual production of new cells. The processes then pene- 
trate between the epithelial cells, enclosing a variable number of them, which 
