Cuap. I. THE GRAAFIAN FOLLICLE. 483 
ent layer, pressing closely upon the exterior of the “tunica granulosa,’ and appar- 
ently developing by the cohesion of the exterior cells of the latter’ (Pl. 8, 
fig. 9). Not long after this, upon an egg just visible to the naked eye, this 
layer exhibits faint traces of bemg doubled, yet withal retains pretty nearly its 
pristine transparency (Pl. 8, fig. 12, a; Pl. 9a, fig. 18, a). Upon an egg one 
sixteenth of an inch in diameter its fibrous structure has become quite appar- 
ent (Pl. 9a, fig. 16, 16a, @); and another ovum one tenth of an inch in diam- 
eter is inclosed by a double membrane, the inner layer of which (PI. 9a, fig. 
18a, a) is as thick as the zona (fig. 18a, e). 
On account of the appearance of bloodvessels in the stroma, at this time, 
by which the thickness of the latter is disguised, we can only say that it 
becomes a more loose, network-like tissue, the outer layer of which is very moy- 
able upon the inner. This is_ particularly noticeable in full-grown eggs. The 
bloodyessels of the stroma develop pretty uniformly over the whole of its extent, 
excepting a circular area at the most distal side, where they suddenly thin out 
into fine capillaries, anastomozing among themselves (Pl. 9, fig. 5, 7, 8, 9, 10; 
Pl. 9a, fig. 32). Just before the exclusion of the egg from the ovary at the 
breeding season, the bloodvessels become very much gorged, (Pl. 9a, fig. 32, 
so that the larger eggs appear to be covered by an almost continuous blood-red 
layer. The bloodvessels, as they come up to this area, the region of the 
“cicatricula,” suddenly bend upon themselves without diminishing their diameter, and 
commence their returning course. Now it is at this sudden bend that the capil- 
laries which supply the cicatricula take their rise, and into this their return cur- 
rents empty (Pl. 9a, fig. 32). After the exclusion of the egg, these vessels 
become paler, and are to all appearances fewer in number; they gradually disap- 
pear with the resorption of the corpus luteum. 
The Tunica graniosa. In a former section? it has been shown, that, at the 
time of the formation of the egg, the cells of the Graafian follicles were not 
arranged in any particular manner in reference to the body which was develop- 
ing among their interstices. By and by the egg has grown to such a size (PI. 
8, fig. 1, ”; Pl. 9a, fig. 10) that the imclosing cells may be said to form an 
enveloping layer, although they have not changed in the least as regards their 
form; nor does this happen even when the egg has attained to a much larger 
size (Pl. 8, fig. 1, 0’; Pl. 9a, fig. 11). As we have before mentioned in pass- 
ing, the cells of the follicle, around the younger eggs, are very transparent, of 
thin contour, with a nearly spherical shape, each containing a central, faint, and 
comparatively large mesoblast. 
1 See, below, p. 484. 2 See Sect. 1, p. 454. 
