
1905.]. Degeneration of Ova in the Rabbit. 263 
It has been argued that the follicle ruptures on account of the tension 
caused by the material secreted therein ; but in the rabbit the follicles do not 
rupture unless copulation takes place and, as I will show below, the ripe 
follicles which do not rupture because copulation has not taken place are 
distended and vascular, so far as I can see, to the same extent as those which 
do rupture. anes 
It has been suggested that the spermatozoa in the infundibulum and, as 
that organ. is closely applied to the ovary, on the surface of the follicle, 
exercise influence; but as has been shown in the sheep, for instance (No. 22), 
ovulation may take place prior to copulation, and hence when no spermatozoa 
are present. 
Again, it has been stated that the vessels surrounding the follicle burst 
and pour their blood into it, so causing increased pressure, which bursts the 
thin wall; but in the rabbit, at any rate, the blood is not poured in any 
considerable quantity into the follicles which burst while it floods those which 
‘do not burst. | 
The fact that in the domestic rabbit ovulation does not occur until after 
<copulation has taken place, while in other animals it may occur prior to the 
-sexual act, suggests the probability that in the former animal additional 
stimulus is necessary to induce the rupture of the follicle. Whether, as has 
‘been suggested (No. 27), the rupture is due to the stimulation of erectile tissue 
-or not my experiments do not show, but the observations made on the nerves 
-of the ovary render such explanation extremely probable (Nos. 9, 17, 18, 20, 
21, and 34). All I can say is that the base of a discharged follicle appears to 
be pinched together, though I have been unable satisfactorily to demonstrate 
‘that the effect is produced by the contraction of the tissues which surround 
‘the follicle, and the actual cause of rupture I have been unable to discover. 
The corpus luteum is formed by the ingrowth of cells surrounding the 
‘follicle together with the follicular epithelium; the ingrowth being at one 
time apparently a forcible rush before which the loosened epithelium is 
driven. The ingrowth takes place in the first instance in n the region of the 
base of the follicle. 
Degeneration of Ripe Follicles and the False Corpus Lutewm.—When a doe 
has not been allowed access to the buck during estrus, the ripe follicles 
‘which are present at that time do not burst, and the ripe ova contained therein 
-do not undergo maturation. | : 
The follicle is distended. and srbjeste on the surface of the ovary; its 
-outer wall is thin and the whole structure is very vascular, precisely as is 
‘the case with the follicles which do rupture after copulation; but: it does 
-not rupture, instead, the surrounding congested vessels rupture and ‘pour 
