DISCHARGE OF THE OVUM. 



871 



The time at which the follicle ruptures, particularly with reference to the menstrual 

 period, is probably not definite ; but it is certain that, while sexual excitement may 

 hasten the discharge of an ovum by producing a greater or less tendency to congestion 

 of the internal organs, ovulation takes place independently of the action of coition. The 

 opportunities for determining this fact in the human female are not frequent ; but it has 

 been fully demonstrated by observations upon the inferior animals, and there is now no 

 doubt with regard to the identity of the phenomena of rut and of menstruation. It is 

 useless, at the present day, to enter into an elaborate discussion of this point, which 

 occupied so much the attention of the earlier writers. From the earliest times, it was 

 recognized, not only that women became fruitful only after the appearance of the menses, 

 but that sexual intercourse was most likely to be followed by conception when it 

 occurred near the periods ; a point which we shall discuss more fully under the head of 

 fecundation. When it was recognized that rupture of Graafian follicles was followed by 

 the formation of corpora lutea, it became easy to verify the supposition that the ova 

 were discharged at regular intervals, by an examination of the ovaries in women who 

 had died suddenly; and such observations, showing corpora lutea in virgins, demon- 

 strated that ovulation was not necessarily dependent upon coitus. 



FIG. 280. Ovum of the rabbit, from a Graafian follicle fa of an inch in diameter. (Waldeyer.) 

 a, epithelium of the ovum ; >, zona pellucida, with radiating Btriations (vitelline membrane) ; c, germinal vesicle ; 



tf, germinal spot ; e, vltellus. 



Observations upon the lower animals have shown, notwithstanding the fact of dis- 

 charge of ova without copulation or even the sight of the male, that sexual excitement 

 has a certain influence upon ovulation. The experiments of Coste upon this point are 

 very interesting. This observer noted that, in rabbits killed from ten to fifteen hours 

 after copulation, there was evidence of the recent discharge of ova. In two experiments, 

 however, he took female rabbits in heat and manifesting the greatest ardor for the male, 

 presented them to the male, in order to show that they were really in heat, but care- 

 fully prevented copulation. This was done for three days in succession, there being, on 

 each occasion, a manifest desire for the approach of the male. One rabbit was killed on 

 the third day, while still in heat ; and six distended Graafian follicles were found in one 



