DISCHARGE OF THE OVUM. 293 



the non-vascular portion, situated at the very surface of the 

 ovary, undergoes fatty degeneration, by which this part of the 

 wall becomes gradually weakened. At the same time, at the 

 other portions of the follicle, there is a growth of cells, which 

 project into the interior, and an extension, into the interior, 

 of blood-vessels in the form of loops. These processes, with 

 an increase in the pressure of liquid and the fatty degenera- 

 tion of the macula, cause the follicle to burst ; and, with the 

 liquid, the discus proligerus and the ovum are expelled. The 

 formation of a cell-growth in the interior of the follicle is 

 really the beginning of the corpus luteum ; and this occurs 

 some time before the discharge of the ovum takes place. It 

 is a disputed question whether or not a haemorrhage occurs 

 into the follicle at the time of its rupture. This may, and 

 undoubtedly does sometimes occur, but it cannot be regarded 

 as constant, and has been denied by many observers. 



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 in- 

 dependently of the act of coition. The opportunities for de- 

 termining 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 atten- 

 tion 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 f ormatiou : 

 of corpora lutea, it became easy to verify the supposition 



