PERIODICAL OVULATION. 569 



rhage, which takes place from the internal surface of the congested 

 follicle, and by which its cavity is filled with blood. This occurs 

 in the human subject and in the pig, and to a certain extent, also, in 

 other of the lower animals. Sometimes, as in the cow, where no 

 hemorrhage takes place, the Graafian vesicle when ruptured 

 simply collapses ; after which a slight exudation, more or less tinged 

 with blood, is poured out during the course of a few hours. 



Notwithstanding, however, these slight variations, the expulsion 

 of the egg takes place, in the higher animals, always in the manner 

 above described, viz., by the accumulation of serous fluid in the 

 cavity of the Graafian follicle, by which its walls are gradually dis- 

 tended and finally ruptured. 



This process takes place in one or more Graafian follicles at a 

 time, according to the number of young which the animal produces 

 at a birth. In the bitch and the sow, where each litter consists of 

 from six to twenty young ones, a similar number of eggs ripen and 

 are discharged at each period. In the mare, in the cow, and in the 

 human female, where there is usually but one foetus at a birth, the 

 eggs are matured singly, and the Graafian vesicles ruptured, one 

 after another, at successive periods of ovulation. 



4th. The ripening and discharge of the egg are accompanied by a 

 peculiar condition of the entire system, known as the "rutting" condi- 

 tion, or " cestruation" The peculiar congestion and functional 

 activity of the ovaries at each period of ovulation, act by sympathy 

 upon the other generative organs and produce in them a greater or 

 less degree of excitement, according to the particular species of ani- 

 mal. Almost always there is a certain amount of congestion of the 

 entire generative apparatus; Fallopian tubes, uterus, vagina, and 

 external organs. The secretions of the vagina and neighboring 

 parts are more particularly affected, being usually increased in quan- 

 tity and at the same time altered in quality. In the bitch, the 

 vaginal mucous membrane becomes red and tumefied, and pours 

 out an abundant secretion which is often more or less tinged with 

 blood. The secretions acquire also at this time a peculiar odor, 

 which appears to attract the male, and to excite in him the sexual 

 impulse. An unusual tumefaction and redness of the vagina and 

 vulva are also very perceptible in the rabbit ; and in some species 

 of apes it has been observed that these periods are accompanied 

 not only by a bloody discharge from the vulva, but also by an en- 

 gorgement and infiltration of the neighboring parts, extending even 



