OVULATION AND MENSTRUATION. 



603 



FIG. 168. 



rupture ; after which a slight exudation, more or less tinged with blood, 

 is poured out in the course of a few hours. 



This process occurs in one or more follicles at a time, according to 

 the number of young to be produced. In the bitch and the sow, 

 where each litter consists of from five to twenty young, a similar num- 

 ber of eggs ripen and are discharged at each period. In the mare, the 

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

 birth, the eggs are matured singly, and the Graafian follicles ruptured, 

 one by one, at successive periods of ovulation. 



4. The ripening and discharge 

 of the egg are accompanied by a 

 peculiar condition of the general 

 system, known as " rutting," or 

 " cestruation. 1 ' The congestion 

 and functional activity shown by 

 the ovaries, at each period of ovu- 

 lation, extend to the other genera- 

 tive organs, producing in them 

 more or less excitement, according 

 to the species of animal. Usually 

 there is vascular congestion of the 

 entire generative apparatus. The 

 secretions of the vasrina and neigh- VARY , WITH GRAAFIA , X Fo ^ LICX f R ^;RED: 



- at a. the egg, just discharged, with a portion of 



boring parts are increased in quan- the membrana granuiosa. 

 tity and altered in quality. In the 



bitch, the vaginal mucous membrane becomes red and tumefied, and pours 

 out a secretion more or less tinged with blood, and possessing a peculiar 

 odor, which appears to attract the male. An unusual tumefaction and 

 redness of the vagina and vulva are also perceptible in the rabbit ; and 

 in some apes there is not only a bloody discharge from the vulva, but 

 engorgement and infiltration of the neighboring parts, extending to 

 the buttocks, the thighs, and the under part of the tail.* 



The system at large is also affected. In the cow, the approach of an 

 cestrual period is marked by unusual restlessness. The animal partially 

 loses her appetite. She frequently stops browsing, looks about un- 

 easily, runs from one side of the field to the other, and then recom- 

 mences feeding, to be again disturbed in a similar manner after a short 

 interval. The motions are rapid and nervous, and the hide rough and 

 disordered, indicating the presence of some special excitement. After 

 cestruation is fully established, the vaginal secretions continue for one 

 or two days unusually abundant ; after which the symptoms subside, 

 and the animal returns to her usual condition. 



In these animals the female will allow the approach of the male only 

 during or immediately after the cestrual period ; that is, when the egg 

 is recently discharged, and ready for impregnation. At other times, 



* Pouchet, Theorie positive de 1'ovulation. Paris, 1847, p. 230. 



