708 OVULATION AND MENSTRUATION. 



foetus at a birth, the eggs are matured singly, and the Graafian follicles 

 ruptured, one after the other, at successive periods of ovulation. 



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

 culiar condition of the general system, known as the " rutting" condition, 

 or " oestruation." The congestion and functional activity manifested by 

 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 ex- 

 citement, according to the particular species of animal. Usually there 

 is a certain amount of congestion of the entire generative apparatus. 

 The secretions of the vagina and neighboring parts are more particularly 

 affected, being increased in quantity and altered in quality. In the bitch, 

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

 a secretion which is more or less tinged with blood. The vaginal secre- 

 tions acquire 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 perceptible in the rabbit ; 

 and in some species of apes there is not only a bloody discharge from 

 the vulva, but also an engorgement and infiltration of the neighboring 

 parts, extending to the skin of the buttocks, the thighs, and the under 

 part of the tail. 1 



The system at large is also visibly affected by the process going on 

 in the organs of generation. 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 uneasily, runs 

 from one side of the field to the other, and then recommences feeding, to 

 be disturbed again in a similar manner after a short interval. The 

 motions are rapid and nervous, and the hide often rough and disordered; 

 and the whole aspect of the animal indicates the presence of some special 

 excitement. After oestruation is fully established, the vaginal secretions 

 show themselves in unusual abundance, and so continue for one or two 

 days ; after which the symptoms subside, and the animal returns to her 

 usual condition. 



It is a noticeable fact, in this connection, that the female of these 

 animals will allow the approach of the male only during and immedi- 

 ately after the oestrual period ; that is, when the egg is recently dis- 

 charged, and ready for impregnation. At other times, when sexual 

 intercourse would be necessarily fruitless, the instinct of the animal 

 leads her to avoid it ; and the concourse of the sexes is accordingly 

 made to correspond in time with the maturity of the egg and its apti- 

 tude for fecundation. 



II. Menstruation. 



In the human female, the return of the period of ovulation is marked 

 by a group of phenomena which are known as menstruation, and which 

 are of sufficient importance to be described lay themselves. 



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



