ii SENSIBILITY OF THE INTEENAL OKGANS 77 



In most animals, other than man, the sexual desire appears 

 with puberty, and is only felt at certain seasons, the periods of 

 " heat " or " rut." In men, on the contrary, and in the higher 

 apes sexual desire is present at all seasons, from puberty to old 

 age ; in women it lasts till the climacteric, when the ovaries cease 

 to function, except in certain cases of retarded sexuality. In 

 animals the female, after fertilisation, obstinately refuses to 

 consort with the male ; in the human race and the higher apes 

 the female has no repugnance to sexual intercourse, even after 

 impregnation. This distinction is not, however, absolute. In the 

 domestic animals, in which the two sexes are continually in 

 contact, the periods of sexual excitement are more frequent, and 

 there is, particularly in the male, a tendency to persistence of 

 sexual desire, as in the higher apes and in man. On the other 

 hand, close observation of the human species reveals a periodicity 

 in erotic desire, particularly in women. 



The most interesting manifestations of sexual appetite in the 

 higher animals are the struggle of the male to possess the female, 

 and the persistent courting of females in the period of heat to 

 induce them to satisfy the male desire. The male is always the 

 more active ; the female is passive, and at first repellent, and only 

 gives way later, when the sexual want is well developed in her 

 too, and the ovule is maturated. According to Darwin, all the 

 gestures and expressive play of affection by which the male seeks 

 to ingratiate himself with the female are directed by sexual 

 desire ; but it may be held with Beaunis^ that they rather aim at 

 increasing the sex impulse in the female, and accelerating the 

 ripening of the ovule, since the love-drama may be observed even 

 in the absence of rivals. 



Sex desire is the most powerful motive of human life. Differ- 

 ences of individual temperament, of climate, of social surroundings, 

 of moral and religious education give a different character to the 

 manifestations of this appetite. The crude, brutal desire is nearly 

 always mingled in man with a psychical element, which may 

 attain the noblest heights of love, based not merely on physical 

 attractions but also upon moral and intellectual worth. But if 

 love purifies and ennobles the erotic impulse, it does not calm it, 

 but increases its vigour and intensity by the introduction of 

 psychical factors. 



When pushed to a morbid degree, sexual desire may assume 

 the form of erotomania or nymphomania. The perversions of 

 sex instinct in different forms and degrees, and the still more 

 frequent cases of sexual inversion, belong to psychiatry and forensic 

 medicine. 



Here we must confine ourselves to considering the sex want 

 or instinct from an exclusively physiological point of view, and 

 must first determine its origin, that is the internal and external 



