Human Physiology. 269 



the* processes of digestion, when the flaccid villi of the stomach 

 and intestines, under the stimulus of food, become enlarged, 

 erect, and active. It is observable in the fulness of the pouting 

 lips, and the sudden enlargement of the nipples ; parts connected 

 by an intimate sympathy with the reproductive system. 



The sudden enlargement of erectile organs, produced by an 

 impression of the senses, by memory, or an emotion, or however 

 excited, is, like the act of blushing, or that of coughing, 

 sneezing, etc., produced by nervous action, and in this case 

 the nerves seem to act upon the blood vessels, enlarging the 

 arteries, and at the same time constricting the veins, so that 

 the blood is forced into the part, and is permitted to return 

 only in diminished quantities, producing a temporary conges- 

 tion. The changes of this kind, both ways, are very rapid. 

 One emotion produces a sudden increase, and a different emo- 

 tion as sudden a diminution. A local irritation may, however, 

 keep up a continuous engorgement of the erectile tissues ; but 

 this is a morbid condition. 



When a mutual attraction, and an animal instinct, have brought 

 the sexual organs into the relation to each other necessary for 

 procreation, there arises an excitement of the senses, generally 

 highly pleasurable. This is the natural and healthful condi- 

 tion; but where the nervous power has been exhausted, the 

 sensibility blunted, by early excitement of the amative organism, 

 by sexual excesses, by any cause, there may be little sensi- 

 bility and no pleasure, or even pain. A great many women, 

 especially, never have pleasure in the sexual embrace ; and to 

 some it is always a cause of suffering. This insensibility or 

 pain may be hereditary, or caused by an early excitement of 

 the amative faculty, of which so many children of both sexes 

 are through their own ignorance, or the errors of others, the 

 unhappy victims. 



The sexual congress terminates in an orgasm, or powerful 

 nervous shock, in which, by a series of spasmodic contractions, 



