268 Human Physiology. 



reproductive process. Male and female are drawn or driven 

 together by an inward impulse, which, in the lower orders of 

 animals, is simply irresistible, but which in man is placed under 

 the government of reason and sentiment. Man differs from all 

 other creatures in having the power to order, regulate, and 

 adapt the instinct of reproduction to the highest uses; to keep 

 it under the control of reason, and make it subservient to the 

 demands of morality and religion. Vegetables and animals 

 obey a blind instinct which urges them to do what is necessary 

 for the continuation of their species. Man feels the powerful 

 promptings of the same instinct, but he also feels a higher and 

 purer sentiment of spiritual love dominating and controlling it ; 

 and he is able also to choose the proper time, and the best con- 

 ditions for offspring; or, if reason and duty demand, to refrain 

 altogether from the gratification of his natural desires. 



It is probable that all sentient beings have a degree of 

 pleasure in the exercise of every natural function, and the 

 strongest feeling of sensual delight may probably be connected 

 with the most important of the voluntary vital processes. Eat- 

 ing, which is necessary Jo sustain life, appears in all animals to 

 bring enjoyment; and the sexual congress, necessary to repro- 

 duction, is, as far as we can judge, also connected with pleasure. 

 Even with fishes, and lower organisations, where fertilisation is 

 produced without contact, the expulsion of ova and the seminal 

 element may give a sensible pleasure, in some proportion to the 

 force of the instinct which urges to the act. 



The higher orders of animals are furnished with tissues and 

 organs, and nerves of sensation and motion, specially formed 

 for the generative act and its accompaniments. The erectile 

 tissue, as it is called, a substance which under nervous excite- 

 ment changes in form, increases in size, and from being soft 

 and flexible becomes rigid and erect, is one of the most curious 

 of all the wonderful provisions and contrivances of nature. 

 This action is seen in the glandular system, on a minute scale, in 



