Human Physiology. 



mental ideas of religion, they must be natural to him a part 

 of, or in harmony with, his life. 



It is true that all animals are alike in many things in the 

 matter of which they are formed, in the physical forces by 

 which they are governed. All are related to the earth and to 

 the sun. All live by water, air, and heat ; all have that some- 

 thing that forming, guiding intelligence which we call life. 

 They are alike in the matter, and to some extent in the forms 

 of bones, muscles, and organs of nutrition and reproduction, 

 thought and volition. But they differ from each other, and all 

 from man so widely that we can nowhere find the missing links 

 between one species and another. The horse and ass may, if 

 you please, have come from the zebra, but whence the zebra? 

 Where is the progenitor of the giraffe, and in what geological 

 strata are the remains of his gradually lengthening neck to be 

 found? Where is the evidence of the progressive development 

 of the food-strainer of the whale? Give us an idea of a trunk- 

 less elephant, or, for that matter, of a trunkless moscheto? Or, 

 putting the cart before the horse, show us how atoms formed 

 molecules, molecules made blood, blood formed heart and 

 arteries, arteries created nerves, nerves expanded into brain, 

 brain secreted thought, and love, and religion, and invented 

 God and immortality. How matter, self-existent and eternal, 

 begot force, and force and matter generated all forms of life in 

 the universe. This is the problem for materialists to solve. 



In considering the forms and operations of life in all the 

 kingdoms of nature, we find it under three conditions indi- 

 vidual, sexual, and social; and no physiology can be complete 

 which does not treat of plants, animals, and men in these three 

 aspects. The male and female element must be considered in 

 every life, for one is not complete without the other. We 

 cannot comprehend the life of man, bird, or rose, if we do not 

 know the functions, influences, and relations of sex; and we 

 can scarcely give too much importance to that which completes 



