34 THE BIOLOGY OP DAILY LIFE. 



remains equally true that these changes are 

 maintained by its instrumentality. . . . 



" In any case it holds good that the sub- 

 stances of which the animal body is built up 

 enter it in a but slightly oxidized and highly 

 unstable state ; while the great mass of them 

 leave it in a fully oxidized and stable state. 



"It follows, therefore, that whatever the 

 special changes gone through, the general pro- 

 cess is a falling from a state of unstable che- 

 mical equilibrium to a state of stable chemical 

 equilibrium. Whether this process be direct 

 or indirect, the total molecular re-arrangement 

 and the total motion given out in effecting it 

 must be the same." (Biology, pp. 34 and 35.) 



Just another much shorter and simpler quotation, 

 this time from an eminent teacher of chemistry, as 

 well as practical experimenter, in that science, and I 

 think the matter will be clear to the general reader. 



" The animal lives upon organized materials, 

 taking up oxygen, and evolving carbonic acid 

 and other oxidized products; the plant lives 

 upon inorganic materials, especially carbonic 

 acid, water, ammonia, and salts, organizing 

 them, and evolving oxygen. The chemical 

 function of the animal is oxidation, that of the 

 plant reduction."* 



Now taking the human body in a state of health 



* Sir Henry E. Roscoe's "Elementary Chemistry," 1886, 

 p. 410. Of course Sir Henry takes a purely chemical view, and 

 very justly. He is not treating of physiology or biology, but 

 of chemistry. 



