CHAPTER VI. 



ELEMENTARY CHEMISTRY OF LIVING BEINGS. 



A ROUGH analysis of any living body, whether animal or 

 vegetable, would show that it consists of water, certain or- 

 ganic compounds, and certain inorganic matter. By a 

 gentle heat the water may be expelled, when it would be 

 found that the body experimented on would have lost, 

 speaking generally, from seventy to ninety per cent of its 

 weight. Living matter, therefore, is very largely made up 

 of water, which, indeed, is an absolute necessity for the per- 

 formance of all vital actions. After driving off the water, if 

 a strong heat be applied, it would be found that a certain 

 proportion of the dried tissue would be burnt and would be 

 completely dissipated. In this way we should eliminate a 

 certain quantity of organic compounds, which would differ 

 according to the character of the tissue we were dealing 

 with, and into the nature of which we shall inquire immedi- 

 ately. Lastly, there would remain a small proportion of 

 mineral or inorganic matter which constitutes the "ash," 

 and which would not be dissipated or affected by the incin- 

 eration. The average amount of ash in animal tissues is 

 about three per cent, but in the case of vegetables the min- 

 eral constituents may be present in larger proportions than 

 this. 



A living body, then, may be said to consist of water, cer- 



