CHAPTER VII 



INCOME OF MATTER. THE ABSORPTION 

 OF FOOD STUFFS 



46. As all forms of vital activity cause a 

 certain amount of tear and wear owing to the 

 breaking down of living matter, or, in other 

 words, the decomposition of complex organic 

 substances into simpler ones, usually accom- 

 panied either with the withdrawal of oxygen 

 (reductions) or with the union of oxygen with 

 oxidizable substances (oxidations), matter 

 must be supplied in the form of food. Food 

 stuffs however, as a rule, are very unlike the 

 tissues of the body. Observation also shows 

 that animals may live on food stuffs that are 

 very unlike in appearance. Thus an ox can live 

 upon grass, a horse on hay and oats, a rabbit 

 on turnips or carrots, a tiger and other flesh- 

 eating animals on flesh of various kinds. 



Man is so constituted as to find a mixed diet 

 90 



