134 



FOODS 



changing, but is approximately correct as an average. The relatively 

 large proportion of water, approximately two-thirds of the body, again 

 reminds us of the fact, important in understanding the movements of the 



FIG. 70 



VEGETABLE 

 PROTEID 



The nitrogen food-cycle. (Hutchison.) 



tissues, that the body, apparently solid, is made up largely of liquid proto- 

 plasm in the ancient medical dictum, corpora non agunt nisifluida. 



FIG. 71 



EXPIRED 



The carbon food-cycle. (Hutchison.) 



Through the agency of light, plants have the power of combining the 

 water of the soil and the carbon dioxide of the air into sugar. Further- 

 more, plants make from this sugar starch and cellulose and fats, and 



