LIFE PROCESSES. 



249 



ened by the fact that our beasts of burden depend chiefly on 

 carbohydrate foods. 



" Proteid, by digestion, becomes peptone, which is absorbed 

 and retransformed into the proteids of plasma and lymph. 

 These fluids surround and permeate the organized elements 

 of the tissue, and the proteids that they carry form the float- 

 ing balance of nutritive matter from which the comparatively 

 fixed capital of living protoplasm is supplied. Of this free, 

 circulating, or coasting proteid, in blood and in lymph, it is 

 supposed that only a small proportion is actually taken into 

 chemical combination in protoplasm as fixed or organ proteid, 

 and that the greater proportion is acted upon and used by 

 living protoplasm without being integrated by it to make 

 part of its own substance. The free or coasting proteid thus 

 used up gives rise to urea, as does that small proportion of 

 fixed or organ proteid which disintegrates and gives place to 

 a correspondingly small proportion of newly integrated pro- 

 teid." WALLER. 



ASSIMILATION 

 CIRCULATION, 



VEGETABLE FOOD 



ULANT \ 

 BOLISM/ 



INORGANIC (MINERAL) MATTER 



Fig. 76. Life Processes. 



While increased muscular action does not very perceptibly 

 increase the amount of urea excreted, the amount of urea is 

 increased by increase of the amount of proteid food taken. 



The building-up, or constructive, processes are included 



