HISTORY OF DIFFERENT FOODSTUFFS IN BODY 1037 



CHAPTER LXXXVI 



THE HISTORY OF THE DIFFERENT FOODSTUFFS 

 IN THE BODY 



General Discussion. The process of alimentation having been 

 completed by the absorption of the foodstuffs, the latter circulate in 

 the blood and are then acted upon by the cells of the different tissues. 

 One of two things may now happen to them, namely, they may be 

 taken up to form an intricate part of the tissue-substance or may be 

 burned up immediately and excreted. Eventually, of course, even 

 the first portion must again be discharged by the cells into the cir- 

 culating media, because activity entails a constant loss of substance. 

 As far as excretion is concerned, it is, therefore, quite immaterial 

 whether a given foodstuff first becomes an actual part of a cell or does 

 not, because both portions are finally turned into waste products. 

 Clearly, every living entity attains at a particular time of its life a 

 mature size which it retains for some time by properly balancing its 

 outgo in waste material by an adequate ingo of nutritive substances. 

 Meanwhile its physiological destiny is to produce energy in its various 

 forms, simulating a steam engine which converts its fuel into waste 

 under an evolution of energy. In order to satisfy its wants; to retain 

 its weight; and to enable it to yield energy, the living substance re- 

 quires fresh air, drink and food. Only when each of these three 

 things is supplied to it can it continue incessantly to oxidize and to 

 produce work. Thus, each cell may be said to be in a state of un- 

 stable equilibrium which favors the building up processes during its 

 period of growth and the tearing down processes during its period 

 of decline. 



While cellular anabolism and catabolism in this general form is 

 not difficult to understand, it is true that we are not as yet in a satis- 

 factory position to follow the different foodstuffs in their journey 

 through the body with exactness. The reason for this lies in the 

 extreme complexity and invisibility of the intracellular processes. 

 Regarded in a general way, it may be said that the body consists of 

 64 per cent, of water, 16 per cent, of proteins, 14 per cent, of fat, 5 per 

 cent, of salt, and 1 per cent, of carbohydrates. Among its constituents 

 might be mentioned carbon, nitrogen, hydrogen, oxygen, sulphur, phos- 

 phorus, fluorin, chlorin, iodin, sodium, potassium, calcium, silicon, 

 magnesium, lithium, iron, and at times also traces of manganese, copper 

 and lead. Excepting oxygen, nitrogen and hydrogen, these elements 



