CHAPTER VIII 

 THE ABSORPTION OF FOODS 



It is very natural to compare the body to a factory and the 

 alimentary tract to the furnace room where fuel is being 

 burned. In both factory and furnace there is motion, work 

 is being done and heat is being produced. 



This comparison is not, however, entirely applicable. In a 

 factory the fuel is burned in the furnace, only the heat from 

 the flames passing through the furnace walls. la our bodies, 

 on the contrary, the materials themselves in the digestive tract 

 pass through the intestinal walls and are transported around 

 the body. No heat at all comes from the digestive tract, for 

 the food gives up none of its stored-up properties until it has 

 passed out of this tract and been carried to its final destina- 

 tion in the hands, in the brain, in the liver or elsewhere. The 

 intestine is therefore not properly comparable to a furnace 



A better analogy would be to compare the human body to a 

 city, from the gas plant of which gas is sent to different parts 

 of the city; some of it is to be used for cooking, some for 

 lighting, some for heating. Some of the heat is, perhaps, 

 employed for producing steam pressure in an engine, which 

 in turn runs a sewing machine, a lathe or a water pump. 

 The material used in producing the heat is prepared in one 

 part of the city, but it gives off neither heat nor power nor 

 tight there, nor while going through the pipes. It is really 

 used only after it has reached some little nook or corner, ii 

 attic or basement, sleeping room, kitchen or shop; there 11 

 gives out its light, heat or power. 



STRUCTURES CONCERNED IN ABSORPTION 



We have traced the food to the intestine and noted it thei 

 in the form of chyle, ready to be absorbed. The small in- 



U2 



