FOODS IN NUTRITION 1/3 



five minutes. In both cases it is oxidized. In the cell oxi- 

 dation is continually going on with the production of heat 

 and of certain excrementitious (oxidation) products de- 

 pending on the kind of food stuffs. 



Fate of Different Foods in the Organism. In the first 

 place, the foods may be divided, into (I) those which pass 

 through the organism unchanged, and (II) those which lose 

 their identity and are discharged as bodies different from 

 those which entered. The first class includes the foods fur- 

 nishing no energy; the second those furnishing energy. 



Only a few foods undergo in the body reactions which 

 alter their identity. They may be regarded as already di- 

 gested and, in fact, when dissolved, ready for discharge from 

 the body. They are, however, useful and necessary constitu- 

 ents of the body, and if they do not take a considerable active 

 part in nutrition, their favorable influence on that process 

 makes them essential to health. The foods producing no 

 energy may be dismissed with a repetition of the statement 

 that they are largely introduced in connection with the pro- 

 teid foods from which they cannot be separated without de- 

 struction of the proteid molecule. Indeed, all the proteid 

 food introduced, whether animal or vegetable, contains inert 

 constituents as a part of the molecule, and these seem as 

 necessary to nutrition as do the energy furnishing constitu- 

 ents. The foods furnishing energy and those furnishing no 

 energy enter, are deposited, and seem to be discharged both 

 together. The few reactions which the inert foods undergo 

 in the body do not materially affect the supply of energy. 



(II) The proteids, carbohydrates and hydrocarbons are 

 all consumed in the organism, none (unless they have acci- 

 dentally escaped digestion) being discharged as they entered. 



i. The nitrogenous foods are changed into peptones in the 

 alimentary canal, undergo some unknown change in their ab- 

 sorption therefrom, appear in the blood as the proteid con- 

 stituents of that fluid, and are offered to the tissues through 

 the medium of the lymph. The complex proteid molecule is 



