CHEMISTRY 233 



as hydrolysis. Essentially they amount to 

 successive splittings of the large molecules 

 of the native substances, each cleavage being 

 accompanied by the addition of a molecule 

 of water, until finally from starches and like 

 substances the simple sugars like glucose result; 

 from the fats, fatty acids and glycerine; 

 from the proteins, the so-called amino acids. 

 The cleavage of fats closely resembles the 

 hydrolysis of a simple ester; the cleavage 

 of proteins and carbohydrates a little more 

 remotely resembles the same process. Accord- 

 ingly, the hydrolysis of the simplest ester, 

 methyl formate, may serve as an illustration 

 of the nature of the reaction: — 



H-C-O^CH 3 +HO lH = H-C-0-H+H-0-CH, 



II : I II 



o o 



This process is nothing less than the typical 

 reaction between water and organic sub- 

 stances. Accordingly, it is not surprising that 

 such reactions are by no means confined to 

 the digestion of food. Once formed, the prod- 

 ucts of digestion are absorbed, the more 

 readily because of their simplicity, and, also 

 because of their simplicity, they carry into 

 the body no trace of the organism in which 

 they previously existed. But, if they are to 



