SECTION III 

 THE FATS 



THESE substances are widely distributed throughout the animal and 

 vegetable kingdoms. In the higher animals they form the main 

 constituents of the fatty or adipose tissue lying under the skin and 

 between the muscles and often forming large accumulations around 

 the viscera. In the marrow of bones they may amount to 96 per 

 cent. They also occur in fine particles distributed through the 

 protoplasm of cells and probably also in combination with the other 

 constituents which make up protoplasm. Large amounts are also 

 found in certain members of the vegetable kingdom, as, for instance, 

 in the fatty seeds and nuts, e.g. linseed, olives, Brazil nuts. 



CHEMISTRY OF THE FATS 



The fats are esters of glycerol and the fatty acids. Glycerol is a 

 trihydric or triatomic alcohol and can therefore form esters with 

 one, two, or three of its hydroxyl groups ; thus with acetic acid 

 the following compounds are known : 



(1) 



CH,OH 



(2) 

 CH 9 OH 



CHOH J 

 | ** 

 CH 2 OC.CH 3 



n -rnonacetin 



CH OC.CHc 



CH 2 OH 



/>monacetin 



(3) 

 CH 2 OC.CH 3 



CHOH 



CH 2 OC.CH 3 



a, a diacetin 



monoglycerides 



(4) 

 CH 2 OH 



CH 00. CH, 



CH 2 0- 



-00. CH, 



a, /3 diacetin 



diglycerides 



(5) 

 CH 2 OC.CH 3 



CH 00. CH, 



CH 2 OC.CH 3 



triacetin 

 triglyceride 



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