CHEMISTRY OF GLYCEROL 163 



Such cyclic alcohols as the sterols also form esters with the fatty acids. 

 Less important quantitatively are vitamins A and D, which are ordinarily 

 present in ester form with fatty acids. A different combination obtains 

 with sphingomyelin and the cerebrosides, where the fatty acids are com- 

 bined through the carboxyl group with an amino group of a basic compound 

 such as sphingosine. A stable combination is fomied whereby the acidic 

 properties of the fatty acid and the basicity of the sphingosine are both ef- 

 fectively neutralized. 



