120 



PHYSIOLOGY 



glycerides of caproic, caprylic, capric, lauric, and myristic acids, i.e. acids 

 with 6, 8, 10, 12, and 14 carbon atoms. In all cases these acids are the 

 normal acids with straight unbranched chains. It seems probable that in 

 the transformation of carbohydrate into fatty acid the latter is built up, not 

 by six carbon atoms, but by two carbon atoms at a time. It has been 

 suggested by Magnus Levy and by Leathes that the transformation may 

 occur by way of lactic acid. We have seen already that glucose and the 

 sugars of analogous composition may be converted under the influence either 

 of sunlight or of micro-organisms into lactic acid. Lactic acid breaks down 

 with readiness into aldehyde and formic acid. 



CH, 



CH. 



CHOH .= CHO +H 



COOH COOH 



Aldehyde undergoes condensation to form aldol. 



CH 3 CH 3 



CHO CHOH 



CH 2 

 CHO 



aldehyde aldol 



Aldol reacts with water and undergoes a shifting of its OH and H groups, 

 in a manner with which we are already familiar as occurring in the conversion 

 of glucose into lactic acid, forming butyric acid. We may represent the 

 reaction in the following way, placing the water molecules opposite those 

 groups of the aldol molecule with which they react : 



CH 3 



H HO iCH 



OH 



CH, 



gives 





 CH 3 



CH 2 



I 

 CHo 



H 



OH 



+ 2H 9 



COOH 



