390 FAT METABOLISM. OBESITY 



of formation of fat from carbohydrate is probably correct, 

 even though further study is necessary. 24 



Chemistry of Fat Formation from Sugar. The problem 

 of the chemical transformations by which sugar is converted 

 into fat has as yet not passed beyond the hypothetical stage. 

 The fact that the high fatty acids concerned in the synthetic 

 production of fat show an even number of carbon atoms sug- 

 gests the idea that groups, each containing two carbon atoms, 

 may, perhaps, be concerned in the construction of the long 

 chains. In review of hypotheses of Nencki and Hoppe- 

 Seyler, Magnus-Levy suggests 25 that the formation of fat 

 from sugar may take place along the same lines as (v. supra., 

 p. 347) the bacterial butyric acid fermentation, that is, by 

 way of lactic acid and acetaldehyde. 26 As is well known, two 

 molecules of lactic acid may be derived from one molecule of 

 sugar, C 6 H 12 6 2C 3 H 6 3 ; the latter, then, by oxidation 



CH, CH, 



gives rise to acetaldehyde, OH.OH + o = COH + CO, + H 2 o. 



COOH 



This under certain condensation conditions is changed into 



CH, 

 CH 3 + CH, = CH.OH 



a four chain group, aldol : ^ QH ^ ^ It has been 



COH 



proved, moreover, that two molecules of this latter substance 

 may be condensed in vitro into an eight-carbon atom group : 



CH, CH, 



CH.OH + CH.OH = CH,-CH(OH)-CH 2 -CH(OH)-CH 2 -CH(OH).CH 2 .COH. 

 CH 2 CH 2 

 COH COH 



The conversion of this last in the laboratory into n. octylic 

 acid, CH 3 .CH 2 .CH 2 .CH 2 .CH 2 .CH 2 .CH 2 .COOH, is easily ac- 



84 A. Magnus-Levy and L. F. Meyer, 1. c., p. 456. 



K A. Magnus-Levy and L. F. Meyer, 1. c., pp. 472-474. 



M A. Magnus-Levy, Verhandl. d. physiol. Ges., Berlin, March 15, 1902, etc. 



