382 BACTERIOLOGICAL CHEMISTRY 



intermediate, proposed the following scheme to account 

 for the production of fats from sugar. Glucose breaks 

 down, probably by the same mechanism as in alcoholic 

 fermentation, to give methylglyoxal hydrate, which gives 

 pyruvic acid and hydrogen : — 



/OH 



CeHiaOe > 2CH3CO.C^OH > 2CH3CO.COOH + 4H. 



\h 



In view of more recent knowledge of alcoholic fermentation 

 methylglyoxal hydrate probably should no longer be 

 considered as an intermediate, the pyruvic acid being 

 formed in accordance with the Meyerhof-Embden scheme 

 of alcoholic fermentation. The pyruvic acid is decar- 

 boxylated to give acetaldehyde and carbon dioxide. 

 Two molecules of acetaldehyde condense to give aldol : — 



O H\ 



ch3c— h + h— ^c.cho > ch3choh.ch2.cho. 



h/ 



The latter loses water with formation of the unsaturated 

 aldehyde, crotonaldehyde : — 



CH3CHOH.CH2.CHO ^ CH3CH = CH.CH0 + H2O. 



The crotonaldehyde is reduced by hydrogen formed during 

 the production of pyruvic acid to give butyraldehyde, 

 CH3CH2.CH2.CHO. The butyraldehyde condenses with 

 another molecule of acetaldehyde to produce a homologue 

 of aldol, j3-hydroxycaproic aldehyde : — 



CH3CH2.CH2.CHO + CH3.CHO — > CH3CH2.CH2.CHOH.CH2.CHO. 



Loss of water gives rise to «j8-hexylene aldehyde, 

 CHsCHa.CHs.CH^CH.CHO, which is reduced to caproic 

 aldehyde, CH3(CH2)4CHO. This process of condensation 

 with acetaldehyde, dehydration and reduction continues 

 until a chain of carbon atoms corresponding to oleic 



