466 FATE OF BODY-FOREIGN SUBSTANCES 



turated higher fatty acids into unsaturated acids acquire 

 special interest in this connection. 



No one knows how the last phases of the combustion of 

 an aliphatic chain take place, and how in particular acetic 

 acid is converted. 0. Forges believes that while a small 

 fraction of acetic acid and its derivatives are oxidized 

 through oxalic acid, the greater part is probably not oxidized 

 but undergoes further synthetic elaboration. 35 However, 

 nothing definite is known in this connection. 



Catabolism of the a-aminoacids. It is generally held that 

 in the decomposition of the physiologically important acids 

 amidized in the a-position, these are catabolized through a 

 stage of an a-ketonic acid with C0 2 cleavage into the acid of 

 the same group with one less carbon atom (v. Vol. I of this 

 series, pp. 49-51, Chemistry of the Tissues) in which process 

 apparently aldehyde may enter as an intermediate product : 



ALANIN RACEMIC ACID ACETALDEHYDB ACETIC ACID 



CH t CH, 



CH, CH, 



CH.NH, > CO 



.NH, > CO > > 



COH C001 



>H 



COH COOH 



COOH COO] 



LEUCIN ISOVALERALDEHTDE ISOVALERIANIC 



This harmonizes with the schema proposed by 0. Neubauer 36 

 for the catabolism of aminoacids by yeast fermentation : 



86 O. Forges, Ergebn. d. Physiol., 10, 32, 1910. 



*O. Neubauer and K. Fromherz (F. v. Mtiller's Clinic, Munich), Zeitschr. 

 f. phyeiol. Chem., 70, 348, 1911. 



