774 URINE. 



acid having two carbon atoms less takes place according to this assump- 

 tion according to the formula: 



R.CH2.CH2.COOH-^R.CH(OH).CH2.COOHR.CO.CH 2 .COO^H-> 



R.COOH. 



The animal body has therefore the ability to transform oxyacids (alcohol 

 acids) into keto-acids by oxidation as well as the reverse, the conversion 

 of keto-acids into oxyacids, and this behavior, which is indicated by the 

 above formula, makes it difficult to state which products are primary 

 and which are secondary. As example of such a reversible process we 

 will mention the following; the 0-oxybutyric acid CH 3 .CH(OH) .CH 2 COOH 

 is transformed by oxidation into the keto-acid, acetoacetic acid, 

 CH 3 .CO.CH 2 COOH, and this latter by reduction is changed into /3- 

 oxybutyric acid. Both processes may take place, as FRIEDMANN and 

 MAASE, DAKIN and WAKEMAN l have shown, in the liver, and as these 

 two so-called acetone bodies have great importance in diabetes, they 

 may serve also as an example of the first stages of a /?-oxidation (of 

 n. butyric acid). 



Most of the investigations on the demolition of fatty acids have been 

 carried out by KNOOP, DAKIN, FRTEDMANN and others upon substituted, 

 especially phenyl-substituted fatty acids, and in speaking of the behavior 

 of the cyclic compounds we will discuss the behavior of these. 



The amino-acids are, when large amounts are introduced into the 

 animal body, eliminated unchanged, and even under physiological con- 

 ditions traces of the amino-acids formed in the animal body can pass 

 into the excretions glycocoll in the urine and serine in the perspiration. 

 Otherwise they are as a rule decomposed and a deamidation takes place, 

 the ammonia split off serving for material for the formation of urea. 

 The two components of a racemic a-amino-acid behave differently in that 

 the alien component is burned with greater difficulty and less completely 

 than the component occurring in the body protein, which is burned 

 more readily and more completely. 



In the demolition of the a-amino-acids, fatty acids, poorer in carbon, 

 are formed; the detailed manner of this demolition has been explained 

 in various ways. 



According to a long-accepted view it was believed that a hydrolytic 

 splitting off of ammonia with the formation of the corresponding oxyacid 

 (alcohol acid) took place, according to the formula R.CHNH 2 .COOH+ 

 H 2 O = R.CH(OH).COOH+NH 3 , and then a further demolition to 



1 Friedmann and Maase, Bioch. Zeitschr., 27; Dakin and Wakeman, Journ. of biol. 

 Chem., 8. 



