216 BACTERIAL ACTION IN THE INTESTINAL TRACT. 



With Millon's reagent a red color develops, which, however, is 

 common to other bodies of this series as well. 



Isolation (see page 221). 



In addition to phenol, indol, skatol, and skatol-carbonic acid, as 

 also the two hydroxylated benzol-derivatives of tyrosin, viz., para- 

 oxy-phenyl-propionic acid (hydroparacumaric acid) and para-oxy- 

 phenyl-acetic acid, we further meet with two non-hydroxylated 

 aromatic acids, which are homologous with benzoic acid, viz., ph.en.yl- 

 propionic or hydrocinnamic acid and phenyl-acetic acid. Accord- 

 ing to Salkowski, these may develop directly from the albuminous 

 molecule, but may also result from tyrosin (see page 85). 



The non-nitrogenous aromatic acids are in part eliminated in the 

 feces. To some extent, however, they are also absorbed. The 

 hydroxylated acids are then eliminated in the urine either as such, 

 or, like phenol, indol, and skatoxyl, in combination with sulphuric 

 acid, while the non-hydroxylated acids combine with glycocoll, and 

 are eliminated as hippuric acid and phenaceturic acid, as already 

 described. 



As regards the fate of the small amounts of leucin, aspartic acid, 

 and glutaminic acid which are also formed during the process of 

 albuminous putrefaction, it seems probable that they are in part 

 absorbed, while a portion no doubt is decomposed in the intestinal 

 canal, with the production of succinic acid, glutaric acid, capronic 

 acid, valerianic acid, butyric acid, and acetic acid. The sulphur of 

 the albuminous molecule is usually set free in the form of hydro- 

 gen sulphide, but traces of methyl-mercaptan are also observed, 

 and still further contribute' to the offensive odor of the feces. 



Of the gases which are constantly present in the contents of the 

 large intestine, methane further deserves especial mention. It is to 

 a great extent, no doubt, referable to the peculiar form of fermenta- 

 tion to which the celluloses are subject. But in part at least it prob- 

 ably also results from the decomposition of the fatty acids and of 

 cholin. 



Ptomains are normally not found in the intestinal contents, but 

 may be encountered under certain pathological conditions. In Asiatic 

 cholera and in cases of cystinuria putrescin and cadaverin have thus 

 been isolated, and in other diseases, no doubt, they also occur. 



The methods which are employed for the purpose of isolating the 

 more important products of albuminous putrefaction are described 

 in the chapter on the Feces. 



BACTERIAL DECOMPOSITION OF THE FATS. 



As in the case of the carbohydrates and albumins, a comparatively 

 small portion of the fats only undergoes bacterial decomposition, and 

 it appears that this principally occurs in the lower portion of the 

 small intestine. As in the case of the lipase of the pancreatic 

 juice, the neutral fats are first decomposed into glycerin and the 



