DIGESTION 



321 



Ou 



OSO,OK 



N' 

 H 



Indican 

 (potassium indoxyl sulfate) 



in the liver and are excreted in this form in the urine. Tyramine, hista- 

 mine, putrescine, and cadaverine occur in feces; they are probably the 

 products of bacterial decarboxylation of the amino acids tyrosine, histi- 

 dine, ornithine, and lysine, respectively: 



HO—/ \— CH.CHNH2COOH 

 Tyrosine 



-* HO- 



r^ 



CH2CH2NH2+ CO2 



Tyramine 



HN-CH 



N-C— CH:CHXH,COOH 



Histidine 



HN-CH 

 -> HC^ +CO2 



N-C— CH2CH2NH2 

 Histamine 



NH 



II 

 NH2-C— NH-CH2- CH2— CH2— CHNH2- COOH 



Arginine 



O 



NH2-C— NH2 + KH2CH2CH2CH2CHNH2COOH - 



argmase 

 + H2O 



Urea 



Ornithine 



NH2CH2CH2CH2CH2NH2 + CO2 

 Putrescine 



NH2CH0CH2CH2CH2CH2NH2 + CO2 

 Cadaverine 



NH0CH2CH2CH2CH2CHNH2COOH - 



Lysine 



Hydrogen sulfide and methane are among the gaseous products of putre- 

 faction in the colon. A typical analysis of the intestinal gases of swine 

 gave 25 per cent methane, 50 per cent carbon dioxide, and 25 per cent 

 hydrogen. In herbiverous animals large quantities of gas are produced 

 in the paunch, in addition to those in the intestines. The decomposition 

 of foods by bacteria, leading to gas formation in the paunch, may account 

 for as much as 25 per cent of the energy loss from the food during the 

 digestive process. 



The nutritional significance of the intestinal bacterial flora has been 



