DIGESTION IN THE INTESTINE 149 



stituent, and appears to contain no enzymes of digestive 

 importance. 



Bacterial Action in the Intestine. The intestine shelters and 

 favors the growth of enormous numbers of bacteria, which feed 

 upon the substances of the intestinal contents. From these 

 materials, bacteria produce a large number of compounds, some 

 of which are harmless, but some extremely toxic to the body. 

 The toxic materials are produced mainly from the digestion 

 products of the proteins, the amino acids. By splitting out 

 COO from the carboxyl group of an amino acid an amine is 

 produced. These substances are known as ptomaines ; many are 

 extremely toxic. An example of this process is the formation of 

 ethyl amine from alanine. 



CH 3 CH. NH 2 COOH-C0 2 +CH 3 CH 2 NH 2 



From tyrosine, by splitting off the side chain, a process which 

 goes in several stages, phenol is produced 



H H 



C C 



/\ / \ 



HC C CH 2 CHNH 2 COOH HC CH 



II I II I 



HO C CH HO C CH 



V \ ' 



c c 



H H 



Tyrosine Phenol 



From tryptophane indol and skatol are produced. 



H H 



C C 



HC C C CH 2 CHNH 2 COOH HC C C.CH 3 



HC C C HC C CH 



V V \ / \ / 



C N C N 



H H H 'H 



Tryptophane Skatol 



