CH. VIII.] 



BACTERIAL DECOMPOSITION. 



223 



the proteins and amino-acids have such powerful physio- 

 logical actions that they merit special attention. 



It is probable that undigested protein is more liable 

 to putrefaction than are the amino-acids themselves, since 

 the latter are rapidly absorbed from the small intestine, 

 where, normally, bacterial action is not very pronounced. 

 For that reason, if the proteins of the food are well cooked, 

 thoroughly masticated, and readily digested, the ill-effects 

 due to the absorption of the decomposition products are 

 not likely to occur. 



The changes are probably due to the action of enzymes 

 secreted by the growing organisms. But such enzymes are 

 not easily extracted from their bodies. The order in 

 which the changes occur has been much discussed. Mr. H. 

 Raistrick has made a special study of certain of the reactions 

 involved, and has suggested the scheme given on the next 

 page as indicating the lines on which the decomposition 

 takes place. 



The following list gives examples of the substances 

 corresponding to-the types A to F of the scheme, which are 

 formed by the bacterial decomposition of tyrosine, trypto- 

 phane and histidine. 



