DIGESTION 37 



tion, as in intestinal juice, in the other instance they are 

 contained within an organism. In bacterial digestion 

 the first stages of digestion are very similar to those 

 induced by trypsin. If the protein is insoluble solution 

 is first effected which is not a rapid process as in the 

 case of trypsin. The proteoses and peptones are next 

 formed but are quickly transformed into lower decom- 

 position products. Proteoses and peptones are much 

 more readily attacked than are the native proteins, 

 which may not begin to undergo a profound change 

 until the former have been broken up to smaller mole- 

 cules. 



Putrefaction may be regarded as causing a different 

 type of cleavage than occurs in ordinary tryptic or in- 

 testinal digestion as exemplified by the specific sub- 

 stances produced. It would appear much more likely, 

 however, that the early stages of tryptic digestion and 

 those induced by bacteria are identical in both instances, 

 amino acids being the final products. On the other 

 hand, little or no putrefaction occurs in the small intes- 

 tine and there is little reason to assume that under 

 ordinary circumstances any unchanged protein or 

 perhaps even proteoses or peptones succeeds in pass- 

 ing the ileo-caecal valve. It is therefore probable that 

 normally putrefactive bacteria act upon the amino acids 

 rather than upon their precursors, the complex protein 

 molecules. It is even doubted whether pure solutions 

 of native proteins will putrefy directly. Accepting the 

 hypothesis that it is the amino acids which are con- 

 cerned primarily in putrefactive processes the forma- 



