THE SAPROGENIC AND SAPROPHILIC BACTERIA 225 



These numerous putrefactive processes may occur in the 

 intestinal tract of all animals. Conditions there are particu- 

 larly favorable to the action of anaerobic bacteria. 



The ultimate end-products of all putrefactive processes are: 

 free ammonia (NH 3 ), carbon dioxide (CO 2 ), hydrogen (H), 

 and water (H 2 O) ; under certain conditions phosphoric acid 

 (H 3 PO 4 ), phosphoretted hydrogen (PH 3 ). Free nitrogen (N) is 

 undoubtedly evolved in some cases. 



The process of putrefaction is greatly influenced by the 

 presence or absence of oxygen. The disagreeable aromatic 

 odors are not produced by aerobic bacterial processes (decay), 

 but are evolved only when oxygen is excluded. The presence 

 of oxygen accomplishes rapid oxidation, and the odor is not 

 noticeable after a short space of time. 



For the purpose of summarizing, we can say that the fol- 

 lowing substances result from the putrefaction and fermenta- 

 tion of organic compounds in all composite decomposition 

 processes. 



i. Proteins: 



(a) Aromatic radicals phenylalanin, tryptophan, and 



tyrosin, which by splitting produce indol, skatol, 

 phenol, cresol. 



(b) Sulphur radicals hydrogen sulphide, ethyl sul- 



phide, ethyl and methyl mercaptan. 



(c) Fatty acid radicals formic, acetic, propionic, 



butyric, valerianic, palmitic, stearic acids, acetone 



Q 



