THE SAPROGENIC AND SAPROPHILIC BACTERIA 221 



that the saprogenic bacteria are acting on the nitrogenous 

 compounds. The processes usually go hand in hand. The 

 process of true putrefaction, however, takes place only in 

 nitrogenous compounds. A distinction is sometimes made 

 between putrefaction and decay. The former is held to be a 

 distinctly anaerobic process, while the latter is applied to 

 those decompositions taking place in the presence of oxygen 

 and due to aerobic bacteria. 



Products Produced. We will discuss as briefly as possible 

 the results of the decomposition and so-called putrefaction 

 of the protein molecule which contains the nitrogen of nearly 

 all organic substances. 



It may be here stated that the protein molecule can be split 

 by many agencies, among which are superheated steam, acids 

 and alkalies in different concentrations, and by bacterial 

 enzymes. The changes produced by bacterial enzymes are 

 the most pronounced, and the secondary products produced 

 thereby are different from the cleavage products produced 

 in other ways. In all cases, the protein molecule is changed 

 into compounds which are closely related to the original 

 typical protein molecule; namely, proteases and peptones. 

 At this point the lines of cleavage may be different and many 

 end-products result. By the action of the bacterial enzymes 

 of saprogenic bacteria these proteoses (albumoses) and pep- 

 tones are split into a series of simple substances which seem 

 to be the usual elementary products of the protein molecule. 

 They are as follows : 



