DECOMPOSITION OF PROTEINS 477 



from "decay;" the latter (often referred to as "eremacausis") was used 

 to designate the decomposition of nitrogenous organic substances in the 

 presence of oxygen, marked by the volatilization of organic constituents 

 while the non- volatile mineral constituents are left behind. 14 



However, both of these phenomena (putrefaction and decay) were 

 not sufficiently understood by the old chemists and bacteriologists 

 and did not have a proper biological or chemical basis. With the 

 advance of our knowledge of the chemistry of proteins, particularly 

 when it was found that ammonia and the "ill-smelling gaseous prod- 

 ucts" were by-products of secondary reactions of protein hydrolysis, 

 the difference between "decay" and "putrefaction," as indicating 

 activities of special groups of bacteria, disappeared. Both of these 

 terms may just as well be dropped from the bacteriological vocabulary, 

 since they do not designate definite chemical processes. Like all 

 chemical reactions brought about by biological agencies, the final 

 products of protein decomposition are a result not only of specific 

 microorganisms, but of various environmental conditions, such as 

 oxygen supply and presence of non-nitrogenous substances, which 

 determine the secondary reactions involved after the hydrolysis of 

 the proteins has taken place. The designation of a process by the 

 nature of these secondary reactions, as a result of environmental condi- 

 tions, led to a great deal of confusion and a lack of proper understand- 

 ing of the processes involved. 



The first systematic study of the chemical reactions accompanying 

 the decomposition of proteins by bacteria (in the so-called process of 

 putrefaction) was made by Nencki. 15 He found that, in the decom- 

 position of fibrin, albumin and gelatin by bacteria, various decomposi- 

 tion products are formed, including leucine, tyrosine, glycocoll and in- 

 dol. When gelatin was decomposed for four days at 40°C. there were 

 formed, for every 100 parts of gelatin, 9.5 parts of ammonia, 24.2 vola- 

 tile fatty acids, 12.2 glycocoll, 19.4 peptone and 6.5 carbon dioxide, 

 71.8 per cent in all. Quantities of gas were also produced in the proc- 

 ess. Nencki concluded that the decomposition of proteins takes 

 place in two stages; viz., processes of hydrolysis and reduction and 



14 Wollny, E. Die Zersetzung der organischen Stoffe. Heidelberg, Winter. 

 1897. 



15 Nencki, M. t)ber die Harnfarbstoffe aus der Indigogruppe und uber die 

 Pankreasverdauung. Ber. deut. Chem. Gesell., 7: 1593-1600. 1S74; 8: 336- 

 338. 1875. 



