86 ENZYMES 



as a normal physiological process by reverse enzyme action, 

 requires that the proper enzymes be present in the cells through- 

 out the body, and within the past few years it has been abund- 

 antly demonstrated that such is the case. 



For over half a century it has been known that amebse digest 

 solid proteids within their bodies, but it is only within a few 

 years that proteolytic enzymes have been definitely isolated from 

 them. It has been much the same with the intracellular pro- 

 teases of the higher organisms. In 1871 Hoppe-Seyler referred 

 to the liquefaction of dead tissues within the body which occurred 

 without putrefaction, and, as he noted, resembled the effects of 

 the digestive ferments. In was nearly twenty years later that 

 Salkowski l showed definitely that this softening of dead tissues 

 was really brought about through a true digestion by intracel- 

 lular enzymes, which produced the same splitting products that 

 were at that time considered characteristic for tryptic digestion 

 (leucin and tyrosin). The process he named "autodigestion." This 

 important observation remained almost unnoticed for ten years 

 more, when Jacoby, 2 in 1900, took up the investigation of this 

 matter of cellular self-digestion, and after this the importance of 

 the principles involved became for the first time generally appre- 

 ciated. Jacoby rechristened the process " autolysis" by which 

 name it is now commonly known. 



AUTOLYSIS 3 



Autolysis is generally studied by the method used by Sal- 

 kowski, which depends upon the difference in the susceptibility 

 of bacteria and of enzymes to antiseptics. The organs are ground 

 up to a pulp, placed in flasks with or without the addition of 

 water or dilute acids, and bacterial action is prevented by the 

 addition of antiseptics that are not poisonous to enzymes toluol 

 and chloroform are most commonly used. It is possible also to 

 secure organs in an aseptic condition and to permit them to 

 undergo autolysis without the use of antiseptics, but the practi- 

 cal difficulties are such that this method is seldom used it is 

 sometimes designated as " aseptic autolysis" in contradistinction 

 to antiseptic autolysis by the Salkowski method. In a short time 

 it can be seen that digestive changes have taken place, particu- 

 larly if comparisons are made with control flasks in which the 



1 Zeit. f. klin. Med., 1890, supplement to Ed. 17, p. 77. 



2 Zeit. f. physiol. Chem., 1900 (30), 149. 



3 Kesum6 of literature by Salkowski, Deutsche Klinik, 1903 (11), 147; also 

 see Schlesinger, Hofmeister's Beitrage, 1903 (4), 87 ; Oswald, Biochem. Centr., 

 1905 (3), 365 ; Levene, Jour. Amer. Med. Assoc., 1906 (46), 776. 



