96 ENZYMES 



tyrosin in a pneumonic lung, as well as lysin, histidin, and 

 purin bases from the decomposed nucleoproteids. Flexner l 

 noted that autolysis, while very rapid in the gray stage, is but 

 slight in the red stage (because of paucity of leucocytes) and 

 also in unresolved pneumonia, which he considers as due to 

 some interference with autolysis. Silvestrini 2 found that in 

 gray hepatization the reaction was strongly acid, in red faintly 

 so ; the gray hepatization showed more peptone, and leucin and 

 lactic acid were both demonstrable. A fibrin-digesting enzyme 

 was isolated, and milk was coagulated. Rzentkowski 3 found 

 an increase of non-coagulable nitrogen in the blood of pneu- 

 monics, probably resulting from autolysis in the exudate. 4 



Necrotic Areas. Jacoby 5 found that if a portion of a 

 dog's liver was ligated off and the animal kept alive for some 

 time the necrotic tissue contained the same products that he had 

 obtained in experimental autolysis. The absorption of necrotic 

 tissues generally is ascribable to either autolysis or heterolysis. 

 Presumably there is no great difference in the self-digestion of 

 an organ which is necrotic because its blood supply is cut off 

 and of a similar organ removed from the body aseptically and 

 allowed to undergo aseptic autolysis in an incubator. At the 

 periphery there might be some effects produced by the inhibi- 

 tive action of the serum or the digestive action of the leuco- 

 cytes, but beyond that no marked differences are to be expected. 



A study of the relation of autolysis to the histological 

 changes that occur in necrotic areas by Wells 6 gave evidence 

 that there occurs early a decomposition of the nucleoproteids of 

 the nuclei, which is probably brought about by the intracellular 

 autolytic enzymes. The liberation of the nucleic acid and the 

 reduction in the bulk of nuclear material through the digestion 

 away of the proteid is probably the cause of the pycnosis 

 observed in necrotic areas. Later the nucleic acids are further 

 decomposed through the special enzymes described by Jones, 

 Sachs, and others the " nucleases." This is presumably the 

 cause of the loss of nuclear staining so characteristic of necrosis. 

 That these changes are due to the intracellular enzymes was 

 shown by implanting in animals pieces of sterile tissues, the 

 enzymes of which had been destroyed by heating; these 



l Univ. of Penn. Med. Bull., 1903 (16), 185. 



2 Bull, del Soc. Eustachiana, 1903, abst. in Biochem. CentralbL, 1903 (1), 

 713. 



3 Virchow's Arch., 1905 (179), 405. 



4 Kietschel and Langstein (Biochem. Zeitschr., 1906 (1), 75), report the 

 isolation of considerable quantities of leucin from the urine of a pneumonic. 

 5 Zeit. physiol. Chem., 1900 (30), 149. 

 6 Jour. Med. Research, 1906 (15), 149. 



