AUTOLYSIS IN PNEUMONIA 91 



act unimpeded by the anti-bodies of the blood plasma. Digestion 

 of the exudate continues after death, accounting for the marked dif- 

 fuse softening observed in pneumonic lungs in bodies kept some days 

 before autopsy. As long ago as 1888, Kossel^^ mentioned that Fr. 

 Miiller had found that glycerol extracts of purulent sputum exhib- 

 ited a digestive action upon fibrin and coagulated protein, whereas 

 non-purulent sputum did not possess this property. In 1877 Filehne 

 extracted ferments in the same way from the sputum in gangrene 

 of the lung; Stolniknow, in 1878, found a similar ferment in pneu- 

 monic sputa, and Escherichin 1885 showed that the proteolytic action 

 of tuberculous sputum was independent of putrefaction. Other early 

 observations of similar nature are reviewed by Simon, 2" who demon- 

 strated the presence of leucine and tyrosine in the autolyzed lungs. 

 In a later work ^Miiller reports finding three grams of leucine and 

 tyrosine in a pneumonic lung, as well as lysine, histidine, and purine 

 bases from the decomposed nucleoproteins. The appearance of free 

 purines during autolysis of pneumonic lungs has been investigated 

 by Mayeda,2i Long and Wells. ^^ Boehm^^ isolated histidine and 

 arginine from the same material. Rietschel and Langstein^'* found 

 0.32 gm. leucine in the urine of a pneumonic child. 



Flexner^' 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 inter- 

 ference with autolysis. Silvestrini^^ found that in gray hepatization 

 the reaction was strongly acid, in red faintly so; the graj"- hepatization 

 showed more peptone, and leucine and lactic acid were both demon- 

 strable. A fibrin-digesting enzjmie was isolated, and milk was coagu- 

 lated. 



Weiss^^ has reported finding a toxic albumose in gray pneumonic 

 lungs. Lord-* has found in pneumonic lungs a proteolytic enzyme 

 active at pH 7.3 to 6.7, but inactive at higher acidity; also an enzjine 

 sphtting peptone to amino acids and active at pH 8.0 to 4.8, but 

 most active at 6.3 to 5.2. He, therefore, pictures resolution of pneu- 

 monic exudates as occurring in two stages: First, proteolysis while 

 the reaction is nearly neutral, and later as the acidity increases the 

 cleavage of the peptone increases. He also finds that the pneumo- 

 cocci cannot long survive a reaction more acid than pH 6.8, and 

 their dissolution takes place at reaction from 6.0 to 5.0, which is of 



19 Zeit. f. klin. Med., 1888 (13), 149. 



20 Deut. Arch. klin. Med., 1901 (70), 604. 

 "1 Deut. Arch. klin. Med., 1910 (98), 587. 

 22 /Wd, 1914 (115), 377. 



23 Ibid., 1910 (98), 583. 



24 Biochem. Zeit., 1906 (1\ 75. 



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



-^ Bull. del. Soc. Eustachiana, 1903, abst. in Biochem. Centralbl., 1903 (1), 713. 

 " Arch. Int. Med., 1919 (23), 395. 

 28 Jour. ExD. Med., 1919 (30), 379. 



