96 EXZYMES 



proteases in leucocytes, find also evidence of an ereptic enzyme act- 

 inpr in either Scid or alkaline fluids. 



Pneumonia. — In the stage of resolution lobar pneumonia presents 

 a striking example of autolysis. The often-remarked phenomenon 

 that the lung tissue itself is not in the least afiPected, while the dense 

 contents of the alveoli are rapidly dissolved and removed is explained 

 by the invariable immunity of living cells to digestive enzymes. Ex- 

 cept for some slight possible assistance by the alveolar epithelium 

 and the enzymes of the serum, the enormous and rapid digestion of 

 pneumonic exudates is accomplished by tlie leucocytic enzymes. The" 

 rapid rate of digestion may be accounted for bj- the absence of circu- 

 lation within the alveolar contents, which permits the leucocytes to 

 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. 

 ]\Iiiller had found that glycerol extracts of purulent sputum exhib- 

 ited a digestive action upon fibrin and coagulated protein, whereas 

 non-i)urulent 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 Escherich in 1885 showed that the proteolytic action 

 of tuberculous sputum was independent of putrefaction. Other early 

 observations of similar nature are reviewed by Simon,^° who demon- 

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

 In a later work IMiiller 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,^^ 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 \ery 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 auto- 

 lysis. Silvcstrini ^^ found tliat in gray hejiatization the reaction was 

 strongly acid, in red faintly so; the gray hepatization showed more 

 peptone, and leucine and lactic acid were botli demonstrable. A 

 fibrin-digesting enzyme was isolated, and u\\\k was coagiilated. 



70Zcit. f. klin. :\rcd., 18SS (1.3), 149. 



80 Dent. Arch. klin. Med., inOl (70), G04. 



81 Dent. Arcli. klin. Med., 1910 (98), 5cS7. 

 8ia/?;tU, 1914 (115), 377. 



»2jhid., 1910 (98), .-iS.^. 

 83Biodicm. Zcit., 1906 (1), 75. 



84 Univ. of Penn. Med. Bull., 190.3 (16), 185. 



85 Bull. del. Soc. Kustaeliiana, 1903, abst. in Biochem. Centralbl.. 1903 (1). 713. 



