BIOCHEMICAL FEATURES 79 



they exert on the saccharolytic enzymes, sucrase, raffinase, inulase, 

 and amylase, of the cell. Aerated extracts, however, have no inacti- 

 vating effect on pneumococcal protease or lipase. 



The relative resistance of the enzymes of Pneumococcus to heat 

 is consistent with their resistance to the action of hydrogen per- 

 oxide. Neill and Avery 903 found, furthermore, that sterile ex- 

 tracts of autolyzed anaerobic cultures of pneumococci contained 

 much higher concentrations of active endocellular enzymes than 

 did filtrates of autolyzed aerobic cultures. The difference may be 

 explained by a destruction of the formed enzymes by oxidative re- 

 actions analogous to the destruction observed during oxidation of 

 sterile broth extracts of unwashed pneumococcal cells. The more 

 complete destruction of enzymatic activity in autolyzed aerobic 

 cultures than in oxidized sterile cell extracts is probably due to 

 the longer exposure to oxidation products. More recently Finkle 

 (1931), 440 in a study of the metabolism of pneumococcal variants, 

 confirmed the fact that oxidation may have an inhibitory effect on 

 sugar fermentation. Under anaerobic conditions saccharolysis is 

 approximately the same for organisms of Types I, II, and III, 

 while, under aerobic conditions, only Type I cells are capable of 

 this action. The difference may be explained by the relatively 

 feebler respiratory capacity of Type I organisms. The capacity of 

 these cells is only 56 per cent of that of Type III pneumococci, 

 which in turn is 71 per cent of that of Type II strains. 



In a later paper, Neill and Avery 956 reported further details of 

 the oxidation-reduction system of Pneumococcus. The thermosta- 

 ble components of the oxidation-reduction system were still active 

 in oxidized extracts, while the thermolabile cellular constituent was 

 destroyed not only by products formed during oxidation, but also 

 by molecular oxygen itself. The labile component of the system 

 was more susceptible to the action of reagent hydrogen peroxide 

 than any other known intracellular substance of pneumococcal ori- 

 gin. Neill and Avery designated the thermostable substances as 



