80 BIOLOGY OF PNEUMOCOCCUS 



i?H, the actual source of the oxidizing agents, and the thermo- 

 labile cellular constituent as C, serving as a catalyst in acceler- 

 ating the reaction, which they formulated thus : 



1) C + -RH -\- 2 — » oxidizing agent 



2) Oxidizing agent -f- C — > inactive C. 



i?H then represents substances that are not present in Pneumo- 

 coccus after thorough washing; they are relatively stable, resist- 

 ing boiling for prolonged periods, and are present in water or al- 

 cohol extracts of muscle, yeast, and vegetable tissue. C represents 

 a labile cellular component, inactivated in ten minutes at 65°. By 

 itself it is non-reactive with 2 and possesses no reducing power, 

 being apparently catalytic in nature. 



Neill 948 observed that both living pneumococci and sterile ex- 

 tracts prepared from unwashed cells were capable of oxidizing 

 hemoglobin to methemoglobin, and that the action was a reversible 

 one, the equilibrium being shifted in either direction by regulation 

 of the oxygen tension. Neill 947 also found quantitative evidence of 

 the reduction of methemoglobin to hemoglobin by sterile animal 

 tissues, such as kidney, testicle, and liver from an exsanguinated 

 rabbit. He concluded, therefore, that "the accumulation of large 

 amounts of methemoglobin in the circulating blood is probably an 

 indication not only of the formation of large amounts of this pig- 

 ment, but also of a poisoning of the normal reducing mechanism of 

 the animal tissues." This statement is difficult to reconcile with 

 that of Stadie (p. 73, ante) that in man, at least, methemoglobin 

 is removed from the circulation as rapidly as it is formed. 



In another note, Neill 949 added that in the presence of air the 

 oxidizing activity of pneumococci was much stronger than their 

 reducing activity in the absence of air, while the reverse was true 

 for anaerobic bacteria. From subsequent studies, Neill 950 was able 

 to elaborate the graphic representation of the oxidation-reduction 

 reaction to include the production of methemoglobin : 



