BIOCHEMICAL FEATURES 73 



presence of reducing agents, the latter are first oxidized, the ac- 

 tion occurring more readily in the presence of oxyhemoglobin. In 

 some instances an alternate oxidation and reduction of the trans- 

 formative agent occurs, so that the reaction is continuous. The ef- 

 fect of the presence or absence of free 2 on the changes in blood 

 pigment induced by chemical agents of known composition sug- 

 gests that the reaction with Pneumococcus follows similar lines. 

 The reaction does not occur in the absence of 2 . If the free 2 be 

 first removed and then replaced, the reaction takes place more 

 rapidly than if the 2 had not been removed. The presence of free 

 2 in excess slightly delays the reaction, possibly because of the 

 inhibition of the reduction process which forms the first part of 

 the reaction. 



In 1924, Morgan and Neill, 916 as a result of their experiments, 

 concluded that: 



Sterile filtrates of aerobic cultures of Pneumococci containing H 2 2 , 

 were capable of converting catalase-free solutions of oxyhemoglobin 

 into methemoglobin. In catalase-containing solutions of hemoglobin 

 from laked corpuscles, the actual methemoglobin-forming system of 

 Pneumococcus involves a labile constituent of the bacterial cell, which is 

 itself susceptible to oxidizing agents and may be rendered inactive if 

 exposed to peroxide or similar substances previous to its introduction 

 into oxyhemoglobin solutions. The activity of this function, in the case 

 of sterile filtrates, depends, therefore, upon the liberation of cell con- 

 stituents into the medium and upon the protection of those cellular sub- 

 stances from the oxidizing agents which are formed when Pneumococ- 

 cus cultures are freely exposed to air. When these cultural conditions 

 are fulfilled, sterile culture filtrates of Pneumococcus convert oxyhemo- 

 globin into methemoglobin independent of the presence of blood cata- 

 lase. 



In 1921, Stadie, 1311 in studying the blood changes in pneumo- 

 coccal infections, found that methemoglobin disappeared rapidly 

 from the blood stream, whether introduced by injection or formed 

 within the circulation by pneumococci or by the action of chemicals 

 (potassium ferricyanide and sodium nitrate). He concluded: "In 



