72 BIOLOGY OF PNEUMOCOCCUS 



with washed rabbit corpuscles, there ensued a diminution of the 

 oxygen-carrying capacity of the cells, owing to the formation of 

 methemoglobin, or some derivative of hemoglobin with identical op- 

 tical constants for these regions of the spectrum. The substance 

 which induced this change was also present in sterile filtrates of 

 autolyzed cultures. The authors concluded that the mechanism of 

 the reduction of the 2 -carrying capacity of the blood in human 

 lobar pneumonia was, in part at least, of the same nature. In rab- 

 bits with a severe experimental bacteriemia it was found that the 

 2 -combining power of the venous blood fell progressively up to 

 the time of death. Coincidentally, there was an even more marked 

 fall in the 2 content of the arterial blood. The changes in the 

 blood of infected animals appeared to be analogous to those seen 

 when Pneumococcus was grown in blood in vitro, the oxygen-car- 

 rying capacity of the cells in both instances being due to the con- 

 version of hemoglobin into methemoglobin. 



In the next year (1914), Cole 253 reported conclusions which, be- 

 cause of their importance, may be summarized here: Pneumococci 

 in contact with hemoglobin transform this substance into methemo- 

 globin, and the reaction occurs only when the pneumococci are liv- 

 ing; it is not induced by the culture fluid or by extracts of the 

 bacteria, differing in this respect from the results of Butterfield 

 and Peabody. The reaction does not occur when hemoglobin is 

 added to an emulsion of washed pneumococci in salt solution. How- 

 ever, if minute traces of dextrose be added to the mixture, the 

 transformation occurs quickly. Dextrose may be replaced by any 

 one of a number of other sugars, and also by some organic com- 

 pounds, if the latter are added in large amounts. Certain other or- 

 ganic substances were unable to replace dextrose, but it was impos- 

 sible to determine any special molecular configuration upon which 

 this property depends. The formation of methemoglobin by pneu- 

 mococci probably resembles the changes induced in the blood by 

 such chemical substances as amino phenol. It seems not unlikely 

 that the transformation is always a reaction of oxidation. In the 



