BIOCHEMICAL FEATURES 75 



only by pneumococci and streptococci and, according to Penfold, 

 is due to the peroxide produced by these organisms. 



In the next year, Felton 395 studied the oxidase reaction of bac- 

 teria by means of the oxidation of p-amino leuco-malachite green, 

 and found that the conditions most suitable for the reaction were 

 the presence of a slight amount of hemoglobin and of dextrose, an 

 acid reaction, the presence of fresh serum heated for thirty min- 

 utes at 56°, and a plentiful supply of oxygen. In order of decreas- 

 ing suitability for promoting oxidation were rat, guinea pig, rab- 

 bit, horse, human, cat, and chicken serum. Of the organisms tested 

 by Felton, only Pneumococcus, S. viridans, and S. haemolyticus 

 exhibited oxidative power, the first named giving the most intense 

 reaction. That this power was not an exclusive character of the 

 three species was shown in the same year (1923) by McLeod, Gor- 

 don, and Pyrah, 884 who added B. bulgaricus and B. acidophilus to 

 the group of peroxide-producing bacteria. 



Directly opposed to the conclusions of McLeod and Gordon and 

 of Cole, but somewhat analogous to those of Felton, were the views 

 of Barnard and Gowen. 80 These two authors discounted the possi- 

 bility that the green disintegration product of hemoglobin refer- 

 able to the growth of pneumococci is methemoglobin, since methe- 

 moglobin will not exist in the presence of hydrogen peroxide. A 

 green pigment, identical in all respects with that produced by the 

 growth of pneumococci on hemoglobin, was prepared by Barnard 

 and Gowen by the action of peroxide and certain nitrogenous com- 

 pounds on blood pigment. A chemical study of this artificial green 

 pigment indicated to the authors that it was not methemoglobin 

 but a xanthoprotein compound. Without more complete informa- 

 tion it is impossible to judge the correctness of the claim, but 

 studies from the Hospital of the Rockefeller Institute seem to 

 prove the case for methemoglobin. It is, however, possible that the 

 appearance of xanthoprotein may be an additional effect of 

 peroxide. 



Avery and his colleagues published a series of papers that mate- 



