I 



L 



roi-I BUNZELL & HASSELBRIXG— PEROXIDASES 2 2*] 



8. Methyl alcohol and ethyl alcohol when gently warmed 

 reduced potassium permanganate to a colorless solution, which 

 when filtered from the brown precipitate gave no oxidase 

 reactions. 



9. Formaldehyde and acetaldehyde reduced potassium per- 

 manganate in the cold, giving brown or black precipitates and 

 colorless solutions which gave no oxidase reactions. This result 



xpected from 



alcohol. 



10. A trace of manganese peroxide shaken up in water oxidized 

 guaiac, potassium iodide (in neutral solution), and pyrogallol. 



In all these experiments, a large excess of the organic com- 

 pounds was used, so that the solutions would be free from potassium 

 permanganate in the sense in which Reed considered his solutions 

 free from unreduced potassium permanganate. The potassium 

 iodide reactions were carried out in solutions of the same strength 

 as those used by Reed. In all cases the reagents and control 

 mixtures failed to give the oxidase reactions. The brown filtrates 

 as well as the colorless ones contained manganese. 



It appears from these experiments that in the reduction of 

 potassium permanganate by organic substances in neutral solu- 



mansanese are formed 



which 



of per- 

 manganic acid are still capable of carrying out oxidations. When 



permanganate 



manganese 



compounds no longer gives the 

 oxidation reactions described. By careful reduction both stages 

 can be obtained with the same compound (glycerine, glucose). 



Inasmuch as the brown solutions contain manganese not 

 reduced to its lowest state of oxidation, and since manganese 

 peroxide itself brings about the oxidation of guaiac, potassium 

 iodide, -and pyrogallol, it becomes extremely probable that the 

 oxidation phenomena observed by Reed were brought about by 

 peroxides of manganese and not by activated plant peroxidases. 

 Moreover, since a number of substances acting on potassium per- 

 manganate give mixtures which oxidize other compounds, there is 

 no evidence in Reed's experiments that the reduction of the 





