234 BOTANICAL GAZETTE * * [march 



3. Potassium, sodium, and magnesium nitrates (0.10N) 

 had practically no effect on oxidation, while nitrates of calcium, 

 barium, manganese, and iron (ferric) decreased it. 



4. Potassium chloride (0.02 N and 0.002 N) had no effect on 

 oxidation, while manganese chloride in these concentrations 

 increased it. 



5. Tartrates, oxalates, citrates, acetates, and carbonates 

 increased oxidation. Marked increase in oxidation in these cases 

 seems to be due, in part at least, to the low acidity of the mixtures 

 of bark, pyrogallol, and salt. 



Marked 



mixtures 



in regulating oxidase activity. 



may be 1m 



1m 



to take into consideration, in the study of oxidase activity, the 

 possible effect of the salts formed thereby. 



9. The chlorides which retard the combustion of tobacco at 

 high temperatures also retard the oxidase action at low tempera- 

 tures. 



10. The effect of the alkali chlorides upon oxidase activity 

 suggests a practical application in preventing the browning of 

 fruits and vegetables during their preparation for canning, pre- 

 serving, or drying. 



Wm 



Crocker for many helpful 



Bureau of Plant Industry 

 Washington, D.C. 



1 



LITERATURE CITED 



Abderhalden, Emil, and Guggenheim, Markus, Versuche iiber die Wirk- 

 ung der Tyrosinase aus Russula delica auf Tyrosin, tyrosinhaltige Poly- 

 peptide und einige andere Verbindungen unter verschiedenen Bedingungen. 



Zeit 



1 907-1908. 



2. Alsberg, Carl L., Beitrage zur Kenntnis der Guajak-Reaktion. Arch. 

 Exp. Path, und Pharm. Festschrift. Schmiedeberg, pp. 39-53- I 9° 8 - 



