112 



BOTANICAL GAZETTE 



[FEBRUARY 



noted were in those cases where the bark powder showed low 

 oxidase activity to begin with, possibly due to injury of the "oxi- 

 dase" during drying. 



TABLE III 



Oxidation of pyrocatechin, guaiacol, and benzidine by healthy and 



DISEASED bark; TEMPERATURE 29.4-29. 7° C. 



That the rate and temperature of drying have an efifect on the 

 oxidase activity as well as on the hydrogen ion concentration is 

 clearly shown in table IV. 



TABLE IV 



Effect of rate and temperature of drying upon oxidase activity and 

 hydrogen ion concentration of healthy and diseased apple bark 



*This figure is the negative logarithmic exponent of 10 where the whole expression 10=5' is a 

 measure of the hydrogen ion concentration in the solution. The larger it is, therefore, the smaller the 

 hydrogen ion concentration it expresses. In this particular case it can be written 2.454X10 "> (6.00 — 

 S .61 =0.30. Antilog 0.39 = 2.454). In the amplified form this becomes 0.000002454 (normal). 



Samples i, 2, 5, 5a, and 6 were all run in one experiment. 

 Oxidation data for samples 3 and 4 are taken from table II and 

 from another experiment not recorded in this paper. Samples 5 

 and 5a were parts of the same lot of ground bark but received 



