io8 



BOTANICAL GAZETTE 



[FEBRUARY 



After the experiment had been set up in the incubator, i hour 

 was allowed for the apparatus and solutions to come to a constant 

 temperature. The manometers were then closed and the solutions 

 mixed. No shaking machine was used, but the apparatus holder 

 was tipped back and forth several times whenever a reading was 

 taken. Allowance for temperature variations was made by run- 

 ning with each experiment a blank containing only water and cor- 

 recting the others by it. 



Table I gives the results of two representative experiments, 

 showing the amount of oxidation of the 3 different reagents by 



TABLE I 



Oxidation of pyrogallol, benzidine, and guaiacol by extracts of healthy 

 AND diseased bark; manometer readings corrected against apparatus 

 containing only water; temperature 28-31° C. 



extracts of both healthy and diseased bark. There are included 

 also data from the earlier paper showing the amount of oxidation 

 of pyrogallol by extract of dried bark. The results indicate that 

 for approximately equal amounts of dry matter the dried bark is 

 considerably less active than the fresh (fig. i). The decrease is 

 probably due to the drying; this is shown more definitely by data 

 to be presented later. It is to be noted that the oxidase activity 

 of diseased bark is definitely greater than that of healthy bark, 



