120 



BOTANICAL GAZETTE 



[FEBRUARY 



that by adding a second portion of the powder to the apparatus 

 in which oxidation by the first portion had ceased he could cause 

 a further increase in oxidation, the amount of increase varying 

 with the oxidase reagent used. The writer has found a similar 

 increase in oxidation when more oxidase reagent is added, after 

 oxidation ceases. . The results of an experiment of this kind are 

 summarized in table VIII. Results are given beginning with the 



TABLE VIII 



Summary of results from an experiment to test effect of adding 

 fresh supply of oxidase reagent. 



Experiment 



Effect of adding 7 and 4 drops i per cent 

 benzidine to apparatus 10 and 11 on 

 ninth day, 8 and 9 as checks 



Effect of adding 10 drops i per cent ben- 

 zidine to apparatus 10 and 11 on 

 eleventh daj^, 8 and 9 as checks 



Total effect of i per cent benzidine, 8 as 

 check 



Effect of adding 0.06 gm. of pyrogallol 

 to 8 on twenty-sixth day 



8 as check 



Effect of adding o . 06 gm. benzidine to 9 

 on fourteenth day, 8 as check 



Effect of adding 10 drops absolute 

 alcohol to 9 on twenty-first day, 8 as 

 check 



Stage of experi- 

 ment 



Increase in oxidation (cm. of 

 mercury rise) 



9th to nth 



0.00 



nth to 14th 0.17 



9th to 26th 0.47 



j 



26th to 41st I 1-53 



9th to 26th I 0.47 



14th to 2ist i 0.19 



2ISt to 26th 



o.n 



0.02 



0.23 



0.74 



0.68 



0.49 



1. 16 

 1-95 



o. 19 



0.71 



1-34 



ninth day of the experiment. Up to that time oxidation in all 

 4 of the tubes was practically the same, the average being 3.12 

 (cm. of mercury rise): Alcohol was used at the beginning of the 

 experiment to discover whether it has an inhibiting effect on oxi- 

 dation, and later, when solid benzidine was added, to bring the 

 benzidine into solution more rapidly. The results show that, in 

 the small quantities used, the alcohol had no inhibiting effect 

 (table VIII, ninth day, apparatus 10 and 11), and probably did 

 bring the benzidine into solution (twenty-first-forty-first day, 

 apparatus 9). 



The most important fact shown by these results is that after 

 oxidation had practically ended, the addition of more oxidase 



