188 BOTANICAL GAZETTE [SEPTEMBER 
to impurities in the hydrogen peroxid. Some substance in the 
potato may be freed by the grinding and brought into contact 
TABLE VI 
JOINT EFPECT OF ACCELERATION AND DESTRUCTION BY RISING 
TURE 
Range of temperature 
30-40° 
Velocity coefficients . 
10-20° | 20-30° a 
ee °.8 0.18 7 
o-I0° 
-5 
with the catalase, which effects its slow destruction. _ It is interest- a 
ing to note in this connection, however, that SENTER (6) found a 
hemase to be oxidized at all temperatures above o° C. 
TABLE VII 
AMOUNT OF CATALASE DESTRUCTION’ AT 30° C. FOR 15 MIN. OVER THAT AT 20° C. FOR 
THE 
cc. O, EVOLVED IN 30-SEC. PERIODS | TOTAL 
: Dre 
POTATO TUBER EXTRACT NATION 
inoeied ist | 2d | 3d §] 4th | sth | 6th 
a) Exposed to 30° C. only during de- r 
termination of catalase.......... 30° C. [14.8)14. 7/14. 1/13. 2/12.5/11.9) 21- 
b to 30° C. during exp. (a), 
then cooled to 20° C. for determina- 
Os ey can ak, eee 20° C. |15.0'14.5\13 7)\13-3/12-7|12-4 21.6 
c) Not exposed above 20°C........ 20° Cy |1rs.0lx6. 314 7\13 9,13 3/12 8} 25-7 
DESTRUCTION OF THE CATALASE DURING THE REACTION WITH 
HYDROGEN PEROXID 
Potato catalase is not unlimited in its power to effect the decom- 
position of hydrogen peroxid. Table VIII shows not only the above 
fact, but also would seem to indicate that it is consumed a 
reaction and that a given amount is capable of decomposing # 
definite amount of hydrogen peroxid. : 
The total extract of a potato weighing 50 grams was diluted a 
500 cc. with water, and 5 cc. of this extract were allowed to “ 
upon 1 cc. of 1.5 per cent hydrogen peroxid until less than 0-1 = 
of oxygen was evolved in 5 min. Another cubic centimeter % 
hydrogen peroxid was then added and the reaction allowed to ye 
to the same point. This procedure was continued until the addi- 
tion of a cubic centimeter of hydrogen peroxid produced only1-* ee 
of oxygen in 25 min.; 6 cc. were required to bring the reaction 
