July is, 1921 
Catalase and Growth in Potato Wart Disease 
59 1 
fresh 12-volume hydrogen peroxid (Dioxogen) previously neutralized 
with calcium carbonate (CaCO) s . The amounts shown are cubic centi¬ 
meters of 0 2 evolved in 5 minutes of slow and approximately constant 
shaking. In most cases 50 gm. of tissue was ground with quartz and 
excess calcium carbonate in a mortar and made up to 1,000 cc. with 
water. In a few cases different amounts of tissue were used, but cor¬ 
rections have been made in the totals. The temperature during the tests 
could not be held constant, but the fluctuation was less than 2 0 C. for 
controls. 
Table II. —Catalase activity in healthy and wart potato tissue from the same plants as 
measured by cubic centimeters of oxygen evolved from 10 cubic centimeters of hydrogen 
peroxid in 5 minutes a 
Variety. 
|Rural New Yorker. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Early Rose. 
'Woodbury’s White Rose 
Do. 
Do. 
Prince Henry. 
Do. 
Do. 
Do. 
Portuguese Purple. 
Do. 
Average. 
Tempera¬ 
ture. 
•c. 
21 
21 
19 tO 20 
20 tO 21 
18. 5 
19 tO 20 
2I - 5 
20. 5 
21. O 
19- 5 
23- 5 
22. 5 
19. 2 
21. o 
22 . 2 
23.O 
22. 5 
21. 7 
Healthy. 
Num¬ 
ber of 
tests. 
Average 
cubic cen¬ 
timeters 
O2. 
IO 
I0 - 5 
7.8 
Wart. 
Average 
cubic cen¬ 
timeters 
o 2 . 
14. I 
17. o 
17. 9 
18.6 
22. 4 
3 
18.3 
11. 7 
22. 4 
28. 1 
17.9 
Num¬ 
ber of 
tests. 
a Results of determinations for tubers of one plant are inclosed in braces. 
The tables show the effect of this parasite in producing acidity in the tis¬ 
sues it infects, the average acidity of healthy tissues expressed by P n 6.49, 
becoming P H 6.00 in the warts. In no case does the acidity of healthy 
tissue approach that of diseased tissue. This indicates that the organism 
will be found to be an acid producer when it is successfully cultivated 
on artificial media and gives also the range of acidity for its activity in 
the host tissue. Similarly, catalase activity is very much greater in the 
overgrowths than in normal tubers, the values being expressed respec¬ 
tively by 17.9 and 7.8 cc. of 0 2 evolved. In no instance does the catalase 
activity of healthy tubers approach that of warts by nearer than 10 per 
