Aug. is. 1914 
Oxidases in Potatoes 
3S9 
the other. The irregularities are due, no doubt, to differences between 
individual samples and to slight differences in the mode of preparation 
of the juice. Great care was used to maintain uniformity of technique 
throughout this work, so that it does not seem very likely that the latter 
factor plays a r 61 e in the variations of oxidase contents observed. 
OXIDASE ACTIVITY OF THE JUICE OF SEED TUBERS 
In connection with these results the oxidase activity of the seed tubers 
of the plants used in these experiments seemed of interest. The average 
weight of the tubers when examined was 90 grams. The oxidase deter¬ 
minations were started on July 18, when the tubers had just begun to 
sprout. The results are given in Table VIII. 
Table VIII .—Oxidase activities of the juice of seed potato tubers from which all the healthy 
material used in this investigation was obtained 
Oxidase activity expressed in units as measured in the oxidation of the reagents. 
Series No. 
i 
Date. 
Benzi- 
din. 
Pyro- 
gallol. 
a-naph- 
thol. 
L. b. of 
m. g.« 
Phloro- 
glucin. 
Aloin. 
Pyroca-i Tyro- 
tech ol. j sin. 
Hydro- 
chi- 
none. 
58. 
July 18 
July 18 
[ July 19 
July 19 
i July 19 
1 July 24 
July 24 
i 
0.261 1 0.109 
0.546 
59 . 
0.179 
0.031 
60.. 
. i . 
61. 
62. 
. 226 
! -055 
.!. 
63. 
0.027 
1 
64.. 
0.254 
0.125 
0.086 
. 
.i. 
i 
: ■ 1 
Oxidase activity expressed in units as measured in the oxidation of the reagents. 
eries No. 
Phlorid- 
zin. 
Resorcin 
Guaiacol. 
Ortho- 
cresol. 
Meta- 
cresol. 
Para- 
cresol. 
j Ortho- 
1 toluidin. 
Meta- 
toluidin. 
Para- 
toluidin. 
j. 
0.312 
0.008 
0.000 
0.094 
0.047 
0. 530 
0.913 
•257 
0-359 
0.008 
1 
1 
1 
i 
a Ueuco base of malachite green. 
OXIDASES OE CURLY-DWARF-DISEASED POTATO PLANTS 
The plot of potatoes from which all the normal material was collected 
turned out to be remarkably free from curly dwarf. The pathological 
material was therefore collected on a larger field several miles remote 
from the other. About 10,000 different kinds of potatoes were grown 
in the field, and on account of the comparative scarcity of the patho¬ 
logical material samples were chosen from a number of different varieties. 
In all of the experiments the name of the variety is stated whenever 
it is known. The conditions of growth with reference to soil and 
atmospheric conditions were practically the same in the case of both the 
diseased and healthy potatoes. 
