Aug. 15, 1914 
Oxidases in Potatoes 
379 
OXIDASE ACTIVITY OF THE JUICE OF THE SHOOTS 
40 
The results obtained in the measurement of the oxidases in the juice 
of healthy potato plants of the same variety at various ages, grown under 
normal and as nearly 
identical conditions as 
possible, are given in 
Tables II to VIII, and 
some of the results are 
also shown graphically 
in figures 2 to 20. ' 0 ^ aGS-oaks 
The sh OOtS Were Fig. 2.—Curve showing oxidation of leuco base of malachite green in the 
taken from the plants presence of the juice of green potato shoots. 
immediately above the point where they emerged from the soil. In fig¬ 
ures 2 to 5 1 the abscissae represent the age of the plants as measured 
from the time of planting, and the ordinates the activities of the 
juices as measured in 
the oxidation of the 
various aromatic 
compounds used. 
These data show a 
distinct downward 
tendency; there is ap¬ 
parently a marked 
diminution in the ox¬ 
idase activities of the 
pressed-out juice of the shoots during the beginning of their growth. 
OXIDASE ACTIVITY OF THE JUICE OF THE STEMS 
Experiments on sugar beets showed that the juice obtained from the 
stems of the plants exhibited very much less oxidase activity than that 
of the leaves (Bunzel, 
1913a; 1913b). It 
seemed probable, 
therefore, that the 
juice of the stems of 
the potato plants ex¬ 
amined would also be 
less active than the 
juice of the leaves. A 
comparative increase 
Fig. 3.—Curve showing oxidation of aloin in the presence of the juice 
of green potato shoots. 
/O 
SO 30 40 
SO 
SO 
Fig. 4. —Curve showing oxidation of tyrosin in the presence of the juice 
of green potato shoots. 
1 Inasmuch as nearly all of the curves obtained in working with the 18 reagents show the same general 
relationships, for the sake of a briefer and, therefore, more comprehensive presentation of the facts, only 
4 to 8 curves are presented in the case of the shoots, foliage, and tubers, respectively. While these curves 
were not picked at random, they are typical of the situation in each case. The writer felt justified in doing 
this, inasmuch as all of the curves can be constructed from the tables in the text, and since the results are 
numerically compared in Table XII. 
