Aug. 15, 1914 
Oxidases in Potatoes 
3 99 
OXIDASE ACTIVITY OP THE JUICE OF THE TUBERS 
The collection of the tubers of the diseased plants and the determina¬ 
tions of the oxidase content of the juices obtained from them were car¬ 
ried out in the same way as was done in the case of the healthy material. 
The results are summarized in Table XI and are included in figures 13 
to 20. As before, the heavy broken lines represent the results obtained 
with curly-dwarf material. 
These results, like those obtained with the tubers of healthy potato 
plants, show no definite tendency. If with age there is a definite vari¬ 
ation in oxidative capacity exhibited toward all of the reagents, it is 
entirely masked by the irregular fluctuations. These irregular fluctua¬ 
tions were also observed in the case of diseased foliage and are illustrated 
in figures 6 to 12. 
DISCUSSION OF RESULTS 
Comparison of the curves of the healthy plants with those of the dis¬ 
eased ones shows at a glance a greater oxidase activity in the case of the 
curly-dwarf material. This is true for both the tubers and the foliage- 
It seemed desirable to express these differences in some numerical form, 
and this was done by taking the averages of all the results obtained from 
material of the same type with the same reagents. These averages were 
then easily compared. 
It was shown that healthy foliage yields juices of diminishing oxidase 
activity from the time of sprouting up to about the fortieth day of growth 
(as counted from the time of planting). For this reason in this summary 
of averages must be included only those of the results obtained with 
healthy leaves which were obtained during the growth periods of the 
diseased material examined. The age of the diseased foliage collected 
ranged from 64 to 91 days; the age of the plants where the whole shoots 
were examined was from 45 to 58 days. The averages were calculated as 
follows: All of the data (oxidase activities) obtained within the age 
periods mentioned were added together with the figures obtained for the 
beginning and the end of the period by interpolation from the curve. 
The sum, of course, was divided by the number of data added. These 
averages are shown in Table XII. 
51131 0 —14- 6 
