402 
Journal of Agricultural Research 
Vol. II, No. s 
As Table XII shows, the differences existing between the oxidase 
activity of the healthy and of the diseased material are generally marked 
and the greater activity is in the curly-dwarf potato plants. The com¬ 
parison of the data for healthy and curly-dwarf shoots shows that among 
the 18 reagents only 3 are oxidized more readily in the presence of the 
juice of the healthy plants. Comparison of the leaves of the two types 
of plants shows 7 of the 18 reagents to be more readily oxidized by the 
healthy juice; in the case of the two types of tubers only two of the 
reagents showed greater oxidation by the healthy material. Among 54 
sets compared, 12 showed a greater activity in the case of the healthy 
material, while the remainder, 42, showed a much greater activity in the 
case of the diseased plants. 
It seems safe to conclude that in general the oxidizing power in the 
juices of curly-dwarf potato plants is greater than in those of healthy 
plants. The writer does not know as yet exactly what bearing, if any, the 
oxidases measured by him have on the oxidation processes going on 
in the cells. A priori, one would conclude that the intensity of oxidation 
processes in the cells would among other factors depend on the concen¬ 
tration of the various oxidases present. If this were the case, one would 
expect cell respiration to be more intense in the cells of the curly-dwarf 
tubers. The diseased plants would be in a condition corresponding to 
“fever” in animals. 
These results agree in their general nature with those obtained in the 
case of the curly-top of sugar beets (Bunzel, 1913a, 1913b) and the leaf-roll 
of potatoes (Doby, 1911-12). In all three cases an increase in oxidases 
and a general retardation of growth are found. It would be extremely inter¬ 
esting, especially to plant physiologists, to find out what the rate of respira¬ 
tion is in such dwarfed, presumably “feverish’ 1 plants. Experiments 
intended to throw light on this point are already being planned in the 
laboratory of the Office of Plant Physiological and Fermentation Inves¬ 
tigations. 
There are a number of facts brought out in this investigation which 
open doors to new aspects of the physiology of development. There 
seems to be a cycle in the activity of the expressed juice of the foliage 
of normally developing potato plants. The juice of the foliage of very 
young plants is more active than that of plants of the same variety 40 or 
50 days older; after that stage of development the activity rises again 
with increasing age. Quite in harmony with these findings is the fact 
that sprouts of artificially sprouted tubers of the same variety are much 
more active than the youngest foliage examined. 
There seems to be a parallelism, therefore, between the intensity of 
physiological activity and the quantity of oxidases present. This belief 
is strongly corroborated by the fact that the physiologically more active 
portions of the plant, such as the leaves, furnish juices with greater 
activity than the obviously less active portions of the same plant, such as 
