Aug. is, 1914 
Oxidases in Potatoes 
403 
the stems. This has been found by the writer not only in the case of 
the potato plants, but also in sugar beets (Bunzel, 1913a, 1913b). 
In this connection the results obtained by Nicolas (1907) are very 
interesting. He studied the respiration of individual parts of plants and 
found that those organs which carry out the assimilating functions of the 
plant show the greatest respiratory activity. The limbs or the organs 
which replace them in function, such as the phyllodia or cladodia, have 
1.4 to 4.5 times as great a respiratory activity as the petiole, stem, or 
tendrils. These results when combined with those obtained by the 
writer in the present investigation would indicate that there is at least a 
general parallelism between the oxidase activity of the juice obtained 
from a plant organ and the intensity of its physiological activity, as meas¬ 
ured by its intensity of respiration. Plans are made to study the ques¬ 
tion more closely in the laboratory of the Office of Plant Physiological 
and Fermentation Investigations. 
SUMMARY 
(1) The oxidase activity of the foliage of normally developing potato 
plants is greatest in the early stages of development; it falls off with 
growth of the plants and rises again when the plant's growth about 
reaches a standstill. 
(2) Curly-dwarf potato plants show a greater oxidase activity than 
healthy ones of the same age, both in the juice of their tubers and in the 
juice of their foliage. 
(3) The oxidative activity of the different parts of the potato plant has 
been established for 18 different reagents. 
LITERATURE CITED 
Bach, A., and Chodat, R. 
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Zelle. In Ber. Deut. Chem. Cesell., Jahrg. 37, no. 10, p. 2434-2440, 2 fig. 
Bertrand, Gabriel. 
1S97. Sur 1’intervention du manganese dans les oxydations provoquees par la 
laccase. In Compt. Rend. Acad. Sci. [Paris], t. 124, no. 19, p. 1032-1035. 
Bunzel, H. H. 
1912. The measurement of the oxidase content of plant juices. U. S. Dept. Agr. 
Bur. Plant Indus, Bui. 238, 40 p., 9 fig., 2 pi. 
1913a. A biochemical study of the curly-top of sugar beets. U. S. Dept. Agr. 
Bur. Plant Indus. Bui. 277, 28 p. 
1913b. Die Rolle der Oxydasen in der Blattrollkrankheit der Zuckerrfibe. In 
Biochem. Ztschr., Bd. 50, Heft 3/4, p. 185-208. 
Dixon, H. H., and Atkins, W. R. G. 
1913. Osmotic pressures in plants. I. Methods of extracting sap from plant 
organs. In Sci, Proc. Roy. Dublin Soc., n. s. v. 13, no. 28, p. 422-432. 
Doby, G$za. 
1911-12. Biochemische Untersuchungen fiber die Blattrollkrankheit der Kar- 
toffel. In Ztschr. Pfianzenkrank., Bd. 21, Heft 1/2, p. 10-17, Heft 6, 
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