TORREYA 



May, 1911 

 Vol.11 No. 5 



THE NATURE AND FUNCTION OF THE PLANT 

 OXIDASES 



By Ernest D. Clark 

 {Continued from April Torreya) 



Pathology 

 In most of the cases first considered, the oxidases played a 

 beneficial or useful part in the activities of plant life, but we 

 are now to see that under certain conditions they may cause 

 pathological processes. There is a disease of tobacco known as 

 the "mosaic disease" which is characterized by the checkered 

 appearance of the green leaves, these checkered places being 

 yellow. In 1902, Woods^^ showed that rapid growth caused 

 by cutting back often induced this disease, which he attributed to 

 the abnormal activity of the oxidases. He believed the trouble 

 was caused by an excessive activity of these enzymes due to lack 

 of nitrogenous and other foods in the cells, which if present in 

 normal quantities, seem to enable the cells to keep the oxidases 

 within bounds. The diseased portions of the leaves showed the 

 presence of great quantities of oxidases, but exhibited a striking 

 lack of starch, nitrogenous matter, etc. In the so-called "mul- 

 berry dwarf" disease of the mulberry tree in Japan, Suzuki^^ 

 found the same state of affairs. When the mulberry trees were 

 repeatedly cut back, they developed a wrinkled and yellow ap- 

 pearance of the leaves, accompanied by a great increase of oxi- 

 dases in the yellow portions, and also by a lack of plant foods 

 in the diseased places. Suzuki thought that anything inter- 



^^Woods. Observations on the Mosaic Disease of Tobacco. Bull. 18, Bur. 

 Plant Industry, U. S. Dept. Agric. 1902. 



"Suzuki. Mulberry Dwarf Troubles in Japan. Bull. Agric. Coll. Tokyo, 4: 

 167 and 267. 1900. 



[No. 4, Vol. II, of Torreya, comprising pp. 77-100, was issued 19 April 1911.] 



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