Nov. i8, 1918 Physiological Studies of Normal and Blighted Spinach 379 



The data which were presented in Table I are given in Table II, re- 

 calculated on the basis just described. 



TabIvE II. — Oxidase activities of healthy and diseased spinach material 

 [Results expressed in units) 



Table I shows three instances and Table II only two in which the 

 activity of the healthy leaves or roots was greater than that of the 

 diseased material. In all other cases there was either no measurable 

 activity in both types of material or the diseased material was more 

 active than the corresponding healthy material. This difference was 

 from 50 to 100 per cent. 



The figures expressing the activity of phloroglucinase, guaiacolase, 

 tyrosinase, and meta-cresolase, are particularly interesting. These 

 figures seem to indicate qualitative differences. 



These results resemble those obtained in several other plant diseases. 

 In the case of the mosaic of tobacco {51), the leaf curl of potatoes (jj), 

 the curly-top of sugar beets (8), and the curly-dwarf of potatoes (9), 

 the diseased material shows a greater power to transfer atmospheric 

 oxygen to certain aromatic compounds than the healthy material. In 

 all these diseases the most characteristic symptom is a marked stunting 

 of the plant. The following generalization seems therefore justified: 

 In the above-mentioned plant diseases, which cause dwarfing of the 

 plants affected, the capacity of the plant juice to utilize atmospheric 

 oxygen for the oxidation of certain chromogens is abnormally increased. 

 How this increase in the catalytic activity of the cell sap is brought 

 about remains a problem. Whether the peroxid-forming substances are 

 increased so that there is an increase in the oxygenases, which, in the 

 presence of an excess of peroxidases might lead to the results outlined (j), 

 or whether a greater quantity of specific activators are formed, which, 



