378 



Journal of Agricultural Research 



Vol. XV. No. 7 



Tabi<B I. — Relative oxygen absorption of various oxidase reagents in the presence of 

 healthy and diseased spinach material 



Inasmuch as the various samples had different moisture contents, the 

 results given in Table I are not strictly comparable. They w^ere made 

 so, however, by means of a calculation based on the following reasoning: 

 If it be assumed that the total oxidase activity of the plant material 

 is in the juice, and the weight of the solids dissolved in the juice be neg- 

 lected, the oxidizing power of o.io gm. of juice can be calculated from 



the equation 



percentage of solids 



o (juice) = a (solids) 



percentage of juice 



The oxidizing power of i liter of juice is then necessarily 10,000 times 

 the figures obtained in this way. But our unit of activity is the juice, i 

 liter of which will transfer 8 gm. of oxygen {8), corresponding at 37.4° C. 

 and 76 cm. pressure to 6,367 cc. The volume of the gas in the apparatus 

 was 19 cc. The equation for calculating A, or the activity of the juice 

 present in the fresh leaves and roots, is therefore 



10,000 



A= — 



25.475 



^= 0-393 



a (solids) 



a (solids) 



Percentage of solids 

 100 — Percentage of solids 



Percentage of solids 

 100 — Percentage of solids 



