1 62 Journal of Agricultural Research voi.xv, No. 3 



On account of its relative inactivity, the quantity of material used was 

 necessarily large, usually 250 or 500 mgm. for each determination. The 

 quantity of reagents used was uniform in all determinations, 10 mgm. 

 of a solid reagent or 2 drops of para-cresol for each determination. 



The different experiments were run for a length of time varying from 

 4J/^ to 24 hours. 



OXIDASE ACTIVITY TOWARD DIFFERENT REAGENTS 



Ten different lots of seeds, comprising Johnson grass, Amaranthus 

 retroflexus, Sudan grass, wheat, and a fixed Tunis grass sorghum hybrid 

 were tested for oxidase activity with pyrogallol, pyrocatechol, and para- 

 cresol.^ With very few exceptions pyrogallol gave the greatest activity, 

 para-cresol next, and pyrocatechol least (11). Frequently the oxidase 

 reaction toward pyrogallol and pyrocatechol proceeded at practically 

 uniform rates throughout the experiment even when the experiment 

 was run for nearly 24 hours. In some of the experiments, however, the 

 rate slowed down perceptibly after the first few hours, although it never 

 reached a definite end point with any of the reagents used. This is in 

 marked contrast to the course of oxidase activity shown by Bunzell (9) 

 with a large variety of plant materials. In his work the reaction seemed 

 to be practically complete in 2 or 3 hours. 



The activity towards para-cresol usually started very slowly (probably 

 on account of the limited solubility of the reagent), increased somewhat 

 in rate after the first few hours so that the total reduction in pressure 

 sometimes temporarily exceeded the total reduction with pyrogallol as 

 the reagent, and then decreased in rate so that the pressure reduction 

 again became considerably less than with pyrogallol. 



All of the material used had relatively low activity. The greatest 

 activity of the most active material used (except scales and sterile 

 florets) caused a total reduction of pressure of about 95 mm. in 1 9 hours 

 with 250 mgm. of the material and 17 cc. as the active volume of gas. 

 This is equivalent to the absorption of only about 10.7 cc, or 15 mgm. of 

 oxygen in 24 hours per gram of the ground seed material ; yet this is more 

 than 10 times as great an activity as that shown by ground peach embryos. 

 Johnson grass seeds were more active than any other seeds used, with 

 amaranthus a close second. The Tunis grass-sorghum hybrid was 

 somewhat less active, and Sudan grass (1911 seed) very much less active. 

 Wheat (entire caryopses) showed very little oxidase activity, and peach 

 embryos practically none at all. 



DETAIIvED ACCOUNT OF OXIDASE EXPERIMENTS 



The results given in the following paragraphs were obtained with 

 pyrogallol as the reagent. The amount of oxidase material used was not 



1 Preliminary trials with Johnson grass seeds showed practically no activity toward hydroquinone 

 and tyrosine. 



