1 68 Journal of Agricultural Research voi. xv.no. 3 



The scales of only moderately well matured Johnson grass seed showed 

 a somewhat greater oxidase activity than the caryopses, but with unu- 

 sually well matured i -year-old seed having intensely pigmented scales 

 the activity of the scales was exactly the same as that of the caryopses. 

 At the same time the sterile florets, though functionless structures 

 scarcely pigmented at all, in which all vital activities must have ceased 

 at a time corresponding to an early stage in the development of the 

 caryopses in the accompanying fertile florets, were about four times as 

 active as either scales or caryopses. In fact, these sterile florets showed 

 greater oxidase activity in limited time (5 hours) than any other material 

 studied in the investigation. 



The light, straw-colored scales of Sudan grass showed 50 per cent 

 greater total oxidase activity in 6 hours than the embryo ends of the 

 caryopses, and about 8 times as great as the endosperm ends. 



A very noticeable feature of the high oxidase activity of Sudan grass 

 scales and sterile florets of Johnson grass is the high initial rate of activity 

 followed by a rather rapid and progressive decline in rate, though activity 

 had not ceased when the experiments were concluded. As shown in 

 Table XXXI, the decrease in pressure with this material was nearly half 

 as great at the end of i hour as at the end of 5 or 6 hours. This is in 

 marked contrast to the progress of the reaction with the other kinds of 

 material used in the investigation, and suggests rather the type of reac- 

 tion reported by Bunzell. By the end of the second hour the initially 

 high rate of activity of Sudan grass scales fell below the constant rate 

 maintained by the embryo ends of the caryopses. 



It is interesting to notice that there was a similar reaction with decrease 

 in rate after the second hour in a control with ground scales and no reagent. 

 In this control tube the reduction of pressure was 6 mm. in 2^ hours, and 

 10 mm. in 6 hours. With most of the other kinds of material used, the 

 controls showed little or no change in pressure until fermentation began, 

 after which the reduction in pressure was frequently rapid. No control 

 was run with the sterile florets. 



One might perhaps see a correlation between the high oxidase activity 

 of these structures (scales and sterile florets) and the high oxidase activi- 

 ties caused by agencies which retard normal growth, as reported by 

 Bunzell (9). He suggests a general 1 elation between retardation of 

 growth, from any cause whatever, and rise in oxidase activity. In the 

 case of the sterile florets retardation or suspension of function has pro- 

 ceeded so far as entirely to prevent the formation of seeds and to with- 

 draw all vitality from the florets. 



EFFECT OK MERCURIC CHLORID UPON OXIDASE ACTIVITY 



Previous work has shown that mercuric chlorid (HgClj) has a strong 

 forcing action upon the caryopses of Johnson grass, the maximum effect 

 being obtained with a Mj 2,000 solution. Table XXXII shows the 



