Oct. 21, I918 



Catalase and Oxidase Content of Seeds 



155 



In heated seeds of Johnson grass the catalase activity more nearly 

 parallels the respiratory intensity than it does the viability or vigor of 

 the seeds, for seeds heated at 81° C. for one hour show a great lowering 

 in the respiratory intensity, but an increase in the rate of germination. 

 Tables XIX and XX shov/ this relation. The respiration rate was 

 determined by the method described by Grafe (22, p. 357-361), with 

 the exception that Reiset instead of Pettenkofer tubes were used for 

 absorbing the carbon dioxid. The intensity of respiration is initially 

 more than twice as high in the unheated as in the heated seeds. It 

 rises in both with time, but heated seeds gain on the unheated. The 

 gain in intensity in both is due to the initiation of germination and the 

 faster gain in the heated seeds is caused by the more rapid germination 

 in them. 



Table yiWll. ^Effect of heating air-dry seeds upon their catalase activity and vitality 



Seed used. 



Amount of heating. 



Oxygen liberated after- 



Per- 

 cent- 

 age of 

 germi- 

 nation 



in 9 

 days. 



Johnson grass i year old 



Do 



Do 



Do 



Do 



Do 



Do 



Amarantkus retroflexus, 

 19 1 7 crop. 



Do 



Do 



Do 



Do 



Do 



None 



K hour, 81° C, 

 2 hours, 81° C. . 



4 hours, 81° C. . 

 17 hours, 81° C. 

 48 hours, 81° C. 



5 hours, 100° C. 

 None 



yi hour 



4 hours, 8i°C. . . 

 17 hours, 81° C. . 

 48 hours, 81° C. 

 4.5 hours, 100° C. 



Cc. 



4.4 



3-1 

 2.9 

 2.6 



■7 



.6 



o. o 



7-5 



Cc. 



9-3 

 6.2 



5-7 

 5-2 



Cc. 



12. 7 

 8.4 



7-7 

 6.7 

 i-S 

 1-7 

 o. o 



14- S 



5-2 

 4-7 

 4.6 



•7 



9-3 



7-1 

 7.8 



1-3 



10. 9 



9-3 

 9. I 

 1.6 



Cc. 



17.8 



II. 6 



10.3 



8.4 



1.8 



2. 2 



o. o 



16. 9 



12. 4 



10. 7 



10.3 



2. o 



82 



95 

 92 



49 

 00 

 00 

 00 

 100 



25 

 00 

 00 

 00 

 00 



Table 'KIX^.^Effect of heating upon the respiratory intensity of l-year-old Johnson 



grass seeds 



[Air-dry seeds heated i hour at 8i° C, then soaked 24 hours at 20° C. Temperature of respiration chamber 

 20° C. Respiratory intensity =milUgram of carbon dioxid produced by 10 gm., dry weight, of seeds 

 per 24 hours] 



Period. 



First (17 hours). .. 

 Second (22 hours) 

 Third (18 hours). , 



Respiratory intensity. 



Heated. Unheated. 



4-5 

 12. 9 

 20. 2 



9.6 

 13-8 

 17.8 



Ratio, 

 unheated 

 to heated. 



2. I 

 I. I 

 .86 



