I50 



Journal of Agricultural Research 



Vol. XV, No. 3 



catalase activity of these seeds can be greatly reduced by repeated sub- 

 jection to germinative conditions followed by drying. 



Table XV. — Effect of drying on catalase activity of Johnson grass; collected on September 



22, 1917; run on October 22, igiy 



Treatment of seed. 



Stored dry 



In germinator 14 days at 20° C 



In germinator 14 days at 20° C, then dried 2 

 days 



Oxygen liberated after- 



Cc. 



6.3 

 4.9 



4.3 



Cc. 



13-7 

 10. 2 



9.1 



Cc. 



19. o 



14. 2 



12. 6 



Cc. 



27.4 



21. 2 



18. s 



Table XVI shows the fall in catalase produced by drying a sample of 

 Johnson grass that has low activity, due to a year's sojourn in a germi- 

 nator, at 20° C. The absolute fall is low, but the percentage fall rather 

 large. 



Table XMl.— Effect of drying on catalase activity of Johnson grass in germinator for 



I year at 20° C. 



In the after-ripened seed of basswood the catalase activity seems to 

 rise with a few days' drying. This rise is only apparent, however, for 

 the pulverized material from imbibed seeds contains more moisture when 

 weighed than does the material from dried seeds, while the same weight 

 was used for the determinations in the two cases. For the same reason 

 the effect of drying, in both peach and Johnson grass, was much greater 

 than the figures above indicate. It was not considered worth while, 

 however, to go to the considerable trouble of correcting for the differ- 

 ences in moisture in the dried and undried material, for it would make a 

 difiference only in the magnitude and not in the direction of the results. 



RELATION OF AGE AND VITALITY OF SEEDS TO CATALASE ACTIVITY 



A number of workers (5, 6, 7, <?, 35) have shown that the oxidizing 

 and digestive enzyms of old seed still persist after the seeds have com- 

 pletely lost their vitality, but it seems that these enzyms also gradually 

 degenerate with age, although their complete degeneration follows much 

 later than the complete loss of vitality. 



