Oct. 21, I918 



Catalase and Oxidase Content of Seeds 



159 



Tabi^B XXIII. — Effect of the temperature of the germinator on the increase in catalase 

 activity of peach seeds; collected on September 15, igij, dried, free from carpels, and put 

 into the germinator on October il, igiy 



Treatment of seeds. 



Period 



Oxygen liberated after- 



I nun. 3 min. 5 mm. 10 mm 



Dry-stored 



In germinator at 20° C 

 In germinator at 7° C. 



Dry-stored 



In germinator at 25° C 

 In germinator at 20° C 

 In germinator at 7° C. 



Dry-stored 



In germinator at 25° C 

 In germinator at 20° C 

 In germinator at 7° C. 



Days. 



9 



9 



9 



30 



30 



30 



30 



54 



54 



54 



54 



C c. 



I 



3 

 4 



13 



5- 



5- 



15 



Cc. 



3-1 



9.6 



II. 9 



2.8 



11. 7 



12. 2 



29-3 



2.6 



13.8 



15-3 

 41. 2 



Cc. 



4-7 



13.2 



16. 9 

 4.2 

 16. o 

 16. 7 

 36.2 

 4. I 

 19.8 

 23. o 

 57- o 



Cc. 



'9-7 

 20. 4 

 23.6 



21. 9 



22. 7 



Certain contrasts between the behavior of peach and Johnson grass 

 seeds are evident and very important. 



Air-dry seeds of peach have very low catalase activity when com- 

 pared with air-dry seeds of Johnson grass, Sudan grass, and other seeds 

 of the same year's collection. This difference is magnified when it is 

 recalled that the peach material is all from the embryo, the active part 

 of the seed, while that of Johnson grass is only about 10 per cent embryo 

 with about 90 per cent endosperm, material of low activity. 



The peach seeds rise in catalase activity when being kept in the ger- 

 minator, and the rise is much faster and greater at 7° than at 20° or 

 25° C. Johnson grass seeds fall in catalase activity with retention in 

 the germinator, and the fall is more rapid at 20° than at 7°. 



After-ripening in the peach involves fundamental time-requiring 

 changes in the embryo. It progresses rapidly in a germinator at a low 

 temperature, apparently not at all in dry storage, and very slowly, if 

 at all, in a germinator at 20° C. or above. It is marked by a very great 

 rise in catalase activity. After-ripening in the Johnson grass does not 

 seem to involve fundamental time-requiring changes in the embryo. 

 It proceeds well, if not best, in dry storage and is accompanied by a fall 

 in catalase activity. 



Other seeds (hawthorn and basswood) with dormant embryos behave 

 like the peach in after-ripening. As in the peach, the catalase changes 

 are accompanied by other chemical changes, already mentioned in the 

 introduction. 



RISE OF CATALASE ACTIVITY WITH GERMINATION 



There is a big rise in the catalase activity of Sudan grass seeds with 

 their germination. This is well shown in Table XXIV for the 191 6 

 crop of Sudan grass. In this experiment the seeds were used without 

 separating them into mature and immature lots. In the germinated 



