Oct. 21, 1918 Catalase and Oxidase Content of Seeds 171 



gators, the same relation holds. In the peach the oxidase activity 

 (Bunzell method) decreases with after-ripening but autocoloration of the 

 ground seed mass exposed to the air increases. 



(13) In amount of catalase and in the general behavior of their cata- 

 lases Johnson grass and Sudan grass seeds are very similar and one finds 

 here no explanation for their marked difference in dormancy and require- 

 ment of alternate temperatures for germination. The same is true of 

 the oxidases of the two seeds, so far as our studies have gone. 



(14) The catalase activity of grass seeds rises rapidly as their germi- 

 nation progresses. This parallels the rise in respiratory intensity. 

 There is no rise in oxidase activity with germination. 



(15) In Johnson grass seeds there seems to be a close correlation 

 between catalase activity and respiratory intensity (factors that modify 

 one modify the other similarly), but there is not a very close correlation 

 between either of them and the vitality of the seeds or vigor of the 

 resulting seedling. In these seeds catalase determination proved an 

 excellent quick method of estimating respiratory intensity and led to the 

 discovery of several interesting features in their respiration. Jn these 

 seeds the catalase also decreases with age and it is a fair measure of age 

 in continuously dry-stored seeds. 



(16) In amaranthus seeds there is no evidence of a correlation between 

 catalase activity on one hand and respiratory intensity, vitality, or age 

 on the other. This lack of correlation may be connected with the greater 

 time and heat stability of the catalase of ajnaranthus^ 



(17) So far as studied to date, seeds that after-ripen with dry storage 

 but which do not have embryos with dormancy self-imposed at any time 

 either show no change in the catalase activity (amaranthus) or a decrease 

 in it (Johnson grass) with after-ripening. 



(18) Seeds that after-ripen in a germinator at low temperature (com- 

 mercial layering) and in which the dormancy of the embryo is self-im- 

 posed and the embryo experiences fundamental time-requiring changes 

 for after-ripening, show a great increase in catalase activity with after- 

 ripening (hawthorns, basswood, peach). 



(19) It has been suggested that the gradual loss of vitality in dry- 

 stored seeds with age is due to the time denaturing or time coagulation 

 of embryo proteins. If this be true, it is evident that the time denaturing 

 of the embryo proteins essential to vitality and the time denaturing of 

 catalase are quite distinct, for in no old seeds studied is there a close 

 parallel between catalase activity and vitality. 



(20) It is evident from the great variations in catalase behavior in the 

 several seeds studied that one can not draw general conclusions for the 

 catalase behavior in all seeds, but it seems evident from the data in this 

 paper that seeds will fall into several physiological types for each of 

 which more or less general conclusions can be drawn. 



(21) Catalase activity of seeds seems to parallel physiological be- 

 havior much more generally than does oxidase activity. 



