jyo Journal of Agricultural Research voI.xv.no.s 



embryo 20 times that of the endosperm. In other grasses studied the 

 catalase activity of the embryo was many times that of the endosperm. 

 The oxidase activity is likewise much higher in the embryo than in the 

 endosperm. 



(6) The physiologically inactive organs (sterile florets atid caryopsis 

 scales) of grass seeds show only a small fraction of the catalase activity 

 shown by the caryopses. This likely agrees with the respiratory inten- 

 sity. The oxidase is as active, or in. some cases several times as active, 

 in the nonliving as in the living organs. 



(7) Equal weights of immature caryopses of Johnson grass or Sudan 

 grass and of seeds of Amaranthus retro flexus give much greater catalase 

 activity than mature ones. The activity of an equal number of the 

 caryopses, mature and immature, of the two grasses is about equal. 

 The oxidase activity X)n weight basis in Sudan grass is slightly highei in 

 mature seeds than in immature, and the reverse holds for Johnson grass. 



(8) Drying the seeds that have been in a germinator reduces enor- 

 mously the catalase activity in the peach, noticeably reduces it in Johnson 

 grass, but not at all in basswood. 



(9) The catalase in air-dry Johnson grass seeds is comparatively time- 

 and heat-labile, while that in air-dry amaranthus seeds is relatively time- 

 and heat- stable. The i^espiratory intensity (measured after the seeds 

 are imbibed) parallels the catalase activity in the first species. There 

 is nothing to indicate such a relation in the latter. The difference in 

 time and heat stability is not determined by the relative proportions 

 of soluble and insoluble catalases in the two seeds. The nonliving organs 

 of Johnson grass (sterile florets and caryopses scales) show much faster 

 time degeneration of their catalase than the living embryo. 



(10) Retention in a germinator, not furnishing conditions for germi- 

 nation, greatly reduces the catalase activity of Johnson grass seeds. 

 One year at 20° C. reduces it more than 66 per cent, and i month more 

 than 50 per cent below that of the same crop dry stored. The rate of 

 fall in the catalase activity is decreased by lowering the temperature of 

 the bath. Retention in a germinator affected the oxidase activity in 

 the same direction but to a much less degree. 



(11) The fall in catalase activity mentioned in the preceding para- 

 graph is accompanied by a commensurate fall in respiratory intensity. 

 A similar response seems to occur in Avena. fatua, and probably occurs in 

 many other seeds. This reduction in respiratory intensity is of great 

 significance in conserving stored foods in seeds lying in the ground, dor- 

 mant and imbibed, for many years. 



(12) The catalase activity in dry peach seeds is very low, but rises as 

 the seeds He in the germinator imbibed. The rise continues for weeks 

 and is much more rapid at 7° C. than at 20° or 25°. The optimum tem- 

 perature for after-ripening seems to be optimum for catalase increase. In 

 other seeds having dormant embryos, so far as studied by other investi- 



