146 



Journal of Agricultural Research 



Vol. XV, No. 3 



In his work on plant oxidases Bunzell (11) frequently uses powdered 

 plant material, but he has apparently made no statement as to the 

 degeneration of the oxidase in it with storage. 



VARIOUS ORGANS OP THE SEED 



In the grains of grasses there is considerable difference in the catalase 

 activity of different regions of the grain. Tables VII, VIII, IX, and X 

 give data on this point. In Stoner wheat (Table VII) the catalase 

 activity of the embryo is 28 to 29 times that of the endosperm. The 

 complete caryopsis shows very low activity as compared with the embryo 

 and less than twice that of the endosperm. The embryo of this wheat 

 constitutes about 3.3 per cent of the caryopsis. The low catalase activity 

 of the endosperm agrees with the claim of Griiss {24, p. 20-34) and others 

 that it is composed in the main of dead cells except for the aleurone layer. 

 Burlakow (4) has found that the respiratory intensity of wheat embryos 

 is about 20 times that of the endosperms. It seems then that in these 

 seed organs high catalase activity parallels high respiratory intensity. 



Table VII. — Catalase activity of embryo, endosperm, and caryopsis of Stoner wheat; 

 collected in August, 1917; run on October 5, igiy 



Part of seed used 



Oxygen liberated af ter- 



I min. 3 mm. s nun. lo nun, 



Caryopsis less embryo 



Caryopsis 



Embr)'-o 



Ratio, embryo to endosperm 



Cc. 

 o.« 



1-3 

 23-3 

 29: 1 



Cc. 



1.4 



2. 2 



39-3 

 28:1 



Cc. 

 1-7 

 2.7 



Co. 



2.0 

 3-5 



With the smaller grass seeds it is an almost endless task to separate 

 enough embryos to make catalase determinations, so in such grasses 

 other methods were used for estimating the activity of various regions. 

 In a fixed hybrid of Tunis grass and sorghum the catalase activity was 

 measured for the caryopsis and the endosperm (Table VIII). The 

 activity of the embryo was calculated from these data and from the fact 

 that the embryo constitutes 9.6 per cent of the caryopsis. Such calcu- 

 lations tally closely with the actual measurements in the wheat, and it is 

 probable they would do so here. 



Table VIII. — Catalase activity of the caryopsis and endosperm, of a fixed hybrid of Tunis 

 grass and sorghum, seeds freshly harvested 



Region of seed used. 



Caryopsis less embryo 



Caryopsis 



Calculated for embryo 



Ratio, embryo to endosperm 



Oxygen liberated after — 



Cc. 

 4.4 



II- 3 



65-7 



16. 4:1 



Cc. 



9.8 



22. 2 

 112. 5 

 II. 6:1 



Cc. 



13-4 

 29. 2 



'^2,2,- I 

 10:1 



Cc. 

 19. o 



37-9 



170. I 



9:1 



