

IQ20] 





JONES— MAPLE SEEDS 



H3 



organ at this time, gives by far the greatest catalase activity. 

 The storage organs (cotyledons) give considerable catalase activ- 

 ity. The inert structures (integuments) give very low catalase 

 activity. The difference here would be still more striking if calcu- 



i 



lated as percentage of dry weight. Crocker and Harrington find 

 the catalase activity of wheat embryo 28-29 times that of the en- 

 dosperm. The same investigators find that in grass seeds in general 

 the physiologically inactive organs show only a small fraction of 

 the catalase activity shown by the embryo. 



Dry dormant seeds stored in the laboratory were used to 

 determine the Q I0 for catalase activity at temperatures ranging 



from 



C. 



Seeds were ground very fine and rubbed 

 ieve. One-tenth gram samples were used 

 for determinations. Ten cc. of dioxygen, 10 cc. of water, and a 



mesh 



small 



Table VII shows 



Qio value for catalase activity. 



Temperature 



TABLE VII 



IO~20° C 



20-30 c 



30-40° C 

 40-50° C 



1 minute 



1-4 

 1-3 



0.1 



0.8 



Qio FOR 



S minutes 



i-3 

 1.2 



0.9 



0.6 



10 minutes 



i-3 

 1. 1 



0.8 



o-5 





In no case does the van't Hoff law, which calls for an increase 

 of 2-3 -fold for every io° C. rise in temperature, hold. The time 

 consumed in heating the sample to the higher temperature intro- 

 duces considerable error. The time required for complete destruc- 

 tion of catalase activity at any given temperature was not deter- 

 mined. There was still some catalase activity at temperatures 

 slightly above 50 C. Appleman (2) found the catalase activity 

 in potato tubers to be entirely destroyed at 50 C. Between c° C. 

 and io° C. he finds the Q I0 for catalase activity to be 1.5. From 

 io° C. to 40 C. he gets lower Q I0 values for potato catalase than 

 was given by the catalase of the sugar maple. 



