142 



BOTANICAL GAZETTE 



[FEBRUARY 



Tilia Rose (22) also found a noticeable increase in catalase activity 

 accompanying after-ripening. Crocker and Harrington con- - 

 elude that "seeds that after-ripen in a germinator at low tempera- 

 tures (commercial layering) , in which the dormancy of the embryo 

 is self imposed and the embryo experiences fundamental time- 

 requiring changes for after-ripening, show a great increase in 

 catalase activity with after-ripening (Crataegus, Tilia, Prunus)."^ 

 Catalase determinations were made upon the dormant and 

 after-ripened seeds and upon the seedlings at various stages of 

 germination. In all cases the integuments were removed and a 

 definite number rather than a definite weight of seeds was used. 

 The material was weighed and samples were run as described for 

 the soft maple. The after-ripened seeds and also the seedlings 

 used were after-ripened and germinated in the dark at io° C. 

 Table VI demonstrates the great increase in catalase activity 

 accompanying after-ripening and germination in seeds of the sugar 



maple. 



TABLE VI 



Stage 



Dormant 



After-ripened 



Seedlings with i cm. 



2 



a. 



it 



a 



cc 



a 

 n 



a 

 a 

 cc 



cc 



ii 

 tt 



3 

 4 

 5 



6 



7 



a 

 tt 

 a 

 cc 

 it 

 cc 



radicle 



cc 



it 

 ii 



cc 



It 

 It 



CC. OF Oa LIBERATED BY I SEED OR 



SEEDLING IN 



5 minutes 



23-4 



33-7 

 31.0 



87.2 



99-7 

 89.2 



113. 2 



125.0 



10 minutes 



311 



39 3 

 370 



60.4 



98.4 

 114. o 



107.0 

 130.0 



142.5 



CC. OF Oa LIBERATED 



PER GM. OF DRY 



WEIGHT 



10 minutes 



754 

 1117 



1058 



1716 



2235 

 2230 



2786 



4481 



4440 



\ 



An increase in catalase activity is evident in both cotyledons 



and hypocotyl. 



Seeds germinated at higher temperatures 



also 



gave slightly increased catalase activity when taken at the same 

 stage of development. Seedlings with radicles 



cm 



used to determine the relative catalase activity of the different 



parts. 



(wet 



integuments liberated in 10 minutes 95, 43, and 5.1 cc. of oxygen 

 respectively. The hypocotyl, which is the most actively growing 



