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BOTAMCAL GAZETTE 



[FEBRUARY 



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

 accompanying after-ripening. Crocker and Harrington con- 

 clude 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, Primus)." 

 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 



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 1 cm. long were 

 used to determine the relative catalase activity of the different 

 parts. One- tenth gram (wet weight) of radicles, cotyledons, and 

 integuments liberated in 10 minutes 95, 43, and 5 . 1 cc. of oxygen 

 respectively. The hypocotyl. which is the most actively growing 



