iQ2o] JONES—MAPLE SEEDS 149 



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found in the hypocotyl of the dormant and after-ripened seeds, 

 one would hardly expect to find a change in the water holding capa- 

 city of the hydrophilous colloids. Determinations on the water 

 content of entire seeds stored in favorable after-ripening conditions 

 show that there is no change in the water holding capacity of the 

 seeds as a whole. 



One of the most consistent phenomena accompanying after- 

 ripening in this type of embryo is the great increase of catalase 

 activity. This appears to be an accompanying feature of more 

 than ordinary importance. A large number of investigators 

 in various branches of animal and plant physiology attempt to 

 correlate catalase activity with metabolic activity in general. 

 Burge (3), by increasing the work of certain fowl muscles and 

 consequently the respiratory and metabolic activity, has made 

 the catalase activity increase enormously. In the castor bean 

 Deleano (9) found a rapid increase in catalase activity at the 

 beginning of germination. A great increase in catalase activity 

 accompanied germination in the sugar and river maples. In the 

 fully imbibed seed of Johnson grass, Crocker and Harrington 

 (6) found catalase activity paralleling respiration. This did not hold 

 for seeds of the amaranth, however. In the potato, Appleman (i) 

 found respiratory and catalase activity closely accompanying each 

 other. Eckerson (ii) found an increase in the catalase activity 

 with after-ripening in the haw. An increase in catalase activity 

 with after-ripening has also been reported for Tilia americana (22). 

 In the sugar maple there was a 66 per cent catalase activity increase 

 in the after-ripened seeds over that of the dormant seeds. Just how 

 closely catalase activity and respiration parallel each other during 

 the course of after-ripening has not yet been determined. From 

 evidence at hand showing the almost universal correlation of these 

 two phenomena we might reasonably expect to find respiration 

 increase noticeably during the process of after-ripening. Respira- 

 tory activity should be determined continually throughout the 

 entire period of after-ripening at the temperature and water rela- 

 tions most favorable for after-ripening. Preliminary respiratory 

 determinations reported in this paper are not conclusive. The 

 seeds were transferred from 5 C. to the 20 C. oven. This change 



