IQ2l] 



PA CK—J UNI PER US 



53 



was probably due to increased acidulation in the presence of an 

 abundance of C0 2 and H 2 which could favor the digestion of fats 

 and germination (25). Desiccation and moistening again of seeds 

 at about the forty-fifth day after being placed in the germinator 

 shortens the after-ripening period from 5 to 10 days. This may 

 be due to one of the following causes : (1) earlier after-ripening of the 

 coats, as they are found to split off more readily when desiccated, 

 (2) upsetting of the chemical equilibrium by the great extraction 

 of water, or (3) the increase of Ht ion concentrations. 



Discussion 



Catalase.— The catalase activity, as has been noted by previous 

 investigators (1,6), was found to bear some relation to respiration. 

 Increased catalase activity accompanied the intense respiration of 

 Juniperus seeds stored in high percentages of oxygen, as decreased 



TABLE XIX 

 Increased catalase activity with development (figured per unit dry weight) 



catalase activity accompanied the low respiration of seeds stored 

 in low percentages of oxgyen. With the intense respiration at 

 high temperatures there was an increased catalase activity, even 

 though the seeds did not after-ripen or germinate. The highest 

 catalase activity and the most intense respiration per unit of dry 

 weight was found in the seedling stage (cf . tables XIX and XVII) . 

 The desiccation of seeds to a slight extent, which makes for a 

 rapid absorption of oxygen through the coat, increased the catalase 

 activity. Desiccation to the extent of retarding respiration reduced 

 the catalase activity. Table XX shows these results. Both the 

 respiration and the catalase activity of seeds were reduced at will 



