iq3o) JONES -MAPLE SEEDS 139 



5 C. and io° C. ; also, some were stored out of doors on the surface 



of the ground and kept covered during the fall and winter to prevent 



drying. 



Temperature and water relations 



When seeds were stored dry, in no case, regardless of storage 

 temperature, did after- ripening reach completion; that is, no dry 

 stored seeds would germinate when placed in Petri dishes on moist 

 cotton at favorable germination temperatures. All dry stored 

 seeds required a prolonged stay at low temperatures with plenty 

 of moisture present to completely after-ripen. Davis and Rose 

 found that after-ripening in the haw proceeded best at tempera- 

 tures near 5 C. The sugar maple was also found to after-ripen 

 best at about this temperature. 



In January, after three and a half months of dry storage, 

 specimens were removed from each of the dry stored samples, 

 and placed at 5 C. under good germinative conditions. The 

 pericarp was removed and the seeds that had been dry stored 

 at 5 C. were the first to complete their period of after-ripening, 

 most of the seeds completing after-ripening during the fifth week. 

 The seeds, however, do not after-ripen uniformly; some precede 

 and others follow the general average time. Seeds dry stored 

 at — 5 C. take the longest time to complete their period of after- 

 ripening, taking 4-5 weeks longer than seeds dry stored at 5 C. 

 Seeds dry stored at 10-30 C. after-ripen more slowly than seeds 

 stored at 5 C, and more quickly than seeds stored at — 5 C. In 

 other words, seeds dry stored at 5 C. have progressed farthest, 

 and those stored at — 5 C. have progressed least in the process 

 of after-ripening at their respective storage temperatures. The 

 factor limiting the complete after-ripening in the dry stored seeds 

 at low favorable temperatures is a deficient water supply. Only 

 in the presence of sufficient water can the various processes go 

 progressively on to complete after-ripening. 



Fruits stored on the surface of the ground were subjected to 

 the temperature ranges of the soil surface. The seeds, however, 

 were kept saturated, due to the extremely wet fall and winter. 

 At time of fall seeds had a water content of 55 per cent, and during 

 the entire fall and winter the water content remained at 55-57 per 



