158 Phydological Pre-deterniination 



seed, the de<iree of maturity depending' also upon whether the seeds are 

 harvested alone or whether they are harvested along with and allowed 

 to dry in organic connection with the parent plant, and (2) by the weather 

 conditions which obtain during the formation and ripening of the seed. 

 In dealing with immature seed of cultivated plants we have to dis- 

 tinguish in the first place between the immature seed as it comes from 

 the plant with a relatively high moisture content, and the same seed 

 after drying in air. This distinction is an important one, but the work 

 dealing with the comparison of immature seed as it comes from the 

 parent plant, and the same seed after air-drying has been for the most 

 part confined to the question of capacity for germination. 



The "Potentiality" of the Seed as influenced by 

 THE Time of Harvesting. 



Maze (19) described experiments with maize in which the germination 

 of immature seeds straight from the parent-plant was compared with 

 that of similar immature seed artificially dried. 



The results of these experiments showed that the drying of the 

 immature seeds did not affect their capacity for germination, which 

 was 100 per cent, in both cases, but altered the physiological condition 

 of the seeds in such a way that germination could take place quickly and 

 normally. Thus, in the experiment quoted below (Table 1) in which 

 immature maize seed in the so-called milky stage was used, the sample 

 previously dried over concentrated H0SO4 for 48 hours at 30° C. ger- 

 minated fully in two days, whereas the sample which was not dried, 

 but set to germinate immediately after removal from the parent plant, 

 showed slow and sporadic germination extending over a period of 

 30 days. 



Similar results were obtained with peas. 



Table I. 



Lot I consisted of a single vertical series of 19 grains, which were dried 

 over concentrated H,S04 for 48 hours at 30° C. before sowing. 



Lot II consisted of a single vertical series of 20 grains (containing 456 per cent, 

 moisture) detached from a liead of maize. These grains were s(-t to germinate 

 immediately after removal from the parent-plant. They were placed one by 

 one in test-tubes containing distilled water and provided with two cotton plugs, 

 one of which supported the seed at the surface of the water whilst the other 

 was used to keep out organisms from the air. 



Percentage of germinations after 



2 days 7 days 14 days 22 days 28 days 30 days 

 Loll 100% _____ 



LotH — 15% 30"' 55 f^,. 95% 100"' 



