VITALITY AND GERMINATION OF SEEDS. 189 



Table D. 





1 week. 



10 days. 



2 weeks „ 



3 weeks. 



Haricots - - 



39 p.c. 



15 p.c. 



3 p.c. 



None. 



Hemp - - - 



52 p.c. 



35 p.c. 



7 p.c. 



None. 



In both cases several of the young seedlings are weak- 

 lings and soon die, so that the percentage of seeds capable 

 of forming normal healthy adult plants is still less than 

 that of those which remain capable of germination. 

 Prolonged dessication at a moderately raised temperature 

 therefore exercises a marked injurious influence upon all 

 seeds, one sign of which is the increase, which is frequently 

 very pronounced, in the time taken in germinating by those 

 seeds which remain living and capable of germination. The 

 resistant power of a seed to dessication is partly dependent 

 upon the nature and thickness of the seed coats and appears 

 also to be connected with the form in which the reserve food 

 material is stored. Thus, other conditions being similar 

 albuminous seeds appear to be the least resistant to dessica- 

 tion, oily seeds next, and starchy seeds most resistant. At 

 ordinary room temperatures (15°C. — 20°C.) dessication is 

 always more or less imperfect and under such conditions 

 oily seeds appear to be quite as resistant as starchy ones 

 (pp. 229 and 230 of previous paper). In very many cases 

 seeds are very intolerant of even ordinary air drying. 

 Thus seeds of Oxalis, Salix and Populus are unable to 

 withstand from one to three weeks air drying, whilst 

 prolonged air drying also exercises a marked injurious 

 influence upon the seeds of Acer, Fagus, Aesculus, etc.* 



* Schroder. Ueber die Austrocknungfahigkeit der Pflanzen. Bot. 

 Untersuch. Tubingen lid. II., Hf't. 1, 1886. 



