1909.] 



Latent Life of Resting Seeds. 

 Germination Tables. 



435 





Percentage 







Kind of seed. 



germination. 



Liquid air. 



Resistance to desiccation. 





(Normal.) 





Apple {Pyrus mains) 



Turnip {Brassica campestris) 



Cress {Lepidium sativum) ... 



Carrot (Daueus carota) I 36 to 65 



Haricot {Phaseolus multi- 

 florus) 



Hemp {Cannabis sativa) 



Mustard (white) {Brassica 

 alba) 



Lobelia erinus 



Parsnips {Peucedanum sati- 

 vum) 



Parsley 



Pea {Pisum sativum) 



Radish {Raphanus sativus).. 

 Ricimcs cambogiensis 



Sunflower 

 anmius) 



{Selianthus 



1 9 





91 



88 



100 



100 



36 to 65 



59 



100 



90 



24 



7 



85 



72 



51 



13 



45 



18 



28 



1 



95 



75 



97 



88 



100 



100 



70 



65 



Sensitive to severe desiccation. 



43 per cent, after 42 days' desicca- 

 tion at 37° C. 



30 per cent, after 4 weeks in abso- 

 lute alcohol. 



Lasts 10 years in dry air. 



2 per cent, after 45 days' desicca- 

 tion at 37° C. 



Nil after 15 days' desiccation at 

 37° C. 



Lasts 10 years in dry air. 



Sensitive to prolonged extreme cold 



(De Candolle). 

 Sensitive to extreme desiccation. 



Nil after 42 days' desiccation at 

 37° C. 



Lasts 10 years in dry air. 



It. communis 40 per cent, after 28 

 clays' desiccation. 



51 per cent, after 42 days' desicca- 

 tion at 37° C. 



The fact that in every experiment except two there is a lower percentage 

 germination in the severely frozen seeds, and that in no instance is the- 

 reverse the case, signifies that to some extent freezing in the liquid air is. 

 deleterious to the germinative power of seed. Another noteworthy 

 observation is that there does not appear to be any particular class of seed 

 which is more injured by the extreme cold than any other class, e.g., of three 

 kinds of oily seeds tested, viz., Hemp, Helianthus, and Eicinus, while the first 

 was strongly affected, the second was little, and the last-named seed not at 

 all injured by —200° C. for two days. 



The starchy seeds of cereals are, however, as resistant to the effects of 

 exposure to liquid air as are the oily seeds. 



Lobelia erinus seeds were selected as good subjects for experiment on the- 

 strength of the statement of De Candolle* that dry seeds of Lobelia erinus. 

 lose their vitality sooner at very low temperatures than at ordinary ones. 



The results tabulated in this paper show that the vitality of some is lost,, 

 but as 13 per cent, were found to germinate after exposure for one and 

 a half to two days to a temperature of approximately —200° C, it is probable- 

 that if the time of their exposure were increased somewhat the vitality of all 

 the seeds would be destroyed. 



* Pfeffer, ' Physiology of Plants,' Engl, translation, vol. 2, p. 234 



