1909.] 



Latent Life of Resting Seeds. 



433 



been exposed to liquid air and the control specimens which had not been so 

 exposed. The same conclusions were arrived at by Thiselton-Dyer,* who 

 subjected seeds to a temperature of —250° G. for a shorter period. 

 Becquerelf also performed experiments dealing with this subject. 

 The results of the experiments performed are as follows : — 



Temperature Extremes. Low Temperatures. 



Kind 

 of seed. 



Percentage 

 germination 

 (normal). 



Percentage 

 germination 



after 

 liquid air. 



Reduction 



with 

 Pehling's 



test. 



Biuret 

 reaction 

 after fibrin 

 digestion. 



Tryptophane 

 reaction after 

 Witte-peptone 

 digestion. 



Contained 

 in — 



Wheat 



100 



100 



Strong 



Faint 



Good 



Sealed tube. 





100 



96 





)> 





h 



Oats 



92 



92 









j> 



Eye 



96 



90 









j) 





90 



90 









ii 



Wheat 



100 



96 









Muslin bag. 



Barley 



100 



100 





)> 





ii 



Oats 



92 



90 





>) 





)» 



Rye 



96 



92 





j» 





ij 



Maize 



90 



90 









ii 



As regards the ferments, there was not the faintest perceptible difference 

 between those precipitated from the two sets of seeds, although it must be 

 remembered that a difference will only be perceptible when a relatively large 

 part of the original amount of ferment has been destroyed or rendered 

 inactive or insoluble. 



It is of great interest to note that the enzymes present within the resting 

 grains of the five different genera of cereals employed throughout these 

 experiments are not destroyed when the thoroughly dried seeds are subjected 

 to the extraordinarily wide range of temperature of —200° C. to +120° C, 

 i.e. a range of 320° C. 



The enzymes of a few varieties of seeds such as the diastatic ferment of 

 barley retains a certain amount of its activity when the range of temperature 

 through which the seeds have been exposed is —200° C. to 130° C, i.e. a 

 range of 330° C. 



The range of temperature through which the capacity for germination is 

 retained is from -200° C. to 100° C, i.e. a range of 300° C, above this the 

 power is apparently entirely lost. 



The conclusions arrived at in this section serve to substantially verify that 

 drawn from the last section, that the capacity for germination is not 



* 1 Eoy. Soc. Proc.,' vol. 65, p. 362, 1899. 

 t 1 Ann. Sci. Nat, Bot.,' ser. 9, vol. 5, 1907. 



