434 



Miss J. White. The Ferments and 



[Mar. 3, 



dependent upon the existence of enzymes in the resting seeds of the cereals 

 mentioned, although the question will not he absolutely closed until it is 

 found possible to germinate seeds which contain no enzymes in the resting 

 condition, or in which these enzymes have been destroyed. Since enzymes 

 appear to retain their activity within a wider range of conditions than does 

 the capacity for germination, this is likely to be a matter of the utmost 

 difficulty, or may be impossible. 



Before concluding the series of experiments in connection with this section 

 of the paper the resistance to extreme cold of certain other varieties of 

 seeds was also tested. Some of the different kinds of seeds were tied up in 

 loosely woven muslin bags, together with shot to ensure their sinking when 

 immersed in liquid air. The bags were lowered into a flask of liquid air in 

 which they were left for one and a half days. 



One hundred of each kind of seeds from the liquid air were set to 

 germinate on damp blotting paper in a special germinating box, whilst 

 100 of each kind which had not been exposed to the extreme temperature of 

 liquid air were set to germinate on damp blotting paper alongside them. 

 The varieties of seeds employed were chosen from sorts possessing widely 

 differing characters, including some which, being sensitive to desiccation, 

 might also be sensitive to extreme cold. 



The names of the seeds used are enumerated in the tables, accompanied by 

 the relative numbers which germinated under normal conditions and after 

 exposure to liquid air respectively. The third column contains data supplied 

 by Prof. Ewart for comparison between the resistance to extreme cold and to 

 desiccation. 



Eeference to the table shows that in not a single instance were the seeds 

 entirely killed as the effect of their immersion in liquid air. 



The influence of the low temperature is naturally most pronounced in 

 the case of samples with a comparatively low germination capacity in which 

 a number of the seeds are only just able to germinate under the most 

 favourable conditions. 



In the case of the carrot seed, freezing appeared to increase the percentage 

 germination, but on re-testing the original seeds a percentage germination 

 of 65 was obtained ; possibly the first test was discontinued too soon. 



The liquid air apparently exerts a retarding influence on the germination 

 as, except in the isolated case of the cress seeds, in which signs of germination 

 were apparent in 100 per cent, of both sets of seeds one day after sowing, 

 germination was always noticeable in the seeds grown under ordinary 

 conditions before those which had been subjected to the intense cold of 

 liquid air. 



