246 



Phijsiolofjical Pre-determination 



diastase, all germinated. The author remarks that "the increased 

 vitality of the diastase lot was very noticeable." 100 per cent, germina- 

 tion was also obtained when seeds from the same lot were soaked for 

 15 hours in a 3 per cent, solution of glucose instead of water, thus indi- 

 cating that lack of suitable food-material was the chief reason for the 

 poor germination capacity of the untreated seeds. 



Remarkable increases in germination percentages were recorded by 

 Waugh (37) for old tomato seeds soaked previous to sowing in a 5 per cent, 

 diastase solution as compared with similar seeds soaked in distilled 

 water (Table XII). Waugh also remarked that the vigour of the young 

 plants was often enhanced by the enzyme-treatment of the seeds. 



Table XII (after Waugh). 



Although such results as these of Babcock and of Waugh and the 

 similar results reported by others, for example, Lehmann(27), who 

 treated seeds of Epilobium hirsnfum with solutions of papayotin, 

 trypsin, etc. and obtained increased percentages and vigour of germina- 

 tion, appear to be quite definite, we cannot readily accept the conclusion 

 that they are to be explained as being due to the specific action of the 

 enzymes added, for it is difficult to understand how such enzymes, 

 when applied externally, can enter the seed. In contradiction to the 

 above results White (39) states that the addition of dissolved ferments 

 does not increase the percentage of germination of old seeds, and when 

 any effect at all is produced, it is a tendency to lower it. 



Experiments in which diffusible organic food-substances have been 

 supplied to germinating seeds with a consequent increase in the 

 germination percentage are more easily explained. Sharpe(34) obtained 

 increased vigour and percentage of germination by germinating seeds 

 in the presence of leucine or asparagin, substances which are of common 

 occurrence in germinating seeds. 



That food-substances can be utilised by the young embryo when it 



