Longevity of Seeds. 187 



the only question is as to the best mode of reniovin<r that layer.i 

 Scratchino:, filing, and such niethnds always tend to daniajre a 

 certain jiercentage of the seed, besides being tedious even with 

 the large seeds. The removal of the seed coats opens the 

 embryo to the attacks nf injurious soil organisms and causes a 

 pronounced fall in the percentage of seed germinating. 



Boiling with water soon injuriously aiffects the seed, although 

 well dried Acacia seed is remarkably resistant to heat. Thus 

 sound two-year seed of Acaria lonyifolia, A. di-rnrrnis, ;uid A. 

 myrtifolia, after heating to 98-100 deg. C. for 6 hours, filing and 

 soaking, gave percentage germinations of 42, 35 and 31 respec- 

 tively, the unheated seed giving germination values of 88, 46 amd 

 52 per cent, respectively. After 2 days at 95 to 102 deg. C, how- 

 ever, none of the seed germinated. In warm water swelling is 

 very slow. Thus a sample of 500 12-year-old seed of Acacia 

 dealhata was soaked in water at 30-40 deg. C for 10 days, and 

 then at 40-50 deg. C. for a month, the swollen seeds being picked 

 out every few days and placed in germination chambers. ■ 



of swollen seeds 

 j'enn. 



6.4 



3 - 43 - 1 - 2.3 



6 

 10 



13 - 85 - 5 - 5.9 

 17 - 58 . 5 - 8.6 

 21 - 50 - 14 - 28 

 31 

 33 

 42 - 33 - 3 - 9 



4.3 



The 64- remaining seeds swelled at once aftei- filing, and gave 

 a percentage germination of 7.8 per cent. Hence the earlier 

 seeds to swell are mostly dead, then the percentage germination 

 rises and finally falls again, possibly as the result of the pro- 



1 In some eases soaking in warm alisolute alcohol makes the coats permeable to water, 

 especially where the cuticle is thin, probably owing to the removal of the waxy materials 

 impregnating the cuticle. Hot water, by melting the wax in the cuticle, aids in making the 

 cuticle permeable. 



2 Seven seeds had disappeared. ' 



