68 



STUDIES IN SEEDS AND FRUITS 



The effect of A few remarks may be made on the influence of age on 



sfed'shygro- the hygroscopicity of seeds. If it is a purely physical process 

 scopicity. ^j^j independent of life, we would not expect any marked 

 effect to be shown with age, provided that the seeds, when 

 first experimented on, had completed the drying process. But 

 if the seed is still slowly drying, we should look for a slight 

 increase in the " hygroscopic range " as time goes on, a result 

 that would be due to the seed losing weight, whilst the 

 hygroscopic variation remained unchanged. In such experi- 

 ments it is absolutely necessary that the seeds of different 

 ages should be subjected at the same time to the same test. 

 Without this condition the results would not be worth com- 

 paring, and for this reason many of my data are excluded. 

 However, it will be seen from my experiments on the 

 seeds of the Horse-chestnut (^Msculus Hippocastanum) and of 

 Tamus communis^ which fulfilled this condition, that the effect 

 of age is slight. 



Results illustrating the Effects of Age on the Hygroscopic 

 Range of Seeds, this Range being the Variation in Weight 

 stated as a percentage of the average weight of the 

 Seeds. 



The samples of the Horse-chestnut consisted of 4 to 7 seeds, weighing in all from 

 500 to 1000 grains. Those of Tamus com/nunis included about 150 seeds, weighing 

 about 37 grains. 



At first sight it might appear probable that a seed's hygro- 

 scopicity would be markedly increased by a hairy covering ; 

 ^eed^shygro- but a little reflection will show that this cannot usually be 

 expected. If we take an impermeable seed loo grains in weight, 

 of which 10 grains belong to the covering of hairs, a propor- 

 tion, I should imagine, much above the average, and if we 

 assume that the hairs have a hygroscopic variation or range of 



