74 STUDIES IN SEEDS AND FRUITS 



permeable hygroscopic seeds are, relatively speaking, in a 

 state of saturation, or perhaps it would be more correct to 

 say in a state of equilibrium, with regard to the moisture 

 of the air. On the other hand, impermeable seeds like 

 those of Guilandina honducella stand in no such relation to 

 the atmosphere, and preserve their abnormally dry condi- 

 tion independently of any atmospheric changes. When, by 

 the removal of their coverings, such seeds have been 

 deprived of their power of resisting the permeation of 

 water, either as vapour or as liquid, they rapidly supply 

 their deficiency by absorbing it from the air. Roughly 

 speaking, the amount of water regained from the air 

 by the bared seed of Guilandina honducella represents the 

 deficiency in its water-contents, as compared with the bared 

 seed of Canavalia ensiformis^ or, in other words, the price 

 of its impermeability. 



As regards their water-contents and other characters 

 diagnostic of permeable seeds, the seeds of Canavalia ensiformis 

 may be placed with our edible leguminous seeds, such as Peas, 

 Broad Beans, Scarlet-runners (Pisum sativum, Faba vulgaris, 

 Phaseolus multiflorus), which usually contain 15 or 16 per cent. 

 of water. But the low percentage of water in the seeds of 

 Guilandina honducella appears quite abnormal when compared 

 with the data given in the ordinary tables of the analyses 

 of seeds used as food, though representative of impermeable 

 seeds. Rice, Maize, Wheat, and other cereal grains, for 

 the most part permeable, contain from 12 to 15 per cent. 

 of water, whilst the flour yielded by them holds 1 1 or 

 12 per cent. 



Up to this point the indications appear to be sufficiently 

 plain, though the subject gives promise of much complexity. 

 But now comes another curious fact. Whilst the coats of a 

 permeable seed like that of Canavalia ensiformis behave hygro- 

 scopically when removed from the seed, neither increasing nor 

 decreasing their previous average weight, it is very different 

 with the impermeable seed. 



