ADDITIONAL EVIDENCE 145 



(5) The results for variable seeds (permeable and impermeable seeds 

 in the same plant) of baring the kernel, or exposing it by cutting it 

 in halves in its coats, are also tabulated ; and it is shown respecting 

 their relations with the moisture of the air (a) that the permeable seeds 

 behave hygroscopically, like ordinary seeds of the type ; (/;) that imper- 

 meable seeds behave also like seeds of their type and add considerably 

 to their weight ; (c) that mixed samples of the two types of seeds 

 display intermediate qualities (p. 122). 



(6) Additional data are given concerning the behaviour of bared 

 permeable seeds that have completed their drying in air ; and it is 

 shown, as in Chapter IV, that the main result is to give a rather 

 freer play to the hygroscopic reaction, the average weight remaining 

 about the same (p. 124). 



(7) Further evidence is then supplied of the association of the ultra- 

 dryness of impermeable seeds with a low water-percentage, and in the 

 first place the necessity of restricting the inquiry to seeds of the same 

 order is pointed out. 



(8) Thus with leguminous seeds we obtain the following general 

 results for seeds broken up or cut open and exposed to the air : — 



Impermeable seeds holding 7-5 per cent, of water add 9*2 per cent, 

 to their weight. 



Impermeable seeds holding 1 1-7 per cent, of water add 5-0 per cent, 

 to their weight. 



Permeable seeds holding 15-0 per cent of water add o-o, behaving 

 hygroscopically. 



(9) The indications of this rough estimate are confirmed by the 

 results of experiments on seeds where both the permeable and imper- 

 meable types of seeds are produced by the same plant. 



(10) More evidence is adduced to show that in impermeable 

 seeds the seed-coats possess the same quality of ultra-dryness as the 

 kernel. 



(11) Additional data are given in support of the conclusion that 

 the capacity possessed by impermeable seeds of considerably adding to 

 their weight when exposed to the air in a broken state is not afiected 

 by first exposing the materials to a temperature of 100° C, whether in 

 the case of the coats or of the kernel. 



(12) Permeable seeds in this respect present a great contrast to 

 impermeable seeds, since in a week or two they gain back from the 

 air only the water lost in the oven and assume a stable weight subject 

 merely to ordinary hygroscopic variation. 



(13) In the case of both permeable and impermeable seeds it is 

 necessary, when comparing their absorptive capacities after heating, to 

 employ only seeds that have completed the drying and shrinking 

 process, since seeds of either type, when incompletely dried, fail to 



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