1 66 STUDIES IN SEEDS AND FRUITS 



(3) That with variable seeds, where there is a mixture of 

 permeable and impermeable seeds, the range is inter- 

 mediate in amount, frequently about i per cent., but 

 varying of course with the proportion of permeable 

 seeds. 

 With those " variable " seeds, as with Entada polystachya 

 and Casalpinia Sappan^ where it is possible to distinguish by 

 inspection between the two types of seeds, the difference in 

 the hygroscopic reaction is well marked. Thus, with the 

 first-named plant, a sample of permeable seeds displayed a 

 range of 2 per cent., whilst a sample of seeds almost all 

 impermeable gave a range of O'l per cent. So also with 

 C<esalpinia Sappan^ I found that seeds which had fallen to 

 the ground in the ordinary way were mostly impermeable 

 and had a range of 0'6 per cent, ; whilst those remaining in 

 the dried but closed pod on the tree were nearly all permeable 

 and varied 3 per cent, in their weight. It would be quite 

 possible for the gardener or the agriculturist to devise a 

 rough and ready rule by which the proportions of hygro- 

 scopic permeable seeds and of non- hygroscopic impermeable 

 seeds in any sample could be approximately estimated. Thus, 

 assuming that with seeds of a certain kind the complete 

 hygroscopic reaction when all the seeds were permeable was 

 3 per cent., then a sample of the same seeds that gave a 

 range of 1*5 per cent, might be regarded as probably contain- 

 ing only 50 per cent, of permeable seeds. At all events a 

 marked departure from the normal might give a valuable hint 

 to the gardener in making a selection. 

 The influence The influence of the coats in restraining the hygroscopic 



coats on the variations of permeable seeds has already been briefly alluded 

 scSkityof ^^ ^'^ Chapter IV. It was there shown that the hygroscopic 

 permeable range of the seed of Canavalia ensiformis with its coats intact 

 (2-5 per cent.) was less than in the case of the seed where the 

 coats had been punctured (3*0 per cent.), and that this again 

 was less than with seeds bared of their coverings (4-0 to 4*5 

 per cent.), thus clearly indicating a progressive increase in the 



seeds. 



