48 STUDIES IN SEEDS AND FRUITS 



(b) Dark olive-green soft seeds, rather firmer than those 

 above, 94 or 95 grains in weight, 23 to 25 mm. in 

 diameter, and representing the pre-resting seed in 

 the earliest stage of shrinking. 



If we open other pods that are commencing to wither we 

 find the seeds in various stages of contraction ; and finally we 

 come upon the dried-up brown dehiscing pod containing hard, 

 grey impermeable seeds very much smaller than those of the 

 a and b stages, and weighing 33 or 34 grains. 



Such is Nature's method, provided we do not interfere 

 with it. But if we remove from the green unopened pod 

 seeds in the a and b stages and allow them to dry on the table, 

 we get the following results. The fully formed pre-resting 

 seed of the a stage shrinks excessively, and when that process 

 is complete we find a greatly shrivelled seed, weighing 27 or 

 28 grains, which takes up water readily, yet fails to germinate. 

 But if we take one of the olive-green b seeds, where shrinking 

 has already commenced, and allow it to dry on the table under 

 the same conditions, we notice that instead of shrinking exces- 

 sively its shrinkage as compared with that of the normal resting 

 seed is deficient, and that instead of weighing about 33 grains, 

 as it would have done if it had been left undisturbed in the pod, 

 its final weight is as much as 42 grains. Such a seed, though 

 permeable and hygroscopic, retains its germinative capacity. 



Now comes the critical part of the experiment. If we put 

 the greatly shrivelled a seed in the conditions for germinating, 

 we find that whilst it swells excessively by absorbing water and 

 increases its weight by about 230 per cent., it fails to germinate. 

 On the other hand, the b seed, which has shrunk deficiently, 

 absorbs water easily, increases its weight by about 150 per 

 cent., and germinates healthily. Very different is the behaviour 

 of the normal resting seed. Its impervious outer coat has to 

 be filed through before it can take up water for germination ; 

 and before that stage is reached it increases its weight by about 

 200 per cent. 



But the important point as indicated in the results tabulated 



