THE REST-PERIOD OF SEEDS 425 



of the early dehiscence of many capsules and the late dehiscence 

 of the legume. For the continuous growth of the embryo, 

 which we assume to be nature's primal condition, the opening 

 of the fruit is wrongly timed in both cases, too early in the 

 one, too late in the other. 



Let us take a conspicuous example of the ushering in of The case of 



• 1-1 CI iri- 1 Poinciana 



the rest-period m the case or the seeds ot a ligneous legume regia. 

 like that of Poinciana regia. In the chapter on seed-coloration, 

 I have already described the remarkable changes which the 

 embryo of these seeds undergo when entering the resting 

 stage and when resuming active life and growth in the 

 germinating process. The embryo of the large, soft pre- 

 resting seed in the green and living pod is a plantlet full of 

 vitality with green cotyledons and green, partially unfolded 

 plumular leaves. When the fruit begins to dry the green 

 hue of the embryo disappears. The plumule folds up its 

 tiny leaves, and the rest-period commences. 



The closing in and the cutting off from the external world 

 of the soft green respiring seeds of Poinciana regia seem 

 almost tragical, and one marvels at the fine adjustment which 

 allows these unresistant seeds to hold their own when every- 

 thing is hardening into tough wood around them. Let one 

 of the seeds fail in its early stage and the ligneous tissue 

 invades its area and occupies its place. What concerns us 

 here is that when the embryo loses its green hue, as the tissues 

 harden around the seed, it ceases to respire, and with its 

 vitality completely suspended it becomes buried in a hard 

 woody fruit that dehisces but tardily. In one's ignorance one 

 almost doubts the wisdom of such a suspension of active life 

 in the warm genial climate which this tree enjoys, since the 

 embryo has already advanced considerably in its growth and is 

 well able to proceed with its development. 



Coming to the special influences that determine the stage The special 

 of development of the embryo when the rest-period begins, determining 

 one may observe that the great variation displayed by the ^jj^ ^^^ °^ 

 embryo in this respect ought to be associated with correspond- period. 



