43^ 



STUDIES IN SEEDS AND FRUITS 



possible, by placing under suitable conditions the soft uncontracted seed 

 of the moist living fruit, to induce it to proceed continuously with its 

 growth and to germinate without any resting stage (p. 421). 



(7) Coming to the question of causation, it is urged that we must 

 distinguish between the general causes of the rest-period and the 

 special influences that determine the stage of development of the 

 embryo at which the period of suspended growth is imposed (p. 422). 



(8) In references to the general causes it is shown that although 

 in some ways certain climatic influences may be recognised, as those 

 concerned with excessive humidity, yet the subject is really far more 

 complicated than such an explanation would suggest. Indeed, the 

 causes must be sought far back in the plant's life history, not in the 

 seed alone, but in the seed as it depends on the fruit, and in the fruit 

 in its dependence on the mother plant, and in the mother plant in its 

 responses to its conditions of existence (p. 422). 



(9) Being unprepared to undertake such a profound inquiry, the 

 author here limits himself to the influence of the fruit, and that only in 

 an illustrative way. He shows that the suspension of the active growth 

 of the seed presents itself as the result of failure in the co-ordination or 

 co-operation of the growth of the seed and the fruit. Only in the 

 truly viviparous plant, as in Rhi-zophora^ is there complete co-ordination. 

 Over both seed and fruit hangs the fate of ultimate detachment from 

 the parent j but this fate may be avoided if the two co-operate, so that 

 when the fruit is ripe the seed has already begun to germinate (p. 423). 



(10) Taking the capsule and the legume, it is remarked that there 

 is a lack of co-ordination in the first because the seeds are exposed in 

 the moist fruit before the embryos can lead an independent existence ; 

 and there is a lack of co-operation in the legume because the pod begins 

 to dry before the seeds can sprout. There is not much significance in 

 the mere statement that dehiscence takes place early in the capsule and 

 late in the legume. But there is a good deal of meaning when, 

 regarding the possibilities of vivipary, we state that dehiscence occurs 

 too early in the capsule and too late in the legume. Nature has 

 wrongly timed the opening of the fruit in both cases (p. 423). 



(11) As showing the way in which the rest-period may be imposed, 

 and how the life of a young plant well able to proceed with its growth 

 may be abruptly suspended, the case of the seeds in the woody legume 

 of Poinciana regia is taken (p. 425). 



(12) With regard to the special influences that determine the stage 

 of development of the embryo at which the rest-period is imposed, the 

 author looks for them in the different stages of growth of the fruit and 

 the seed. Since, however, the rest-period is directly determined by 

 the limit of the fruit's growth, and since the limit of the fruit's growth 

 is determined by the mother plant, it follows that the mother plant has 



