372 STUDIES IN SEEDS AND FRUITS 



according to my observations, retain their white hue until the 

 capsule opens, when they begin to brown, a circumstance 

 probably to be connected with the hard ligneous character of 

 the fruit, the walls of which are 10 millimetres or nearly half 

 an inch thick. 



On the other hand, there is no difficulty in showing that 

 with capsules and with similar fruits the absence of colouring 

 before the fruit opens is the exception and not the rule. In 

 baccate capsules, like those of Thespesia populnea, as already 

 pointed out in Chapter XI, the white soft seeds of the green 

 fruit, as they harden, become first purplish and then brown 

 long before they are freed by the decay of the dried-up fruit. 

 But here in Devonshire one has not to walk far to find the 

 same indications in the plants growing around. The seeds of 

 Iris fcetidissima acquire their orange colour, those of Scilla nutans 

 become shining black, those of Allium ursinum become deep 

 reddish brown, and those of Arenaria peploides take on a similar 

 hue, whilst the capsule is still moist and green and long before 

 dehiscence occurs. So, again, the seeds of Stellaria Holostea 

 and of Primula veris redden and brown before the capsule 

 opens ; whilst the seeds of Aquilegia assume their black hue 

 in the moist unopened follicle. The common weeds around 

 one's house in the tropics follow the same rule. In the cases 

 of Argemone mexicana, Datura Stramonium^ and Portulaca oleracea 

 the soft white seeds become more or less black in the closed 

 capsule whilst the fruit is still green and moist. The seeds of 

 Sesuviutn, a genus of beach plants, behave in precisely the same 

 way. With Ricinus also the soft white seed hardens and 

 colours in the green closed coccus. 



(c) Pods of In Chapter XI we found the same behaviour in the seeds 



plants. of leguminous pods, as exemplified by those of C^salpinia 



sepiaria and Ulex europteus. But in legumes the coloration of 

 the seeds is often more complete when dehiscence occurs than 

 it is in capsules, because, as established in Chapter XIII, the 

 fruit opens at a later stage of the drying process. It has 

 already been indicated that the seeds of capsules often deepen 



