276 STUDIES IN SEEDS AND FRUITS 



and dehisces. With the capsule, therefore, the mechanism of 

 dehiscence is concerned with a living fruit. In the legume it 

 has to do with a dead one. 

 The pre- In both the green capsule and the green legume there is 



mellowmg generally a preliminary mellowing stage, corresponding, as 

 stage. shown in Chapter XI, to the ripening of the berry ; but it may 



be transient or disguised by other changes, more especially 

 with the legume. It marks the completion of active growth 

 and indicates seemingly the commencement of the severance 

 of the biological connection between the fruit and the parent. 

 In this mellowing stage the green fruit often assumes a 

 yellowish tinge or a paler hue, and its tense, turgid appearance 

 gives place to one of relative flaccidity. Its firm, rigid walls 

 become softer and more yielding, and the cohesion along the 

 sutures is loosened. This is best exemplified in the capsule, 

 though the same may be noticed in legumes, as in the Pea. 

 But whilst with the capsule the immediate result is the dehis- 

 cence of the fruit, with the legume no such effect is produced 

 at that stage, and dehiscence occurs at a much later stage as a 

 relief from the tension produced from outside by the drying 

 up of the pod. 

 Observations I will now refer to some of my observations on the opening 



hiscenceof of capsules on the living plant, and will begin with Iris 

 theliifng" fattdissima. This plant, growing as it often does in more or 

 plant. less shady woods, offers one a better chance of eliminating 



the drying factor than does Iris Pseudacorus^ which frequents 

 more exposed situations. Though the mellowing stage is not 

 so easily recognisable as in the species last named, we can 

 detect the approach of dehiscence in the lessened turgidity of 

 Iris foetid- the green fruit and in its paler hue. The capsules, when 

 they display the earliest signs of their opening (a slight 

 separation of the valves at and near the apex) are quite 

 moist fruits and show no signs of drying. But, once 

 begun, the process is rapidly completed by drying, and in 

 a few days the valves stand well back, exposing the bright 

 scarlet seeds. That the first rupture is due to some cause 



issima. 



