THE DEHISCENCE OF FRUITS 



281 



bring about the separation. I found that the follicles just 

 beginning to dehisce were usually the heaviest. 



Dehiscence may take place in the most watery of capsules, Contrast in 

 as with those of Momordica, where 95 per cent, of the fruit contTnt*sof 

 (excluding the seeds) consists of water, and in the hardest and capsules, 

 most ligneous of capsules, as with those of Mahogany (Swietenia 

 Ma/iogani), where the woody walls hold only about 66 per cent. 

 of water and are 10 millimetres or nearly half an inch thick. 

 The dehiscence of the fruits of a species of Momordica observed Momordica. 

 by me in Jamaica (seemingly a cross between M. Charantia 

 and M. Bahamind) was quite regular, and took place when the 

 fruits were ripe and moist. After the seed-contents were 

 removed, a ripe fruit not yet beginning to open lost 94 per 

 cent, of its weight when dried in air, whilst a similar fruit just 

 beginning to dehisce lost 91 per cent. The first stage In 

 dehiscence seems to be due to the tension produced in the 

 walls of the softening fruit by its contents. With the woody 

 fruits of Mahogany the exact stage at which dehiscence occurs Mahogany, 

 on the tree is not easy to determine ; but one can get an 

 approximate idea. The full-grown green fruits, which seem 

 to average about four-fifths of a pound in weight (5600 grains 

 or 363 grammes) lose about two-thirds of their weight when 

 detached and allowed to dry for several months, but they begin 

 to open when they have lost about one-fourth of their weight. 



Drying in Air of a Detached, Green, Full-grown Capsule (not 



YET dehiscing) OF MAHOGANY (SwiETENIA MaHOGANi), INCLUDING 



Seeds. 



Dehiscence will probably occur also if drying is prevented, as shown below. 



These results for the drying of a detached fruit of Ma- 

 hogany are, as far as dehiscence is concerned, very much the 



