CLUE TO THE HOMOLOGIES OF FRUITS 247 



ment before described, has already sustained before dehiscence 

 a loss of water to the extent of 17 per cent, of its original 

 weight as a soft white seed. When such seeds after removal 

 from the naturally dehiscing fruit are allowed to dry in the air 

 of a room, the total loss of weight finally amounts to about 

 ^2 per cent. Thus, to take an example, a soft white seed 

 freshly removed from a full-sized green capsule and weighing 

 300 grains would weigh about 250 grains when first exposed 

 as a brown, hardening seed in the fruit commencing to dehisce. 

 In the air it would rapidly dry, until it ultimately assumed a 

 stable weight, subject only to hygroscopic variations, of about 

 142 grains. Stated as percentages, these changes in weight in 

 the successive stages of drying would be as follows : — 



Soft white seed . . . . . .100 



Same seed after some hardening and shrinking in ) ^ 



the closed capsule j ^ 



Same seed after the drying process has been ) 



completed in the open capsule J ^' 



Such are the indications supplied by the Horse-chestnut 

 seeds and by comparing them with the data before given for the 

 berries of Berberis^ Passiflora^ Arum maculatum^ and Tamus communis^ 

 it will be at once perceived that they run well together with 

 the indications of the berry. There is the same preliminary 

 shrinking of the seeds within the closed ripening fruit, and 

 there is the same great loss of weight when the fruit has passed 

 maturity and begins to dry. Whether the seed undergoes 

 the greater part of its drying within a shrivelling berry or 

 exposed in an open capsule, the process belongs to the same 

 stage in the history of the fruit. We can now perceive how 

 the shrinking of the seed in the ripening berry comes to our aid 

 in contrasting other fruits in their several stages of maturation 

 by enabling us to fix on a stage that is common to all. 



My next example of a capsular fruit will be that of Iris iris Pseud- 

 Pseudacorus. Here, as in ^senilis Hippocastanum^ the Horse- 

 chestnut, the soft white seeds of the green full-sized capsule 

 begin to shrink and harden and commence to " brown," whilst 



acorus. 



