chestnut. 



SEED-COLORATION 383 



associated with a shrinking and hardening of the soft, unripe, and 

 pre-resting seed. But the brown coloration, with its associated 

 processes, is to be noticed alike under moist conditions, as in 

 baccate fruits, or under dry conditions, as in drying capsules and 

 leguminous pods, a subject dealt with in preceding chapters. 



Although seeds acquire their brown colour in the closed not con- 

 capsule and pod, their coloration, early shrinking, and harden- Si?drying of 

 ing are so conspicuously associated with the early drying of the fruit, 

 the fruit that it is not a matter for surprise that there should 

 seem to be some causal connection between them. However, 

 experiment showed that these changes in the seed may take 

 place where no drying of the fruit has occurred. Perhaps the 

 most conclusive piece of evidence in this direction is afforded 

 by the aborted seeds of the Horse-chestnut {Msculus Hippocas- Horse- 

 tanum). In full-grown moist capsules showing no signs either 

 of dehiscence or of drying, and containing full-sized white 

 moist seeds, it is not uncommon to find two or three aborted 

 seeds only 2 to 4 millimetres across, but typically brown 

 and hard-coated. The behaviour of the white moist seeds in 

 a full-grown green capsule that has been placed in wet moss in 

 a closed tin is also very significant. Though the capsule at the 

 end of the experiment shows no signs of drying, since the air 

 in the tin would be quite saturated with moisture, the seeds in 

 a few days become normally brown, and experience a slight 

 shrinking in size and a hardening of the coats. In spite, 

 therefore, of their moist conditions, the Horse-chestnut seeds 

 in this experiment experience the same changes that they 

 exhibit in the drying capsule, thus behaving like the seeds of 

 a berry. 



We can therefore no longer suppose that the drying of The regime 



the capsule is needed for the preliminary shrinking, hardening, fsreprodu^d 



and coloration of the seeds within. In the case of brown or p the colour- 

 ing seeds of 

 black seed-coloration the inference is the same. In the pod, the pod and 



as shown in the case of Phaseolus multiflorus, and in the capsule, 

 as illustrated by Msculus Hippocastanum^ the regime involved 

 in the coloration, early shrinking, and preliminary hardening 



the capsule. 



