384 



STUDIES IN SEEDS AND FRUITS 



The brown- 

 ing of unripe 

 seeds in 

 capsules and 

 pods is 

 associated 

 with shrink- 

 ing and 

 hardening 

 of the coats. 



of the seed and its coats is that which is displayed by the 

 colouring, shrinking, and hardening seed in the moist berry. 



Whatever the nature of the connection may be, there is 

 no doubt that the browning process of soft unripe seeds is 

 associated in capsules and in leguminous, pods with shrinking 

 and hardening of the seed-coats. It has already been shown in 

 the case of the soft, moist white seeds of the Horse-chestnut 

 {/Esculus Hippo castanuni) that they suffer a loss of 1 7 per cent, 

 of their weight during the browning that accompanies the 

 preliminary drying in the closed capsule (see Chapter XI). In 

 the instance of Entada scandens, where the soft white seeds on 

 removal from the green pod were allowed to dry on a table, 

 the seeds did not attain their normal dark reddish-brown hue 

 until they had lost about half of their weight. Passing through 

 a preliminary yellowish stage, they lost in five or six days about 

 .20 per cent, of their weight and became a light mahogany brown. 

 After between two and three weeks, when they had lost about 

 ^^ per cent., they assumed the typical colour of the resting seed, 

 the drying process being prolonged until the loss amounted to 

 60 per cent. The white soft seeds of Entada polystachya turn 

 brown in a similar way ; and here the two varieties, the large 

 pale brown seed containing 10 per cent, of water, and the small 

 dark brown seed with only 6 per cent., clearly show that the 

 colour deepens as the seed becomes drier (see Chapter V). The 

 white flabby seeds of the closed woody capsule of the Mahogany 

 tree {Swietenia Mahogani) harden and turn light brown in four 

 or five days after their removal. As a final example, the seeds 

 of Iris Pseudacorus may be taken, which, when first exposed by 

 the opening capsule in the early stage of browning, have already 

 lost about 20 per cent, of their original weight as soft white 

 seeds. It should, however, be observed that with fruits ripen- 

 ing late in the season, as, for instance, in October instead of 

 the latter part of August and in September, the seeds may 

 be drier and farther advanced in the browning process before 

 dehiscence occurs. Such fruits, however, are backward in 

 maturing, and may even fail to dehisce altogether. 



