THE PROPORTION OF PARTS IN FRUITS 317 



proportion of the pericarp decreases up to the time of maturity. 

 The subsequent decrease in the drying stage is due to the peri- 

 carp holding relatively more water than the seeds, and to its 

 giving it up to the air more readily. It will be noticed in the 

 table on p. 303 that when allowed to dry in the air, the pericarp 

 of the moist mature fruit reduces its weight from 135 to 16 

 grains, a loss of as much as 88 per cent, of its weight, whilst in 

 the full-grown soft seeds of the ripe fruit there is a reduction 

 in weight from 115 to 49 grains, a loss of about 57 per cent. 



We may here cite the case of the acorn, which acts quite The acorn, 

 in accordance with the principle that the proportional weight 

 of the fruit-case is a continually decreasing quantity as the 

 fruit develops, ripens, and dries. As high as 6^ per cent, 

 in an immature fruit only one-third of the mature size, the 

 relative weight of the shell or pericarp is reduced rapidly, 

 being 44 per cent, when the seed has attained its maximum 

 size and weight in the moist condition, and as little as 19 

 per cent, in the air-dried acorn lying on the ground. These 

 results are those given in the general table on p. 303. 



It will be observed in the same table that a small divergence Small de- 



in behaviour is displayed by the fruit of Iris fatidissima in the from the 



drying stage ; and we notice it also in the fruits of Barringtonia frSfSidS- 



speciosa and Cocos nucifera (Coco-nut). Here during the drying sima, Cocos 

 ^ . 1 , , , . ■ J 1 1 nuc'fera, and 



process, as previously remarked, there is a period when the Barringtonia 



loss in weight of the seed is checked and the loss in that ^P^*^^°^*- 



of the pericarp proceeds very rapidly. In time, however, 



the seeds, like the pericarp, surrender their water to the air ; 



and the temporary check is indicated by the circumstance 



that the lowest proportional weight of the pericarp is found, 



not in the completely dried state, as in Iris Pseudacorus and in 



yEscu/us Hippocastanu7n (Horse-chestnut), but in the earlier 



stage of the drying process. The cause of this check to the 



drying of the seeds arises in Iris fcetidissima from the amount 



of saccharine material in the seed-coverings, and in Barringtonia 



speciosa and Cocos nucifera from the hindrance imposed on the 



seed-drying by the enveloping pericarp. The history of the 



