THE HOMOLOGIES OF FRUITS 267 



drupes of the Coco-nut {Cocos nucifera) and of Cocos plumosa. 

 In the first case there is a loss of quite 80 per cent. In the 

 second case, where the coverings contain a good deal of sugar, 

 the loss is only about ^^ per cent. 



As with the sugars of berries, the presence of oil in the The effect of 

 pericarp of fruits greatly retards the air-drying process. This *"'*" 

 explains why, in my experiments, the drupaceous berries of 

 Oreodoxa regia (Palmaceae) lost only 22 per cent, of their weight. 

 In the same way, fragments of the pericarp of the Cashew- 

 nut {Anacardium occidentale), which contain a caustic oil in 

 abundance, dry but slightly, losing less than 15 per cent, of 

 their weight when exposed to the air. 



In connection with the loss of weight sustained by fruits immature 

 when dried in air, some curious considerations arise from the ,^re ^^r 

 fact illustrated in the table below, that immature fruits contain **« mature 

 more water than mature fruits. Although the data there 

 given refer almost exclusively to immature fruits of nearly the 

 maximum size that are characterised by incompletely developed 

 seeds, they illustrate a process of change that runs through 

 nearly the whole of the fruit's life-history, from the time of its 

 occurrence as a young fruit, until, with maturity passed, the 

 fruit dries up and loses its vitality. But in this respect, 

 namely, in the progressive decrease of the water-contents as 

 they pass from youth to maturity, and thence to the loss of 

 vitality, fruits share the fate of all vegetable substances. 



If we regard only the percentage of water in the whole or in this re- 

 in the part of a plant, whether stem, leaf, root, fruit, or seed, a?u;^ate a 

 we can construct a scale beginning with the young growth, principle 

 containing, we will say 70 or 80 per cent, of water, and ending teristicofthe 

 with the air-dried dead substance that holds only the water wwld. 

 of hygroscopicity, amounting only to 12 or 15 per cent., the 

 water which it derives from the air and which it gives up in 

 the oven. Between the initial and terminal stages of this scale 

 there is an ever-progressive decrease in the proportion of = 



water that the living plant-substance yields up when drying to 

 the air. But this progressive decrease in the proportion of the 



