290 TROPICAL FRUITS. 



of the tropical plants. Their epidermis, or exter- 

 nal rind, is very compact, and, in general, highly 

 polished and shining. Thus the light and heat 

 of the sun are reflected from it in the hot and dry 

 season, so that the internal parts are not excited 

 to more than ordinary action. Then the com- 

 pactness renders the evaporation far less than it is 

 in the common plants of Europe, with a very in- 

 ferior degree of temperature. In like manner, as 

 the peculiarly smooth and close epidermis prevents 

 evaporation to parching in the dry season, it pre- 

 vents evaporation to chilling -in the humid; and 

 so, notwithstanding that intense action of heat 

 and light which produces so much beauty and 

 fragrance in the tropical fruits, the germs in the 

 plants there have certainly a more equable tem- 

 perature throughout the year, and probably not a 

 higher one than they have in Lapland. In all 

 tropical countries the fruits are delightfully cool- 

 ing, even when they are gathered under the burn- 

 ing sun ; and as the pulp of fruits has accom- 

 plished its purpose, and is about to be yielded up 

 to the general doom of materials, if man do not 

 appropriate it to his use, if that be found to retain 

 so very cool a temperature, much more so must 

 the common juices of the plants, many of which 

 outlive the oaks and the chestnuts of temperate 

 climates. 



The whole of the orange tribe, and the orange 

 itself in an especial degree, show how well the 

 tropical vegetables are, by a very simple provision 

 of nature, protected from the vicissitudes of tem- 

 perature. The volatile oil which is contained in 

 the pellicles of the rind, absorbs and flies off with 

 much of the heat ; and the soft white substance of 



