502 



THE PHILOSOPHY 



has hardened, the animals, by an inftin<fl:Ive impulfe, march back to 

 thofe mountains which they had formerly deferted. In Jamaica, 

 where they are numerous, the land-crabs are regarded as great deli- 

 cacies; and they are fo abundant, that the flaves are often fed entire- 

 ly upon them. 



The migrating principle is not confined to men, quadrupeds, birds, 

 and reptiles : It extends to many of the infeB tribes. Numberlefs 

 inhabitants of the air pafs the firft ftages of their exiftence in the wa- 

 ters. There they remain for longer or fliorter periods, according to 

 the fpecies. Previous to their transformation into chryfalids, they 

 quit the waters, and come upon dry ground, where they undergo 

 their amazing change. Inftead of adtive water-worms, they dig or 

 find holes in the earth, where they are converted into chryfalids, or 

 feemingly inanimated beings, and, in a fliort time, mount into the air 

 in the form of winged infedls. Similar migrations are to be obfer- 

 ved among land-infefts. But migration is not confined to water- 

 wornjs. Many fpecies of caterpillars which feed upon the leaves of 

 trees, (hrubs, and other vegetables, when about to undergo their 

 transformation, leave their former abodes, defcend from the trees, 

 and conceal themfelves in the earth. The hiving of bees, when nu- 

 merous colonies remove in order to eftablifli new fettlements, is an- 

 other inftance of the migration of infc£ls. Indeed, if we except bees, 

 wafps, ants, and a few others, moft infeds, whether they inhabit the 

 air, the earth, or the waters, are perfed wanderers, having no fixed 

 place of refidence. Some of them, as the fpider tribes, build tem- 

 porary appartments ; but, when difturbed, they migrate to another 

 commodious place, and ercil new habitations. 



From the fads which have been enumerated, it is apparent, that 

 the principle of migration, or the defire of changing fituations, is 

 not confined to particular birds, but extends through almoft the 



whole 



