OF NATURAL HISTORY. 225 



.animals are at full liberty, they prevent this effea, by an 

 inftindt which teaches them to make frequent changes from 

 moift to drv food : If they are reftrained in their choiccj 

 thev will eat, as a fuccedaneum, paper, linen, and even vvool- 

 len cloths. 



Though fome animals, and many vegetables, would be nox- 

 ious to man, if ufed as food, yet in general, that matter is 

 more regulated by chance and cuftom than by rational mo- 

 tives. By experience, and the aid of our fenfes, we acquire 

 a tolerable facility of diftinguifhing falutary from noxio us 

 food. Other animals fele<Sl: their food inftinclively j and 

 their choice is chiefly determined by the fenfe of fmelling. 

 The fpaniel hunts his prey by the fcent j but the grey-hound 

 depends principally upon the ufe of his eye. When thQ 

 grey-hound lofes fight of a hare, he inftantly gives up the 

 chace, and looks keenly around him, but never applies his 

 nofe, in order to difcover the track. Some rapacious ani- 

 mals, as wolves and ravens, difcover carrrion at difiancesj 

 which, if we were to judge from our own fenfe of fmellingj 

 would appear to be altogether incredible. Others, as eagles, 

 hawksj gnlls, &c. furprife us no lefs by the acutenefs of their 

 fight. They perceive, from great heights in the air, micej 

 fmall birds, and minute fifhes m the water. 



One great caufe of the difi:ufion of animals over every 

 part of the globe, is to be derived from the diverfity of ap- 

 petites for particular fpecies of food, implanted by Nature 

 in the different tribes. Some fifties are only to be found 

 in certain latitudes. Some animals inhabit the frigid, others 

 the torrid zones •, fome frequent deferts, mountains, woods, 

 lakes, and meadows. In their choice of fituation, they arc 

 uniformly determined to occupy fuch places as furnifli them 

 with food accommodated to their natures. Monkies, the 

 elephant, and rhinoceros, fix on the torrid zone, becaufe 

 they focd or^ vegetables which flourifli there during the 



