INTRODUCTION. xli 
to the nature of their food. Among birds, 
for example, the graaivorous generally die in 
the fpace of from forty-eight to fixty liours, 
while the entomophagi, thofe who feed on in- 
fers, will hold out for a fhort period longer. 
But thofe which can leaft bear abfti- 
nence are fuch as live on fruit ; a property 
that is owing probably to their ftomach, 
which, digefting more fpeedily, has more 
frequent need of aliment. This quick digtn- 
tion, however, is attended with one advan- 
tage, which is, that, reduced to an equal de- 
gree of inanition by abfiinence, the animal, 
if affifted, wll! recover and refume its ftrength 
fooner than others. With the granivorous 
fpecies this is not the cafe. Debilitated to a 
certain point, if nothing but the feeds on 
which they ufually feed be givea them, they 
can never be reftored ; their ftomach having 
k)ft, in part, its power of digeftion. The 
carnivorous, on the contrary, retain their di- 
c 3 geftiou 
