NATURE OF THE FOOD OF ANIMALS. 145 
144. The first division of aliments is naturally into those 
which are derived from the Animal and Vegetable kingdoms 
respectively. Wherever plants exist, we find animals adapted 
0 make use of the nutritious products they furnish, and to 
restrain their luxuriance within due limits. Thus among 
Mammals, the Dugong (an animal having the general form 
und structure of the whale, but adapted to a vegetable diet) 
browses upon the sea-weeds that grow beneath the surface 
of the tropical ocean ; the Hippopotamus roots up with his 
husks the plants growing in the beds of the African rivers, 
and fills his huge paunch, not only with these, but with the 
Jecaying vegetable matter which he finds in the same situa- 
tion ; the Antelopes, Deer, Oxen, and other Ruminants, crop 
the herbage of the plains and meadows ; the Giraffe is enabled 
by his enormous height to feed upon the tender shoots which 
are above the reach of ordinary quadrupeds ; the Sloths, living 
entirely in trees, and hanging from their branches, strip them 
sompletely of their leaves ; the Squirrels extract the kernels 
of the hard nuts and seeds; the Monkeys devour the soft 
pulpy fruits ; the Boar grubs up the roots and seeds buried 
ander the soil ; the Reindeer subsists during a large part of 
the year upon a lichen that grows beneath the snow; and 
the Chamois finds a sufficient supply in the scanty vegetation 
of Alpine heights. ‘Not less is this the case among Birds ; 
but in the classes of Reptiles and Fishes, the number of 
vegetable-feeders, and consequently the variety of their food, 
is much less. 
- 145. Among Insects, a very large proportion derive their 
food entirely from Plants, and many from particular tribes of 
plants only; so that, if from any cause these should fail, the 
race may for a time disappear. There is probably not a 
species of plant which does not furnish nutriment for one or 
more tribes of insects, either in their larva state or their per- 
fect. condition ; and in this manner it is prevented from mul- 
tiplying to the exclusion of others. Thus, on the Oak no less 
than twé hundred kinds of caterpillars have been estimated 
to feed ; and the Nettle, which scarcely any beast will touch, 
supports fifty different species of insects,—but for which 
it would speedily annihilate all the plants in its neigh- 
bourhood. The habits and economy of the different races 
existing on the same plant, are as various as their structure. 
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