48 COMPARATIVE ZOOLOGY. 
Many animals, as most Insects and Mammals, live solely 
on vegetable food, and some species are restricted to par- 
ticular plants, as the Silk-worm to the white mulberry.* 
But the majority of animals feed on one another; such are 
hosts of the microscopic forms, and nearly all the radiated 
species, marine Shells, Crustaceans, Beetles, Flies, Spiders, 
Fishes, Reptiles, Birds, and clawed Quadrupeds. 
A few, as Man himself, are omnivorous, 2. ¢., are main- 
tained on a mixture of animal and vegetable food. The 
use of fire in the preparation of food is peculiar to Man, 
who has been called “the cooking animal.” A few of the 
strictly herbivorous and carnivorous animals have shown 
a capacity for changing their diet. Thus, the Horse and 
Cow may be brought to eat fish and flesh; the Sea-birds 
can be habituated to grain; Cats ar@?fond of alligator- 
pears; and Dogs take naturally to the plantain. Certain 
animals, in passing from the young to the mature state, 
make a remarkable change of food. Thus, the Tadpole 
feeds upon vegetable matter; but when it becomes a Frog 
it lives on Insects. 
Many tribes, especially of Reptiles and Insects, are able 
to go without food for months, or even years. Insects in 
the larval, or caterpillar, state are very voracious; but 
upon reaching the perfect, or winged, state, they eat lit- 
tle—some species taking no food at all, the mouth being 
actually closed. The male of the minute Votommata 
takes in no nutriment from the time it quits its egg till its 
death. 
In general, the greater the facility with which an ani- 
mal obtains its food, the more dependent is it upon a con- 
stant supply. Thus, carnivores endure abstinence better 
than herbivores, and wild animals than domesticated ones. 
