hell and knocked it repeatedly against a stone, trying
first one snail and then another. After fifteen minutes' hard work, the
thrush managed to break one, and after that it was all easy. A certain
predisposition to beat things on the ground was doubtless present, but
the experiment showed that the use of an anvil could be arrived at by an
untutored bird. After prolonged trying it found out how to deal with a
difficult situation. It may be said that in more natural conditions this
might be picked up by imitation, but while this is quite possible, it is
useful to notice that experiments with animals lead us to doubt whether
imitation counts for nearly so much as used to be believed.

Sec. 6

The Mind of the Mammal

When we watch a collie at a sheep-driving competition, or an elephant
helping the forester, or a horse shunting waggons at a railway siding,
we are apt to be too generous to the mammal mind. For in the cases we
have just mentioned, part of man's mind has, so to speak, got into the
animal's. On the other hand, when we study rabbits and guinea-pigs, we
are apt to be too stingy, for these rodents are under the average of
mammals, and those that live in domestication illustrate the stupefying
effect of a too sheltered life. The same applies to domesticated sheep
contrasted with wild sheep, or even with their own lambs. If we are to
form a sound judgment on the intelligence of mammals we must not attend
too much to those that have profited by man's training, nor to those
whose mental life has been dulled by domestication.

Instinctive Aptitudes

What is to be said of the behaviour of beavers who gnaw the base of a
tree with their chisel-edged teeth till only a narrow core is left--to
snap in the first gale, bringing the useful branches down to the ground?
What is to be said of the harvest-mouse constructing its nest, or of the
squirrel making cache after cache of nuts? These and many similar pieces
of behaviour are fundamentally instinctive, due to inborn
predispositions of nerve-cells and muscle-cells. But in mammals they
seem to be often attended by a certain amount of intelligent attention,
saving the creature from the tyranny of routine so marked in the ways of
ants and bees.

Sheer Dexterity

Besides instinctive aptitudes, which are exhibited in almost equal
perfection by all the members of the same species, there are acquired
dexterities which depend on individual opportunities. They are also
m