or believing that the young
Mound-birds, young crocodiles, and young turtles have an intelligent
appreciation of what they do when they are hatched. They act
instinctively, "as to the manner born." But this is not to say that
their activity is not backed by endeavour or even suffused with a
certain amount of awareness. Of course, it is necessarily difficult for
man, who is so much a creature of intelligence, to get even an inkling
of the mental side of instinctive behaviour.

In many of the higher reaches of animal instinct, as in courtship or
nest-building, in hunting or preparing the food, it looks as if the
starting of the routine activity also "rang up" the higher centres of
the brain and put the intelligence on the _qui vive_, ready to interpose
when needed. So the twofold caution is this: (1) We must not depreciate
the creature too much if, in unusual circumstances, it acts in an
ineffective way along lines of behaviour which are normally handed over
to instinct; and (2) we must leave open the possibility that even
routine instinctive behaviour may be suffused with awareness and backed
by endeavour.

Sec. 2

A Useful Law

But how are we to know when to credit the animal with intelligence and
when with something less spontaneous? Above all, how are we to know when
the effective action, like opening the mouth the very instant it is
touched by food in the mother's beak, is just a physiological action
like coughing or sneezing, and when there is behind it--a mind at work?
The answer to this question is no doubt that given by Prof. Lloyd
Morgan, who may be called the founder of comparative psychology, that we
must describe the piece of behaviour very carefully, just as it
occurred, without reading anything into it, and that we must not ascribe
it to a higher faculty if it can be satisfactorily accounted for in
terms of a lower one. In following this principle we may be sometimes
niggardly, for the behaviour may have a mental subtlety that we have
missed; but in nine cases out of ten our conclusions are likely to be
sound. It is the critical, scientific way.

Bearing this law in mind, let us take a survey of the emergence of mind
among backboned animals.

Senses of Fishes

Fishes cannot shut their eyes, having no true lids; but the eyes
themselves are very well developed and the vision is acute, especially
for moving objects. Except in gristly fishes, the external opening to
the ear has been lost, so that