to stimulation, so as to place themselves in harmony with an environment which has become more complex, and that higher in the scale this power, of which reason is the outcome, increases more and more, till in amphibians and reptiles, the traits acquired by virtue of it sometimes contradict and overpower the dictates of instinct. But even the highest reptiles, with few exceptions, are provided with an equipment of reflexes and instincts sufficient to enable them to enter on the battle of life unaided immediately on emerging from the egg. It is far otherwise with birds and mammals, which, to an increasing extent, as they are higher placed in the scale, depend for survival less and less on instinct, on inborn inherited knowledge and ways of thinking and acting, and more and more on reason, on acquired knowledge and ways of thinking and acting; and therefore to an increasing extent are helpless and unfit for the battle when hatched or born, and for an increasing length of time are protected by, and receive tuition from, one or other of their parents, whereby they acquire such knowledge and ways of thinking and acting as enable th$m to enter on the battle with advantage.
In the lower birds and mammals, in which the cerebrum is least developed, instinct still predominates over reason. A young chick, for instance, emerges from the egg the possessor of a large amount of hereditary knowledge,[1] supplemented later by an amount of acquired
- ↑ " The late Mr. Douglas Spalding, in his brilliant researches on this subject, has not only placed beyond question the falsity of 1 that all the supposed examples of instinct may be nothing more than cases of rapid learning, imitation, or instruction,' but also proved that a young bird or mammal comes into the world with an amount and a nicety of ancestral knowledge that is highly astonishing. Thus, speaking of chickens, which he liberated from the egg and hooded before their eyes had been able to perform any act of vision, he says that on removing the hood after a period varying from one to three days, ' almost invariably they seemed a little stunned by the light, remained motionless for several minutes, and continued for some time less active than before they
