stimulation. The acquired characteristics of the fullydeveloped mind, like those of the body, possess a certain fixity, which, since mind is in a sense the product of a physical structure, the brain, is exactly what was to be expected. Therefore it is that adult animals do not so readily change their acquired mental traits as young animals; therefore do slave-holding ants capture only the pupse of the servile species; therefore do we usually fail in taming adult wild animals, except in some few cases (e.g. monkeys and elephants), when the power of acquiring mental traits is so great, that new traits may be superimposed even in the adult animal on traits previously acquired in youth; and therefore is the right training of young human beings so highly important.
It is within the knowledge of every one that many animals, like men, afford tuition to their offspring, that they endeavour to develop in them the traits that conduce best to survival. The higher the animal, the smaller its equipment of instinct, the greater its power of acquiring mental traits, the more elaborate is the system of education to which it is subjected. The instinct which impels the human mother to teach her offspring is developed in bird and beast as well. Poultry may be seen in every farmyard instructing their broods in the arts of discovering food or of avoiding enemies. In our homes the cat plays a game of hideand-seek with her kittens, mimicking the hereditary warfare against mice. Books of sport and travel tell how wild dogs, bears, lions, tigers, and especially elephants and monkeys, instruct their ytmng. All higher creatures, in fact, instinctively seek by example to educate the next generation, which by virtue of strong, imitative instincts is able to profit by the lessons. Thus, the instinct of the parent assists in the development of reason in the offspring, but in this the instinct of the offspring also assists. The sports in
