What generalization, then, can be drawn from this somewhat indefinite group of facts, to which many others of like import could be added from observations on the young of mammals? What is their relation to instinctive procedure in general? It would seem that they are characterized by a special relation of the external stimulus to the response. When this stimulus is afforded by the behaviour of another animal, and the responsive behaviour it initiates is similar to that which affords the stimulus, such behaviour may be termed imitative. A chick sounds the danger note; this is the stimulus under which another chick sounds a similar note, and we say that the one imitates the other. Such an action may be described as imitative in its effects, but not imitative in its purpose. Only from the observer’s standpoint does such instinctive behaviour differ from other modes of congenital procedure. It may be termed biological, but not psychological, imitation. And if it be held that the essence of imitation lies in the purpose so to imitate, we must find some other term under which to describe the facts. This does not seem necessary, however, if we are careful to qualify the term “imitation” by the adjective “instinctive” or “biological.” And the retention of the term serves to indicate that this is the stock on which deliberate imitation is eventually grafted. The fact that instinctive imitation leads, under natural conditions, to behaviour which is already familiar to us in the species concerned, prevents us from recognizing the influence of this social factor so easily as might otherwise be the case. The abnormal arrests our attention more readily than the normal, and hence the cases commonly cited are generally those which strike us as unusual, such as the imitation of human sounds by the parrot. But if the young inherit a tendency to imitate certain actions of their parents, and if there is among the members of a gregarious species such instinctive imitation as shall tend to keep them gregarious, we have here a social factor in animal life of no slight importance. Just as the higher type of reflective imitation is of great value in bringing the human child to the level of the adults who form the family and social environment, so, too, does the sub-conscious instinctive imitation of the lower animals bring the young bird or other creature into line with the members of its own species. In broods of chicks brought up under experimental conditions, there are often one or two more active, vigorous, intelligent, and mischievous birds. These are the leaders of the brood; the others are their imitators. Their presence raises the general level of intelligent activity. Remove them, and the others show a less active, less inquisitive, less adventurous life. They seem to lack initiative. From which one may infer that imitation affords to some extent a means of levelling up the less intelligent to the