some extent to learn to drink. Their first attempts were awkward; instead of dipping in their beaks, they pecked at the water, or rather a', specks in the water, or at the edge of the water. All animals have a capacity to learn; each individual must learn the topography of its locality, and numerous other facts. Many dogs, horses and elephants may be able to learn more than some men. But I have no doubt that observation will bear out the popular belief that what may be called the professional knowledge of the various species—those special manifesta- tions of practical skill, dexterity and cunning that mark them off from each other, no less clearly than do the physical differences whereon naturalists base their classifications—is instinctive, and not acquired. As we shall see, the creatures have not in a vast multitude of instances the opportunity to acquire these arts. And if they had the opportunity, they have not individually the eapacity to do so, even by way of imita- tion. We have seen as a matter of fact that it is by instinct that the chicken, and, I may now add, the turkey, scratch the surface of the earth in search of insects; also, that the turkey has a method of catching flies so remarkably clever that it cannot be witnessed without astonish- ment. Now, chickens like flies no less than turkeys, and, though with less success, often try to catch them. But it is a significant fact that they do not copy the superior art. To give every opportunity for imi- tation, I placed a newly-hatched chicken with my turkey, when the latter was eleven days old. The two followed me about for several weeks, and when I deserted them they remained close companions throughout the summer, neither of them ever associating with the other poultry. But the chicken never caught the knowing trick of its companion—seemed, indeed, wholly blind to the useful art that was for months practised before its eyes.
Before passing to the theory of instinct, it may be worthy of remark that, unlooked for, I met with in the course of my experiments some very suggestive, but not yet sufficiently observed, phenomena; which, however, have led me to the opinion that not only do the animals learn, but they can also forget—and very soon—that which they never practised. Further, it would seem that any early interference with the established course of their lives may completely derange their mental constitution, and give rise to an order of manifestations perhaps totally and unac- countably different from what would have appeared under normal condi- tions. Hence I am inclined to think that students of animal psychology should endeavor to observe the unfolding of the powers of their subjects in as nearly as possible the ordinary circumstances of their lives. And perhaps it may be because they have not all been sufficiently on their guard in this matter, that some experiments have seemed to tell against the reality of instinct. Without attempting to prove the above proposi- tions, one or two facts may be mentioned. Untaught, the new-born