of the hedge was invisible. The horse was scared and
shied violently, and even in the stable he could not see the
handkerchief without trembling, and it was difficult to reconcile him to
the sight of it. I repeated the experiment with slight variations on
other horses, and the issue was always more or less the same.

Again, I placed a scarecrow or bogey in a parti-coloured dress in the
spacious kennel of a hound while he was absent from it. When the dog
wished to return to his kennel, he drew back at the sight of it, and
barked for a long while. After going backwards and forwards, snuffing
suspiciously, he decided to enter, but he remained on the threshold of
the kennel, anxiously inspecting the bogey. In a few days, however, he
became accustomed to it, and was indifferent to its presence. I ought to
add that I had taught him on the first day, by punishment and
admonition, that he must not destroy the bogey. One day when the dog was
lying down I violently moved the puppet's arms by a cord, and he jumped
up and ran barking out of the kennel, soon returning to bark as he had
done at first. Finally, he again became accustomed to it, but whenever I
repeated the movement with greater violence, it took a long while for
him to become reconciled to it.

I put into a room various kinds of wild birds, which had been taken in
nets after they were full grown. The window, which looked upon a garden,
was unglazed, and closed by a wire netting, through which the outer air
entered and was constantly renewed. I placed in the middle of the room a
pot containing a shrub of some size, on which the birds used to perch.
Since they had been reared in the open air they were certainly
accustomed to the wind, and to the way in which it moves trees and
branches, so that they were not alarmed by a phenomenon which they
recognized from experience. I fastened a cord to the head of the shrub
which I passed through a hole in the door, making another to look
through, and in this way I moved it to and fro as the wind might have
done. One day when there was a high wind which could be heard in the
room, and when the current of air through the window was perceptible, I
tried the experiment when the conditions of resemblance were perfect.
And yet when the violent movement and oscillation of the shrub was
combined with the noise of the wind, the frightened birds all fluttered
about, and after repeating the movement, and then allowing it to
subside, they ke