Page:Popular Science Monthly Volume 77.djvu/137

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 Cedarbird No. 4 was probably starved by its more vigorous mates, after the second day. Cuckoo No. 2 fell out of its nest. "0" indicates the egg.

cedar waxwing, and has based his results upon a much larger number of cases. He also considers that the three stages enumerated correspond to stages in the development of muscular coordination, of association and the instinct of fear. During the first period, when the power of motor coordination is weak, according to this observer, "the first crude discriminations and associations are made," and the first signs of instinctive fear noted. In the intermediate period (fourth to seventh day), discrimination improves, and association is perfected, while from the beginning of the last period "there is an abrupt change in all the reactions, the food-reaction ceasing for all the artificial stimuli, excepting occasionally for the visual, and fear begins to develop rapidly through several forms of manifestations."

Kuhlmann recognizes five different manifestations of fear, beginning with "cessation of the food-reaction to stimuli that at first aroused it," and ending with "escape from the nest when approached." Discrimination and the formation of associations between the food and certain stimuli are thought to develop simultaneously, and "all stimuli with which no pleasant associations are already formed are then at the same time instinctively feared." The food-reaction is not only modified by association, but is inhibited by fear, and while the development of association is gradual, the passage of one manifestation of fear to the next in order is often very abrupt. Such animals, he says, "come to fear particular things not so much because of unpleasant associations that are connected with them, as because the taming process has not been completed."