Though, with birds, anger may be the chief
and commonest cause of the erection of the feathers, it is probable
that young cuckoos when looked at in the nest, and a hen with her
chickens when approached by a dog, feel at least some terror.
Mr. Tegetmeier informs me that with game-cocks, the erection of
the feathers on the head has long been recognized in the cock-pit
as a sign of cowardice.
The males of some lizards, when fighting together during their courtship,
expand their throat pouches or frills, and erect their dorsal crests.[16]
But Dr. Gunther does not believe that they can erect their separate
spines or scales.
We thus see how generally throughout the two higher vertebrate
classes, and with some reptiles, the dermal appendages are
erected under the influence of anger and fear. The movement
is effected, as we know from Kolliker's interesting discovery,
by the contraction of minute, unstriped, involuntary muscles,[17]
often called _arrectores pili_, which are attached to the capsules
of the separate hairs, feathers, &c. By the contraction of these
muscles the hairs can be instantly erected, as we see in a dog,
being at the same time drawn a little out of their sockets;
they are afterwards quickly depressed.
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