100 MEANS OF EXPRESSION Chap. IV. 



As soon as they recover from their fear or surprise, the 

 first thing which they do is to shake ont their feathers. 

 The best instances of this adpression of the feathers and 

 apparent shrinking of the body from fear, which Mr. 

 Weir has noticed, has been in the quail and grass-parra- 

 keet. 15 The habit is intelligible in these birds from 

 their being accustomed, when in danger, either to squat 

 on the ground or to sit motionless on a branch, so as to 

 escape detection. 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 ap- 

 proached by a dog, feel at least some terror. Mr. Teget- 

 meier 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 Kolli- 

 ker'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 



15 Melopsittacus undulatus. See an account of its habits 

 by Gould, ' Handbook of Birds of Australia,' 1865, vol. ii. 

 p. 82. 



16 See, for instance, the account which I have gh<en 

 (' Descent of Man,' vol. ii. p. 32) of an Anolis and Draco. 



17 These muscles are described in his well-known 

 works. I am greatly indebted to this distinguished ob- 

 server for having given me in a letter information on 

 this same subject. 



