CHAP. IV. IN ANIMALS. 95 brate classes. These appendages are erected under the excitement of anger or terror; more especially when these emotions are combined, or quickly succeed each other. The action serves to make the animal appeal- larger and more frightful to its enemies or rivals, and is generally accompanied by various voluntary move- ments adapted for the same purpose, and by the utter- ance of savage sounds. Mr. Bartlett, who has had such wide experience with animals of all kinds, does not doubt that this is the case; but it is a different question whether the power of erection was primarily acquired for this spe- cial purpose. I will first give a considerable body of facts showing how general this action is with mammals, birds and rep- tiles; retaining what I have to say in regard to man for a future chapter. Mr. Sutton, the intelligent keeper in the Zoological Gardens, carefully observed for me the Chimpanzee and Orang; and he states that when they are suddenly frightened, as by a thunderstorm, or when they are made angry, as by being teased, their hair becomes erect. I saw a chimpanzee who was alarmed at the sight of a black coalheaver, and the hair rose all over his body; he made little starts forward as if to at- tack the man, without any real intention of doing so, but with the hope, as the keeper remarked, of frighten- ing him. The Gorilla, when enraged, is described by Mr. Ford9 as having his crest of hair " erect and projecting forward, his nostrils dilated, and his under lip thrown down; at the same time uttering his characteristic yell, designed, it would seem, to terrify his antagonists." I saw the hair on the Anubis baboon, when angered bris- tling along the back, from the neck to the loins, but not 0 As quoted in Huxley's * Evidence as to Man's Place in Nature,' 1863, p. 52.