Chap. III. ACTION OF THE NERVOUS SYSTEM. 77 



the sight of a plate of food, when they get it do not 

 show their delight by any outward sign, not even by 

 wagging their tails. Now with animals of all kinds, 

 the acquirement of almost all their pleasures, with the 

 exception of those of warmth and rest, are associated, 

 and have long been associated with active movements,, 

 as in the hunting or search for food, and in their court- 

 ship. Moreover, the mere exertion of the muscles after 

 long rest or confinement is in itself a pleasure, as we 

 ourselves feel, and as we see in the play of young ani- 

 mals. Therefore on this latter principle alone we might 

 perhaps expect, that vivid pleasure would be apt to show 

 itself conversely in muscular movements. 



"With all or almost all animals, even with birds, 

 Terror causes the body to tremble. The skin becomes 

 pale, sweat breaks out, and the hair bristles. The se- 

 cretions of the alimentary canal and of the kidneys are 

 increased, and they are involuntarily voided, owing to 

 the relaxation of the sphincter muscles, as is known to be 

 the case with man, and as I have seen with cattle, dogs, 

 cats, and monkeys. The breathing is hurried. The heart 

 beats quickfy, wildly, and violently; but whether it 

 pumps the blood more efficiently through the body may 

 be doubted, for the surface seems bloodless and the 

 strength of the muscles soon fails. In a frightened horse 

 I have felt through the saddle the beating of the heart 

 so plainly that I could have counted the beats. The 

 mental faculties are much disturbed. Utter prostration 

 soon follows, and even fainting. A terrified canary-bird 

 has been seen not only to tremble and to turn white 

 about the base of the bill, but to faint; 11 and I once 

 caught a robin in a room, which fainted so completely, 

 that for a time I thought it dead. 



11 Dr. Darwin, ' Zoonomia,' 1794, vol. i. p. 148. 



