jq THE DESCENT OF MAN". [Part I. 



that there is no danger, all show their joy by much 

 clamor. 



With respect to the impulse which leads certain ani- 

 mals to associate together, and to aid each other iu many 

 ways, we may infer that in most cases they are impelled 

 by the same sense of satisfaction or pleasure which they 

 experience in performing other instinctive actions ; or by 

 the same sense of dissatisfaction, as in other cases of pre- 

 vented instinctive actions. We see this in innumerable 

 instances, and it is illustrated in a striking manner by the 

 acquired instincts of our domesticated animals ; thus a 

 young shepherd-dog delights in driving and running round 

 a flock of sheep, but not in worrying them ; a young fox- 

 hound delights in hunting a fox, while some other kinds 

 of dogs, as I have witnessed, utterly disregard foxes. 

 What a strong feeling of inward satisfaction must impel 

 a bird, so full of activity, to brood day after day over her 

 eggs ! Migratory birds are miserable if prevented from 

 migrating, and perhaps they enjoy starting on their long 

 flight. Some few instincts are determined solely by pain- 

 ful feelings, as by fear, which leads to self-preservation, or 

 is specially directed against certain enemies. No one, I pre- 

 sume, can analyze the sensations of pleasure or pain. In 

 many cases, however, it is probable that instincts are persist- 

 ently followed from the mere force of inheritance, without 

 the stimulus of either pleasure or pain. A young pointer 

 when it first scents game, apparently cannot help pointing 

 A squirrel in a cage who pats the nuts which it cannot eat> 

 as if to bury them in the ground, can hardly be thought to 

 act thus either from pleasure or pain. Hence the common 

 assumption that men must be impelled to every action by 

 experiencing some pleasure or pain may be erroneous. 

 Although a habit may be blindly and implicitly followed, 

 independently of any pleasure or pain felt at the mo- 

 ment, yet if it be forcibly and abruptly checked, a vague 



