Her RICK, Instinctive Traits in Animals. 117 



science of play. Nearly akin to the positive overflow of stored 

 nerve force and its pleasurable accompaniment is the discomfoi^ 

 which in man is termed ennui which follows mental and physi- 

 cal inactivity. The nature of the physical element may be ren- 

 dered clearer by an illustration. In this state of relaxation and 

 aimlessness, the muscular tone is weakened and the accumulation 

 of nervous force overflows spasmodically in yawning and stretch- 

 ing. The discomfort which, -precedes these overflows is a 

 genuine form of pain as the acts themselves produce a genuinely 

 pleasurable sensation. In sleepiness we have a peculiar change 

 in the vaso-motor centres which, when consumated produces a 

 change in vascular tone causing sooner or later a slowing up of 

 the accumulation and discharge. It appears to be due to the 

 fact that the two processes are not simultaneously altered that 

 the system finds necessary the paroxysmal discharge of the yawn, 

 etc. Now, as we have seen, the delayed discharge has its pain- 

 ful accom])animent, so also in ennui there is a real physical com- 

 plex of unpleasant sensations which have their counterparts 

 also in the purely mental experiences of ennui. 



Both forms of restlessness doubtless exist in animals and, 

 when a suitable encitement is present, predispose to playfulness. 

 Animals however, are much more prone than man, in the absence 

 of external stimuli, to fall into a sort of hypnotic slumber so that 

 they endure the monotony of confinement with less discomfort. 

 Some animals accustomed to a life of constant and violent activ- 

 ity are exceptions to the rule, as witness the puma, and most 

 strictly carnivorous animals of large size. Granting then that 

 the play instinct is at bottom impulsive — that its origin is the 

 overflow of accumulated vitality, how comes it to assume the 

 playful form, what is the directive or modifying agency ? It is 

 here in fact that we reach the sphere of instinct. Those activi- 

 ties which must occur take the form for which the organism is 

 best prepared. The preparation consists of hereditary tenden- 

 cies, primary instincts. In the lower animals such an instinct is 

 that of the chase. When the kitten, whose restless predisposi- 

 tion forces to activity, catches sight of its moving tail the instinct 

 to seize or follow it is of this sort. It is umimpeded by any 

 inhibiting judgement and when the motion produces an opposite 

 motion in the elusory member the excitement of the chase grows 



