ANIMAL BEHAVIOR 



power of the animal, which enables him to go directly to the 

 latch and press it in preqsely the right manner each time. In 

 those cases, however, where the dog's behavior has been ob- 

 served from the very beginning, it is found that reason is not at 

 the bottom of the act, but simple intelligence, which has utilized 

 the results of many experiments. Thus the first time the dog 

 approached the closed door and sought to open it, he followed 

 his instinct by scratching and pushing against it ; eventually his 

 paws came upon the latch and the door swung open. After re- 

 peated experiences he came to associate scratching in a particu- 

 lar place with the opening of the door, and finally the pressing 

 of the latch itself was distinguished as the necessary opera- 

 tion. Thus his experiences became more and more condensed, 

 the man_\' useless, unnecessary movements were eliminated, and 

 the result was what has been called functional selection, the 

 survival of only such movements as were necessarv for the 

 successful accomplishment of the act. A young child would 

 attack the problem in the same manner as the dog ; an older 

 individual would resort to reason. 



There is, then, in animals an innate capacity for meeting the 

 difficulties of new conditions, an ability toaccommodate themselves 

 to a changing environment through intelligent experimentation ; 

 and this innate capacity, characterized by extreme plasticity, max 

 be conceived to be inherited, although the particular motor mani- 

 festations of it in each case are acquired. Just how intelligence 

 is able to modify behavior, it is difficult to say. The impres- 

 sion made on the nerve centers by the performance of an act 

 recurs at its repetition, but this memory is selective ; it omits de- 

 tails, retaining only the salient features of the act, thus giving 

 psychologically a generic image; it is a concentration of ex] 

 rience. 



There are one or two forms of animal behavior which we 

 have not yet touched upon, which deserve a word of notice 

 here. One of the most familiar manifestations of activity 

 in animals is play, observable in animals of almost any age to 

 some extent, but more especially in the young. The puppy 

 seizes a shoe, shakes it violently, and tears it to pieces ; he tus 

 sles with another puppy, biting his ears and legs as they roll 

 over and over. The kitten rolls a ball across the floor, springi 



