STUDIES ON THE MENTAL LIFE OF ANIMALS. 



553 



of dog No. 1 in box O, similar to box K in which was shut cat No. 3. 

 Apart from an abrupt rise in the curve followed by an immediate 

 descent, we see no such marked irregularity, and, in particular, we 

 see no interruption; that is to say, no failure. 



The experiments made with chickens were arranged in a little differ- 

 ent manner. The subject was placed in a pen with two exits, one of 

 which led to the place where were the other chicks and food, the other 

 to a second pen from which there was' no issue. The number of these 

 false exits could ])e arl)itrarih' increased. There were other pens in 

 which an o])stacle was placed in the chicken's path, a few steps to 

 climb, a piec^e of stovepipe, 11 inches long, forming an inclined plane 

 which led the subject to an open platform from which the animal 

 could jump down among his companions. In other cases he could 

 escape by pecking at the door of the cage, by climbing up a spiral 

 staircase and out throujili a hole in the wall. 



Fig. 7.— Cat No. 10 in box C. (Thorndike, p. 19. fig. 3.) 



Everything being equal, and making allowances for the modifica- 

 tions due to the influence of heredity, the behavior of the chicks shows 

 the same general character as that of the cats. The subject first shows 

 extreme agitation. Its conduct appears to be governed by the law 

 which may henceforth be considered as having a universal application: 

 "An animal shut up and isolated tends to execute, for the purpose of 

 getting out, all the acts which ordinarily give him his lil^erty under 

 analogous conditions.'''* The alternation of successes and failures 

 produces a selection: it is the pleasure that attends the .successful act 

 or series of acts that causes it to survive. 



Chickens are. in general, slower in forming associations than the 

 animals previously considered. Our author explains this by a differ- 

 ence in their bodily organs and instinctive impulses. The anatomical 

 and phj'^siological constitution of the chicken is on a lower plane than 



«^ " In scientific terms this hi,«torv means that the chick, when confronted by 

 loneUness and confining walls, responds by those acts which in similar conditions in 

 natnre wonld lie likely to free him." Thorndike, p. 36. 



