340 Jounial of Couiparativc Xciirology mid PsycJwlogy. 



The obtaining of the food ma\' have first occurred acci- 

 dentally and the successful movements have been rapidly select- 

 ed for retention b}' being "stamped in," or b}- the elimination 

 of random movements not pleasurably emphasized ; or an in- 

 telligent factor may have entered into the selection of move- 

 ments once found to produce the desired result of obtaining 

 food. At an}' rate, it was found that "No form of problem 

 which the adult rat is capable of solving presents insurmount- 

 able difficulties to the rat of twenty-three days of age" (p. 84). 



The guinea pig stands in complete contrast to the white 

 rat. Though no experimental records of memor\- were ob- 

 tained from the guinea pig during its first day, a simple path 

 was learned upon the second day. and upon the third day the 

 most complex problem was solved, being a complicated laby- 

 rinth. 



No experiments were made with the rat to determine how 

 early a complicated lab\rinth could be learned, but Watson's 

 rats solved a simple lab>'rinth at nineteen days. 



When the guinea pig has found his way through a labyrinth 

 he has reached the end of his psychical powers. He cannot 

 pull a latch nor push a bolt, he will not depress an inclined 

 plane, he will not chew a string nor stamp his foot. All the 

 ingenuity which the white rat acquires after he has solved the 

 lab}'rinth is a tc/ya ijicognita to the guinea pig who thus pays 

 the penalty of his early maturity. 



The experience of the white rat extends to strange com- 

 binations of wires and springs, and all the delightful surprises 

 revealed by secret doors. But when the guinea pig has turned 

 the proper number of corners his dinner must be waiting for 

 him or he does not get it. 



The rat at three days is just learning to crawl, has never 

 seen an object and remembers nothing. The guinea pig at that 

 age has triumphantly recalled a complex path, at the end of 

 which he sits eating his well-deserved carrot. 



At twenty-three days the rat is lifting latches neatly, and 

 forming what Hobhouse calls "practical judgments" as to the 

 value of an inclined plane in a situation at the center of which 



[48] 



