10 



essary with otKfer problems. It was found that the rats 



were quite ready to solve any problem offered them with- 

 out such preparation. They were active at all times 

 and not unduly disturbed by the change in their environ- 

 ment. After the preliminary runs in the square maze, 

 the rats were fed for two days in the problem box. They 

 were then given for the first time the problem to solve. 

 At first the entrance box was taken to -the cage in 

 which the rats were confined and then a transfer was 

 made to the hood, but this method was soon abandoned as 

 it was found exceedingly difficult to tame the rats with- 

 out some handling. An untrained and excitable rat became 

 greatly disturbed when carried in a closed cage and it 

 usually took several minutes before it calmed down. A 



rocedure was therefore adopted. A rat was carried 

 by hand to the entrance box of the hood and then admitted 

 to the hood surrounding the latch box. The rats were 

 handled as little as possible and at no time were they 



