11 



petted or coddled. When a rat was greatly excited or 

 very timid, it was left a short time in the entrance box 

 before it was permitted to enter the hood. 



A group of rats was given one trial, another group 

 three trials and a third group five trials a day. The 

 rats having had one trial were permitted to feed for a 

 short time in the problem box. They were then removed 

 and fed in their own cages. The ones which had three 

 or five trials were allowed,after each trial, to nibble 

 food for a very short time before starting the next trial. 

 At the end of all trials these rats, like those given one 

 trial, were fed in the cages. Ho harm seems to have re- 

 sulted from not feeding the rats entirely in the problem 

 box. On the other hand.there was a material advantage, 

 for a variety of food was given which would have been 

 impossible if fed in the box alone. 



Daily experimentation was continued until a group 

 of rats reached a norm or average of one second in three 



