III. KXPSHIIOTTT 1: TIffi lilAZE. 



The apparatus used in thiB experiment was the Wat- 

 son liaze (Plate l). This n;ir,e if» circular in forn, five feet 

 in dijijneter, witji entrancea from outer runways to the next 

 inner at alterjiiate ends of a quo.drant arc. The partitions are 

 of aluninun and rise to a heij^ht of five inchen above the floor 

 of the maze. A heavy wire screen resting on top nerves the 

 purpose of preventing the rats from climbing over the parti- 

 tions, and also allovs the experimenter to observe all move- 

 ments within. The perfect course of the aninal running is, 

 from the entrance, E, through runway entrances 1, 2, 3, 4, 



5, 6 and 7 to F (food). Each side of runv/ay entrances 2 to 

 6 inclusive lead into cul-de-sacs. 



The object of the experiment was to have each rat 

 learn to reach the centre, F, in the least possible time, the 

 starting time being taken when the animal crossed runway en- 

 trance 1, and the finishing time when he crossed entrance 7. 



In preparation, each animal, beginning at the a/re 

 of sixty-five days, was fed alone in the centre, F, for ten 

 minutes daily for five consecutive days. During this period 

 the centre was barred from the rest of tVie maze at entrance 



6. At the age of seventy days the experiment began. Eleven 

 males and ten females from the inbred strain were used and, 



as control, an equal number of males and females from the nor- 

 -al series. Of the inbred rats, foutteen were from the 6th j.en- 

 cration and seven from the 7th. The stimulus used was the food 

 to which they had becoiae accustoiaed, bread soaked in milK. 



f^ach rat was reouired to run from E to ? five times 

 each day. At the end of the fifth trial it was allowea to feed 



