REDINTEGRATION IN ALBINO RAT— A STUDY IN RETENTION 49 



turn imbedded in the base of the problem. The plane 

 was raised at an angle 15 degrees, approximately, and was 

 held in this position by means of a spring beneath. The 

 weight of a rat stepping on the plane was sufficient to 

 force the plane down far enough that a contact would 

 be made under the plane, thereby raising the armature 

 in the solenoid coil and the door would open inward. The 

 plane and plate were constructed of aluminum but were 



Figure III 



insulated by wood fiber. The plane was located 12 cm. 

 behind the problem box. 



The plane and box were placed on a base 92 cm. square, 

 inside measurement, and were covered by a glass top, 

 68 cm. from the base, and glass sides in a wooden frame- 

 work. The object of the glass sides was to prevent excess 

 waste of movement and effort which always occurs in 

 problem boxes with a mesh covering. Because the glass 

 sides limited the rat's activities to the floor of the problem 

 box, there resulted a greater conservation of movement 



