INTEGRATION OF MOVEMENTS IN LEARNING IN THE RAT 427 



beginning of progression to the latch. The position of the plat- 

 form in the entrance box and the position of the latch on the 

 problem is seen in figure 1. 



The latch, figure 2, consisted of a hollow aluminum sheath 

 with an easily movable insert of hard rubber. Attached to the 

 inside of the upper middle part of the sheath was an insulated 

 brass lever which made electric contact with the sheath when 



FIG. 2. THE LATCH 



the hard rubber insert was pressed upward. The electric con- 

 tact points were of platinum and of gold. The rubber insert 

 was held in place by a screw. The screw also served to adjust 

 the distance which the rubber insert would have to be moved in 

 order to raise the lever. Attached to the insert was a curved 

 bronze spring on which the lever rested. Slight pressure on the 

 under surface of the insert increased the tension on the spring 

 thereby raising the lever, making electric contact with the lever 



