DISCRIMINATIVE ABILITY OF THE TURTLE 5 



making it necessary for the turtle to crawl to the back of the 

 electrode before the food is discovered. 



f-^r 



Heoatat 



"^ 



electrode 



electr-Dclc 



Irvsuilafi-an. 



elscirad-e 



stsarvd- 



/aier 



^v 



5Ucij 



vva-ter- 



FiG. II — Ground plan of apparatus with boxes removed, showing electrical con- 

 nections. 



The food and electric boxes are of tin, exactly similar in 

 size and shape, their dimensions being, height 26 cm. width 

 18 cm., depth 17 cm. They are without bottoms, the lower 



