460 'Journal of Comparative Neurology and Psychology. 



will suffice for the purposes of this paper. A sketch of the experi- 

 ment box used by us in this investigation appears as fig. i, and a 

 ground plan of the box with its electric attachments, as fig. 2. 

 This apparatus consisted of a wooden box 94 cm. long; 30 cm. 

 wide; and 11.5 cm. deep (inside measurements), which was divided 



Fig. I. 



Fig. 2. 



Fig. I. Discrimination box. /F, electric box with white cardboards; B, electric box with black card- 

 boards. 



Fig. 2. Ground plan of discrimination box. A, nest-box; B, entrance chamber; W W , electric 

 boxes; L, doorway of left electric box; R, doorway of right electric box; E, exit from electric box to alley; 

 0, swinging door between alley and A; IC, induction apparatus; C, electric battery; K, key in 

 circuit. 



into a nest-box, J, (fig. 2) an entrance chamber, B, and two elec- 

 tric boxes, fV, fF, together with alleys which connected these boxes 

 with the nest-box. The doorways between the electric boxes 

 and the alleys were 5 by 5 cm. On the floor of each electric box, 

 as is shown in the figures, were the wires of an interrupted circuit 



