CANADA PORCUPINE 55 



permitted to tear off the pocket and get the food which was 

 in it. He must find the box wherein there was food which was 

 obtainable. In the search for food, color or brightness was 

 introduced as guides. The boxes were covered on the outside 

 with colored or gray paper. A two-inch strip of the same paper 

 was placed vertically in the middle of each of the inner sides. 

 It will be observed that each box had eight different positions 

 in which it might be presented to the animal. It could be 

 turned so that the animal must approach one and then the 

 other of the four similar sides and reach across each of the four 

 edges in turn. Then the box could be inverted to present an 

 equal number of variations in the second position. Special 

 precaution was taken not only to shift the position of the boxes 

 according to a regular schedule but also to rotate and invert 

 them in such a manner as to break up any secondary associa- 

 tion which might be formed. Porcupines Nos. 3 and 10 were 

 used in this experiment and the results are shown in tables 

 IX and X respectively. 



TABLE IX 



Color and Brightness Discrimination. Porcupine No. 3 



Blue-Green 10, 11, 11, 13, 16, 11, 7, 12, 11, 14, 10, 14, 12, 10 (failure). 



Grays 1-50 H, 10, 13, 12, 14, 10, 12, 12, 13, 10, 14, 13, 11, 15, 14, 13, 



16, 17, 18, 20. 



" 11-50 20. 



" 21-50 20. 



" 32-50 20. 



" 41-50 20. 



" 45-50 13, 13, 15, 13, 14, 15, 13, 9, 13, 13, 15, 17, 14, 15, 15, 12, 12. 



" 41-50 12,11,13. 



1-50 20. 



1-45 20. 



1-41 20. 



1-32 20. 



1-21 20. 



1-11 14,20. 



1-11 (New).. 12,14,17,20. 



" 11-41 20. 



« 21-32 14, 18, 14, 12, 12 (failure). 



Blue-Green 18, 20. 



B^-GoAlt. B2-G2... 18. 



B^-G2 18. 



B^-G, Food in light 10. 



Blue-Green 13,19. 



B^-G^Alt. B2-G2... 18. 



B2-G, Food in light 11. 



B^-G, Alt. Bj-G^ . . 17. 



B^-G, Food in light 6. 



It should be noted that No. 3 had been undergoing daily 

 experimentation for four months while No. 10 had been out of 



