HABIT FORMATION IX THE DOG 



71 



% Error... 90 100 70 80 60 20 30 10 10 

 % Accuracy 10 30 20 40 80 70 90 90 100 100 100 

 Av.time... 3.2 3.1 2.1 2.3 1.7 1.9 1.4 1.2 1.0 1.1 



Dogs I and 2 were operated on, 25 March, igii, by Dr. Walter 

 E. Dandy, of the Johns Hopkins Hospital. The operation was 

 quite successful and healing followed without a trace of infec- 

 tion, but the corneas were found in bad condition. About 

 three weeks after the operation Dog 2 received a scratch on 

 the right cornea during a fight. This wound became infected 

 and an abscess near the iris followed. So far as gross behavior 

 indicated the animal was blind. Some tests were made on Dog 

 I to discover whether the eyes were functioning. (Her corneas 

 were not as clouded in appearance as were those of Dog 2 ; 

 the pupils reacted well to light and she seemed in better general 

 condition.) 



Following the operation the dogs had been kept in a dark- 

 room for ten days, until the wounds had entirely healed. Dog 

 I was then taken into the laboratory and subjected to a few 

 rough tests of the presence of vision. The experimenter stood 

 at one end of a room forty feet long, holding food in his hand. 

 The animal was held by another person at the opposite end 

 of the room. When the experimenter called, the animal was 

 released and came quickly to the experimenter for food. This 

 was repeated four or five t'mes. Then a white pine board, two 

 feet wide and eight feet long was set on edge and supported 

 by props placed against the side away from the animal. When 

 the dog was called she ran directly into the board. The posi- 

 tion of the latter was changed four or fi^•e times but with no 

 effect. A rope was then stretched across the room. The animal 

 tripped over it each time, but after the fourth or fifth trial began 



