282 FREDERICK S. IiRKED 



lid J, containing the source lamps for the stimuli; and (3) the 

 experiment box, divided into the two compartments, A and C. 

 The illumination box and the experiment box were separated 

 by a sliding frame F, containing three openings each 12 x 12 

 cm., in which were mounted the desired screens, Ni, N=, N 3 . 



The point of the partition separating the electric passage- 

 ways D and D' was 31 cm. from the nearer ends of the metric 

 scales. 



In some respects a different adjustment of the apparatus from 

 that used by Cole was employed by the writer. A 2 c. p. elec- 

 tric lamp instead of a 16 c. p. was located in the hover box. 

 The inclined planes G, which Cole discarded, had been satisfac- 

 torily used throughout the present investigation. It may be 

 more natural for a chicken to run up hill than down, as Cole 

 intimates, but it is not quite so clear why the reader is asked, 

 in explanation of the difficulty of descent, "to imagine a man 

 descending a steep incline with his body leaning far forward." 

 The difference in the results with this device is no doubt partly 

 explained by the dark-room conditions maintained throughout 

 the present test. The animals were attracted to the lamp in 

 the hover box and did not wander off into the darkness after 

 they reached it. 



The source lamps in the illumination box were two turnip- 

 shaped reflectors, having the lower half of the bulb frosted and 

 the upper half mirrored. When operated at no volts, the 

 end-on candle power, as measured at a distance of 3.048 meters, 

 was 35.4 and 39.4 for no. 1 and no. 2, respectively, at the termi- 

 nation of the experiments. These measurements were made by 

 the Electrical Testing Laboratories, 80th Street and East End 

 Avenue, New York City. 



The feet of the chicks were kept damp by a wet pad of cloth 

 in the gateway B. This condition of the feet of the chicks 

 insured greater regularity of the shock upon contact with the 

 electric wires. 



The experiments were all conducted in a ' dark-room. The 

 apparatus within and without was painted a dull black. As a 

 further precaution the discrimination compartment C, of the 

 experiment box, was covered with a black cardboard hood so 

 arranged that an opening above B was left of sufficient size to 

 permit the experimenter to observe the behavior of an animal 



