88 JOSEPH U. YARBROUGH 



i 



II 



1. Cats tested on light. — The four cats used in these tests 

 were Jim $ , Tom J* , Fay 9 . and Bobby $ . Jim and Bobby 

 were both about ten months old, vigorous, healthy animals, 

 and their records may be accepted as typical. The other two 

 were young cats that had not been properly cared for. They 

 were weak and died before they were well into the experiments. 



2. Cats tested on sound. — Four cats were used in the tests on 

 sound. Bess 9 and Phil cf were each about two years old. 

 Judy 9 was about one year and Kitty 9 at least two years 

 old. Bess and Phil continued strong and did excellent work 

 throughout the experiments. Judy and Kitty, on the other 

 hand, died early in the work. From this it is seen that four 

 cats were at work practically all the time, — two on the light 

 tests and two on the sound tests. 



One would think from the number of deaths reported that 

 the cats were in poor physical condition. Such, however, was 

 not the case. Their general health was very good. Those that 

 died did not experience a long period of sickness, but died within 

 thirty-six hours of the appearance of distress. There was only 

 one exception to this, and in this case the cat was replaced by 

 another rather than risk her recovery. 



It was much more difficult than 1 had expected for them 

 to become physically adjusted to their new environment. They 

 were kept in a wire cage 12' by 3|' by 6' high, in a room adja- 

 cent to the experiment room. Their room was well ventilated, 

 and a large east window provided an inlet to the morning sun- 

 shine. The difficult thing was to find the most nourishing food 

 for them. Milk, with a small amount of raw steak, proved to 

 be the most satisfactory. 



Ill 

 DESCRIPTION OF APPARATUS AND METHODS 



In Fig. 1 is shown the ground plan of the box used. The 

 box was made of \" boards and was 26" high, with the doors 

 at a, b, c, 10" high by 7" wide. The distance between these 

 doors was respectively 20", and the distance from the release 

 door E to each of the doors was 44". The door E of the release 

 box was raised by a cord passed over a pulley directly above 

 it and 6|' above the floor of the apparatus. Besides this pulley 



