METHODS OF STUDYING VISION IN ANIMALS 25 



represented in fig. 4 happens to be one which was made for 

 experiments with kittens. It is extremely simple. The essen- 

 tial parts are the entrance chamber, A ; the discrimination cham- 

 ber, B; a partition, C, between A and B, with a pair of sliding 

 doors, D, D; the identical passage-ways, E, E, the floors of which 

 consist of a slab of slate wound with phosphor bronze wire so 

 that the animal can, when necessary, be given an electric shock; 

 the partition, P, between the electric passage-ways; the stimulus 

 areas, S, S, which during experiments are approximated to the 

 two opal glass plates, of the stimulus adapter; the doors 

 (and doorways), F, F, which remain closed except when the 

 experimenter raises them by means of cords running over the 

 pulleys I, I; the alleys, G, G, which, through H, H, give access 

 to the entrance chamber. 



This experiment box is by no means perfect. It is described 

 in this connection merel}^ for the purpose of exhibiting the 

 relations of the several portions of the apparatus. 



TABLE 4 



List and Approximate Cost of Parts op " Brightness " 



Apparatus 



Light box $ 2 5 . 00 



Lamp carriages 6 . 00 



Lamp rods and adjusters 2.50 



Aubert diaphragms ' 



Tracks 5 • 00 



^Millimeter tapes (Starrett) 3 ■ 00 



Cooling cells i o . 00 



Steel plate for end of light box 8 . 00 



Stimulus adapter 2 5 . 00 



Standard stimulus plates (each S.75) lO ■ 5° 



Sheaves, cords, levers 5 • 00 



Experiment box 5 • 00 



Lamps, rheostat, meters $50.00-100.00 



Total cost, exclusive of last item $124.00 



The apparatus can undoubtedly be made, now that the plans 

 have been perfected, for about one hundred dollars. 



' No estimate of cost of the Aubert diaphragms is given because we have not 

 as yet designed accurate forms thereof. 



