84 



EUPHA FOLEY TUGMAN 



The discrimination box is shown in Fig. 1 as that portion of 

 the apparatus below the line EE 1 and marked DB. It is built 

 of wood and blackened inside and out with several coats of 

 lamp black and oil so as to make it a dull black. Very little 

 light is reflected from the sides of the box. The box consists 

 of an entrance chamber (C, Fig. 1) which is 5 x 4.5 x 19.5 cm.; 

 the discrimination chamber is 54.5 x 46 x 19.5 cm., and is 



Figure 1. Discrimination Box. Openings indicated by D, chambers and alleys 

 by C. Route of bird could be either C, D,, C, D 2 , C 2 , D 3 , C 3 , D 4 , C, or C, Di, C„ 

 Dt,, C 5 , D 6 , Co, D 7 , C. Discrimination made after passing through D. Cross lines 

 in discrimination chamber indicate perches 2cm. above floor. Split brass tubes, 

 stuck on wooden core with paraffine, form broken circuit which could be closed by 

 bird grasping perch in alighting. 



divided at the end next the light box by a partition 30 cm. long, 

 into two identical compartments, Ci and C. Alleyways, C. 

 and Ca, which are 86 x 8 x 10 cm. connect C, and C* respectively 

 with the compartments Ca and Ce, both of which open into the 

 entrance chamber C. These various compartments are separated 

 by sliding doors D,, D 5 , D 8 , D<, D 6 , Do and D?, operated by 



