568 



KARL T. WAUGH 



The next problem undertaken was that of ascertaining whether 

 the mouse discriminates between white and red lights when they 

 are of about the same degree of brightness. 



For this experiment four incandescent lamps were used as 

 sources of light. Two, measuring 4 c.p. each, were used back of 

 ruby glass to yield the red light, and two measuring 13 c.p. each 

 back of ground glass to yield the white light stimulus. The posi- 

 tions of these lamps in the light box were changed as indicated 

 in the following tables of results. 



Lamp of 13 c.p. 84 cm. from red glass; lamp of 4 c.p. 80 cm. from white glass 

 (This yielded a red and a white stimulus which seemed of equal intensity to the 

 human observer) 



Lamp of 13 c.p. 14 cm. from red glass; lamp of 4 c.p. 90 cm. from white glass 



Lamp of 13 c.p. 54 cm. from the red glass; lamp of 4 c.p. 10 cm. from white glass 



Lamp of 13 c.p. 14 cm. from red glass (one of the two thicknesses of ruby glass 

 used previously removed) ; lamp of 4 c.p. 90 cm. from ivhite glass 



