494 



ALFRED O. GROSS 



The colors indicated on the hnes are compared with those of 

 the columns as was done in the table of percentages for the adult 

 blow-fly. For example in the blue-red pair the number 93 in 

 the blue column opposite the red denotes that in this test 93 

 per cent of the flies went to the blue and away from the red. In 

 a similar manner the result of the experiment with any pair of 

 hghts may be readily determined. 



100 



90 



80 



7V 



SO 



SO 



40 



30 



20 



JO 



Fig. 34 Curves representing the percentages of the responses of the pomace 

 flies to the four monochromatic lights. Percentages of responses of animals to 

 the respective colors as ordinates and wave lengths as abscissae. The wave 

 lengths of the middle band of each light are indicated by points marked on the 

 axis of the abscissa. 



The results presented on the foregoing pages may be expressed 

 graphically in a series of curves in which each color is compared 

 with each of the other four colors (fig. 34). 



The results of these experiments demonstrate that of the four 

 colors the ones containing the more refrangible rays exert the 



