500 ALFRED O. GROSS 



able place to be stimulated by any color when the body is oriented 

 away from its source, hence in the above experiment, the varia- 

 tion in time of response probably depends, to a certain extent, 

 on the accidental exposure of the ommata to the green light. 

 In the record shown in figure 45 the larva was started from 

 the right at A in the green light and was allowed to crawl to 

 B before the yellow light from the opposite side was turned on. 

 In no case of the many tests made was the larva reversed in 

 its course by the yellow when the latter was opposed with green. 

 In similar experiments made with each of the remaining pairs 

 of lights the larvae were shown to be most responsive to the 

 colors having the more refrangible rays. The effectiveness of 

 the colors in stimulating the leopard-moth larvae corresponds 

 to their sequence in the spectrum, namely, beginning with the 

 strongest: blue, green, yellow, red. 



E. Feltia suhgothica Haworih {adult) 



1. Material. Adult specimens of the leopard-moth could not 

 be obtained at the time of these experiments, but I was fortunate 

 in securing numbers of another species of Lepidoptera (Feltia 

 subgothica Haworth). These moths were very common around 

 the arc-lights at night during the month of September. Through 

 the kindness of the Bussey Institution at Forest Hills an excel- 

 lent arc-light insect trap was placed at my disposal by means 

 of which the necessary material for the following experiments 

 was secured. The moths thus collected were placed in ventilated 

 pasteboard boxes, which were shielded from the light until the 

 specimens were required in the experiments. In addition to this 

 precaution, since it was desirable to have each individual dark- 

 adapted, none of the moths were used in two succeeding experi- 

 ments. 



2. Methods. The chief feature of the apparatus was an elon- 

 gated glass chamber, 10 x 10 x 45 cm., which had an opening at 

 the middle of the side nearest the experimenter through which 

 the moths could be liberated from the paper boxes. This appa- 

 ratus, as that of the previous experiments, was placed in the 

 middle of the field of light midway between the two generators. 



