440 E. A. ANDREWS 



it was wet, though it was very active, and as soon as dry it re- 

 sumed the Ught color. 



This response of the thorax and elytra to water is very pro- 

 nounced and instantaneous, so that if a drop of water be placed 

 on the shell of these regions the light color at once changes to 

 dark in that round spot where the water wets the shell. This 

 becomes striking in case a piece of wet filter paper be laid for a 

 moment upon the thorax or elytra and then removed leaving a 

 black area of the size and form of the paper. 



That changes in moisture are the only cause of changes in 

 color was not at first suspected, but became more patent even- 

 tually when the indirect action of light was found out. When, 

 as above stated, a beetle stands long with one side brilliantly 

 illuminated and that side becomes light and the other remains 

 dark, it is strongly suggested that the light acts as such upon 

 either the surface exposed directly, or else upon the eye, and so 

 eventually effects change through the nervous system. 



When an electric bulb (having a ground glass, ten inches from 

 the beetle) was allowed to shine its light upon one side of male 

 beetles for three minutes, then the side of the beetle toward the 

 light had changed from red to yellow and the very strict bilateral 

 difference between the two sides was very pronounced. Four 

 minutes afterwards, light color appeared in blotches on the less 

 illuminated side and in ten minutes after the beginning of the 

 illumination both males were light colored on both sides as a 

 result of the illumination. 



These beetles were in a small closed glass dish, an elongated 

 trough with glass lid laid on and the bottom was wet with filter 

 pajDer. Two hours after removal of the light both males were 

 dark again. 



Also, when the beetle stands with a shadow across its body so 

 that, say the anterior part is brightly illuminated and the pos- 

 terior in the shadow though all is in the light of the room, the 

 dark color changes in the most illuminated jDart, leaving the 

 back of the beetle very strangely and sharply marked cross- 

 wise with light yellow anteriorly, and dark red posteriorly, as if 

 painted. 



