COLOR CHANGES IN DYNASTES TITYRUS 447 



periphery as a circular area that became all solid red, but van- 

 ished in a few seconds when the moist air ceased to be applied. 



As to the rapidity with which the dead beetle changes color, 

 a few experiments show that the change from dark to light is 

 much more rapid than the change from light to dark, when the 

 air alone is the factor concerned. Thus, when removed in the 

 dark state from wet air into that of the room, there was marked 

 bleaching in fifteen seconds and in sixty-five seconds nearly 

 all the surface was bleached white, and in one hundred seconds 

 only the natural spots remained dark red. Put back into the 

 wet air it was again all dark red within one hour. 



On another occasion, the same dark beetle removed to the 

 air of the room on a dark rainy day, showed visible lighter areas 

 on the elytra in three to five seconds but there were only white 

 clouds in thirty-five seconds and white clouds on the thorax 

 in sixty seconds. The entire surface was chiefly white in eighty 

 seconds. A live female at the same time showed yellow in five 

 seconds and was all light yellow in forty seconds. 



When the beetle was held in running water its elytra and thorax 

 turned dark and then when returned to the air of the room it 

 became a noticeable yellow on both thorax and elytra in ten 

 seconds. In sixty seconds, only clouds of sooty black remained 

 on thorax and elytra in place of the universal dark. Then again 

 held in running water, which glides over it as if not wetting the 

 surface but gradually here and there produces a darkening, in 

 one and a half minutes it was again dark. The surface, now 

 dry save for a few small drops that did not run off, in five seconds 

 began to be light colored and in sixty seconds was again light 

 except for a few clouds on the thorax. 



PART 3 



It being then evident that both dead and living beetles be- 

 haved alike in changing color under conditions that might be 

 interpreted as chiefly involving changes in the amount of water 

 presented to the surfaces of the thorax and elytra, being dark 

 red when wet or in saturated air and light yellow or white grey 



