COLOR CHANGES IN DYNASTES TITYRUS 449 



absolute, it instantly changed to mottled white. Also, when 

 the elytra were wet with filter paper and absolute alcohol was 

 brushed on, the dark red color there turned to white in fewer 

 seconds than did other parts of the shell having only water on 

 them. 



Under the microscope it is evident that the absolute alcohol 

 enters the shell at certain centers only and thence spreads within 

 the shell substance making circles of dark which rapidly vanish 

 as evaporation takes place. Some areas of the shell are much 

 more resistant to entrance of absolute alcohol than other areas 

 and various results arise. 



In the live beetle, also, painting with absolute alcohol causes 

 areas to turn black, especially on the edges of areas treated, 

 and on the other hand, when the shell is dark from washing with 

 water, addition of absolute alcohol causes bleaching, though at 

 the same time extension into dry areas may turn them dark. 



While the behavior of the shell toward alcohol and toward 

 the other substances might be explained as the result of hydration, 

 perhaps in all cases, it was found that when well boiled and 

 boiling linseed oil was applied in minute drops to the shell, that 

 it entered into the shell and produced the same dark color though 

 it can not apparently be thought that the oil carried any water 

 with it. 



Spots of dark so produced remain permanently in the shell and 

 are very similar to the natural spots of the elytra, though they 

 do not have the sharp cut boundaries, but on the other hand, 

 under the lens are seen to fade out gradually as distributed out- 

 ward in the substance of the shell. 



It is then inferred that any liquid that can enter the shell may 

 cause it to change from light to dark. 



Microscopic examination 



The shell, under the microscope, it pitted with minute hol- 

 lows of different sizes which are dark at the bottom and in the 

 larger size bear each a minute bristle or spine rising from the 

 bottom. The colored spots visible to the eye have often a con- 

 centric structure, that is, there may be dark rings more or less 



