450 E. A. ANDREWS 



filled in with less dark, and in like manner, when moisture dries 

 away there is an intermediate state in which the wet spot is 

 represented by a dark rim and light center which suggests that 

 the material of the shell holds the liquid by some adsorption 

 (?) phenomena. When the spots are made more than normally 

 pale by heating they show more distinctly the concentric struc- 

 ture and formation as if from conglomeration of coalescent spots. 

 Breathing upon these paled spots is sufficient, in a second and 

 a half, to make them turn more dark; to again turn pale in some 

 two seconds. 



Though the changes from dark to light are usually quite 

 reversible, there are sometimes changes that remain more or 

 less permanent as above indicated, and seen in the following. 

 After wet paper on the beetle dry for thirty years, had at once 

 made a dark area, the edges of this long remained darkened 

 somewhat, though the area reverted to the light color. Again, 

 after great heating with an electric bulb, under black paper, the 

 edge of the thorax long remained very pale. Gradually the 

 experimented beetle ceased to turn quite light on the right of 

 the thorax and remained more red there, as is the case where 

 linseed oil was applied. 



All this is thought to indicate that the phenomena are due to 

 spread of substances through some peculiar structure of the 

 shell, with permanent changes only in so far as the added sub- 

 stance remains permanently, or else changes the structure as 

 by carrying substances from one place to another. 



That the water may dissolve substances and so carry them 

 to other regions was suggested by the observation that when 

 the beetle had stood long in wet air, drops of water collected 

 somewhat in rows along the elytra and thorax and that when 

 these were wiped off with filter paper the paper was stained 

 yellow. The beetles also, whether alive or dead, have, when 

 moist, a strong and disagreeable odor that may be associated 

 with some substance soluble in the shell. 



Examined under a Spencer Binocular 25 nnn. 10 X in direct 

 sunshine, the yellow areas of the elytra show, besides the scat- 

 tered pits, a uniformly distributed structure of very fine scintil- 



