66 CHARLES W. BARGITT 



rather than the mechanical effect of darkness, or other physical 

 agent. 



In this connection may be mentioned the case of one specimen 

 which was taken in the wood and brought to my home. When 

 taken it had been of the usual whitish grey coloration; but 

 when taken from my box and placed in a large glass fruit jar 

 it was very dark, almost black. Exposed to the light on the 

 open piazza it very soon became very light colored. Covered 

 with a black hood for half an hour it was found to have again 

 become very dark. On exposure to light the whitish color reap- 

 peared. This was several times repeated and with similar results. 

 Similar experiments the following day, and on subsequent days, 

 failed utterly to show similar reactions. May one venture the 

 suggestion that the creature had acquired such familiarity with 

 conditions as to dissipate to a degree its emotional sensitiveness? 



HYLA ARBOREA 



During my recent occupancy of the Smithsonian Table at 

 Naples, for the courtesy of which my acknowledgment is here- 

 with tendered, I was fortunate in securing through the labor- 

 atory staff, some twenty specimens of this beautiful tree-frog, 

 and was able to keep them under observation for an entire 

 month. Normally this species is a bright green color over 

 the back and sides and legs, while below it is pale pinkish to 

 salmon color, with a black line extending from the eye along 

 the side to the base of the leg. Considerable differences, or 

 color variations are frequent and have been the occasion of 

 several proposed species, as may be seen from any casual 

 review of the systematic literature. (Cf. Boulenger, The Tail- 

 less Batrachians of Europe, p. 250.) 



It need hardly be said that the color changes of this species 

 has had considerable attention by many observers; but as is 

 the case with the previous species, it has been for the most 

 part rather general. So far as I am aware, the most critical 

 and detailed investigations are those of Bieclermann ('92). 

 While very much in the results of this investigator must have 

 an abiding value, especially those features dealing with the chem- 

 istry and mechanics of color phenomena, still there are others 

 which have been questioned, and which I have not been able 



