72 BULLETIN OF THE ESSEX INSTITUTE. 



red one less green with patches of reddish hue and some 

 of buff. The other colors of my upholstering he copied 

 more closely, except that in the white chamber he was 

 very green with markings that were almost black. This 

 seemed very strange because, on white surfaces, these ba- 

 trachians usually conform to them in color, and because 

 with buff there was no green but only shades of light ash. 

 With the darker colors, his hues were generally tones of 

 dark ash. 



The markings upon the back remained more or less 

 manifest throughout, but in the green and blackish state 

 merely as a deeper shade of the same color. Thus, in 

 general, I find that the color of the back varies from 

 almost white to a dark ash and from these colors to a leaf 

 green. The buif or reddish patches referred to seemed 

 like an effort towards an unusual result. No altera- 

 tion of the colors of the toad's inferior surface was observ- 

 able. Doubtless the effects from exposure on a plain 

 surface of color would differ sometimes from the chromatic 

 changes which come by transmission of light more than 

 by reflection from below. Whether these changes are 

 occasioned through the retina, or by some more direct 

 influence on the epidermis, might perhaps be determined 

 by a simple experiment but one which seemed too cruel 

 for the writer to make. Can it be questioned that all this 

 variation of color is protective and has its relation to dis- 

 cussions on evolution? 



The tree-toad, wherever it may be, is difficult to dis- 

 cover. You may hear its note near by, but clinging 

 closely to a limb, where it is usually found, its flattened 

 body conformed in color to the hark and less noticeable 

 for the markings, which simulate lichens and the irregular 

 lines of fracture and shade, it seems only a knot. 



This Hyla also has a way of dodging underneath and 

 around its perch and one or two more resources that I 



