COLOR AND THE BEHAVIOR OF ARTHROPODS 101 



color changes are without doubt commonly brought about by 

 the direct effect of light on the chroma to phores which contain 

 pigment (Keeble and Gamble, '04). Rynberk ('06) in his ex- 

 cellent summary of the whole question says (p. 427) that such 

 changes are not voluntary, and that they are induced not through 

 seeing so much as by the changes brought about through nour- 

 ishment. 



The experiments described in the present paper make it 

 apparent that the reactions of the crayfish are not influenced 

 by a prolonged sojourn in a monochrome environment even 

 though there is a corresponding change in the color of the skin; 

 i. e. crayfishes show no tendency to go toward the color which 

 most nearly resembles their own. Keeble and Gamble ('00) 

 make a statement concerning another crustacean, Hippolyte 

 varians, which apparently does not harmonize with this con- 

 clusion — they say (p. 601) " That the prawns exert powders of 

 selection with respect to their weed, this will be readily realized 

 from Pis. 32 and 2iZ^ ^Rs. i to 9, representing praw^ns placed 

 in a dish with sea water, to which subsequently pieces of different 

 coloured weeds were added. The prawns were left free to select 

 their weeds, and, as will be seen in the figures, they succeeded 

 in making wonderfully accurate color matches." Notwithstand- 

 ing the striking similarities they present in their figures, Keeble 

 and Gamble give no evidence to show that the prawns 

 selected particular weeds on account of their color, and the 

 selection may have been due, wholly or in part, to some other 

 factor, such as food or a particular sort of tactile or chemical 

 stimulation to which the prawns had been accustomed. The 

 following quotations from Keeble and Gamble's paper support 

 this view (p. 621) : " Its prime object in life is to anchor itself. 

 Once fixed, rather than release its hold it will allow" the ebb tide 

 to leave it stranded. By its immobility it has grown into its 

 surroundings and become colored like them. Should it become 

 separated from its favorite weed its movements become of an 

 aimless sort." Hippolyte evidently becomes accustomed to a 

 certain seaw^eed; it seems but natural that if it were separated 

 from this and placed in a dish containing various plants it would 

 choose the one to which it had become accustomed ; and further- 

 more, it seems to the writer that such selection could not be 

 assumed to be due to color alone unless it were shown that the 



