Vol. X] VON GELDERN—SKIN OF ANOLIS CAROLINENSIS 83 



Parker, in experimenting with Phrynosoma regale, found that 

 the claw-like scales which fringe the lateral edge of the body be- 

 came white when the animal was subjected to a temperature of 

 32°C. and placed in the dark, and when placed in the light these 

 claw-like scales became almost black. At i9°C., these scales 

 became black in 15 minutes when the animal was placed in the 

 light, and they became white in 30 minutes in the dark. At i5°C. 

 light again caused black, while darkness brought about a light 

 color, but not white. From these results he concluded that a low 

 temperature favored the production of the black state, whereas a 

 higher temperature, the white state. Thus light produces in this 

 animal, as in Anolis, a dark state, while its absence brings about 

 the light state. 



Parker further believes that even in Stellio, Uromastix, and 

 Veranus, which have always been considered to have a reversal 

 of the light reaction, in that light causes just the reverse effect 

 as in Anolis, namely, the production of light coloration in the 

 light and dark coloration in the dark, that the apparent reversal 

 is really a temperature effect and not a true reversal of the effect 

 of light. 



Parker and Starratt mention the observations of Doctor Caswell 

 Graves who stated that in the neighborhood of Beaufort, N. C, 

 on hot, sunny days about as many green lizards as brown ones 

 may be captured. These results are explained by Parker and 

 Starratt by considering that some of tlfe animals are more sensitive 

 to light than to heat and thus become brown, while others are more 

 sensitive to heat than to light and become green. 



I do not believe that this explanation suffices, for if one notices 

 individual lizards for a considerable length of time, one is struck 

 by the frequent and rapid changes from green to brown and back 

 again to green, apparently regardless of temperature and light. 

 How much influence the otherwise varying nervous conditions 

 exert on these color changes, it is difficult to say for it would seem 

 almost impossible to control them. I have watched animals which 

 were sunning themselves and apparently undisturbed and quiet 

 undergo these changes in a rhythmic manner. Rapid changes 

 are also frequently noticed when an Anolis changes slowly from 

 one object to another, the change occurring while the transfer is 

 being made. 



Redfield, after nimierous carefully checked experiments on 

 Phrynosoma cornutum, was able to verify the conclusions of Parker, 



