CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE 

 MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE. 

 E. L. MARK, DIRECTOR. — No. 155. 



THE EFFECT OF HEAT ON THE COLOR CHANGES IN 

 THE SKIN OF ANOLIS CAROLINENSIS Cuv. 



By G. H. Parker and S. A. Starratt. 



Presented October 12, 1904. Received September 29, 1904. 



I. Introduction. 



About a year ago Carlton (:03, p. 264) published the statements 

 that, when a brown Anolis is put in the dark it invariably turns green iu 

 about twenty-five minutes, and when a green one is exposed to light it 

 almost invariably turns brown in about four minutes. In attempting to 

 ascertain what sense organs were concerned with these color changes, 

 we repeated Carlton's experiments to determine independently the rate 

 of change, and obtained results that were often far from uniform. 

 Marked differences in the time required for the color changes on dif- 

 ferent days and at different times on the same day made the experiments 

 very unsatisfactory. The change from brown to green was often slower 

 at the beginning than after the experiments had been carried on for a 

 few hours. This led us to suspect that one might apply to Anolis 

 Pouchet's ('76, p. 73) conclusion concerning turbots : that exercise 

 shortened the period for color changes. In fact this seemed to be con- 

 firmed by the following observations : On the morning of December 28 

 a set of animals was found that remained brown in the dark for three 

 hours. Subjecting them alternately to the dark and to the light in a 

 box provided with an electric lamp soon brought them to a state at 

 which they would change from brown to green. This they did in an 

 average time of 19.80 minutes, the last four records giving an average of 

 13 minutes. Thus it seemed that exercise played an important part in 

 (leterminins the rate of change. 



