CARLTON. — COLOR CHANGES OF THE FLORIDA CHAMELEON. 271 



Secondly, when a brown Anolis is put in the dark, the skin becomes 

 green. The transfer to the dark is certainly not accompanied with any 

 cessation of the circulation, and I therefore believe that the change in this 

 instance is dependent upon the withdrawal of the stimulus transmitted 

 over the sympathetic nerves, which, as I have already shown, can call 

 forth the brown state. 



It follows from these observations that when a piece of skin is cut 

 from an Anolis, -the cause of the change to green may be either the loss 

 of circulation, or the loss of nerve stimulus, or both, and that in experi- 

 menting these two factors must be kept constantly in mind. It is greatlv 

 to be regretted that these factors cannot readily be separated in experi- 

 ments. Because of the small size of the animals it has been found im- 

 practicable to cut nerves without interfering with blood-vessels, or to 

 ligate blood-vessels and leave the nerves uninjured, hence some impor- 

 tant and interesting lines of experimental work have of necessity been 

 abandoned. 



In one direction, however, a definite conclusion has been reached. 

 As already described, a ligated leg with the nerves functional, and the 

 whole animal in the light, turns and remains green. This observation 

 shows that, notwithstanding the influence of the nerves, the loss of cir- 

 culation, even under conditions favorable for brown, is followed by the 

 green state. The circulation, in other words, is a more important factor 

 than the influence of nerves, and it is my belief that the change of a 

 piece of excised skin to green is more dependent on the loss of circula- 

 tion than on the loss of nerve connections. 



It is interesting to observe that a piece of excised skin assumes the 

 green color more quickly than the animal from which it comes. The 

 following experiment illustrates this point. A normal Anolis was placed 

 in the dark several times and found to change from brown to green in 

 about twenty minutes. It was then kept in the light, and its right hind 

 leg ligated so as to stop the circulation, but not to interfere with the use 

 of this leg in locomotion and hence to leave its efferent nerve supply un- 

 interrupted. Under these circumstances the leg changed from brown to 

 green in about six minutes. The ligature was then removed and the 

 animal was allowed to assume the brown condition, whereupon it was 

 killed by decapitation and the leg previously ligated was immediately cut 

 off. This leg became green in between three and four minutes. These 

 observations show that the change to green comes on more quickly when 

 both nerve action and circulation are interrupted, than when only the 

 circulation is interrupted, and that, therefore, the sympathetic nerves 



