CARLTON. — COLOR CHANGES OP THE FLORIDA CHAMELEON. 269 



with the result that no color changes, muscular trembling, or other such 

 disturbances were observed. The iujection of ^^^ per cent nicotine 

 caused a change from brown to green and induced a slight muscular 

 trembling, but the animals recovered in two or three hours in all respects 

 except that the injection blister remained dark. With y^ per cent 

 nicotine no muscular trembling was ol)served, but the brown animals 

 within one minute became green, and remained so for about three hours. 

 AVheu green animals were injected with either ^^ per cent or i^g per 

 cent nicotine, they remained green in the light about the same length of 

 time as those did which were oriijinully brown. It was remarkable that 

 the side of the animal on which the injection was made remained green 

 somewhat longer than the other side, and that all these animals chani;ed 

 to green, and remained so, in full daylight. 



These results favor the conclusion already reached, that the change 

 from green to brown is under the influence of the sympathetic nerves. 

 Yet it might be maintained, so far as any facts thus far presented are 

 concerned, that the action of the nicotine was not on the sympathetic 

 system, but directly on the melanophores. That this is not so, may be 

 shown in the following way. If the blood supply be cut off from any 

 portion of the skin of Anolis, that part becomes green even when ex- 

 posed to daylight, and will not turn brown from light stimulation until 

 the blood is again freely admitted to the part. It follows from this, that 

 since cutting off a piece of skin stops the flow of blood in it, one would 

 expect such a piece to turn green, and such in fact is true. A piece of 

 skin which by removal from the animal has become green, may, however, 

 be made to assume the brown state by gently tapping it with a blunt 

 instrument, provided it is kept on moist Hlter paper to prevent drying. 

 The mechanical stimulation thus applied is sufficient to induce the tem- 

 porary assumption of the brown condition, and demonstrates that the 

 melanophores are not dead, but that they have simply drawn back their 

 pigment. If now such a piece of skin is placed on filter paper moistened 

 with nicotine solution and allowed to rest there till the solution has 

 thoroughly permeated it, it will still, on being tapped, change to brown. 

 Thus it is not the melanophores that have been changed, but the deeper 

 mechanism through which the outward movement of their pigment is 

 induced, and this, as we have already seen, is the sympathetic nervous 

 system. 



Although I was unsuccessful in my attempt to poison the sympathetic 

 ganglia by local application, some evidence of local poisoning was 

 obtained from the injection experiments. As I have already mentioned, 



