268 PROCEEDINGS OF THE AMERICAN ACADEMY. 



test this I etherized some six or seven animals and destroyed the spinal 

 cord by pithing from the middle trunk region posteriorly. After twenty- 

 four hours, when the shock effects of the operation had probably passed 

 off, I experimented on these animals by exposing them while in the green 

 state to the light. Much to my surprise, in all cases the whole body, 

 both in the regions with and those without cord, eventually turned 

 brown; the ^^ortion with cord turned as in a normal animal, that with- 

 out cord turned with less uniformity, though in the end it was iudistin- 

 guishable from the part containing cord. 



These results seemed at first sight to contradict the conclusion that 

 the change from green to brown is controlled by nerves, but in reality 

 they sliowed merely that the spinal nerves are not directly concerned 

 with this change. Since it seems impossible to explain the conditions 

 without assuming some nerves to be involved, and since the only other 

 nerves present are the sympathetic, these observations point to the 

 sympathetic fibres as the ones controlling tlie change from green to 

 brown. When it is remembered that in mammals the muscles of the 

 integumentary blood-vessels, and of the hair and the sweat glands are 

 controlled by the sympathetic, this conclusion, that a change in the 

 tegumentary chromatophores of Anolis is under the control of the same 

 nerves, seems natural enough. 



It is greatly to be regretted that Anolis carolinensis is so small that 

 operations on the sympathetic ganglia, etc., such as have been carried 

 out so extensively on mammals, could not have been resorted to in order 

 to test this conclusion in detail ; but such operations, though tried, were 

 in the end abandoned. It is, however, well known, chiefly through 

 the researches of Langley, that nicotine is a powerful poison, especially 

 for the sympathetic ganglia. I therefore hoped to get localized effect 

 by opening the body cavity of Anolis and painting certain ganglia with 

 a solution of this drug ; but here again, because of the small size of the 

 lizard, my efforts were without avail. However, I experimented with 

 subcutaneous injections and observed the influence of this drug on the 

 color changes. 



As a rule I injected under the skin of the flank of the lizard about 

 ^ of its body weight of nicotine solution. The strengths used were 

 1 per cent, -^ per cent, and ^Jq per cent. The first of these caused the 

 animal to change from brown to green, induced a pronounced muscular 

 trembling, and resulted very shortly in death. To show that these 

 effects were not brought about by the simple operation of injection, a 

 like amount of pure water was injected under the skin of several lizards 



