84 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



Carlton, Starratt, and others that the daily rhythmic changes of 

 color are produced by the direct action of light and heat upon the 

 melanaphores. He further states that Phrynosoma adapts itself 

 to its surroundings, namely, if placed on a substratum of white 

 sand it slowly assumes a light coloration irrespective of light or 

 heat and if placed on a substratum of cinders it slowly takes on a 

 dark coloration. He concludes that the color adaptation depends 

 upon stimuli received through the eyes. 



He was able to bring about a pale coloration in various ways, 

 such as forcibly opening the mouth or by the application of a weak 

 faradic current to the mucous membranes of the mouth or cloaca. 

 He believes that this proximal migration of the pigment may be 

 brought about in two ways, namely, by nervous impulses which 

 stimulate the melanophores through the sympathetic nervous 

 system or by secretion of a hormone (adrenin) from the adrenals. 

 The impulses are carried from the mouth or cloaca along the spinal 

 cord to a center situated between eighth and thirteenth vertebrae 

 and thence by sympathetic fibres to the adrenals. The stimulated 

 glands secrete adrenin which is taken up by the blood stream and 

 acts directly on the melanophores causing a proximal migration 

 of the pigment. 



Redfield concludes from the fact that adrenalin produces 

 proximal migration of the pigment in Anolis and from the work of 

 Carlton, that impulses through the autonomic nervous system 

 cause a distal migration of the pigment, that the melanophores of 

 Anolis must possess a double innervation from two divisions of the 

 autonomic nervous system. That this is possible he shows by 

 analogous tissue, namely, the smooth muscle, the latter one "known 

 to be innervated by antagonistic fibres belonging to two morpho- 

 logically distinct parts of the autonomic nervous system." 



The explanation for emotional manifestations in Phrynosoma, 

 Anolis and other animals is readily explained by his conclusions 

 regarding the secretion of adrenin. 



When first placed in captivity the brown and green lizards in 

 the same cage are about equally divided, but after remaining in 

 captivity for a few weeks the greater proportion become brown 

 in the daylight and the green produced by the absence of light has 

 lost its former brilliance. 



Much has been written about the true chameleon and its adap- 

 tation of color to its surroundings. Keller found, after placing speci- 

 mens of Chamcsleon vtdgaris in a green house, that in a short space 



