320 Mr Edwards on Change of Colour in the Chameleon". 



two colours, and the predominance of the one over the other, 

 could not but produce all the variations which were exhibited 

 during the life of the animal. 



This greenish pigment appeared, moreover, to have the great- 

 est analogy with the purple one which was found in No. 1. It 

 underwent the same changes with the various chemical agents, 

 and as the light happened to strike upon it exhibited a very 

 deep green colour, or one which approximated to the violet. 



It is known that there are many colouring substances, which, 

 viewed by the transmission of light, thus being transparent, or 

 by the reflection of the light, or, finally, examined in masses more 

 or less dense, change their hues. The reddish green colour of 

 Carthamus presents a remarkable example of this phenomena ; 

 and it appeared probable that the difference which existed between 

 the hues of the deeper pigment in these two chameleons, depend- 

 ed on some slight difference in its state of cohesion. If this hap- 

 pens, the same individual might present not only those changes 

 which we noticed, but also a change from green to purple. 



However this may be, we see — 



Ist, That the change in the colour of chameleons does not de- 

 pend essentially either on the more or less considerable swelling 

 of their bodies, or the changes which might hence result on the 

 condition of their blood or of their circulation ; nor does it de- 

 pend on the greater or less distance which may exist between 

 the several cutaneous tubercles ; although it is not to be denied 

 that these circumstances probably exercise some influence upon 

 the phenomenon. 



2 J/z/, That there exists in the skin of these animals two layers 

 of membranous pigment, placed the one above the other, but 

 arranged in such a way as to appear simultaneously under the 

 scarf-skin, and sometimes so that the one may conceal the other. 



3%, That every thing remarkable in the changes of colour 

 which manifest themselves in the chameleon, may be explained 

 by the appearance of the pigment of the deeper layer to an ex- 

 tent more or less considerable, in the midst of the pigment of 

 the superficial layer ; or from its disappearance underneath this 

 layer. 



4^%, That these displacements of the deeper pigment can in 

 reality occur ; and it is probably a consequence of them that the 



