Page:Natural History, Reptiles.djvu/85

Rh becomes of a yellow green, till it recovers its liberty, is well nourished, and without pain, when it regains its former colour; this being the consequence of an equilibrium in the liquids, and of a due proportion of them in the vessels.”

To mention the various hypotheses by which these interesting changes of colour have been attempted to be explained, would not suit our pages; we content ourselves with adding the conclusions of Dr. Milne Edwards, who, in an elaborate memoir on the subject, is considered by some to have solved the problem. We have room only for the results at which he arrives, which he embodies in the following propositions:

1. That the change in the colour of Chameleons does not depend essentially either on the more or less considerable swelling of their bodies, or the changes which might hence result to the condition of their blood or circulation; nor does it depend 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. That there exists in the skins of these animals two layers of membraneous pigment, placed the one above the other, but disposed in such a way as to appear simultaneously under the cuticle, and sometimes in such a manner that the one may hide the other.

3. That everything remarkable in the changes of colour that manifest themselves in the Chameleon, may be explained by the appearance of the pigment of the deeper layer to an extent more or less considerable, in the midst of the pigment of