Chameleon's and Lizards' changing of Colour. 229 



indeed, by no means clear that another and a distinct species 

 is not here indicated, intermediate, perhaps, in its characters 

 between the two ifcfotacillae, of which it is supposed to be the 

 hybrid offspring. — Tooting, Surrey, March 11. 1835. 



Reptiles. — The Chameleon and some Lizards ; an Abs- 

 tract of a Theory in Explanation of the Phenomenon of their 

 changing at will the Colour of their Skins. — Mentions of this 

 phenomenon in the chameleon have been made in 1. 157. 192. ; 

 II. 469.; III. 188.; IV. 469.; VII. 581. 583.; in other lizards, 

 in VII. 581. 583. Speculations on the cause of it have been 

 offered in I. 157., and VII. 581. 583. A theory distinct from 

 these is given in the Edinburgh New PhilosophicalJournal, the 

 number for Oct. 1834, in a communication " On the Change 

 of Colour of the Chameleon. By H. Milne Edwards, Esq." 

 The author details the phenomena which he had had an op- 

 portunity of observing in two chameleons living, and the 

 results of his researches, after the animals had died, on the 

 structure of their skin and the parts immediately beneath it. 

 His conclusions are these: — 



1st, 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 on the condition of their blood or of their 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. 



2dly, 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 simulta- 

 neously under the scarf-skin, and sometimes so that the one 

 may conceal the other. 



3dly, That every thing remarkable in the changes of co- 

 lour which 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 the superficial layer, or from its disappearance 

 underneath this layer. 



4thly, .That these displacements of the deeper pigment 

 can in reality occur ; and it is probably a consequence of 

 them that the chameleon's colour changes during life, and 

 may continue to change even after death. 



5thly, That there exists a close analogy between the me- 

 chanism by the help of which the changes of colour appear 

 to take place in these reptiles, and that which determines the 



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