Mr Edwards on Change of Colour m the Chameleon. 319 



the superficial bed of greyish pigment, which appeared extend- 

 ed over the whole surface of the skin, and very well represented 

 the coat which by anatomists is denominated the rete mucosum. 



This structure once recognised, it became an easy matter to 

 understand how the deep pigments could now mount up through 

 the middle of the superficial, and exhibit its own colour more 

 or less completely, or at another time might wholly be hid- 

 den beneath it. For the production of the first of these ap- 

 pearances, it would suffice that the lower part of these vesicles 

 should contract, or be compressed by the contraction of the 

 deeper parts of the skin, so as to cause the fluid contained in 

 their interior to flow into the minute ramifications with which 

 their surface is supplied, so as to render the fluid visible from 

 without. For the skin thus coloured to return to its yellowish- 

 grey tint, all that would be required would be the contraction 

 or the compression of these same superficial ramifications, which 

 thus emptying themselves into the vesicle below, would lose 

 their colour, and more or less completely disappear. 



It may now be remarked that this phenomenon is not alto- 

 gether unique in nature. Many of the mollusca cephalopoda 

 exhibit something analogous. The skin of these animals is fur- 

 nished with a number of differently coloured spots, which alter- 

 nately appear and disappear ; and if a portion is put under a 

 microscope, it may be perceived that these changes depend on 

 the contraction of small vesicles filled with a coloured liquid, 

 which reach from the surface of the skin to a considerable depth. 

 When one of these spots appears, the liquid corresponding here 

 to the pigment in the other case, is propelled towards the super- 

 ficial part of the vesicle, and there displays itself; whilst during 

 its disappearance it is forced into the deeper parts by the con- 

 traction of this superficial point itself, which then becomes al- 

 most invisible. 



The dissection of the second chameleon confirmed the results 

 obtained by the researches we have just been describing. For 

 here we found two very distinct pigments ; the one superficial, 

 yellowish or white, according to the portions of the surface which 

 were examined ; the other deeper, and of a bottle-green colour, 

 verging to the black. It is evident that the mixture of these 



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