OR ANIMALS WITH BLOOD. 239 



move independently of the other. When the outer skin of 

 the eye of a chamseleon is removed, he says, a shining body, 

 like a small bronze ring, is exposed.* This refers to the 

 iris, which is seen, after removal of the skin, as a bronze- 

 like ring surrounded by a series of radial bands with black 

 pigment about their outer ends. 



The change of colour of a chamaeleon, Aristotle says, 

 takes place when it is puffied out, and it exhibits a dark 

 colour, not very different from that of a crocodile, and a pale 

 colour, not unlike that of some lizards, variegated with dark 

 parts, like that of a leopard. This change takes place, he 

 adds, over the whole of its body, for its eyes and tail change 

 like the rest of its body, but, when dying, it becomes of a 

 pale colour, and so it remains after death.! 



It is true that a marked puffing-out is noticeable when a 

 chamaeleon changes colour, during a state of agitation. The 

 changes of colour are due, however, to the shifting of pigment 

 granules towards or away from the epidermal layer, in 

 branches of chromatophores beneath the skin. These 

 changes of colour, as Prof. Poulton of Oxford suggested to 

 me, might be compared with blushing. Aristotle's de- 

 scription of the various changes of colour is not clear. They 

 depend to a large extent on the state of a chamaeleon as 

 regards fear or anger, sleeping and waking, the colours of 

 surrounding objects, the brightness of the light, and the 

 temperature. One which I had some time ago was nearly 

 white, when terrified, except for some brownish spots, and, 

 when asleep, its colour was much the same, but greyish 

 instead of nearly white. When among trees and bushes it 

 gradually assumed a greenish colour, with brown spots, but, 

 when angry, it drew in large quantities of air, blowing itself 

 out, hissing, and becoming nearly black. The changes of 

 colour occurred over all parts of the body, except that the 

 under parts, and especially the parts between the legs, were 

 not nearly so sensitive as the upper parts. 



The colour of the common chamaeleon, after death, is 

 usually yellowish-white, but one chamaeleon, after death by 

 chloroform, was black, except on the under parts between 

 the legs. Prof. Poulton says that one chamaeleon, which 

 died a natural death, was of the usual light colour after 

 death, but dark before it died. 



Aristotle says that the viper, which he sometimes denotes 



* H. A. ii. c. 7, s. 5. f Ihid. ii. c. 7, ss. 3 and 4. 



