Page:Natural History, Reptiles.djvu/82

74 from a species found in Central Africa by the occipital keel reaching forward to the centre of the eye, by the back of the head being only slightly lobed, and by the frontal scales being tubercular. It is spread over the whole north of Africa, and the south of Asia, and is said to extend even into Spain.

The changes of colour to which this reptile is subject are so curious as to have attracted popular observation from early times; and though much of fable has been mingled with the descriptions of the phenomenon, it is still exceedingly interesting; and not the less so because of the obscurity which has huughung [sic] over the causes of the changes, baffling the researches of acute physiologists, and giving rise to many diverse theories. The popular notion is that the Chameleon assumes the tint of the surface on which it rests, becoming green on a leaf, brown on the branch of a tree, white on a stone, &c., but this opinion is at variance with fact, and is now universally exploded by naturalists. Hasselquist, who considers the changes to be the result of a kind of disease, remarks, that he never observed the Chameleon assume the colour of an external object presented to its view, although he made several experiments for the purpose. He says that its natural colour is an iron grey, or black mixed with a little grey. This it sometimes changes, and it becomes entirely of a brimstone yellow, which, except the former, is the colour it most frequently assumes. It sometimes takes a darker or greenish yellow, and sometimes a lighter. He did not observe it assume any other colours, such as blue, red, purple, &c. When changing