130 THE DARWINIAN THEORY 



appearance of dried leaves. But the best example 

 perhaps is that of Phyllium, the leaf insect found in 

 the East Indies, which has in the adult condition a 

 most extraordinary resemblance to a leaf, or rather a 

 bunch of leaves. The colour is green, and the wing- 

 cases are marked with lines like the veins of a leaf: 

 some of the joints of the limbs are flattened and 

 expanded. Andrew Murray relates how an Indian 

 species exhibited in the Botanical Garden at 

 Edinburgh deceived everybody by its resemblance 

 to the plant upon which it lived. The deception 

 was ultimately the cause of its death ; for the visitors, 

 sceptical as to its animal nature, insisted on touching 

 it before they would be convinced. (Fig. 23.) 



Variable Protective Resemblances. 



Instances of this we have already mentioned 

 in the case of the Trout, which changes colour 

 according to that of the bottom of the stream. 

 This effect is always produced through the eye, 

 and is consequently absent in blind animals. How 

 far it is under the control of the will is difficult 

 to determine. Another excellent illustration is 

 afforded by the Chameleon and many lizards 

 which possess the power of changing colour. This 

 power depends on the presence of chromato- 

 phores or pigmented bodies found in the skin, which 

 have the power of changing shape. These are of 

 different colours, and are arranged in layers, some 

 near the surface, some deeper ; the light yellow cells 

 being most superficial, then the red and brown, and 



