FIELD NATURALISTS' CLUB. 133 



limited to one note and it is something like tack-e-tack-e-tack 

 Consequently houses where Geckos are common are pretty certain 

 to be known as haunted. And in the middle of the night when 

 people hear Master Gecko's tack-e-tack they cover up their 

 heads with a sheet and lie trembling waiting for the ghost to take 

 himself off, when after all the cause of alarm is nothing more 

 than a harmless little lizard. Another lizard* found in our 

 garden is also a useful little creature living almost entirely upon 

 the little white cottony insects! which creep about the cro tons and 

 other plants. This lizard is not subject to much persecution, but 

 another and larger one, commonly known as the "Chamseleon"! 

 is slaughtered without mercy. With the Gecko, they also rejoice 

 in the appellation of " Twenty-four hours" and they are supposed 

 to be fearfully poisonous. This lizard possesses the power, 

 together with the gecko and anole, of changing its colour and it is __ 

 to this faculty that its misfortunes are to be attributed, [There 

 is nothing strange about this changing of colour, many animals 

 such as fish, frogs etc. are able to do it. It is generally believed 

 that the lizards change colour to suit their surroundings ; 

 recent investigations, however, have shown that this is not always 

 the case. The change of colours is effected by many agents and 

 is dependent on the nerves. The agents which would come into 

 play are hunger, thirst, anger, fear. The change of colour is also 

 affected by heat, light, dampness etc. AVith regard to how these 

 animals are able to change colour I will tell you what Pro- 

 fessor Semper says : " One example — the skin of the frog will 

 " suffice for all cases. The skin consists of two distinct portions, 

 " the epidermis and the cutis. The former is entiiely composed 

 " of cells and the innermost layer contains cylindrical cells ; the 

 " cutis is chiefly fibrous and encloses nerves, large cavities for 

 " glands and cell elements. These last are commonly filled with 

 " pigment, and the remarkable changes of colour in the frog's 

 " skin depend entirely on the distribution of these highly ramified 

 " pigment cells and their power of shrinking under certain kinds 

 " of irritation. The pigment in these contractile cells, — known 

 " as the chromatophores — is dilferent in different individuals and 

 " in different parts of the body, yellow, brown, black, sometimes 

 " even i - ed or green. Besides, the colour of the chromatophores 

 " varies with the state that they happen to be in, and differs during 

 " contraction and expansion. Heincke, for instance, has shown 

 "that 'uxGobiim ruthensparri the chromatophores that are yellow or 

 "greenish-yellow, when destended become orange-coloured when 

 " contracted while the orange or red ones when shrunk become 



* Anolis alligator, Dum. Bibr. 



f Orthcsia insignis, 



} Polyihru; mannoratus, Linn. 



