148 i GUIDE TO THE 
has no fangs, or poison glands. But a poisonous lizard 
does exist in Mexico, and this reptile is known as the 
Heloderma , and its specific name is suspectum referring 
to the original suspicion that the bite of this lizard was 
injurious. It has been proved, within the last year or two, 
by Dr. J. G. Fischer, that this lizard has poison glands, 
and an experiment made in the Zoological Gardens of 
London has confirmed this observation, as a guinea-pig 
bitten by one of these lizards fell unconscious two or 
three minutes after the bite had been inflicted, and died 
exactly as if it had been bitten by a viper. There is in 
Borneo, a lizard known as Lanthonoius borneensis which is 
also suspected to be poisonous. 
The Chameleon is one of the most extraordinary 
looking animals in nature, and is an object of great interest 
from the remarkable changes of colour which it undergoes, 
and which are induced by the will or passions of the animal, 
and also, apparently, by the influence of differently coloured 
lights falling upon it. These changes are brought about by the 
action of two kinds of nerves on a series of structures 
V " 
found in the skin and called chromatophores . These 
structures are little sacs distributed below the surface 
layer of the skin, and containing minute corpuscles of 
various colours. Each sac has an aperture which, when 
open, allows the colour to become visible, and when closed, 
conceals it ; one set of nerves contracting and the other dis¬ 
persing. Besides these chromatophores there is a yellowish 
colouring matter in the skin and a dark blue layer. The 
Chameleon is also provided with huge lungs which are in 
connection with air-cells distributed throughout the body, 
and this arrangement allows of the reptile distending itself 
with air and so rendering its skin transparent. When the 
