CHAMELEONS. 
107 
glands of its own. But other glands moisten the tongue, as it 
lies in the recess of the lower jaw. 
The tongue is a tube, the axial cavity of which is occupied 
by a slender cartilage, the glosso-hyal or ento-glossal, supporting 
nearly the whole length of the organ in its state of rest. The 
soft parts of the tongue consist of (1) epithelium ; (2) pig- 
mentary and submucous tissue separated by loose interstitial 
connective tissue from a fibrous sheath, and (3) longitudinal 
muscles, besides nerves glands and vessels. There is also an 
inner fibrous sheath with a smooth free surface, which glides 
over the glosso-hyal cartilage. The club has peculiar muscles, 
well described by Zaglas. The existence of minute smooth 
intrinsic muscles within the substance of the worm is still 
disputed. 
It is probable that four sets of muscles successively promote 
the extension of the tongue, namely, (1) certain of the hyoid 
muscles, (2) the longitudinal muscles, (3) the smooth muscular 
fibres of the worm, and (4) the muscles of the club. Other 
hyoid muscles retract it. To the same muscles,- however, dif- 
ferent uses have been assigned by different observers. It has 
even been conjectured that the extended condition should be 
regarded as the more passive state of the organ. Others con- 
sider the protrusion of the tongue as a sort of erection ; but 
such vascular turgescence must here play quite a subordinate 
part. Nor can the mere elasticity of the sheath effect much. 
We cannot here discuss these diverse explanations. The whole 
subject demands fresh researches. As Milne-Edwards has well 
said, the mechanism of this movement has not yet been explained 
in a satisfactory manner. 
Though very carefully aimed, the tongue darts from the 
mouth as if its previous training thoroughly suited its own 
spontaneous energy. Perrault erroneously supposed that it was 
coughed out by air driven into it from the lungs. Bibron has 
graphically compared its expulsion to the act of spitting. 
Pagenstecher, on one occasion, saw a Chamseleon eject its tongue 
with such force that the animal lost its hold in consequence, 
and tumbled off the tree on which it was resting. 
From the tongue of the ChamEeleon we naturally pass to its 
eyes. For by these the prey is first perceived, and if we could 
trace the intermediate changes which take place in the nervous 
system we should then be in a position to understand how the 
tongue receives the orders to do its work. 
The eyes are relatively large. Each as a whole is nearly 
spherical, the equatorial slightly exceeding the axial diameter 
(8J : 8 millimeters). But what may be termed the morpho- 
logical equator of the eye, corresponding to the border of the 
