194 



with quicksilver, though necessarily not as conclusive as might be 

 desired, was nevertheless sufficiently so, in my opinion, to place the 

 matter beyond a doubt. 



An additional argument in favour of the supposition, that the 

 chameleon's tongue undergoes in being protruded an erectile action, 

 may be found in the influence which the state of warmth and vigour 

 of the animals had on their projectile powers ; for except about 

 noon-day, and during the sunshine, or while the animals were near 

 the fire, they could seldom be excited to attack a fly ; any attempt, 

 except under such circumstances, rarely being successful. I have 

 several times seen one of them, when cold and sickly, make the effort. 

 it opened its mouth, and advanced its tongue a short distance, about 

 as far as the muscles going from the chin to the os hyoides might 

 effect it, but could succeed little farther : the prehensile part either 

 did not leave the style at all, or bent towards the ground, and fell 

 short of its object. In this state of the animal the power of chang- 

 ing the colour of its skin was as imperfect as that of protruding its 

 tongue ; both failures perhaps alike resulting from the same cause, 

 the languid state of the circulation. 



If, by any cause, the chameleon were provoked to anger, of whicii 

 it appeared very susceptible, its tongue, as well as its skin gave 

 evidence of the same excitement ; it swelled out prodigiously in the 

 throat, so that had the style, which pressed forcibly against the in- 

 teguments under the chin, been elevated, I have little doubt the 

 organ would have undergone a partial elongation. 



The effect on the animal of frequently protruding its tongue 

 might also be advanced in support of the same theory. An interval 

 of rest was always taken between the acts, which I have never seen 

 repeated above six or eight times in succession ; and even this was 

 evidently followed by fatigue. Mere muscular action would riot so 



