of the Tongue of the Chameleon. 173 



account for all the phenomena : namely, that the projection of 

 the chameleon's tongue is caused, partly by the advancement of 

 the OS hyoides, but chiefly by blood rushing into the number- 

 less vessels of the organ distending and elongating its erectile 

 portion : and that its subsequent replacement in the mouth is 

 effected by the retreat of the os hyoides and subsiding of the 

 turgescence, aided by the contraction of the hyoglossi muscles. 



7. The appearance of the tongue when protruded during life, 

 its rigidity, its dark colour, and the turgid condition of its ves- 

 sels, first suggested the idea of its being an erectile organ. The 

 peculiarities of its organization discovered after death, its hio-ji 

 vascularity, the remarkable size, course, and termination of its 

 veins, and above all, the unique and beautiful provision near 

 the heart to receive the sudden reflux of blood, gave it addi- 

 tional confirmation. And the experiment of imitating the na^ 

 tural process by filling the vessels with quicksilver, though ne- 

 cessarily not as conclusive as might be desired, was neverthe- 

 less 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 tire, they could seldom be excited to at- 

 tack 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 ad- 

 vanced 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 changino- the 

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

 tongue; both failures perhaps alike resulting from die same 

 cause, the languid state of the circulation. 



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

 which it appeared very susceptible, its tongue, as well as its 

 skin, gave evidence of the same excitement : it swelled out pro- 



