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the cornua of the os hyoides are not so much as an incli long, and 

 the space they have to move in is so Hmited, that tlie muscles extend- 

 ing from them to the lower jaw could not, by pulling them forwards, 

 advance the tongue out of the mouth more than half an inch. Since 

 then, the structure of the prehensile portion of the tongue will not 

 admit of its elongation ; and since also the point of the style cannot 

 be advanced from the mouth more than half an inch, to which two 

 circumstances alone the Baron attributes the protrusion of the organ, 

 it is evident that his explanation is incomplete, inasmuch as it does 

 not account for its usual propulsion to the distance of five, six, or 

 seven inches. 



Having thus passed under review the several theories advanced in 

 explanation of this remarkable process, and shown their respective 

 insufficiency to that end, I venture to offer one which to me appears 

 not only unobjectionable, but adequate to account for all the phe- 

 nomena : 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 numberless vessels of the organ distending, 

 and elongating its erectile portion : and that its subsequent replace- 

 ment in the mouth is effected by the retreat of the os hyoides and 

 subsiding of the turgescence, aided by the contraction of the hyo- 

 glossi muscles. 



The appearance of the tongue when protruded during life, its 

 rigidity, its dark colour, and the turgid condition of its vessels, first 

 suggested the idea of its being an erectile organ. The peculiarities 

 of its organization discovered after death, its high 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 additional confirmation. And the 

 experiment of imitating the natural process by filling the vessels 



VOL. XV. H H 



