Three tongues from nature (exact size).
The reader will concur with Mr. P. H. Gosse and the Penny Cyclopedia, that ‘no instrument is less adapted for licking.’
There is yet one more of our English scientific writers who must be quoted, and who, though he wrote so far back as 1834, shows us that even then this tongue was far better understood by the French and German zoologists than ourselves. Roget, in his Animal Physiology (one of the Bridgewater Treatises), says: ‘Hellmann has shown us that the slender, bifurcated tongue of snakes is used for the purposes of touch.’
It is to be regretted that we have no translation of this and of several other German ophiologists of whom mention is made by Roget and others. Lenz gives us to understand that in 1817 Hellmann had decided that a snake uses its tongue as an insect does its antennæ. And in watching with unprejudiced eyes the varying play of the organ, the similarity of action will at once be recognised.
After all, how little can we ever know of these organs beyond conjecture! Who shall say whether each or both may not possess a sense of which we ourselves have no true perception? Close observers are convinced that the tongue of a snake is endowed with peculiar sensibilities; and it is the more astonishing, therefore, that reason and observation have so long been blinded and enslaved by prejudice regarding it.
Some naturalists think that the sense of smell lies in antennæ. The sense of smell itself is dull in snakes; yet they have means of ascertaining what other animals learn by smell. Says Huxley, ‘The great majority of the sensations we call taste are in reality complex sensations, into which smell and even touch largely enter.’[34] It is certain that the snake’s tongue is in constant use for some purpose or other, though beyond what we see of its form and actions we can only speculate, or, at best, draw conclusions from observation.
Both Dumeril and Lenz give the result of their own observations. The former, however, devotes so many pages to the tongue and its functions under the various headings of ‘touch,’ ‘nutrition,’ ‘the senses,’ etc., that it will be necessary to curtail a good deal, particularly as this great author has been quoted by those other physiologists whose words were given above. Of the sheath into which the tongue is received he says:—‘Une gaîne cylindrique, charnue; mais l’extrémité de cette langue est fourchue, ou divisée en deux pointes mobiles, vibrantes, susceptible de se mouvoir indépendamment l’une de l’autre, de s’écarter et d’être lancées, pour ainsi dire: ce que la fait regarder par le vulgaire comme une sorte de darte, auquel même quelques peintres ont donné dans leurs tableaux la forme d’un fer de flêche. Le vrai est que cette langue est molle, humide, très faible, et que l’on a fait des conjectures, plutôt sur les usages auquels on l’a cru destinée, que sur l’utilité réelle dont elle peut être aux serpents dans l’acte de la deglutition; car les serpents ne mâchent jamais leurs alimens.’[35] ‘Quoiqu’on ignore le véritable usage de la langue humide et charnue que les serpents brandissent et font continuellement sortir de la bouche et vibrer dans l’air, il est facile de concevoir qu’à cause de la forme cylindrique et de son etroitesse elle ne pourrait faciliter la mastication, quand même les dents seraient propres de cet usage.’[36]
This first volume of Erpétologie générale treats of all reptiles inclusively; but in the sixth volume, where the ophidia particularly are introduced, the tongue is, with the rest of the organs, more minutely described. Some repetition necessarily occurs; but there is still a good deal that will repay perusal.
After stating that in serpents the sense of touch is dull, on account of the integument, and the absence of what may be regarded as tactile organs, and that the sense of smell is dull, the nostrils being feebly developed, Dumeril adds: ‘The tongue, though fleshy, very mobile, and constantly moist, is rather an especial instrument for touch, for the action of lapping, and for other functions, than to perceive the nature of liquids;’ in other words, than as an organ of taste. ‘It is, however, very remarkable; though smooth and even above, it is furnished with little fringes or papillæ along the sides. Notwithstanding its length and narrowness, it is singularly protractile and retractile; and in its exceedingly rapid vibrations has impressed the vulgar with the idea that it is formed with the two spear-like points. It is clothed with a delicate skin.’[37]