TONGUE. 



1151 



the tongue in birds. A, is that of, the snipe 

 (ScoUupax gallinago'), which is seen to be 

 linear; B, of the fieldfare (Turdus pilaris), the 

 epithelium breaking up into a leash of filaments 

 at its extremity ; C, that of the king-fisher (Al- 

 cedo isjrida),$o short that it hardly projects from 

 the surface at the bottom of its long bill ; D, 

 is the tongue of the common goose, furnished 

 with a linear series of spines on each side, 

 forming a serrate margin, which, with a corre- 

 sponding serration in the upper mandible, con- 

 stitutes a sort of sieve, through which the bird 

 sifts and strains, as it were, the mud and water 

 which it palpates in search of food. In the 

 back part of the tongue, both in this and in the 

 other figures, there is seen to be a peculiar 

 armature of recurved spines, whose arrange- 

 ment in the different species is constant and 

 characteristic. Some good representations of 

 different varieties of tongues are given in the 

 article AVES. 



Mammalia. The tongue of mammals differs 

 not in any material point from that of man. 

 The proportion of the different parts of its 

 muscular structure differ more or less widely 

 from the human type, and we find certain 

 muscles that have no place in the tongue of 

 man: to enter into the minutiae of these diver- 

 sities would not, however, comport with the 

 scope of the present article ; they must be 

 sought in monographs especially devoted to this 

 part of the subject. The coincidence of the 

 -size and form of the tongue with that of the 

 inferior maxillary arch is very general ; in the 

 rodents this is very conspicuous, the tongue being 

 of the same wedge shape as their cuneiform 

 jaw. In some animals, as in the ant-eater and 

 giraffe, the tongue admits of great elongation, 

 and becomes an important organ of prehension. 

 The different elements of the tegumentary sys- 

 tem are merely modifications of those found 

 in man : the three orders of papillae are gene- 

 rally sufficiently conspicuous, and in most in- 

 stances they are more regularly arranged, and 

 their structure is more typical than in the 

 human subject; for instance, the circumvallate 

 papillae are symmetrical, they present a greater 

 contrast to the rest in number, being fewer 

 than in man, and none of the fungiform ap- 

 proach them in form; the shape of the fungi- 

 form too is not liable to any variety, and they 

 are implanted with great regularity among the 

 conical. The conical papillae are generally 

 true cones, and are arranged with mathemati- 

 cal precision in lines in different directions, 

 accordingly as they are viewed. All these 

 papillae may be well seen in the dog. In the 

 felidcB the conical papillfE of the centre of the 

 dorsum are converted into recurved spines of 

 great size and strength, which the animal uses 

 in scraping the meat from the bones when 

 feeding, and in combing its fur. 



FUNCTIONS OF THE TONGUE. The phy- 

 siology of the tongue, like its organisation, 

 is double, all its functions being referable 

 either to those sensory or muscular endow- 

 ments which it possesses in so remarkable 

 a degree. Naturally, these are intimately 

 associated, its sensibility being necessary for 



the direction of its muscular action, and its 

 movements necessary for the perfection of its 

 sensibility; a systematic consideration of them, 

 however, necessitates their separation, and 

 those functions that are referable to the 

 tongue as an organ of sensibility, have already 

 been treated of in the articles TASTE and 

 TOUCH, to which the reader is referred ; it 

 only remains for me to consider those that it 

 possesses as an organ of motion. 



These are prehension, mastication, insaliva- 

 tion, deglutition, speech, and one or two unim- 

 portant and non-essential offices in which it 

 is engaged, which may be called the accidents 

 of its physiology, as despuilion or spitting, 

 ivhistimg, &c. Of these the four first-men- 

 tioned belong to the tongue as an organ of 

 digestion ; they are, in fact, the first four stages 

 of that process; all four exist in all mammalia, 

 the first and the last in all vertebrata ; speech 

 and the other non-digestive motor functions 

 are peculiar to man. 



Prehension. The tongue is not, properly 

 speaking, in man, an organ for the prehension 

 of solid food, that office being performed by 

 the hand, for which the opponent arrange- 

 ment of thumb and fingers eminently fits it, 

 so that the human tongue has not those ad- 

 ditional qualifications which we find in other 

 animals to adapt it for an organ of pre- 

 hension. And this, I may remark, is an in- 

 stance of a very general law that the ascent 

 in the animal scale is not a passage from 

 animals with simple organs to animals with 

 complex organs, but from simple individuals 

 with organs of complex function, to complex 

 individuals with organs of simple function, the 

 addition as we ascend being, not of functions, 

 but of parts to discharge those functions, and 

 the advantage gained, not another thing done, 

 but the same thing done better. Thus in man, 

 instead of having one office more, the tongue 

 has one office less than in many animals below 

 him ; and the delicate and extended prehen- 

 sion supplied by his hands, diminishes by one 

 item the complexity of function, and, there- 

 fore, of organisation of his tongue. So that 

 in judging of the elevation of animals by their 

 individual organs, supposing such a method 

 to be admissible, we must not look to complex- 

 ity of structure of those organs, but to the 

 perfection of the resulting function. But to 

 return. 



In the prehension of liquids, or suction, the 

 tongue in man is engaged ; constituting a 

 movable wall of the oral cavity, it acts as a 

 piston, and draws the liquid into the mouth 

 by the formation of a temporary vacuum. 

 Bichat enumerates three methods of the pre- 

 hension of liquids, by suction, by drinking 

 from a vessel, and by infusion into the throat; 

 in the first two the tongue is concerned ; in 

 the last, which seems to me hardly to deserve 

 the name of prehension, it is not. In suction, 

 which is peculiar to the infant, the nipple is 

 seized by the lips, which are compressed 

 around it by the orbicularis oris ; the velum 

 palati is elevated so as to close the posterior 

 nares : the tongue forms, by the contraction 



