TONGUE. 



1137 



Ftg. 754. 



Circttmvnllittc papilla seen in vertical section. 



a, Truncated surface, or base of the cone ; b, cir- 



cumvallation ; c, raised border. (Mag. 1C diam.) 



cone is attached. At the attached portion the 

 nerves and vessels enter, and the free trun- 

 cated surface, or base, of the cone is covered 

 with small secondary papillae, concealed by 

 the epithelium (fig. 754. a) ; the free border is 

 also surmounted by secondary papillae, so that 

 it is, in fact, a circular compound papilla (c). 

 The circumvallate papillae possess the utmost 

 irregularity as to size, number, shape, and 

 arrangement. Their number has been much 

 overstated by some anatomists ; Cruveilhier 

 gives it as from sixteen to twenty, Marjolin 

 from nine to fifteen, Soemmering from twelve 

 to fourteen, and Meckel from three to twenty. 

 I think the number given by Messrs. Todd 

 and Bowman, as from eight to ten, is much 

 nearer the truth ; certainly, if ten can be 

 counted, they must be considered well deve> 

 loped ; frequently the number is below this 

 I have seen as few as five, or even four. In 

 size they vary from that of an ordinary fungi- 

 form papilla to upwards of -g-th of an inch in 

 diameter. They always assume more or less 

 of the V-shaped arrangement, but the per- 

 fection with which the linear series is main- 

 tained, the straightness of the lines that form 

 the angle, and the size of the angle so formed, 

 all vary very much ; I have seen them stretch- 

 ing across from side to side of the tongue, 

 almost in a straight line, with a third arm 

 projecting back from the centre, something 

 like the form of a tripod ; it is not uncommon 

 to find a stray one or two scattered to a great 

 distance beyond the prescribed line; the cen- 

 tral one is frequently thrown back half an 

 inch, and sometimes a lateral one is found 



quite at the edge of the tongue. In shape, the 

 varieties are chiefly owing to the relative size 

 and development of the central tubercle and 

 the circular ridge surrounding it. Sometimes 

 one of these parts is suppressed, and then 

 you either get what appears to be a large 

 fungiform papilla, or a set of ridges having 

 something of a circular or quadrilateral ar- 

 rangement, not to be distinguished from the 

 fused rows of conical papilla? which surround 

 the circumvallate on all sides, and which 

 are, in fact, continuations and prolongations 

 of their calices. Haller mentions having seen 

 the circumvallate papillae in two rows on 

 each side ; T have met with a similar arrange- 

 ment on one side. This appearance may in 

 some degree be accounted for by the supposi- 

 tion that the rows of conical papillae, among 

 which the large fungiform immediately in front 

 of the circumvallate are planted, have attained 

 a circular or calyx-like arrangement around 

 them ; for a large fungiform papillae, situated 

 in a calyx so formed, would produce a very 

 perfect papilla circumvallata. This change is 

 just the reverse of that which reduces a cir- 

 cumvallate papilla to a fungiform by the sup- 

 pression of its surrounding ridge, and both, no 

 doubt, are sources of irregularity. These 

 papillae are supplied by branches from the 

 glosso-pharyngeal nerve, which may be dis- 

 tinctly traced to them ; their vascular supply 

 is abundant, and their epithelium thin and 

 fine, so that during life, and when injected, 

 they appear very red. 



The fungiform papillae, as their name indi- 

 cates, have more or less of the form of a 

 sphere supported on a pedicle ; this is their 

 typical form, but they often deviate from it ; 

 in size they vary from J^th to -J^th of an inch. 

 They are scattered over the sides and tip 

 of the tongue, and on the dorsum in front 

 of the circumvallate. They may be dis- 

 tinguished from the filiform, among which 

 they are implanted, by their red colour, 

 in which, in the thinness and smooth- 

 ness of the epithelium investing them, and 

 in the abundance of their vascular and 

 nervous supply, they resemble those last de- 

 scribed. When examined microscopically, 

 they are seen to be covered on their sides and 

 summit with secondary papillae (fig. 755. A), to 

 755. 



Fungiform papilla, showing the secondary papillse on its surface, and at a the epithelium covering 

 them over. (Mag. 35 diam.) 



, Another, with the capillary loops of its simple papillae injected, a, artery ; v, vein. The groove 

 around the base of some of the fungiform papillae is here represented, as well as the capillary loops, c c, 

 of some neighbouring simple papillae. (Mag. 18 diam.) (After Todd and Bowman.') 



4 D 



