THE TONGUE. 453 



The physiological results of the anatomical data which have been 

 communicated, may be thus summed up : the papillce filiformes are 

 neither gustatory nor delicate tactile organs, since their thick, and what 

 is more to the point, greatly cornified epithelium, is very little fitted to 

 allow of the passage of fluids capable of being tasted, or of other in- 

 fluences, to the scattered nerves, which only attain to the base of the 

 simple papillae. With Todd and Bowman, I consider that the p. fili- 

 form.es have a similar office to the lingual spines of animals, which are 

 nothing but modified filiform papillae, and I therefore ascribe to them 

 a certain importance for the conveyance and retention of the morsels of 

 food, and I consider that their epithelium serves, at the same time, as a 

 protecting investment for the tongue. The two other kinds of papillae 

 subserve the sense of taste and are, besides, the seat of ordinary sensa- 

 tion (for mechanical irritation, temperatures, &c.), for which functions 

 they are excellently fitted by their thin, soft epithelium, the softness 

 of the tissue of their papillae, and by the superficial position (in the 

 secondary papillae), and the great number of their nerves. The sensi- 

 bility of the tongue is most delicate where the papillce fung if or mes are 

 most closely set, i. e., at the apex, which, on that account, and also per- 

 haps by reason of the solid axile corpuscles in many of the papillae, is 

 especially fitted fop a tactile organ ; at the root of the tongue it is more 

 obtuse, and is accompanied by peculiar sensations ; the sense of taste is 

 much more acute at the root of the tongue than in the other regions, 

 the point not excepted. The reason of this lies neither in the epithelium, 

 nor in the fundamental structure of the papillae, which are essentially 

 similar in both the papillce circumvallatce and fungiformes, but is, very 

 possibly, to be sought for in the nerves. In the p. circumvallatce, the 

 nervous fibres are always finer, and not only absolutely, but also rela- 

 tively, considerably more numerous than in the fungiformes, so that they 

 possess more papillae and nervous terminations in the same space. The 

 fineness of the nerves especially, together with the smaller quantity of 

 medullary sheath and the more superficial position of the axis-fibre, 

 which indeed is the case in all the nerves of the high'er senses, may 

 perhaps explain why tas table substances act here not only more power- 

 fully, but when they are no longer perceptible by more dense elements 



surface are generally very granular, and from being contracted and in close apposition, they 

 bear a certain resemblance to fibrous tissue. The use of reagents, however, especially of 

 alkalies, will always render their cellular nature apparent 



The dark color of the fur, sometimes seen, may be owing to large accumulations of the 

 fungi between the cells, or else to the presence of pigment granules. The latter, if 

 abundant, may cause the tongue to appear as if covered with a thin layer of ink. A 

 case is reported by Dr. Eulenberg (Archiv f. phis. Heilk. 1853), in which the whole tongue 

 was covered by a perfectly black fur, which, when examined microscopically, consisted of 

 distinct, angular pigment corpuscles lying between the epithelial cells. DaC]. 



