868 



OF SENSATION, AND THE ORGANS OF THE SENSES. 



of capillaries, and a bundle of nerve-fibres (Fig. 205), both terminating in 

 loops which enter the simple papillae that clothe the surface of the compound 

 body ; but, instead of being covered with a thin scaly epithelium, they are fur- 



Fig. 205. 



A. Secondary papilla of the conical class, treated with acetic acid : a. Its basement-membrane. ft. Its nerve- 

 tube forming a loop. c. Its curly elastic tissue. The epithelium in this instance is not abundant; but the 

 vertical arrangement of its particles over the apex of the papilla is well seen, d, and illustrates the mode of 

 formation of the hair-like processes described in the text. Magnified 160 diameters. 



B. A similar papilla, deprived of its epithelium : a. Basement-membrane. 6. Tubular fibre, probably form- 

 ing a loop, but its arch not clearly seen, c, c. Elastic fibrous tissue at its base and in its interior. Magnified 

 320 diameters. 



c. Nerves of a compound papilla near the point of the tongue, in which their loop-like arrangement is dis- 

 tinctly seen. Magnified 160 diameters. 



nished with bundles of long pointed processes, some of which approach hairs in 

 their stiffness and structure. These are immersed in the mucus of the mouth, 

 and may be moved in any direction, though they are generally inclined back- 

 wards. The simple papillae which occur in an isolated manner, with those which 

 are aggregated in the circumvallate and fungiform bodies, doubtless minister to 

 the sense of Taste ; but there seems much reason to coincide in the opinion of 

 Messrs. Todd and Bowman, with regard to the different office of the filiform 

 papillae. " The comparative thickness of their protective covering, the stiffness 

 and brush-like arrangement of their filamentary productions, their greater de- 

 velopment in that portion of the dorsum of the tongue which is chiefly employed 

 in the movements of mastication, all evince the subservience of these papillae 

 to the latter function, rather than to that of taste ; and it is evident that their 

 isolation and partial mobility on one another, must render the delicate touch 

 with which they are endowed, more available in directing the muscular actions 

 of the organ. The almost manual dexterity of the organ, in dealing with 

 minute particles of food, is probably provided for, as far as sensibility conduces 

 to it, in the structure and arrangement of these papillae." It may be added, 



