TASTE. 



225 



in being compound. The papillae are of three kinds. Thickly 



disposed over the whole surface are those of smallest size, 



the filiform kind, which are long and 



slender prominences, as their name j 



indicates, and have a few simple/ 



papillae at their extremities. Scattered ' 



sparsely among the filiform are the 



fungiform papillae, which have a 



rounded shape, and sometimes remain 



red when the rest of the tongue is 



furred, giving a spotted appearance to 



the surface. The papillae of the third 



description are called circumvallate, 



and are several times larger than the 



fungiform. They are usually less than 



a dozen in number, and are arranged 



near the back of the tongue in two 



lines diverging from the mesial groove Fig. 111. TONGUE, 



in a curved fashion. They, as well as showing the , circum- 



the fungiform kind, have simple papillae ^^4 " 



on their broad tops, and they get their fungiform scattered 



name from each being sunk into a over the surface. 



hollow, whose outer wall rises up like a rampart to a level 



with it. 



The epithelium which covers the tongue is of a thick 

 stratified squamous description ; and the variations in the 

 distinctness of the papillae, in different states of health, depend 

 more on the condition of the epithelium than on differences 

 in the prominences which they clothe. 



166. The sensory nerves of the tongue end in a variety of 

 ways. End-bulbs (p. 68) are found in the papillae close to 

 their extremities. Also, on the frog's tongue, nerves have been 

 traced into elongated cells with forked extremities, situated 

 in the epithelium; and although the mammalian tongue is 

 very different from that of the frog, yet it is likely that some 

 similar mode of nerve-termination is scattered over the 

 tongue of the mammal also; for forked cells, continuous 

 with nerve-fibres, have been described in the epidermis of 

 general integument. But the most remarkable mode of 

 nerve-termination found in the tongue is in the taste-cones of 

 H p 



