452 SPECIAL HISTOLOGY. 



which become isolated and swell up by the action of caustic potassa and 

 Fiir 177 soda, especially with heat, and are derived 



from the epithelial processes of the papillce 

 filiformes; the granular cortex again, is 

 nothing but the matrix of a mucedinous 

 fungus of only 0*0006 of a line in diameter, 

 which, agreeing completely with the well- 

 known filaments upon the teeth, is often 

 rooted in immense quantities in it. In the 

 dead subject we readily recognise the epi- 

 thelial cells, covered with fungi, either with 

 or without projecting mucedinous filaments, 

 even in situ (Fig. 177) ; and in living per- 

 sons, they may be procured in any quan- 

 tity by scraping the tongue. In twenty or thirty healthy young people, 

 I have hardly once failed to find the granular covering upon the epithe- 

 lial processes, even in a perfectly clean, red tongue. 



The more fur there is, the more abundant is the matrix, and the 

 mucedinous filaments are also apparent, though they are rarely (three 

 or four times in thirty cases) found so clear and distinct as in Fig. 176, 

 and in general are not met with in more than a third of those persons 

 whose papillce filiformes are not altogether in a normal condition.* 



FIG. 177. A papilla filiformis, whose, here, short epithelial processes are invested by the 

 matrix of the fungus, from which also single filaments are growing out. 



*[This vegetable is probably the one to which Robin (Hist, natur. des Vegetaux Para- 

 sites), has given the name of oidium albicans. He has most frequently met with it in 

 a variety of aphtha, the " muquet '' of the French. In this disease the irregular white 

 patches on the mucous membrane of the tongue, which were formerly supposed to be the 

 result of a diphtheritic inflammation, are found to consist of a vegetable growth. Robin (loc. 

 cit.) describes this vegetable as formed by distinct tubular filaments, which sometimes enclose 

 granules, and which always originate from spores. The spores are spherical and have well- 

 marked contours and a brilliant centre. They generally enclose numerous fine molecules, 

 sometimes one or two larger movable granules. Robin has observed this vegetable growth 

 whenever the mucus of the oral cavity was changed in its character. He agrees, there- 

 fore, with Kolliker in considering it neither as a constant symptom of any disease, nor as a 

 disease in itself. 



In some recent investigations upon the " fur " of the tongue, I have satisfied myself 

 of the almost constant presence of these fungi, especially of the granular matrix. In acute 

 diseases (as in erysipelas and peritonitis), in which the tongue was much coated, the 

 mucedinous filaments were also always found well developed. They were firmly adhe- 

 rent to isolated epithelial cells, by which they were sometimes concealed, but were easily 

 rendered apparent by the aid of a solution of carbonate of soda. In one case of typhoid 

 fever I discovered large distinct spores. Prof. Clark, of New York, has observed these 

 vegetable growths in cases of extreme debility, especially in infants exhausted by diar- 

 rhosa and dysentery. 



The main constituents, however, of the fur of the tongue are layers of epithelial 

 cells in different stages of development. If the tongue be much coated, the cells on the 



