466 SPECIAL HISTOLOGY. 



with in the fluid of the mouth, and are usually supposed to be derived 

 from the mucous or salivary glands, yet wrongly, since the examination 

 of both these kinds of glands, and of their ducts, teaches us that they 

 excrete no formed elements. In my opinion the mucous corpuscles are 

 nothing but products of the mucous membrane of the oral cavity not 

 normal, although they are almost constant, but a kind of exudation- or 

 pus-corpuscles, with which they have, as is well known, the closest pos- 

 sible resemblance in structure. Many authors consider them to be 

 abortive epithelial cells of the oral cavity ; but in that case the epithe- 

 lium of the localities in which they are found must want the outermost 

 layer of large, flattened scales, which is by no means the case. In my 

 own person, at any rate, I find mucous corpuscles on the gums, the lips, 

 cheeks, and tongue, in localities in which the epithelium is wholly un- 

 injured ; and by scraping with a knife I can often obtain entire 

 lamellae of epithelial plates, covered with mucous corpuscles. I do not 

 mean to affirm by this, that in little sores, arising from whatever cause, 

 upon the gum, for instance, where the epithelium is wholly or partly 

 wanting, or when it is lost more extensively, in consequence of disease, 

 that mucous- or exudation-corpuscles may not be developed, as upon 

 other sore surfaces, and then might be regarded as abortive epithelium- 

 cells, but only, that this does not take place in the oral cavity under 

 ordinary circumstances. I consider, therefore, that the so-called mucus, 

 or salivary corpuscles, are exudation-corpuscles, and consequently totally 

 distinct from epithelial cells ; and I regard their formation to be analo- 

 gous to that of the pus-corpuscles in catarrh, which also very often takes 

 place upon unbroken epithelial surfaces. It is thus readily explained 

 how it is that they are almost entirely absent in many individuals, while 

 in others who are subject to irritation of the mucous membrane of the 

 mouth they are very abundant, arid that they have been observed in 

 saliva, obtained from a fistulous aperture (Sebastian, in "Van Setten, 

 Diss. de Saliva." 1837, p. 12). 



The best mode of examining the oral mucous membrane is by making 

 perpendicular sections of portions, either fresh, or dried, or hardened 

 in absolute alcohol, in which the papillae and epithelium are very dis- 

 tinct, and become still more so by the use of very dilute caustic soda ; 

 by the aid of which also the deepest perpendicular epithelial cells are 

 rendered readily visible. The papillae may be studied in macerated 

 portions, or if it be only required to ascertain their position and form, 

 in perpendicular or horizontal sections, treated with concentrated caustic 

 potassa, on which the epithelium is dissolved. The lingual papillae may 

 be treated in the same manner; the epithelium upon which, especially 

 on the filiformes, moreover, is often entirely absent. The nerves of all 

 these parts are best seen under the use of dilute caustic soda ; acetic 



