136 ORGANS CF DIGESTION. 



The lymphatic vessels, e. g., in the pharynx and at the root of 

 the tongue, can be filled by the puncture method, after which 

 the injected parts must be hardened in alcohol, and used for 

 the preparation of sections. To see the loops of fine capil- 

 laries in the papilla of the mouth, tongue, and pharynx, these 

 parts must be injected. As regards the distribution of the 

 fine nerves, see Chapter Y. 



Stomach. The relation of the muscularis mucosse, the 

 submucous tissue, the musculosa and the ganglia to each 

 other, can be well shown in sections of organs hardened in 

 chromic acid. For the study of the glands, the best method 

 is to open the stomach of the cat or dog immediately after 

 death, carefully inverting it so as to empty it of its contents, 

 and then to stream it gently with water. Thin folds of the 

 membrane must be snipped off with sharp curved scissors and 

 placed in common alcohol. After three or five days the ob- 

 jects are ready for the preparation of sections, the direction of 

 which must be parallel or vertical. The parallel sections must 

 be made at various depths. For the*coloring of these sections 

 a staining liquid prepared after Beale's formula (omitting the 

 alcohol) answers well ; but it is necessary to free it from excess 

 of ammonia, either by careful neutralization with acetic acid 

 or by warming it in the water-bath. The sections having been 

 placed in this liquid in a watch-glass, it is put in a closed ves- 

 sel along with a second watch-glass containing water with a 

 trace of ammonia. After twenty-four hours the sections are 

 removed, washed in dilute glycerin, and transferred to con- 

 centrated glycerin in another watch-glass, which is then placed 

 in the closed vessel along with a glass containing common 

 acetic acid. After twenty-four to twenty-eight hours the 

 sections may be finally covered in glycerin. In such prepara- 

 tions the gland tubes of the fund us (the so-called peptic 

 glands), with their two kinds of epithelium, are well seen. 

 Next the cavity of the gland it consists of cylindrical cells 

 (the Hauptzellen of Heidenhain), which are scarcely colored 

 by the carmine, and are very finely granular. The nuclei of 

 these cells are occasionally colored, but usually not so. Un- 

 derneath them, i.e., next the membrana propria, both in 

 vertical and parallel sections, ovoid granular cells are seen 

 which are strongly stained. These last (the Belegzellen of 

 Heidenhain) do not form a continuous layer in either direc- 

 tion : they occur in small numbers in the half or two-thirds of 

 the gland next the muscularis mucosse, i.e., in the body of the 

 gland more abundantly in the adjoining part, which is 

 usual ly called the neck, where they more or less conceal the 

 cylindrical layer. The short duct, in which usually two 

 tubes open, possesses an epithelium of the same kind as that 



