168 1311. E. KLKIN. 



Ill the sublingualis of the guinea-pig we have to deal with a 

 common mucous gland ; hence the relation of duct and alveoli is 

 the same as in other mucous glands e.g. those of the root of the 

 tongue, palate, pharynx, and rosophagus. The small branches of 

 the intraobular duct are lined with a single layer of polyhedral 

 cells, which directly pass into the columnar mucous cells of the 

 alveoli. 



I have shown (^ Quarterly Journal of Microscopical Science,' 

 January 1881, p. 116) that in the guinea-pig, both in connection 

 with the parotid and the submaxillary, there is a small flat mucous 

 gland, i.e. the admaxillaris superior and inferior, the duct of each 

 of which joins the duct of the respective salivary glands. As 

 regards the structure of the intralobular ducts, the admaxillary 

 glands resemble those of the submaxillary of the dog; but the 

 alveoli of the former, i.e. of the admaxillary glands, are lined 

 only and exclusively with columnar mucous cells, no real crescents 

 being present. But there exist here pseudo-crescents (Boll), i.e. 

 local thickenings of the membrana propria. 



To summarise, {a) In the parotid of the dog and ape, in the 

 serous portions of the human submaxillary gland, and in the sub- 

 maxillary of the ape, the smallest branches of the salivary tubes, 

 i.e. the intralobular ducts with columnar epithelial cells, whose 

 outer portion is conspicuously fibrillated, pass through a narrow, 

 shorter, or longer neck, with cubical epithelial cells, with small 

 crowded nuclei deeply staining in dyes, into the intermediary or 

 intercalated portion, a narrow, longer, or shorter branched canal 

 and composed of an inner limiting nucleated membrane, and an 

 outer membrana propria, and between the two a layer of trans- 

 parent flattened epithelial cells with elongated nuclei. In the 

 parotid and submaxillary of the rabbit and guinea-pig there is 

 only an indication of the neck, but otherwise the relations are the 

 same as before. (5) In the submaxillary gland of the dog, in 

 the mucous portion of the submaxillary of man, in the sublingual 

 gland of the rabbit, and in the admaxillary glands of the guinea- 

 pig, the salivary tubes pass through the neck of the same nature 

 as above directly into the alveoli. The intermediary part is 

 therefore absent, (c) In the sublingual gland of the dog and 

 guinea-pig the intralobular ducts of the same nature as in the 

 ordinary common mucous glands, and they pass directly into the 

 alveoli. 



The alveoli of all the glands examined are tubes more or less 

 branched and convoluted. In all those that are concerned in 

 the secretion of mucus, i.e. the submaxillary gland of the dog, 

 the mucous portion of the submaxillary of man and the ape, the 

 subungual of the dog, rabbit, and guinea-pig, and the admaxil- 

 lary glands of the last-named animal, the tubular and branched 



