174 DR. E. KLEIN. 



the crescents. The crescents are not so marked as in the sub- 

 maxillary gland of the dog. 



(c) — T/ie Simple Mucous Glands. 



As mentioned above, the sublingual gland of the dog, the 

 subKngual of the guinea-pig, the upper and lower admaxillary of 

 the guinea-pig, and lastly, the mucous portions of the submaxil- 

 lary of man and the ape, belong to this group. 



The alveoli of the sublingual gland of the guinea-pig and the 

 two admaxillaries of the same animal are of exactly the same 

 nature as those of the mucous glands at the root of the tongue 

 or palate, both in the size of the alveoli as a whole and of their 

 lumen, as well as in respect to the nature and size of the lining 

 epithelium ; this latter is a single layer of typical mucous cells. 

 What has been said above (submaxillary of the dog) with refer- 

 ence to the disappearance of the nucleus in some of the epi- 

 thelial cells applies also to these simple mucous glands. 



In the sublingualis of the dog the relations are somewhat 

 different. Here we find the alveoli either lined only with mucous 

 cells or only with albuminous cells, or with both. Compare 

 Heidenhain (1. c, p. 21) and also fig. 8 accompanying this Report. 

 The mucous cells are columnar and slightly difl'erent from those 

 of the submaxillary of the dog, inasmuch as there appears in 

 most of them, in the resting gland, a trace of granular-looking 

 protoplasm left in the outer part of the cell, i.e. next to the 

 membrana propria, and in this part lies the spherical or slightly 

 oval nucleus. The albuminous cells are also columnar or pyra- 

 midal, and their substance appears longitudinally striated owing 

 to the intracellular network having pre-eminently a longitudinal 

 arrangement, such as I described of the columnar epithelial cells 

 of the intestine. Those alveoli that are lined only with albumi- 

 nous cells are smaller, and their lumen is smaller than those Imed 

 with mucous cells. In many alveoli a direct transition is noticed 

 of the mucous cells into the albuminous cells, as also the coexis- 

 tence in the same alveolus of the two kinds of cells. A similar 

 condition has been pointed out above to exist^ in the mucous 

 portion of the sub-maxillary of man and the ape. Where the 

 two kinds of cells are side by side, it is generally noticed that 

 there are cells which, as regards appearance, stand about midway 

 between the two ; that is to say, a smaller or larger inner portion 

 of the cell presenting the transparency of the mucous cells, while 

 the rest consists of the more opaque substance of the albuminous 

 cells ; the greater transparency being due, as in the other mucous 

 cells, to the distension of the meshes of the intracellular reticulum 

 by mucigen or mucin respectively. 



The albuminous cells in the sublingual gland of the dog bear, 



