170 BU. E. KLEIN. 



side these are the crescents of Giauuzzi^ e.g. the submaxillary of 

 the dog and the sublinguahs of the rabbit. (c) Simple mucous 

 glands ; as such are considered those the alveoli of which are 

 lined with mucous cells, but outside these there are no cells 

 comparable to the cells of the " crescents/' They are of two 

 kinds. (1) The admaxillary glands (superior and inferior) of 

 the guinea-pig, and the mucous portion of the submaxillary of 

 man and ape ; in these the ducts are similar in structure to the 

 salivary tubes of the above glands {i.e.) conspicuously fibril- 

 lated in the outer part of the substance of the columnar epithe- 

 lium), and the alveoli are lined with uniform typical columnar 

 or goblet-shaped transparent mucous cells ; (2) the sublingual 

 gland of the dog and the sublingual gland of the guinea-pig : in 

 these the intralobular ducts are, like the ducts of the common 

 mucous glands at the root of the tongue and palate, lined with 

 cubical cells without conspicuous fibrillation ; the alveoli are 

 lined either only with typical columnar transparent mucous 

 cells (guinea-pig), or with mucous cells and albuminous cells 

 (dog). (See below.) 



{a) As regards the albuminous glands, the lumen of their 

 alveoli is a small canal, which in the state of active secretion of 

 the alveoli may dwindle down almost to its disappearance. The 

 cells lining the alveoli are a single layer of columnar or pyra- 

 midal cells, whose substance is in hardened specimens a uniform, 

 dense, honeycombed reticulum. I have preparations of the 

 hardened resting parotid and submaxillary of the ape, and 

 especially of the submaxillary of the rabbit, where in all alveoli 

 the epithelial cells show a uniform beautiful reticulum, and as I 

 have described in my paper on the structure of cells and nuclei 

 in the April number, 1879, of the ' Quarterly Journal of Micr. 

 Science/ Heidenhain (1. c, p. 18) thinks this representation 

 diagrammatic; but against this I have this to say, that the 

 reticulum in the cells in my preparation of the above-mentioned 

 glands is so uniform and beautiful that it is impossible to make 

 of it a diagrammatic representation. 



In the parotid of the rabbit I have noticed in some instances 

 that some of the alveoli arc marked from the others by the pre- 

 sence of smaller and larger globular highly refractive granules, 

 such as are mentioned by Langley {' Proceedings of the Royal 

 Society,' No. 198, 1879). The granules stain slightly in hema- 

 toxylin, and differ in size between that of a coloured blood-cor- 

 puscle and a minute dot. Where the cells are viewed in profile, 

 the granules are seen to occupy the inner part of the cell-substance 

 (Langley's state of secretion) the outer part is therefore non- 

 transparent, and here the intracellular reticulum can be made 

 out. Also in the inner part with good illumination and high 



