CELLS OF THE LACHRYMAL GLANDS. 465 



which form the proper secreting parenchyma, present but 

 slight variations. They form sacculi, in which we can distin- 

 guish an investing membrane (membrana propria), and the 

 secreting epithelium. 



The epithelial cells are of very various shape, but form 

 polyhedric bodies of nearly equal size, that are bounded by a 

 variable number of surfaces which come into apposition at dif- 

 ferent angles, but almost always have sharply defined borders. 



Not unfrequently tolerably well-defined delicate grooves are 

 met with upon the surfaces. None of the different diameters 

 of the epithelial cells are especially developed at the expense 

 of the others, so that they invariably appear in the form of 

 irregular cubes. The spheroidal homogeneous nucleus, not 

 always containing well-marked nucleoli, is in all instances 

 excentric, being situated near the base of the cell which is 

 turned towards the membrana propria. A tolerably strong and 

 long bright process, staining deeply witli carmine, is, it would 

 appear, constantly given off from the cell (Heidenhain), which 

 seems to end by a free extremity at some distance from the 

 cell, without forming any other connection. Its length may 

 almost amount to the diameter of the body of the cell. The 

 other angles of the cells are not unfrequently drawn out into 

 long processes, the size of which is usually considerably less 

 than that of the basal process. Not unfrequently, also, the 

 nucleus of the cell exhibits a pointed process, which can never 

 be followed beyond the limits of the cell, but which constantly 

 runs in the direction of, and is sometimes contained within, the 

 basal process itself. 



As Henle first demonstrated, and as Heidenhain has lately 

 again pointed out, the acinous glands are divisible into 

 those which contain mucus in their secretion, and into 

 those in which it is absent .Certain histological characteristics 

 of the secreting parenchyma correspond to these peculiarities 

 of the secretion, especially in regard to the glandular epi- 

 thelium, which, when no mucus is present, constantly remains 

 protoplasmatic, whilst when it is present, the protoplasm 

 undergoes a metamorphosis into mucus that is very easily 

 demonstrable under the microscope. The lachrymal glands 

 of Man and the other animals examined, as the Sheep, Ox, 



VOL. III. H H 



