THE LACHRYMAL GLAND 167 



thin sections of this tissue previously fixed in anmioniuni niolyb- 

 date (Technique VI, 1) show that all the intercellular secretion 

 capillaries are stained. See Secretion capillaries. 



Histological structure of ducts and tubules 



Main ducts. The excretory ducts hi the superior lid are so 

 tortuous in their course that it is impossible to obtain a continu- 

 ous duct in longitudinal sections — only portions of one duct can 

 be obtained. The ducts he close to the conjunctival surface. 

 As the terminal of the duct is approached there is seen a gradual 

 increase of lymphoid tissue which surrounds th(^ t(^i'minal open- 

 ings as true lymph nodes. 



Fig. 7 Epithelium of main duct. Drawing, Zeiss, oc. 4, obj. 8, as seen in 

 cross section of duct near its terminal in lid. A, goblet cells; B, epithelial cells. 

 The large clear goblet cells are readily seen surrounded by smaller epithelial 

 cells. 



A cross section of the duct near its terminal shows the follow- 

 ing characteristics: The lumen is either slit-like or very much 

 corrugated, the epithelium being thrown up in folds with crypts 

 between. Two types of cells line the duct — goblet cells and more 

 or less irregularly elongated or cuboidal epithelial cells arranged 

 in layers (fig. 7). The former cells occur in great numbers. 

 They average as a rule 40^ by 20/x although there is much vari- 

 ation. Sections stained in iron haematoxyhn and counterstained 

 with mucicarmin show the surface epithelium to the best ad- 

 vantage. Here the goblet cells are stained red and can readily 

 be differentiated from the epithelial cells in general. Many of 



