174 JOHN SUNDWALL 



in size and structure to the interlobular ducts. The intralobular 

 ducts present as a rule the following characteristics. There is 

 a reduction in the cells of the outer layer so that the smaller 

 ducts appear to possess but a single layer of cells which show the 

 same characteristics as those described for the interlobular 

 ducts. The nuclei are elliptical. Frequently, however, one 

 sees ducts with two layers of cells wherein the cells of the outer 

 layer are as pi-ominent as are the cells of the inner layer. This 

 is true even in some of the smallest of the intralobular ducts. 

 The connect i\'e tissue surrounding these ducts is much less 

 abundant than that of the interlobular structures sometimes 

 foi-ming only a thin layer or again it may be considerable in ciuan- 

 tity. It is derived from the intralobular connective tissue. 

 Mallory's connective tissue stain shows a definite basal mem- 

 brane. The wall is made up almost entirely of collagenic fibres. 

 Only occasionally are elastic fibres seen. Capillaries are seen 

 in these walls. 



No secretory granules or secretion capillaries are present in 

 these ducts. I did not observe by using the ordinary stains the 

 basal filaments described by Hornikel in the cells of these ducts 

 in the lachrymal gland of the ass and the more or less indefinite 

 pencil like structures described by Fleischer in the ox. How- 

 ever these are seen in special preparations (see Basal striations) . 

 Merkel saw none in the lachrymal gland of the dog. 



Cement lines. These are seen in connection with the surface 

 epithelium of all the collecting ducts — primary, interlobular, 

 intralobular. On the surface they outline the polygonal margins 

 of the cells and at the various angles appear as dots. In longi- 

 tudinal sections this cement substance forms a well defined 

 point which pi'ojects some distance basalward between the cells 

 sometimes half the length of the cell. As they near the base 

 these intercellular cement structures become finer and are finall}^ 

 lost in the cell membrane (fig. 20). Fleischer failed to observe 

 this characteristic of the cement lines in the lachrymal gland 

 of the ox. Kolossow saw no cement lines in his studies on glands. 

 Zimmermann, on the other hand, noted this peculiar arrange- 

 ment of the cement lines in the human lachrvmal gland. He 



