lyo American Quarterly Microscopical Journal. 



anastomosing, circular, elastic fibers from that coat. Its fibers 

 are likewise both circular and longitudinal. The vessels enter- 

 ing it are comparatively large and go straight through to the 

 middle layer. The nuclei in this layer are less numerous than 

 in the middle one (PI. XIII., Fig 3, c). 



In the branches of the duct, the middle layer becomes rela- 

 tively thicker, and the outer coat is composed mostly of longi- 

 tudinal fibers. 



According to J. Arnold, in Strieker's Manual of Histology 

 (31,150), the pancreatic duct of the cat contains a proper mus- 

 cular layer, but he does not give its position. Although sec- 

 tions were made of ducts hardened in Miiller's fluid and alco- 

 hol, and in alcohol alone, and stained with picro-carmine and 



PLATE XIII. 



All the Figures original, and drawn by camera lucida. 



Figures i and 2 are lettered alike, but their corresponding parts point in oppo- 

 site directions. 



Fig. I. Stained in hsematoxylin. Section nearly at right angles to the duct of 

 Santorini in its passage through the intestinal walls (PI. XII., Fig. 2). The 

 narrower end is the surface of the papilla, exclusive of the mucous membrane, upon 

 which the duct opens. The wide end is toward the muscular coat, x 48. 



b. Muscularis mucasse cut obliquely. 



c. Sub-mucous connective tissue. 



d. Slender bundles of unstriped muscles rising toward the mucous surface, and 

 surrounding the duct. 



e. Cross section of the duct. 



f. A band dividing the lumen into two parts. 



Fig 2. Stained in hsematoxylin. A section like the preceding, but near the 

 terminatiort of the duct. x 48. 



a. Transverse section of the glands or crypts of Lieberkiihn. 



e. The lumen of the duct very greatly divided by anastomosing folds. 



g. Glands of Brunner. 



Figures 3 and 4 are similarly lettered, and are a small part of a transverse sec- 

 tion of the trunk of the duct of Wirsung, and both sections were made of the fresh 

 duct by means of Rutherford's freezing microtome. Both x 150. 



Fig. 3- Doubly stained in picrocarmine and hsematoxylin. 



a. Single layer of short columnar epithelium. 



b. Middle coat of the duct, very dense next the epithelium, and composed of 

 circular and longitudinal elastic tissue and blood vessels. 



c. External areolar coat composed mostly of circularly arranged connective tis- 

 sue, with many fine anastomosing elastic fibers. 



d. Cross section of two simple glands imbedded in the middle coat. 



e. Circular, elastic anastomosing fibers. 

 y. Cut ends of longitudinal elastic fibers. 



