ROBERT RUSSELL BENSLEY 37 



one located in the mucous membrane, the other in the submucosa. The former, except 

 for the interruptions caused by the lymphatic nodules, form an almost continuous layer 

 occupying exclusively the outer half of the mucous membrane, the inner half being 

 occupied by the glands of Lieberkuhn and the villi. The lobulation is not very strik- 

 ing, although, as shown in Fig. 14, the groups of glands which empty into a single 

 duct may be easily recognized. These groups are somewhat elliptical or triangular in 

 section, the long axes being perpendicular to the surface of the mucous membrane. 

 From the inner end of each group one, two, or more ducts emerge, which either join 

 to form a single duct, or open separately into the same gland of Lieberktihn or into 

 side branches of the latter. 



Each group is composed of a cluster of tubules, which are the primary branches 

 of the duct, and of the numerous ramifications of the latter. The most prevalent 

 mode of branching is as follows: the duct divides near its origin into a tassel-like 

 group of wavy tubules which pass outward in the direction of the lamina muscularis 

 mucosa3. Each of these tubules gives off on all sides radial descending branches, 

 which in their turn, after a very short course, subdivide and terminate either as short 

 tubules of the same diameter as the parent tubules, or as slightly expanded, elongated, 

 pear-shaped acini. Some of the groups extend through the interrupted muscularis 

 mucosse to form lobules or groups of lobules in the inner layer of the tela submucosa. 



The group of glands in the submucosa is composed of elliptical and fusiform 

 lobules of small size, placed with their long axes nearly parallel to the free surface of 

 the duodenum. These lobules are confined to the inner layer of the tela submucosa, 

 there being usually an outer layer nearest the tunica muscularis free from glands and 

 containing aggregations of adipose tissue. The lobules are not all independent of one 

 another, several being often strung out along the same tortuous duct. Again, many of 

 the larger lobules are subdivided into marginal lappets which represent the groups of 

 branches clustered around each of the radial branches of the principal duct of the lobule. 



The lobules of the submucous group of glands are derived from three sources. 

 Some consist of the continuation into the submucosa of groups of tubules, the main 

 bulk of which is located in the mucous membrane. In a second series a tubule, after 

 giving off a number of branches in the mucous membrane, passes through an aperture 

 in the lamina muscularis mucosae, and gives rise to one or several lobules in the submu- 

 cosa. In the third series a duct of variable size passes directly from the bottom or side 

 of a gland of Lieberkuhn to the submucosa, where it terminates in a lobule or a series 

 of lobules. In the pars superior duodeni of the cases examined the second, in the pars 

 horizoutalis and pars ascendens of the organ the third, was the prevailing type. 



The point of junction with the gland of Lieberkuhn is a variable one, but I have 

 not observed, in either of the two duodena examined, a single instance of the duct 

 reaching the free surface independently of the intestinal glands, although that such 

 cases do occur, is shown by the observations of Schaffer and Castellant. 



As regards the distribution of the glands of Bruuner in man, the observations of 



