ROBERT RUSSELL BENSLEY 39 



intestinal glands. In strong mucicarmine a similar result is obtained. The appear- 

 ance of the stored-up secretion when stained in muchsematein depends on the mode of 

 fixation and subsequent treatment. In the material fixed in alcoholic bichromate sub- 

 limate, imbedded in celloidin, sectioned and stained, without passing through water, 

 the secretion is in the form of minute granules of smaller size and less closely packed 

 than those in cells from the glands of Brunner of the opossum. In sections cut in 

 paraffin, fastened to the slide by the water method, and stained with muchaematein, 

 the secretion presents itself in the cell in the form of a coarse-meshed network. A 

 result similar to the latter is obtained with material fixed in 70 per cent, alcohol, except 

 that the meshes of the mucin network are much larger and are formed of thicker 

 trabeculae. 



In the ducts the cells are similar to those in the tubules and acini; indeed, many 

 of the ducts of the small lobules are indistinguishable from the other tubules forming 

 the lobules except by the method of tracing them out in serial sections. In the larger 

 ducts, however, and particularly in locally dilated portions of them, the cells, while 

 similar to those of the acini, tend to be more protoplasmic in nature. In such cells 

 the division of the secretion into two masses and the transverse band of cytoplasm 

 separating them are particularly obvious, and the cell presents a structure exactly 

 comparable to that shown in Fig. 2, which is taken from the cells of the opossum. 

 Zimmermann (1898) described and figured this condition in the cells of the glands of 

 Brunner of man, but did not recognize the fact that the outer clear zone near the 

 nucleus represented a second accumulation of secretion in that part of the cell. 



In passing from a duct to a side branch of it, there is a gradual transition from 

 this more cytoplasmic type of cell with spherical nucleus and two distinct masses of 

 secretion to the secretion-filled cell with a single continuous mass and crescentic 

 nucleus. 



A similar transition occurs in the tubules of the glands located in the mucosa. A 

 small gland from this source, together with a portion of the gland of Lieberkuhn into 

 which it opens, is shown in Fig. 12. In the gland of Lieberkuhn in this figure the 

 three typical elements cylindrical cells, goblet cells, and one Paneth cell are seen. 

 The change to the epithelium of Brunner's gland, as indicated by Schaffer (1898), is 

 abrupt, i. e., there are no intermediate stages between it and the intestinal epithelial 

 elements. In the Brunner's gland, however, a gradual transition is to be observed 

 from the cell with a narrow band of secretion along the lumen, a large mass of cyto- 

 plasm, and a spherical nucleus, to the secretion-filled cell with a crescentic, basally 

 situated nucleus. In some of the latter the remains of the band of cytoplasm separat- 

 ing the two primary masses of secretion may be clearly seen. 



A point of considerable interest is the occurrence in the human glands of Brunner 

 of a very small number of parietal cells exactly similar to those seen in the gastric 

 glands. These cells occur in very small numbers, but their structure is so character- 

 istic that there can be no doubt of the correctness of their identification. They 



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