30 THE STRUCTURE OF THE GLANDS OF BRUNNEB 



work. In such rnuchsematein preparations the relations of the two masses of secre- 

 tion may be readily studied. In some of the cells the two masses may be quite distinct ; 

 in others there is a deeply staining mass on the free border of the cell, another in the 

 interior, and a faintly staining neck of secretion connecting them. Sometimes the 

 proximal mass is subdivided into two secondary masses, one on each side of the 

 nucleus. In all cases the proximal mass of secretion is closely applied to the surface 

 of the nucleus. 



None of the cells in my material was so filled with secretion that the nucleus was 

 flattened by compression. 



The cells of the pyloric glands for a short distance (about 6 mm.) above the 

 sphincter are exactly like the glands of Brunner, but exhibit a progressive transition 

 to the type of gland cell which is characteristic of the rest of the pyloric area. In the 

 latter the cells in form and size, as well as in the position and shape of their nuclei, are 

 very similar to the cells of the glands of Brunner. The differences between the cells 

 from the two sources are concerned only with the amount of secretion in the cell. In 

 the pyloric-gland cells the basal cytoplasm extends to very near the free border. The 

 mass of secretion along the free border (distal mass) is much narrower than in the 

 glands of Brunner. The proximal mass in the interior of the cell is represented by a 

 few scattered granules or is absent altogether. The same differences thus occur 

 between the glands of Brunner and the pyloric glands of the stomach as have been 

 already remarked in the mink and the porcupine. 



The Myomorpha are represented in the writer's material by the mouse, white rat, 

 dormouse (Muscardinus avellanarius), deer mouse (Peromyscus), and muskrat (Fiber 

 zibethicus). All of these are distinguished from the forms already discussed in this 

 paper by the specialized condition of the stomach. This specialization is carried to 

 the highest degree in the muskrat and deer mouse, in which the gastric glands have 

 disappeared from the whole stomach with the exception of a circular area of fundus 

 glands at the summit of the curvatura major, the pyloric glands being represented only 

 by a very narrow zone, in Fiber a few millimeters in width, around the pyloric orifice. 

 In Mus the specialization is not so great as in Fiber and Peromyscus, the whole right 

 division of the stomach being occupied by gastric glands. In the dormouse the 

 stomach is also specialized, but as the specialization is of a different kind, the com- 

 parison with the other genera as regards its degree cannot be made. In the dormouse 

 this specialization consists in the formation of a bulb-like dilatation containing fundus 

 glands, at the point where the oesophagus joins the stomach. 



In all these genera the glands of Brunner are of small extent and present obvious 

 differences from the pyloric glands, more particularly in the muskrat, deer mouse, and 

 dormouse. 



In the muskrat, the glands begin abruptly on the distal side of the pyloric 

 sphincter as a thick mass completely filling the tela submucosa of the intestine and 

 extending into the submucosa underneath the small pyloric-gland area; most of which 



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