42 THE STRUCTURE OF THE GLANDS OF BBUNNER 



cells from the following sources: mucous cells from the submaxillary, sublingual, 

 lingual, palatine, tracheal, and oesophageal glands; the gastric epithelial cells; the 

 cells of the cardiac glands of the stomach ; the cells of the pyloric glands ; the neck 

 chief cells of the f undus glands of the stomach ; goblet cells ; and the cells of the 

 glands of Brunner (except the dark tubules of the rabbit's glands). It docs not slain 

 the secretion in cells from the following sources ; demilune cells of the salivary glands ; 

 the cells of the parotid gland; the serous cells of the submaxillary or sublingual 

 glands; the serous portions of the palatine glands and tracheal glands; nor the fer- 

 ment-forming cells of the pancreas and of the fundus glands of the stomach. 



An idea of the intensity of the resulting color got by this method may be obtained 

 from Figs. 14 and 15, which are half-tone reproductions of photomicrographs of sec- 

 tions of the human glands of Brunner stained in stronger muchsematein. An equally 

 strong stain was obtained in the glands of Brunner of all the animals examined, with 

 the single exception of the sheep, in which the secretion stained positively, but more 

 slowly and with less intensity. 



For mucicarmine the conditions of success are that the solution be employed 

 undiluted in the form of Mayer's stock solution, and that it be freshly prepared. In 

 the writer's hands the solution, after twenty-four to forty-eight hours, refuses to stain 

 and cannot be filtered. The solution is to be applied in exactly the same way as 

 muchsematein and gives similar results, both on the glands of Brunner and on the other 

 glands mentioned. In view of the results in the several glands of known character 

 which are enumerated above, we are justified in concluding that the solutions employed 

 as recommended do stain mucous cells and do not stain serous (zymogenic) cells. 



In view of Mayer's observation that the clear cells of the submaxillary gland of 

 the hedgehog, which do not secrete mucin, stain with muchfematein, some conservatism 

 must, however, be exercised in interpreting the results. It is obvious that no absolute 

 proof of the mucous character of the glands of Bruuner can be brought forward until 

 a positive microchemical test for the various mucins is devised, or until some one 

 undertakes and completes the laborious task of isolating the lobules of Brunner's 

 glands carefully by dissection and studying them by the ordinary macrochemical 

 methods. The mucous nature of the glands is, however, supported by the recent work 

 of Ponomareff (1902) in Pawlow's laboratory, who isolated a portion of the duodenum 

 by Thiry's method as modified by Pawlow. The juice obtained was colorless, thick, 

 and very viscid. 



Further evidence is, however, afforded by the tests applied to determine the 

 solubility of the secretion in various solutions. This is accomplished by using muchse- 

 matein as an indicator. The sections are fastened to the slide by the water method, 

 and are placed in the solution to be tested. From time to time a section is taken out, 

 washed thoroughly, and stained by muchsematein. By this means it has been deter- 

 mined that the contents of the cells of the glands of Brunner of the opossum and of 

 man are soluble in weak alkaline solution, insoluble in 5 per cent, solution of hydro- 



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