KOBEET RUSSELL BENSLEY 



Brunner of man with hsematoxylin ; and concluded that the mucus which they secreted 

 differed materially from that formed by goblet cells and by the salivary glands. 



Castellant (1898) concluded that the glands of Brunner could not be regarded as 

 mucous glands, but should rather be compared with the pyloric peptic glands. He 

 added, however, that the differences, considerable in the rat, slight in the dog, 

 between the glands of Brunner and the pyloric glands, led him to believe that their 

 secretion was not identical, but that the glands of Brunner secreted a special digestive 

 liquid. 



A similar view of the nature of the Brunner's glands is taken by von Ebner 

 (1899), who bases his conclusions as to their non-mucous nature on the failure to stain 

 them with Mayer's mucicarmine and muchsematein. 



The lack of unanimity of opinion as to the nature of the glands of Brunner is to 

 be traced to a number of causes. Of the first importance, in this connection, is the 

 resemblance of the glands of Brunner to the pyloric glands of the stomach which 

 Heidenhain (1870, 1878) and his pupils had shown, apparently conclusively, on physio- 

 logical grounds, to be pepsin-forming serous glands. This conclusion, as far as the 

 pyloric glands are concerned, has been shown to be erroneous by the writer (1896, 

 1898) on histological and microchemical grounds, and for chemical reasons by Glassner 

 (1902), who has confirmed the conclusion of the writer that the glands of the pyloric 

 region do not contain pepsin -zymogen (propepsin). A second cause which has con- 

 tributed to this confusion of results is the lack of precision in our morphological 

 criteria for distinguishing between mucous and serous cells. In the absence of specific 

 knowledge of the chemistry of the secretion of a gland, a mucous gland in which 

 the nucleus was spherical and the cytoplasm abundant would invariably, according to 

 the older ideas, be interpreted as a serous gland. 



The classification of glands into mucous glands and serous glands is at the best a 

 mere makeshift. When we have decided that a gland is a serous gland, we may still 

 know absolutely nothing about the nature of its secretion, beyond the fact that it does 

 not contain a mucin. There are, however, a number of serous glands the secretion of 

 which it is possible to collect and examine chemically, and which are known to be 

 largely engaged in the secretion of digestive enzymes. To this category belong certain 

 of the serous salivary glands, the pancreas, and the chief cells of the gastric glands. 

 In recent years these zymogenic glands have been the subject of numerous investiga- 

 tions, as a result of which we now have a tolerably exact knowledge of their structure 

 in the different phases of physiological activity. The serous glands have been inves- 

 tigated by Solger (1894, 1896, 1898), Erik Mailer (1895), Zimmermann (1898), Gar- 

 nier (1900), and others; the pancreas, by Eberth and Muller (1892), Mouret (1895), 

 Macallum (1891, 1895, 1898), and Matthews (1899); the gastric glands, by Bensley, 

 (1896, 1898, 1902), Zimmermann (1898), Theohari (1899), and Cade (1901). 



These researches show that serous glands which are known to be zymogenic in 

 function, whatever their source, have certain features in common, due to the presence 



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