6 THE STBUCTURE OP THE GLANDS OF BBUNNEB 



in the cell of the several substances antecedent to the secretion. These are, briefly, 

 the zymogen granules which occupy the portion of the cell nearest the lumen, and 

 which are easily visible in the fresh cell, and the jwozymogen, a nucleoproteid sub- 

 stance probably of nuclear origin, remarkable for its staining power, located in the 

 base of the cell. The latter substance is often unequally distributed in the basal cyto- 

 plasm, giving rise to the appearance of radial striation, to which we owe the name 

 "basal filaments," first employed for the prozymogen of the glandula submaxillaris of 

 man by Solger (1896). 



Both of the substances mentioned above as characteristic constituents of the 

 zymogenic cell give microchemical reactions which enable one to distinguish them 

 with some confidence from the substances antecedent to secretion in a mucous cell. 

 The fact that the prozymogen is a nucleoproteid enables one to employ the micro- 

 chemical tests for iron and phosphorus for its identification, and no structure in any 

 cell should be likened to the basal filaments of the serous zymogenic cell unless it does 

 give a positive result with these tests. Furthermore, the granules of zymogen may be 

 positively distinguished from granules of mucigen by the fact that after careful 

 extraction with alcohol and ether in a Soxhlet apparatus to remove the lecithins, they 

 give a strong reaction by Macallum's method, showing the presence in them of organic 

 phosphorus as an elementary constituent. 



Mucous cells, on the other hand, do not contain any basal filaments, and the feeble 

 reaction for organic iron which they give indicates that they contain a relatively small 

 amount of diffused prozymogen. As pointed out above, the secretion granules of 

 mucous cells do not give any reaction for organic phosphorus. 



In addition to the above characters which we can apply in distinguishing serous 

 from mucous cells, we are able, owing to the researches of Paul Mayer (1896) on the 

 methods of staining mucus, to obtain, with much greater certainty than before, a 

 positive staining reaction for this substance in cells by employing the special solutions 

 of hsematein and carmine devised by him. 



Up to the present, there has been no attempt to apply these methods to the study 

 of the glands of Brunner. We must, therefore, compare these glands as regards the 

 structure, staining and microchemical reactions, and the changes exhibited by them in 

 different phases of functional activity, not only with the nearly adjacent gastric and 

 intestinal glands, but also with the many glands from other sources which have been 

 the subject of exact investigation. 



A point on which most writers agree is the great similarity between the glands of 

 Brunner and the pyloric glands of the stomach, although recent researches of 

 Kuczynski (1890), Castellant (1898), and others do not confirm the conclusions of 

 Bentkowski (1876) and Schiefferdecker (1884) that the two sorts of glands are iden- 

 tical. 



The question of the relationship of the glands of Brunner to the pyloric glands 

 is mainly interesting from the standpoint of the phylogenesis of the former. Although 



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