502 



Erethizon, Cavia, Fiber, Mus rattus var. albus, Mus decumanus, Mus 

 musculus, Arctomys, Sciurus, Perodicticus, Ovis, Sus, and Homo. In 

 all these the secretion in the cells in the glands of Brunner stains 

 intensely in stronger muchaematein and mucicarmine and in none 

 of the genera mentioned are there any elements re- 

 sembling the dark tubules of the glands of Brunner of 

 the rabbit. 



It is, of course, obvious that the staining reactions do not furnish 

 proof that the glands of Brunner are mucous glands. In view of 

 Mayer's (97) observation that certain cells of the submaxillary gland 

 of Erinaceus, in the secretion of which no mucin occurs, stain strongly 

 with muchaematein , some conservatism must be exercised in the 

 interpretation of the results. No positive proof of their mucous nature 

 can be forthcoming until true microchemical reaction are devised for 

 the detection of the various mucins or until some one undertakes the 

 laborious task of isolating the lobules of the glands carefully by dis- 

 section and testing them for mucin by the ordinary chemical methods. 



The conclusion that these cells are mucous cells is, however, 

 supported by the recent work of Ponomareff in Pawlow's laboratory, 

 who found that the juice secreted by the proximal portion of the 

 duodenum when isolated by the Thiry-Pawlow method, was thick 

 and viscid in consistence. 



In the opossum (Didelphys) and in man, I have tested the solu- 

 bility of the contents of the cells of the glands of Brunner, using 

 strong muchaematein as an indicator, and have found that the se- 

 cretion can be completely extracted in a few hours from sublimate 

 bichromate material, by a saturated solution of barium hydroxide, or 

 a weak solution of potassium carbonate, but is insoluble in dilute 

 acids. These facts again point to the cell being a mucous cell. 



The question naturally arises as to whether the cell possesses in 

 any degree the morphological properties of a serous cell. The older 

 classification of glands into mucous and serous glands depended, in 

 the case of those glands the secretion of which could not be collected 

 and examined chemically, on the most superficial cytological characters, 

 as, for example, the shape of the nucleus and the relative intensity 

 of the staining of the cellular contents. These unsatisfactory criteria 

 are still employed by many histologists, to determine to which class 

 a given cell belongs. In recent years, however, a large number of 

 glands of known nature have been carefully investigated and it has 

 been shown that the serous glands which are engaged in the pro- 

 duction of large amounts of digestive ferments, present certain features 



