505 



zymogen of the pancreatic, gastric, and salivary enzyme-secreting cells, 

 is indicated by the results obtained with Macallum's microchemical 

 tests for phosphorus and iron, both of which give intense reactions 

 in the substance of the basal deeply staining zone of the cell. These 

 reactions furnish proof that in the two kinds of cells of the rabbit's 

 glands of Brunner we are dealing with elements which are morpho- 

 logically and chemically (as regards their products) distinct from one 

 another ; one is a mucous cell, the other a serous cell, engaged prob- 

 ably in the preparation of an unknown digestive ferment. The serous 

 elements only occur, as far as present knowledge goes, in the glands 

 of Brunner of the rabbit. They certainly do not occur in any of the 

 species of mammals enumerated above. 



Bogomoletz has come to the conclusion that the two sorts of 

 cells are physiological phases of the same element. The only evidence 

 that he brings forward in favor of this extraordinary conclusion is his 

 observation that in his animals, stimulated by feeding, the mucous 

 cells appeared to be more numerous than in the fasting animals. One 

 may well ask in this connection if he has examined a sufficient number 

 of animals to determine the range of individual variation, or if he has 

 taken into consideration the variable relative numbers of the two kinds 

 of tubules at different distances from the stomach. 



My own observations agree with Castellant's that intermediate 

 stages do not occur. The serous tubules never at any stage of se- 

 cretion show a reaction for mucous with stronger muchaematein and 

 mucicarmine ; the mucous tubules show this reaction at all stages ; in 

 his Fig. 4, Taf. XXVII, Bogomoletz figures a serous tubule which, 

 as a result of carbohydrate feeding, has extruded all- its granules; 

 it nevertheless is sharply distinguished by its staining reaction from 

 the surrounding mucous tubules. 



The facts in connection with the rabbit's glands of Brunner may 

 be briefly summed up as follows: The glands of Brunner are mixed 

 glands (well compared by Castellant to the mixed glands of the 

 trachea) composed of mucous portions, the cells of which stain 

 strongly in stronger muchaematein, mucicarmine, etc.; and serous 

 portions, the cells of which do not stain in these solutions, but, on 

 the contrary, possess a rasially striated, basal zone containing a great 

 deal of the nucleoproteid prozymogen as may be demonstrated by the 

 microchemical reaction for iron and phosphorus, and an apical zone 

 filled with minute granules of zymogen. 



In all other mammals examined up to the present, the glands of 

 Brunner are pure mucous glands. This fact, of course, does not 



