46 THE STRUCTURE OF THE GLANDS OF BRUNNER 



ontogenetically the glands of Bmnner do not develop as downgrowtks of pyloric 

 glands, but develop simultaneously as independent elements in the duodenum. 

 Furthermore, if we assume this extremely early specification of the respective epithelial 

 elements of the stomach and intestine, how are we to explain the occurrence of glands 

 of Brunner in the horse at a point seven meters from the pylorus, and the relatively 

 great extent of the glands in the rabbit, sheep, pig, and man? It might, of course, be 

 urged that it is possible that in the rapid growth of the midgut, gastric epithelial 

 elements may be carried a considerable distance from the pylorus and there serve as 

 foci for the development of glands of Brunner. A similar argument might be 

 employed to explain the occurrence of characteristic intestinal epithelium in the 

 stomach, as observed by Schaffer (1897), Boeckelman (1902), and Hari (1901). Such 

 arguments are unanswerable because they do not admit of proof or disproof. 



It does not seem possible to me to reconcile the facts of the distribution of the 

 glands of Brunner and of their ontogenetic development with Oppel's theory that they 

 are developed as a further downward growth of the pyloric glands into the intestine. 

 For the present it would seem to be more probable that the glands of Brunner are 

 caenogenetic structures developed in mammals from the hypoblast of the midgut. The 

 occurrence of serous tubules in the glands of Brunner of the rabbit is evidence of a 

 new functional need in the intestine. 



Oppel (1899) has, however, promised further explanations of his theory to adapt 

 it to the facts of distribution, and in the meantime these may be awaited with interest. 



In conclusion I should like to emphasize the fact that I do not regard the evidence 

 brought forward in this investigation to show that the glands of Brunner are mucous 

 glands as at all excluding the possibility that they also form small quantities of 

 digestive ferments. The latter, however, if they are formed, are not present in suffi- 

 cient quantities to appear in the cells as definite formed elements recognizable by the 

 microscopic or microchemical means at our disposal. 



BIBLIOGRAPHY 



BENTKOWSKY, K. " Beitrage zur Histologie der Schleimhaut des Magens und des Duodenums." 



Gaz. lek., Warszawa, 1876 (quoted after Oppel). 

 BENSLEY, R. R. " The Histology and Physiology of the Gastric Glands." Proc. Canad. Inst., 



Toronto, Vol. I (1896), pp. 11-16. 



" The Structure of the Mammalian Gastric Glands." Quart. Jour. Micr. Soc., London, 



N. S., Vol. XLI (1898), pp. 361-89. 



" The Cardiac Glands of Mammals." Am. Jour. Anat., Baltimore, Vol. II (1902), pp. 



105-56. 



BERDAL, H. Nouveaux tUments d'histologie normale. 4th ed. Paris : A. Maloine, 1894. 

 BERNARD, C. " M6moire sur le pancreas et sur le r6le du sac pancreatique dans les ph6nomenes 



digestives." Supplement aux Compt. rend. Acad. d. sc., Paris, Vol. I (1856), pp. 379- 



663 (quoted after Castellant). 



322 



