178 American Quarterly Microscopical Journal. 



one opening into the intestine with the ductus choledochus,. 

 and duct of Santorini for the one opening independently. 



4. The pancreas in the cat is covered on both sides by 

 peritoneum. 



5. Occasionally there occurs a reservoir for the pancreas, 

 like the gall-bladder for the liver, which communicates freely 

 with the duct of Wirsung. The presence of this anomaly 

 seems to have been noted but once before, and then, as in the 

 present case, in the domestic cat. 



6. The pancreatic ducts are composed of a lining of columnar 

 epithelium, a middle layer of elastic tissue, and an external 

 coat of areolar tissue or a tunica adventitia. The vascular 

 supply is very dense, especially in the middle coat next the 

 epithelium. 



The structure is like that of gland-ducts in general as given 

 by Robin (16), and somewhat comparable to the elastic type of 

 blood-vessels as given by Strieker (37,200) and Ranvier (26,561). 



7. As the ductus choledochus and duct of Wirsung pass 

 through the longitudinal muscular coat of the duodenum, 

 they are provided by it with a common, and each with a special 

 sphincter. 



8. The ductus choledochus and the duct of Wirsung 

 empty into a common reservoir, the Ampulla of Vater, situated 

 between the muscular and mucous coats of the duodenum. 



9. The Ampulla, and the terminal part of the ducts of 

 Wirsung and Santorini, and the ductus choledochus are pro- 

 vided with valvular folds whose free edges are directed to7vard 

 the orifices in each case. 



10. The structure of the mucous membrane of the Ampulla 

 is like that of the terminal part of the duct of Wirsung and 

 the ductus choledochus, and not like that of the duodenum; 

 hence, it should be considered, in the cat at least, as an append- 

 age of the ducts and not of the duodenal mucous membrane. 



LIST OF WORKS REFERRED TO.* 



1. Bernard, M. Claude; Memoir sur le pancreas. Supple'm. aut Comptes Ren- 

 dus, I., p. 379, (1856). 



2. Brown-Sequard; Journal de la physiologie de riiomme et des animaux 

 Vol. V. 



3. Chauveau ; Anatomie compare'e des animaux domestiques. Paris, 1871. 



♦All the works referred to in the above list were consulted except 7, 28, 29, 33, 34, 35, 37, 3S, 

 39, and these are known by quotations from them in the others. 



