The Ampulla of Vater. 125 



two ducts. He figured the pancreas and the two ducts, with 

 their mode of opening; viz., the larger into the ampulla of 

 Vater, with the ductus choledochus, and the smaller independ- 

 ently into the duodenum nearer the pylorus than the ampulla 

 of Vater (28 and i, 383). The description and figures of San- 

 torini seem to have been forgotten or ignored down to the 

 time of CI. Bernard, in 1846 (i, 383). At this period, the opin- 

 ion was universal that the presence, in the adult, of two ducts 

 opening separately was anomalous; and, although Meckel had 

 shown conclusively in 1835 that two ducts constantly exist in 

 the human foetus, he supposed that one of them normally atro- 

 phied, and that its presence in the adult was merely an un- 

 usual persistence of the foetal condition (20, 316, 317, 474 and 

 476). He was followed in this opinion by all anatomists. 



Bernard called attention to the constant presence of two 

 ducts in the adult, and his observations, which were very nu- 

 merous, together with those of several other great anatomists, 

 have shown that the absence of two ducts is the exceptional 

 condition in the adult human being (18, 1 137; i, 385 , 22, 509; 29; 

 10,331 and 38). It is necessary to state that some modern 

 anatomists and physiologists do not coincide with the above 

 opinion, although they recognize the occasional presence of a 

 second duct. Among these may be mentioned Quain (25, 

 II., 396), Gray (14, 793), Colin (7, I., 794), Hyde Salter (27, 85), 

 and Owen (23, 497). Prof. Owen looks upon the anomalous (?) 

 second duct as an indication of the homology of the so-called 

 head of the human pancreas with the duodenal pancreas of the 

 lower mammalia. 



With reference to the mammalia below man, Marshall 

 (^9) 595) has made the important generalization that the nor- 

 mal number of pancreatic ducts, opening independently into 

 the duodenum, is two. Milne Edwards (22, 510), in confirma- 

 tion of this idea, says: "Until lately, it was thought that with 

 all the ruminants there was but a single pancreatic trunk, but 

 it is now known that in the ox there are ordinarily two ducts 

 opening separately, and sometimes even three; and it is prob- 

 able that careful investigation will reveal a similar condition 

 in many other mammals." This idea is further supported by' 

 the fact that with the animals most fully studied there have 

 been found normally two pancreatic ducts, at some time of 

 life at least. This is the case with man, the horse, dog, cat, and 

 many others (i, 383; 22, 508; 23, 492; 27, etc.). 



