THE PANCEEATIC DUCTS IN THE DOa. 



BY 



DANIEL G. REVELL, B. A., M. B., Tor., 

 Associate in Anatomy, University of Chicago^ from the Hull Laboratory of Anatomy. 



With 14 Text Figukes. 



Of recent years it has been established that in nearly all mammals 

 the pancreas is double in origin^ one anlage arising from the duodenum, 

 dorsal and isolated, the other ventral and connected with the bile- 

 duct. Correspondingly there are two ducts which nearly always inter- 

 communicate within that part of the gland which is formed by the 

 union of the two anlages. That part of either duct which lies between 

 this communication and the bowel wall may remain small, or disappear 

 either wholly or more usually only in part. As a rule the part that 

 disappears is that adjoining the bowel and only one pancreatic orifice 

 is then present in the adult type. All these modifications of the 

 embryonic condition may occur even within one species of animal, but 

 one of them is most frequent, and is known as the " normal " for that 

 species. To determine this normal and also the occurrence and fre- 

 quency of other types, it is necessary to examine many individuals, 

 more or fewer according to the inconstancy or constancy of the normal. 

 The curves (Fig. 3) of relative frequency of the various types observed 

 in the instances examined by the author show how fallacious may be 

 inferences 'drawn from meagre early statistics. 



The beginnings of the duct-radicles in the acini have been carefully 

 studied by many observers since Langerhans's publication in 1869, the 

 findings of the various workers being reviewed by Oppel, 1900. 

 Magiarski has reconstructed the lobule of the pancreas. Much atten- 

 tion has also been given to the development of the pancreas, by which 

 the variations of the ducts are explained. The following communica- 

 tion deals with the two ducts, their relation and distribution in the dog. 



Methods. — The topography was studied in dissections ^ and trans- 



J 75cc. of formalin injected in to the A. carotis communis when the dog is killed will 

 so harden the tissues in two hours that the form and relations of the viscera can be 

 readily ascertained by ordinary dissection, one examination made in this way giving 

 clearer, more exact and correct knowledge than many made without hardening. The 



