OBSERVATIONS. 



vehicle for the conveyance of pancreatic secretion. In the 

 carnivorous Marsupial, as well as the Opossum and the 

 herbivorous Kangaroo, the pancreatic duct opens into 

 the common bile duct, as in the more primitive Mono- 

 tremes, whilst in the Koala and Wombat the condition — ■ 

 with an independent control — resembles Man more 

 closely. In the Koala a diverticulum is noted at the ter- 

 mination of the pancreatic duct. This animal is ex- 

 clusively an Eucalyptus-leaf eater. By means of the 

 reservoir, or diverticulum, a more perfect control of the 

 pancreatic secretion necessary for digestion is instituted. 

 In the Wombat and Kangaroo the entrance of the bile 

 duct is nearer to the duod-intest. flexure than to the 

 pyloric sphincter, whilst the reverse is noted in the Mono- 

 tremes and other Marsupials. The reason is not easy of 

 explanation. The duod-intest. flexure is to be regarded 

 as a constant. In all the animals described it corresponds 

 to the entrance of a direct branch of the right vagus. If 

 we regard the liver as an outgrowth of the duodenum, i.e., 

 of that portion of the gut whose dorsal mesentery (meso- 

 duodenum) represents comparatively a failure to de- 

 velop, then the site of the entrance of the duct will depend 

 on function. In the Wombat, e.g., the lining membrane 

 of the duodenum, down to the entrance of the duct, is 

 rugous and scarcely distinguishable from that of the 

 stomach. In this animal pancreatic and hepatic secre- 

 tions are not necessary till the food has almost traversed 

 the duodenum, i.e., almost immediately before the release 

 at the duod-intest. flexure of the food into the small gut, 

 m marked contrast to Koala and the Monotremes. As the 

 entrance of the vagus nerve at the duod-intest. flexure is 

 to be regarded as a constant, and the entrance of the duct 

 as a variable, it points to the importance in control of 

 the former. 



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