PANCREAS OF MAMMALIA. 



497 



381 



the detached condition which prevails in some lower mammals : the 

 splenic portion, ib. pa, contracts near the spleen, sp. The thick 

 upper border receives in a groove or canal the splenic artery and 

 vein. The main dnct tra- 

 verses the substance of the 

 {Hand nearer the lower than 



C_7 



the upper border ; it is com- 

 monly joined near its end 

 by the duct from the lesser 

 pancreas, or ' head,' h : but 

 the homology of this with the 

 duodenal pancreas of lower 

 mammals and birds is some- 

 times instructively exempli- 

 fied by the independent 

 entry of its duct into the 

 duodenum, as in fig. 382, B, 



In the ordinary arrangement the duct ot the larger, b, unites 



d 



Pancreas, exposed by raising the stomach 



CXLTIII". 



Human. 



C. 



382 



with that of the lesser pancreas, and the common pancreatic duct 

 penetrating the duodenal tunics joins the common bile-duct at the 

 ampulla, before entering the intestine, as shown in fig. 376. In the 

 variety B, the duct of the larger 

 pancreas, &, alone has this rela- 

 tion with the gall-duct, a : in a 

 rarer variety, C, the common 

 duct of the pancreas, b, opens 

 distinctly from the common 

 bile-duct, a : in a still rarer 

 anomalv, D, the duct of the 



V * 



lesser pancreas receives tribu- 

 taries from the larger pancreas, 

 becoming a tube of equal size, 

 and the two, b, c, unite, before 

 the usual junction with the bile- 

 duct, a. The proper coat of 

 the pancreatic duct is a firm 

 tissue of interwoven, mainly 

 longitudinal, fibres ; with an 

 outer loose areolar covering and 

 an epithelial lining. This, in 

 the minute beginnings of the carrying system, consists of co- 

 lumnar cells so packed that their ends next the duct-cavity pre- 

 sent a penta- or hexa-gonal pavement, fig. 383. The initial ductlets 

 arise from the interspaces of the follicular or cell-structure of the 

 VOL. in, K K 



Varieties in the termination of the pancreatic duct 

 Man. ccxxxi. 



