PANCREAS OF THE PIG 223 



to be struck by the similarity of the process here described to 

 the growth of an artery from the primitive plexus (Thoma 70). 

 The suggestion immediately occurs that the pancreatic duct 

 appears, like an artery, because there is a hydrostatic necessity 

 for it; in other words, because fluid is passing through the plexus^ 



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... % .. 





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Fig. 8 Pancreas and (kiodcnum of a pig foetus 40 mm. long, ventral view. 

 Partial injection of ducts, from stomach. First suggestion of a duct-channel run- 

 ning through the capillary net. /), duodenum; Pij, pylorus; £", entrance of duct 

 into duodenum; Di. beginning formation of duct-channel. X 17. 



and demands a passage way. There is some slight evidence in 

 favor of this hypothesis; the new channel becomes larger and 

 larger toward its outlet, as more and more capillaries enter it; 

 again, the pancreatic cells contain zymogen granules as early as 

 20 mm., as shown by examining the fresh tissue in salt solution. 

 Both these facts hint at the presence of a secretion, and there- 



