120 NATUUAI. THEOLOOi^. 



death — wherein the gastric jui^e, not having been weakened 

 by disease, retains its activity — it has been known to eat a 

 hole through the bowel which contains it.^ How nice is 

 this discrimination of action, yet how necessary. 



But to return to our hydraulics. 



IV. The gall-bladder is a very remarkable contrivance. 

 It is the reservoir of a canal. It does not form the channel 

 itself, that iS; the direct communication between the liver 

 and the intestine, which is by another passage, namely, the 

 ductus hepaticus. continued under the name of the ductus 

 communis ; but it lies adjacent to this channel, joining it hy 

 a duct of its own, the ductus cysticus : by which structure 

 it is enabled, as occasion may require, to add its contents to 

 and increase the flow of bile into the duodenum. And the 

 position of the gall-bladder is such as to apply this structure 

 to the best advantage. In its natural situation, it touches 

 the exterior surface of the stomach, and consequently is com- 

 pressed by the distention of that vessel ; the effect of which 

 compression is to force out from the bag, and send into the 

 duodenum, an extraordinary quantity of bile, to meet the 

 extraordinary demand which the repletion of the stomach 

 by food is about to occasion.! Cheselden describes^ the 

 gall-bladder as seated against the duodenum, and thereby 

 liable to have its fluid pressed out by the passage of the 

 aliment through that cavity, which likewise will have the 

 effect of causing it to be received into the intestine at a right 

 time and in a due proportion. 



There may be other purposes answered by this contriv- 

 ance, and it is probable that there are. The contents of 

 the gall-bladder are not exactly of the same kind as what 

 passes from the liver through the direct passage. § It is 

 possible that the gall may be changed, and for some pur- 

 poses meliorated, by keeping. 



The entrance of the gall-duct into the duodenum fur 



* Phil. Trans., vol. 62, p. 447. t Keill's Anat., p. C4. 



t Anat., p. 164. ^ KelU, (from Malpighius,) p. 63. 



