250 EXCRETION. 



Mechanism of the Secretion and Discharge of Bile. 

 The liver lias no analogue in the glandular system, either in 

 its anatomy or its physiology. There is no gland in the 

 economy which we know to have two distinct functions, 

 such as the secretion of bile, and the production of certain 

 elements destined to be taken up by the current of blood 

 as it passes through. In other words, there is no organ in 

 the body which has at the same time the functions of an or- 

 dinary secreting gland and a ductless gland. If we regard 

 the liver-cells as the anatomical elements which prodiice the 

 bile, it is evident that their number is very much out of pro- 

 portion to the amount of bile secreted ; and the liver itself 

 is an organ of much greater size than it seems to us would 

 be required for the mere secretion of bile. "We explain this 

 disproportionate size by the fact that the liver has other 

 functions as a ductless gland. 



There is no gland in which the arrangement of secreting 

 tubes is the same as in the liver. It is hardly possible that 

 the intercellular plexus of fine tubes in the lobules should be 

 any thing but the plexus of origin, or the secreting portion 

 of the hepatic duct. These are certainly not blood-vessels, 

 and the only vessels that could have the appearance we have 

 described, except the bile-ducts, are the lymphatics ; but the 

 communication between these vessels and the excretory bile- 

 ducts, and the fact that they have been seen distended with 

 bile in icteric livers, are pretty conclusive evidence of their 

 nature. This arrangement, then, must be regarded as pe- 

 culiar to the liver, as the arrangement of a capillary plexus, 

 surrounded with cells and enveloped in a dilated extremity 

 of a secreting tube, is peculiar to the kidney and is found 

 in no other glandular organ. 



Do the liver-cells, situated outside of the plexus of origin 

 of the biliary duct, secrete the bile, which is taken up by 

 these delicate vessels and carried to the excretory biliary pas- 

 sages ? There are very good reasons for answering this ques- 

 tion in the affirmative ; though, if we do, we must recognize 



