404 



OF SECRETION. 



tinct nucleus ; and it is usually around this, that the yellowish hue of 

 the cell is the deepest. The cavity of the cell is chiefly occupied by- 

 biliary matter, much of which is in the condition of fine granular parti- 

 cles too minute to be measured. In the midst of these, there are usually 



Horizontal section of tw 



tralobular veins; 2, 2, trunks of biliary ducts, p 

 interlobular tissue; 4, parenchyma of the lobul 



bowing the interlobular plexus of biliary ducts : 1, 1, in- 

 ng from the plexus which traverses the lobules ; 3, 

 es. 



one or two large adipose globules, or five or six small ones (Fig. 122) ; 

 but the amount of this fatty matter is liable to great variation ( 754). 



The biliary matter which these cells contain, 

 Fig. 122. marks them out as the real agents in the se- 



%creting process ; this process consisting, it is 

 evident, in the growth of the hepatic cells, 

 which, in the course of their development, 

 eliminate from the blood the biliary matter, 

 for which they have a special affinity. The 



^^^M^WSJT 5 mode in which the particles thus eliminated, 



are discharged into the hepatic ducts, to be 



by them conveyed to the intestine, cannot be understood, until the rela- 

 tion between the secreting cells and the ultimate ramifications of the 

 ducts shall have been more precisely determined. 



724. The Bile which has been secreted by the hepatic cells, and 

 which has found its way into the ramifications of the hepatic ducts, 

 may be directly conveyed by the trunk of the latter into the intestine, 

 or it may regurgitate along the cystic duct into the gall-bladder. It is 

 probable that the secreting process is constantly going on ; although, 

 as in other cases, it may vary in its degree of activity at different 

 times. When the process of digestion is taking place, and the small 

 intestine is filled with chyme, there is probably an uninterrupted flow 

 of bile into its cavity ; but when the intestine is empty, the bile seems 

 not to be admitted into it, but rather to flow back into the gall-bladder, 

 in which it is stored up, as in a reservoir, until the time when it may 

 be needed. In this reservoir it undergoes a certain degree of concen- 

 tration, by the absorption of its watery part ; and it also becomes 

 mixed with a large proportion of mucus, which is secreted by the walls 

 of the gall-bladder. As the analyses of Bile have been chiefly made 

 upon the fluid obtained from this receptacle, they probably over-esti- 

 mate the proportion of solid matter contained in this secretion ; which 



