534 



THE TISSUES. 



These cells are so arranged in the islets as to appear to form a 

 network by the mere apposition of their flat surfaces, without any 

 intermediate substance or investing coat. The meshes of the net- 

 work are mere perforations and passages for the capillary plexus 

 and the commencement of the hepatic vein, and are of course con- 

 formed to their diameters. The cells are generally arranged in 

 from one to three rows (rarely four or five), to form the network 

 itself (Fig. 118), so that the meshes are thus y^^ to 5 Jo of an inch 

 apart. Their true relation to the minute hepatic ducts will be 

 specified on page 536. 



The hepatic ducts had been traced to the margin of the hepatic 

 islets by Kolliker, but not into them ; and he suggests that the finest 

 ducts are open at their extremity, and abut on the hepatic cells, as 

 shown by Fig. 118. Far more probable, however, was the view of 

 Prof. Leidy on this subject, viz., that the hepatic ducts commence 

 in the substance of the islets as a network of distinct tubules, lined 

 by a basement-membrane and an epithelium. 1 (Figs. 366 and 367.) 



Fig. 366. 



Fig. 367. 



Transverse section of a lobule of the human liver, 

 showing the reticular arrangement of the bile-ducts ; 

 with some of the branches of the hepatic vein in the 

 centre, and those of the portal system at the periphery. 



A small portion of the preceding section, 

 more highly magnified, showing the secret- 

 ing cells within the tubes. (Leidy.) 



But Dr. Beale's recent investigations on this point seem quite con- 

 clusive. He finds the hepatic cells to be arranged in lines radiating 

 from the centre of the lobule, as shown in Fig. 368 ; though pre- 

 cisely this appearance is presented only when the section is made 

 at right angles to the small twig of the hepatic vein in the centre of 



1 Researches into the Comparative Structure of the Liver, American Journal of 

 the Medical Sciences. Jan. 1848. 



