536 THE TISSUES. 



The precise connection of the ducts between the lobules, and the 

 tubes just mentioned, is as follows: Numerous finer branches leave 

 the small trunk of the duct, in the spaces between the islets, and 

 pass towards the secreting cells, without branching or anastomosing 

 with each other; and, pursuing a tortuous course around the 

 branches of the portal vein, pass at once to the cell-containing net- 

 work of tubes just described, and with which jthey are continuous. 

 Near to the point where the duct joins the network of cell-contain- 

 ing tubes, it becomes very much narrowed; being frequently 



Fig. 370. 



Communications of interlobular ducts, a. With the cell-containing tubular network, b. Part of 

 tubes containing cells filled with oil and free oil-globules, c. Narrowest portions of the ducts (pig.) 

 The shaded parts are filled with injection. Magnified 215 diameters. (Dr. Beetle.) 



of an inch, or even less, in diameter in the uninjected state. Fig. 

 370 represents the narrowest ducts in the pig, and Fig. 371 those 

 in the human liver. 



The epithelium lining the minute ducts between the islets (^Jois 

 of an inch in diameter) is of the simple scaly variety; its cells being 

 far smaller than the secreting cells in the network before described, 

 or only about ^Vtr f an mcn i Q diameter. Fig. 372 shows their 

 size compared with that of the former. It terminates abruptly 

 where the secreting cells begin. In the ducts 3 to %\Q of an inch 

 in diameter, the epithelium is more conoidal ; and it becomes com- 

 pletely so in those above y^ of an inch. The latter also have a 

 dense layer of areolar tissue (corium) externally to the epithelium 

 and basement-membrane. The ductus communis choledochus, and 

 the cystic duct, have both a mucous layer and a submucous areolar 

 layer; the former containing a few smooth muscular fibres, but no 



