328 



EMBRYOLOGY. 



A further increase in the size of the liver is due to the fact that 

 from the hepatic cylinders united into a network new lateral 

 branches grow forth and undergo anastomosis, whereby new meshes 

 are being continually formed. 



Herewith the essential parts of the liver are present in the fun- 

 dament : (1) the secretory liver-cells and the bile-ducts, (2) the 

 peritoneal covering and the suspensory apparatus, both of which are- 



rig. 1S7. — Section through the fundament of the liver of a Chick on ^e sixth day of incubation.. 



Slightly enlarged. 

 k, Network of hepatic cylinders ; Ic^, hepatic cylinder cut crosswise ; g, blood-vessels ; gis, wall 

 of the blood-vessel (endothelium) ; bl, blood-corpuscles ; bf, peritoneal covering of the liver. 



derived from the ventral mesentery. The changes in these parts 

 which lead to the permanent condition are now to be considered. 



The epithelium of the ducts and the secretory liver-parenchyma 

 are derived from the two hepatic tubes and from the network of 

 hepatic cylinders, — products of the entoblast. 



The parts of the two primitive liver-tubes first formed become the- 

 right and left ductus hepatici. In .Birds and Mammals these open 

 at first, as we have seen, into the duodenum close together ; then at 

 their place of entrance there is formed a small evagination of the- 



