GO Anatomy and Physiology. 



tinct membrane exist round each lobule ? Valentin is in- 

 duced to admit the existence of this membrane, and Krause 

 affirms that he has been able to see it. We too are induced 

 to believe in its existence, not as surrounding each lobule, 

 but as encircling each islet situated within the meshes of the 

 capillaries. The capillaries would then be outside the proper 

 substance of the liver, and would expand only on the surface 

 of the lobules : the islets lying between the meshes would, in 

 consequence, present the culs-de-sac of glands, which in the 

 liver adopt a polygonal form. In short in no gland do we 

 see the blood vessels penetrate into the parenchyma itself, and 

 we cannot suppose an anomaly in the case of the liver. We 

 are not therefore to consider the lobule or acinus of the liver 

 as analogus to the culs-de-sac of lobulated glands, but these 

 last are in reality separated by the polygonal islets which the 

 capillaries enclose. 



As to the origin of the biliary canalicles, we do not yet 

 know whether they commence by a radicle from each islet, 

 or by a common trunk in the lobule : further, we do not 

 know whether, as in the inferior animals, these radicles are 

 provided with a special membrane, though it is probable they 

 are. For the rest, the hepatic cellules are in general very 

 coherent in the inferior animals, through the medium of an 

 inter-cellular substance which connects them, and this ought 

 to be enough to account for their absence in the bile. Thus 

 to sum up, each lobule is composed of a number of islets 

 pressed against each other, which gives them their polygonal 

 form. Provided with a special membrane, like the culs-de- 

 sac of all other glands, they are encircled by capillary vessels. 

 The portal vein encircles the lobules : the hepatic vein reaches 

 their centre accompanied probably by a biliary canalicle, the 

 origin of which is still unknown. No portion of the blood 

 vessels penetrates the real substance of the liver. 



In conclusion, we must express our regret at finding some 

 authors deny facts, such as the existence of hepatic cellules, 



