Chap, x] DIGESTIVE APPAEATUS IN THE ANIMAL SERIES. 169 



Such is, schematically, the elementary structure of the gly- 

 cogenous hepatic organ, forming in itself the major part of the 

 liver. But by the side of 

 this organ, the former of 

 sugar, and which we must 

 consider as a gland without 

 excretory conduit, a san- 

 guineous gland, there is 

 another organ, the secreter of 

 bile, constituting, schemati- 

 cally also, a gland of clus- 

 tering form. It consists of 

 small groups of glandular 

 csecums, agglomerated in the 

 fashion of fern leaves, and 

 dispersed along the branches 

 of a greatly ramified excretory 

 conduit, into which they open 

 and secrete. The wall of the 

 glands and of the conduits 

 is clothed with epithelial 

 cells of divers form. 



Between the glycogenous elements and the biliary elements 

 there is only a relation of juxtaposition. The superior verte- 

 brates offer us, therefore, here an example of organic inter- 

 mingling such as we find so many of in the inferior animals. 

 In them the liver has separated itself from the renal glands, 

 with which it is confounded in certain invertebrates; but it 

 remains still joined to the glycogenical gland. If, as some 

 partisans of the doctrine of evolution believe, the present 

 superior vertebrate is not yet the last term of organic progress 

 and differentiation on the earth, the two glandular apparatus 

 may separate in the future in the more perfect being destined 

 to arrive as successor. 



The hepatic biliary conduit or choledochal canal, debouches into 



Fig. 12. 



CapiUaiy network of the liver, irgected Avm 

 the super-hepatic veins. 



