THE LIVER. 157 



gland ; the difference depending chiefly upon differ- 

 ences in the structure of the epithelial layer which 

 lines them; this, in the larger ducts, is columnar, 

 and in the smaller, flattened. 



TECHNIQUE. 



Section of Gland of Dog. Small pieces of a perfectly 

 fresh gland are hardened in absolute alcohoL Very thin 

 sections are to be stained with haematoxylin and eosin, 

 and mounted in glycerin or balsam. One frequently 

 finds in a gland taken from a dog shortly after eating, 

 certain groups of alveoli with the cells in an active, others 

 with the cells in a resting, condition. 



THE LIVER. 



The liver presents three distinct elements of 

 structure: i. The cellular elements, which in form, 

 function, and arrangement, characterize the organ 

 the liver-cells or parenchyma. 2. The connective- 

 tissue framework the interstitial tissue, which sur- 

 rounds the organ as a capsule, and in its interior 

 supports the parenchyma and carries the larger 

 vessels. 3. The blood,- lymph,- and gall-vessels. 



The liver-cells are large, have the form of irregu- 

 lar, often somewhat elongated polyhedra ; they have 

 a granular body which frequently encloses granules 

 of pigment and larger or smaller droplets of fat ; 

 they have one or more vesicular nuclei and nucleoli. 

 When living, they are very soft, and the isolated 



