l62 NORMAL HISTOLOGY. 



preserved, as hardened cells will be seen in the following 

 preparations. 



Sections of Pigs Liver. A small piece of pig's liver 

 should be hardened in Miiller's fluid and alcohol, and 

 very thin sections made near the surface, both parallel 

 and at right angles to it, so as to cut the lobules, which 

 are quite regularly arranged at the surface, in different 

 directions. The sections are stained double and mounted 

 in balsam. The lobules being here surrounded by toler- 

 ably distinct layers of connective tissue, in which the 

 interlobular vessels run, the lobular structure is quite 

 evident, and the pictures obtained by sections in different 

 directions are easy of interpretation. 



Sections of Human Liver. Sections are made from a 

 bit of human liver hardened as above, stained double 

 and mounted in balsam. Here the lobular structure is 

 very ill-defined, because of the small amount of con- 

 nective tissue between the lobules, and for the recogni- 

 tion of the different parts of the latter we are largely 

 dependent upon the determination of the different 

 kinds of blood-vessels, since these always bear a definite 

 relation to the lobules. It is to be remembered that the 

 branches of the portal vein^lie only in the periphery of 

 the lobules, that they are usually accompanied by other 

 vessels besides capillaries, and are in most cases sur- 

 rounded by a greater or less amount of connective tissue. 

 The central vein, on the other hand, is usually unasso- 

 ciated with other dissimilar vessels, except capillaries, 

 and surrounded only by a scarcely appreciable amount 

 of connective tissue. 



Injected Liver. The general arrangement of the 



