THE LIVER. 73 



network. (Indicate the columns of liver-cells in PI. XV., Fig. 3.) The radiate arrangement is 

 best seen in the columns of cells nearest the hepatic vein. Between these cell-columns narrow 

 spaces exist, which indicate the position of the intra-lobular blood-capillaries. In an unin- 

 jected liver the capillaries appear relatively small. Search between lobules for a transverse section 

 of a branch of the portal or interlobular vein, hepatic artery, and bile-duct, all of which run to- 

 gether and are surrounded by connective tissue, which constitutes part of Glisson's capsule. 

 (Indicate these structures in PI. XVI., Fig. 2.) The channels in which they lie are known as 

 portal canals. Fix the bile-duct in a field and examine with (H). The bile-duct may be easily 

 distinguished on account of its being lined by low, columnar, almost cubical, epithelium. In its 

 wall may be found circularly disposed non-striped muscular fibres, and if a particularly large 

 bile-duct be found, the walls may be seen to contain sections of mucous glands, which secrete 

 mucin and add it to the bile as it passes along the bile-ducts. The portal vein is large, and 

 neither it nor the hepatic artery present anything peculiar in their characters. Surrounding 

 these is the connective tissue of the capsule of Glisson. The tissue is more or less lamellar ; 

 the bundles run in various directions, and between them are flattened connective-tissue cor- 

 puscles stained blue. Note its amount. A very small amount of intra-lobular connective tissue 

 is to be found ; it is best seen around the hepatic veinlet. 



Study the liver-cells (H). They are polygonal or cubical cells of nearly the same size, 

 uniformly granular in appearance, are devoid of an envelope, and contain a spherical and 

 deeply-stained nucleus, though some may contain two nuclei, and rare examples are met with 

 without a nucleus. The cells at the outer part are usually slightly smaller than the others. 

 Note particularly the network formed by these cells, and how they intertwine with the blood- 

 capillaries between them. Each cell contains a dense infra-cellular and intra-nuclear plexus 

 of fibrils, which give it a granular appearance (PL XV. Fig. 4). See p. 1 3, where these points 

 are alluded to. 



Stain similar sections with logwood and picrocarmine, and mount them in Farrant's solu- 

 tion. In this medium the finer details can be more carefully studied. 



Mount an unstained section, which has been steeped in osmic acid, in Farrant's solution. 

 This is an excellent method for sharpening the outline of the various parts. Any oil-globules 

 present within the liver-cells are blackened, osmic acid being an excellent test for the presence 

 of fatty infiltration or degeneration. 



BLOOD-VESSELS OF THE LIVER. 



PREPARATION. The blood-vessels of the liver of a rabbit or other animal may be in- 

 jected either from the portal or hepatic vein, or both. It is well to examine a liver whose 

 vessels are injected either with a red or a blue carmine mass, or if desired the portal vein 

 may be injected with a blue mass and the hepatic vein with a red, or vice versa. In injecting 

 from the portal vein the mass should flow freely from the hepatic vein, which should then 

 be ligatured, and then the blood-vessels will fill properly. One must judge of the amount 

 to be pressed into the vessels by the appearance and colour of the liver-lobules. Compare 

 p. Hi for general directions. Harden the organ in two per cent, potassic bichromate and then 

 in alcohol, or place the liver at once in alcohol. Make sections, and mount them, stained or 

 unstained, in dammar. 



EXAMINATION (L). Select a lobule which has been cut transversely, and observe the 

 origin of the hepatic vein in its centre, and at the periphery of the lobule sections of the portal 

 vein. Within the lobule, and connecting these two vessels, observe the blood-capillaries 



L 



