PHYSIOLOGICAL ANATOMY OF THE LIVER 359 



the ox and the horse, and composed of non-striated muscular fibres 

 interlacing with each other in every direction. 



In addition to the bloodvessels just described, the liver receives 

 venous blood from vessels that have been called accessory portal veins, 

 coming from the gastro-hepatic omentum, the surface of the gall- 

 bladder, the diaphragm and from the anterior abdominal walls. These 

 vessels penetrate at different points on the surface of the liver, and they 

 may serve as derivatives when the circulation through the portal vein is 

 obstructed. 



Structure of a Lobule of the Liver. Each hepatic lobule, bounded 

 and more or less distinctly separated from the others by the interlobular 

 vessels, contains bloodvessels, radicles of the hepatic ducts and the 

 so-called hepatic cells. The arrangement of the bloodvessels has just 

 been described; but in all preparations made by artificial injection, the 

 space occupied by the bloodvessels is exaggerated by excessive disten- 

 tion, and the difficulties in the study of the relations of the ducts and 

 the liver-cells are thereby much increased. 



Liver-cells. If a scraping from the cut surface of a fresh liver is 

 examined with a moderately high magnifying power, the field of view 

 will be found filled with rounded, ovoid or irregularly-polygonal cells, 

 measuring y^Vo" to TTroo" ^ an ^ nc ^ (16 to 25 /*) in diameter. In their 

 natural condition they are more frequently ovoid than polygonal ; and 

 when they have the latter form the corners are always rounded. These 

 cells present one and occasionally two nuclei, sometimes with and some- 

 times without nucleoli. The presence of small pigmentary granules 

 gives to the cells a peculiar and characteristic appearance ; and in addi- 

 tion, nearly all contain a few granules or small globules of fat. Some- 

 times the fatty and pigmentary granules are so abundant as to obscure 

 the nuclei. The cells also contain more or less glycogen in the form of 

 granules surrounding the nuclei. As regards intimate structure, the 

 liver-cells present a delicate honeycomb network in the meshes of which 

 are contained the granules just described. They have no distinct cell- 

 walls, and they adhere together by portions of their surface so as to 

 form rows, or columns radiating from the centre of each lobule (see 

 Plate VII, Fig. 6). 



Arrangement of the Bile-ducts in the Lobules. In the substance 

 of the lobules is a fine and regular network of vessels of nearly uniform 

 size, about yo'ilFo ^ an mcn ( 2 or 3 /*) m diameter, which surround the 

 liver-cells, each cell lying in a space bounded by inosculating branches 

 of these canals. This plexus is independent of the bloodvessels, and 

 it seems to enclose in its meshes each individual cell, extending from the 

 periphery of the lobule to the intralobular vein. These canals or inter- 



