THE LIVER. SECRETION OF BILE. 583 



caudatus" is its " lobular appendage ;" but the left " lateral" lobe, with its 

 " lobular appendage," is altogether undeveloped. 



624. In examining into the minute structure of the Liver, we shall first con- 

 ,ider the peculiarities in the arrangement of its Bloodvessels and Ducts ; for our 

 present knowledge of which we are almost entirely indebted to Mr. Kiernan, 1 

 whose account of them will be here followed ; his researches having been con- 

 firmed in all essential particulars by other Anatomists. When the Liver is 

 closely examined with the naked eye, it is seen to be made up of a great number 

 of small granular bodies, about the size of a millet-seed, of an irregular form, 

 and presenting a number of rounded projecting processes upon their surfaces. 

 These are commonly termed lobules, although by some Anatomists they are 

 spoken of as acini. When divided longitudinally, they have a somewhat foli- 

 ated appearance (Fig. 152), arising from the distribution of the Hepatic Vein ; 

 which, passing into the centre of each divi- 

 sion, is termed the intralobul&r vein. The 

 exterior of each lobule is covered by a pro- 

 cess of the "capsule of Glisson;" which is 

 very dense in the Pig and other animals, 

 but is so thin as to be almost undistin- 

 guishable in the Human liver. Its substance 

 is composed of the minute ramifications of 

 the before-mentioned vessels, arranged in the 

 manner preset- tly to be described; the spaces 

 between whu , are filled with a parenchyma, 



Composed Of nucleated Cells, like those Connection of the Lobules of the Liver with 



Shown in Fig. 157, B. The Structure of " Hepatic Vein: 1, trunk of the vein; 2,2, 



, , , , 9 .' .IT lobules depending from its branches, like leaies 



each lobule, then, gives US the essential cha- O n a tree; the centre of each being occupied by 



racters Of the whole gland. The lobules, a venous twig, the Intralobular Vein. 



when transversely divided, are usually found 



to present somewhat of a pentagonal or a hexagonal shape, the angles being 

 somewhat rounded, so as to form a series of passages or wfcrlobular spaces 

 (Fig. 159); in these lie the branches of the Vena Portge, and of the Hepatic 

 Artery and Duct, from which are derived the plexuses that compose the lobules. 

 Each lobule, when examined with the microscope, is found to be apparently 

 composed of numerous minute bodies of yellowish color, and of various forms, 

 connected together by vessels; to these the name of acini was given by Mal- 

 pighi ; and to these, if they deserve a name, it ought to be restricted. They 

 will be presently shown, however, to be nothing else than the irregular islets, 

 left between the meshes of the plexus formed by the ultimate ramifications of 

 the portal vein. The Vena Portae, which is formed by the convergence of the 

 veins that return the blood from the chylopoietic viscera, probably also receives 

 the blood which is conveyed to the liver for the purpose of nutrition by the 

 Hepatic Artery. Like an artery, it gradually subdivides into smaller and yet 

 smaller branches; and at last it forms a plexus of vessels, which lie in the inter- 

 lobular spaces, and spread with the freest inosculation throughout the entire 

 Liver. To these vessels, the name of mfcrlobular Veins was given by Mr. 

 Kiernan. They ramify in the capsules of the lobules, covering with their 

 ramifications the whole external surface of these; and then enter their substance. 

 When they enter the lobules, they are termed lobular veins; and the plexus 

 formed by their convergence from the circumference of each lobule towards its 

 centre (where their ultimate ramifications terminate in those of the intralobular 

 or hepatic vein), is designated as the lobular venous plexus (Fig. 153). In the 

 islets of this plexus (the acini of Malpighi), the ramifications of the hepatic 



1 "Philosophical Transactions," 1833. 



