Structure of the liver.—The liver is com posed of lobules, of a connecting medium called Glisson's capsule, of the ramifications of the portal vein, hepatic duct, hepatic artery,. hepatic veins, lymphatics and nerves. For an accurate knowledge of these different structures, anatomy is indebted to the labours of Mr. Kiernan, to whose paper on " The Anatomy and Physiology of the Liver," con tained in the Philosophical Transactions for 1833, I shall have constant occasion to refer.
The small bodies (lobules, acini, corpuscula, glandular grains, granulations) of which the liver is composed were discovered by \Vepfer in the liver of the pig, about two years pre viously to the appearance of Malpighi's cele brated work, " De Viscerum Structurh Ex ercitatio Anatomica." Malpighi, unacquainted with Wepfer's discovery, examined and des cribed these bodies, both in animals and in man, under the name of lobules; and the lo bules he found to consist of smaller bodies, which he named acini. From some want of precision in Malpighi's descriptions, these two names have been confounded by the majority of succeeding anatomists ; the term lobules, with its distinctive application, has been disre garded and forgotten, and the term acini has been applied to those minute bodies of which the liver appears to be formed when examined beneath the microscope with a moderate power, —the acini of Malpighi. So great, indeed, is the confusion of terms even in 1838, that we find a justly celebrated authority in minute anatomy, Aliiller, in speaking of Kiernan's discovery, using the following words. " Ile" (Kiernan) " describes the lobules of the liver (which by other anatomists are termed acini)," and further on he observes : "his description of their form is indeed similar to that which we have given above of the acini of the mace rated liver of the polar bear." Now, setting aside the anachronism of discovery contained in the above quotation, which, as it appears to me, should have been, our description the acini of the polar bear is similar to his des cription the firm of the lobules, inasmuch as Kiernan's discovery was published in 1833, and Miiller's description of the macerated liver of the polar bear in 1835, I cannot but feel somewhat surprised in observing that Miller draws no line of distinction between the lo bules and their supposed constituents the acini. Nay, that he would seem to imply that all anatomists were acquainted with the lo bules, but that they assigned to them a dif ferent name. To prove that this is not the case, 1 quote a passage from his work upon the glands, published in 1830, in which he ex presses himself unable to distinguish the ele mentary structure of the liver either in man or in numerous other mammalia, for he says, " In homine, ut in plurimis mammalibus, in he patis superficie certa qumdain particularum 1 elementarium sive acinorum conformatio con 1 spiel non potest." Now the question to be de is the meaning which he assigns in this qyotation to the word acinorum ; does he mean that word the lobules or the acini of Mal hi ? The solution is simple; we have it in own words, and exhibited in a figure in which his peculiar views of the anatomy of the organ are clearly illustrated. In this figure,
(fig. 217, page 485,) he says, " Observantur fines ductuum biliferorum elongati, seu cylin driforines acini, in figuris ramosis et foliatis vane dispositi." So that the acini of Muller in 1830 are the terminations of the biliferous ducts, corresponding therefore with the acini of Malpighi, and the lobular biliary plexus of Kiernan. In 1835, as instanced in the " ma cerated liver of the polar bear," the acini of Midler are the lobuharw-of Malpighi and Kiernan.
Now seeing this indecision of opinion upon a subject of so great importance in relation to the proper understanding of the minute anatomy of the liver, I have deemed it my duty, in the service of anatomy, to place before my readers this cursory sketch of the history of the anatomy of the organ, and to establish the meaning of the terms I shall have occasion to use in des cribing its intimate structure. By the word lobules I shall mean, not the acini of anato mists, " which are anything or everything or nothing as the case may be," but the lobules of Malpighi and of Kiernan ;—by the word acini I shall indicate the smaller bodies of which the lobules appear to be composed (acini of Malpighi and of all writers); but which have been shewn by Kiernan to be the meshes of a plexus of biliary ducts, the " lobular biliary plexus." The lobules are small granular bodies of about the size of a millet-seed, of an irregular form, and presenting a number of rounded pro jecting processes upon their surface. When divided longitudinally (fig. 34) they have a foliated appearance, and transversely (jig. 35) an irregularly pentagonal or hexagonal outline with sharp or rounded angles in proportion to The smaller or greater quantity of Glisson's capsule contained within the liver. Each lobule is divided upon its exterior into a base and a capsular surface. The base (fig. 34, 4) corresponds with one extremity of the lobule, is flattened and rests upon an hepatic vein, which is thence named sub-lobular. The capsular surface (fig. 34, 3, 3) includes the rest of the periphery of the lobule, and has received its designation from being inclosed in a cellular capsule derived from the capsule of Glisson. In the centre of each lobule is a small vein, the intra-lobular (fig. 34, 5, 6, fig. 35, 3) which is formed by the conver gence of six or eight minute venules from the rounded processes situated upon the surface of the lobule. The intra-lobular vein thus con stituted takes its course through the centre of the longitudinal axis of the lobule, pierces the middle of its base, and opens into the sub-lo bular vein. The circumference of the lobule with the exception of its base, which is always closely attached to a sub-lobular vein, is con nected by means of its cellular capsule with the capsular surfaces of surrounding lobules. The cellular interval between the lobules is the in terlobular fissure (fig. 34, 8, fig. 35, 2), and the angular interstices formed by the appo sition of several lobules are the interlobular spaces (fig. 34, 9, fig. 35, 1).