The small bodies of which the liver is composed, and which have been known to anatomists, since the time of Malpighi, by the various names of acini, lobules, corpuscula, glandular grains and granulations, were discovered by Wepfer in the liver of the pig about two years before the appearance of Malpighi’s celebrated work De Viscerum Structurâ Exercitatio Anatomica. Wepfer contented himself with indicating the existence of the lobules in one animal*. Malpighi, unacquainted, as it would appear, with Wepfer’s discovery, commenced his researches on the lower animals, and pursuing them through every class, ascertained that a similar arrangement of structure existed in all. In shell-fish, he says†, the lobules resemble bunches of grapes, and are composed of small conglobate bodies, like grape-stones, which are connected together by means of central vessels. He observed a similar conformation in lizards, in which animals the edges and interstices of the lobules are denoted by dark points. After describing the liver of the ferret, mouse, squirrel and ox, he informs us that the human liver also is composed of lobules, which represent a congeries of clusters, and may be rendered apparent by boilig the organ and taking off its external coat. The lobules, he says, are appended to the extremities of the vessels contained in Glisson’s capsule, and are invested in membranous tunics connected together by transverse bands. They vary in form in different animals: in fishes they resemble the leaf of the trefoil; in some animals they are pisiform; in the cat they have six or more sides; and they assume the hexagonal form in the human liver. Biliary calculi found in the liver were thought by Malpighi to be petrified lobules. Respecting the structure of the lobules, Malpighi informs us, that the glandular acini of which these bodies are composed have six or more sides; that they are connected by their vessels and bound together by proper membranes, the interstices between them being very apparent in the lower animals and in fishes, but obscure in the higher animals. Malpighi, having thus convinced himself of the existence of glandular acini in the liver, similar to those already known in the pancreas and thymus, classed this organ among the conglomerate glands*; but as he gave no representations by plates of the important discoveries he made, some difficulty has been experienced in understanding his descriptions†. Thus, he speaks of two kinds of bodies, of lobules and of acini: anatomists‡, however, having used these terms indifferently to designate the same objects, have not understood them in the sense in which they were employed by Malpighi. Malpighi’s discoveries in the anatomy of the liver are almost confined to the ascertaining its lobulated structure: he was unacquainted with the form of the lobules, with their peculiar arrangement around the hepatic veins, and with the manner in which the vessels are distributed; nor has much light been thrown on these points by the researches of more modern anatomists, although very considerable additions have been lately made to our knowledge of the ultimate structure of the liver and of other glands by the important discoveries of Müller*.