and the fact may account for the way in which the vicarious action of the liver and lung is stimulated.

Analyses of the gland tissue prove it to contain albumen, fat, and alkaline salts very freely, and about 68 per cent. of water. More recent analyses have shown that sugar is abundantly present. The coats of the liver are two, a serous and a fibrous, the capsule of Glisson, which its discoverer thought was muscular. Kiernan, whose famous investigations we have now to detail, regarded this capsule "to the liver what the piamater is to the brain ;" and as it forms sheaths for the vessels, fills the spaces between the lobules, and forms part of the lobular tissue, he divided it into vaginal, interlobular, and lobular portions. The branches of the hepatic artery and porta, which enter the liver, and those of the duct, which leave it, can be similarly named. As to whether the capsule invests the lobules, all physiologists are not agreed, Kiernan and Müller contending that they are a view very probably correct, as such a covering can be demonstrated in the pig and polar bear. Bowman, Beale, and others cannot find this capsule in man, so that the lobules are not distinctly isolated. As the larger branches of the porta run through the "portal canals," they are accompanied by branches of the artery, but their size, and of the duct, and are surrounded by loose areolar tissue, which allows them to collapse when cut across; not so the larger hepatic veins as they run towards the posterior thick edge of the gland, for no other vessels run with them, and if cut, they gape open, being fixed to the lobules around them. The hepatic veins may be said to begin by a vessel running through the centre of each lobule, "the intra-lobular." This ends in a vein along the base of each, "the sub-lobular," and these join the branches of the hepatic vein. The ultimate branches of the artery do not end in these hepatic veins, but in the lobular branches of the porta; and thus, besides supplying the nutrition of the gland,

they yield bile after they have fulfilled their primary function. To the sides of the hepatic ducts are appended several small cocal tubes, with very narrow openings into them. These are the vasa aberrantia, discovered by Weber, and they probably secrete mucus, or may act as "little gall-bladders."

Before we leave the subject of the vascular supply, it may be mentioned that Kiernan has shown there is no separate red and yellow tissue as once supposed, but that such appearances are due to congestion of different vessels. Thus, when he tied the cava-or, if the return of blood through it was obstructed by cardiac or pulmonary disease, the intralobular vein filled with bloodand the surrounding tissue being more empty, gave the

Diagram, altered from Kiernan, showing a Portal Canal containing a vaginal branch of the vena porta, which gives off interlobular branches; also a branch of the duct and artery which lie to the right side. Just after the bifurcation of the vein, its branches are removed to show the canal which contains areolar tissue. Several lobules are seen-those above being normal, those to the right congested in their caval branches, and those to the left in the rare condition of portal congestion.

appearance of a red centre on a yellow ground, whereas in portal congestion (a much rarer condition-only found in children), the centre was pale and the portal plexus engorged, presenting a yellow centre and red ground. The lobules (acini of Malpighi) are of a conical shape, with the base towards the surface of the liver or the portal and hepatic venous canals; the intralobular vein, running up like a midrib and branching laterally, gives them a foliate appearance. By transverse section they seem polyhedral, as if by mutual pressure.

Concerning the intimate structure of the lobules there is some obscurity, Kiernan stating them to consist of a capsule and plexuses of the vena portæ, artery, hepatic vein, and duct; and he appeals to the unravelled lobules in the left lateral ligament to support this view. There may also probably enter nerves and absorbents, which latter are remarkably abundant on the surface of the gland. Another disputed point is whether the secreting cells are placed among the capillaries, as believed by Handfield Jones, or are surrounded by a basement membrane continuous with the hepatic ducts, in the same way as all other glands-a view supported by Beale and most modern microscopists. The hepatic cells are of a

The Hepatic Cells.

somewhat rounded form, are well defined, and contain a nucleus and granules. They may be normally filled with bright, yellow pigment, or, in fatty liver, with numerous oil globules. Their diameter averages 1300. These cells are the active agents in secreting bile, which they select from the lobular plexus of the vena portæ, in which have previously terminated the lobular branches of the artery after they have ministered to nutrition. That the porta affords the greater part of the bile, was shown by Simon, who tied it, and there was no bile secreted; whereas ligature of the artery produced no such effect-but it led to fatty degeneration of

the whole organ in some recent experiments. The four cases recorded by Lieutaud, Huber, Abernethy, and Lawrence, where the vena portæ terminated in the cava, have been often urged as disproving that this vessel affords the bile; in Abernethy's case, however, the umbilical vein remained pervious, and branched out like the porta; and in the other instances there, very probably, was another vessel, more truly the porta, beginning in a cul de sac, and not receiving its ordinary tributaries. From this blood bile is separated, despite the fact that chemists cannot detect in it all its elements, as Glisson long ago expressed it, "peculiari colatorio."

The Bile is a most abundant secretion, about 54 ozs., including 2 of solids, being daily poured out, according to Bidder and Schmidt; and Dr. Budd quotes cases where, by tapping distended gall-bladders, a quantity corresponding to over a pint daily was removed from the human subject. More is secreted on a flesh diet, and the greatest quantity about 15 hours after a meal, As obtained from the gall-bladder, where it may have undergone some changes, it has a specific gravity of about 1.028, and is alkaline, or according to Boisson, usually neutral. It is greenish yellow, to a depth differing much if spread out, or in large quantity, and has a bitter taste, followed by a sweetish after-taste. Its odour is faint, and somewhat like musk. It is viscid, froths if shaken, and feels like soap between the fingers. Scourers use it as a detergent. It tardily decomposes, especially if strained of mucus, and is supposed to have antiseptic power on the fæces, which are very fetid in jaundice, no bile acting on them. Berzelius' often-quoted analysis found ox-gall to contain

Salts (chloride of sodium, phosphates, &c.) 12.6

1000.0

Free soda, the alkali present, and its salts are found in most animals, including fresh-water fishes; whereas, in those inhabiting sea-water, strange to say, the potash salts are substituted. The term "bilin" groups a number of substances of very different properties-for instance, the two peculiar acids which Strecker named cholic and choleic, corresponding respectively to the glycocholic and tauro-cholic acids of other chemists. The former contains nitrogen, but no sulphur; the latter contains both, and they are fatty acids united with soda sa a soap. As they cannot be found in the blood even after expiration of liver, they are supposed to be elaborated in the gland. The choleic or tauro-cholic acid, or its soda salt, hold the cholesterin dissolved. This fat has been described at page 44. Taurin, another body found in ox-gall, is a neutral crystalline substance, abounding in sulphur. Its formula is C4 H7 N O6 S2. Strecker has made it artificially from isethionate of ammonia. Biliphain, or the pigment, is as yet imperfectly known. Its tints vary much, owing, perhaps, to the degree of oxidation. By the addition of an alkali, Berzelius obtained from it " biliverdin," a matter identical with chlorophyl, the colouring matter of leaves. I believe it is almost identical with the urine-pigment, and both are but altered conditions of the hæmatin. Effused blood, as in a bruise, shows every tint which either bile or urine possesses, and all three contain iron. The green stools and pale skin, which result from the action of mercury, are due to the blood-cells being destroyed in the over-stimulated liver; and I regard the suddenly fatal effect which Moriarty termed mercurial erethism, to be due to such a sudden impoverishment of the blood. Carbonate of soda has an effect contrary to that of mercury, for it checks the secretion, and was thus advised in cases of gallstones by Prout, who, however, erroneously supposed it saponified the cholesterin.

Bile may be recognised by the following tests, which