— co -. 
STRUCTURE OF THE LIVER. 1071 
the vena cava, as it leaves the liver, and immediately before it pierces the diaphragm. 
The smaller branches open into it lower down. The branches of the portal difter from 
those of the hepatic vein in the following points :—(1) The branches of the portal vein 
converge towards the portal fissure; those of the hepatic veins towards the vena cava. 
(2) On section of the liver the portal branches are always seen to be accompanied by 
branches of the hepatic artery and duct, whilst those of the hepatic vein run alone ; and 
(3) owing to the loose wrapping of connective tissue (Glisson’s capsule) which surrounds 
the branches of the portal vein, their walls fall away from the liver substance when 
empty, and collapse, whilst the hepatic veins, which are destitute of this wrapping, are 
closely connected to the liver substance, and consequently do not collapse so easily as the 
portal vessels. 
The lymphatics of the liver are arranged in a superficial and a deep set :—1. The superficial 
set lies beneath the peritonewn on both (a) the visceral and (b) the parietal surfaces of the organ. 
(a) The vessels from the visceral surface pass chiefly to the hepatic glands, which lie between “the 
layers of the lesser omentum; but some of them, from the back part of this surface on the right 
lobe, join the lumbar glands, and others from the back part of the left lobe, go to the coeliac glands. 
(b) The vessels from the parietal surface pass in various directions. Those from the adjacent 
parts of the right and left lobes pass up in the falciform ligament, and pierce the diaphragm to 
reach the anterior mediastinal glands, and end finally in the 1 ‘ight lymphatic duct. Those from 
the anterior part of this surface pass down to the inferior aspect, and join the hepatic glands 
in the lesser omentum. The lymphatics from the back of the right lobe pierce the diaphragm 
between the layers of the coronary ligament, and join some glands in the thorax around the upper 
end of the inferior cava; others run in the right lateral ‘ligament, and either pierce the dia- 
phragm and end in the anterior mediastinal glands, or, turning down, join the coeliac group. 
2. The deep lymphatics accompany either (a) the portal or (6) the hepatic veins. (a) The 
former set pass out through the portal fissure and join the hepatic glands, the efferent vessels of 
which join the caelac glands, (b) Those which accompany the hepatic veins pierce the diaphragm 
with the vena cava, and havi ing formed connexions with the group of glands at its upper end, 
within the thorax, turn down and j join the beginning of the thoracic duet. 
The nerves, which are chiefly of the non- -medullated variety, are derived from the left 
pneumogastric and the solar plexus of the sympathetic. The branches of the former pass from 
the front of the stomach up between the layers of the lesser omentum to the liver. Those of 
the latter pass from the cceliac plexus along the hepatic artery—forming the hepatic plexus—to 
the portal fissure, where they enter the liver with the blood-vessels. They are distributed chiefly 
to the walls of the vessels and of the bile-ducts. 
STRUCTURE OF THE LIVER. 
The liver is invested by an outer serous coat (tunica serosa), already described in 
connexion with the peritoneum. Within this is a thin areolar coat (capsula fibrosa 
Glissonil) of delicate fibrous tissue, which is most evident where the serous coat is absent. 
In the neighbourhood of the portal fissure it is particularly abundant, and bere, under 
the name of Glisson’s capsule, it surrounds the vessels entering the fissure, and accom- 
panies them through the portal canals in the liver substance. This coat is continuous 
with the fine areolar tissue which pervades the liver, surrounding its lobules and holding 
them together. 
The liver substance proper is made up of an enormous number of small lobules, 45th 
to ,!;th inch (1 to 2 mm.) in diameter, closely packed, and held together by a small 
amount of connective tissue. In man the lobules are not completely separated from one 
another all round their circumference, but coalesce in places; the reverse is the case in 
certain animals. These lobules are arranged around the branches of the hepatic veins, 
to form the compact mass of the liver, in the following manner :— 
The hepatic veins radiate from the inferior vena cava, at the back of the liver, to all 
parts of the organ, dividing and re-dividing until the vessels are reduced to branches of a 
very small size, known as sublobular veins—the whole arrangement may be aptly com- 
pared so far to the branching of a tree (Fig. 720, A). On all sides there open into these 
sublobular veins numerous closely-crowded vessels—the intralobular or central veins 
(which, following our simile, may be compared to an enormous number of thorns grow- 
ing out on all sides from the sublobular twigs of the tree). On each of these little 
central veins there is impaled, as it were, a lobule (which is more or less like a conical 
bullet in shape—Purser). These little conical lobules, with their intralobular or central 
veins running through them, are so numerous and so closely packed together, that they 
give rise to the practically solid liver tissue. 
As regards the veins: The lobules are surrounded by the interlobular branches of 
the portal vein, from which numerous twigs enter the lobule on all sides, and converging, 
