STRUCTURE OF THE LITER. 
305 
it to tlie liver, through, which it is distributed by the sub¬ 
divisions of this vessel, which acts the part of an artery 
(§ 267). Its branches proceed to the surfaces of the lobules, 
amidst which they form by mutual inosculation a tolerably 
regular network (fig. 170, b , b, b ); and from these branches a 
Fig. 170.— Transverse Section of three Lobules of the Liver; 
Showing the passage of the ramifications of the portal vessels from the network 
b b bb, which surrounds the lobules, towards the centre of each lobule, near 
which they become continuous with the rootlets a a a of the hepatic veins. 
set of capillary twigs proceeds inwards towards the centre of 
each lobule, traversing in their course its aggregation of 
secreting cells. These capillaries finally terminate in the 
rootlets of the hepatic veins, which diverge from the centre of 
each lobule (fig. 170, a, a , a), and which collect the blood 
that has traversed its capillary system, to transmit it through 
larger trunks into the Vena Cava (§ 266), and thence to the 
heart. The liver is also supplied with arterial blood by the 
Hepatic artery; but this seems to have for its function rather 
to nourish the solid tissues of the organ, than to supply the 
materials for secretion. The bile-ducts, which convey away 
the fluid that is elaborated by the hepatic cells, appear to form 
a network which surrounds the lobules, connecting them 
together and sending branches towards the interior of each 
(fig. 171). It is still doubtful, however, whether they extend 
through the entire substance of the lobules, and whether the 
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