ARRANGEMENT OF THE BILIARY DUCTS. 
377 
naturally to examine other points in the minute anatomy of the liver. Some of 
these observations accord with the notions previously entertained, while others are 
at variance with the opinions usually held. In this communication I wish to restrict 
myself, as far as possible, to the consideration of the anatomical arrangement of the 
biliary ducts and the relation which these bear to the secreting cells of the liver, and 
shall therefore only allude to some of the more general points incidentally. It may, 
however, be desirable to offer a few remarks upon the nature of the lobule as it 
occurs in the livers of different animals. 
Lobules . — If by a lobule is understood a perfectly circumscribed portion of hepatic 
substance containing within itself all the structural elements necessary for the 
formation of bile, which can be separated from adjacent portions, the only livers in 
which such lobules are to be demonstrated, so far as is yet known, are those of the 
pig, and Polar bear (according to Muller). In the pig each lobule possesses a 
distinct capsule of its own, and can be readily separated from its neighbours. The 
capsule is perforated by branches of the vessels and duct which are distributed in its 
interior. This arrangement of separate lobules would permit a considerable amount 
of movement upon each other, whilst the capsule would have the effect of preventing 
undue engorgement and distension of each individual lobule, a provision which 
seems to be especially needed in the pig. 
There is not this division into distinct and separate lobules in the livers of other 
animals which I have examined. As numerous authors have described, there is a 
sort of mapping out of small spaces produced by the arrangement of the smallest 
vessels and ducts, to be seen more or less distinctly in the livers of all vertebrate 
animals ; but it is impossible to separate these apparently isolated portions from 
each other, without tearing the hepatic tissue of which they are composed, thereby 
leaving a rough and jagged surface. In fact, while the lobules of the pig’s liver are 
provided each with its separate capsule, and in many instances separated from its 
neighbours by a certain quantity of areolar tissue, and the branches of the vessels and 
duct for their supply, the so-called lobules of the liver of man and other animals are 
only separated from each other at certain points by the fissures in which the portal 
vessels and duct lie. There is no distinct capsule, nor areolar, nor fibrous tissue 
between them, and the capillaries and the cell-containing network of one lobule are 
continuous at various points with those of its neighbours. 
Most writers seem to have regarded the pig’s liver as the type of structure to 
which all others should be referred ; but it seems more natural to look upon this 
beautiful liver as exceptional, and bearing the same relation in structural peculiarity 
to the livers of other animals, as the much-divided kidney of the porpoise bears to 
the corresponding solid organ of man and most other mammalia. 
It may be said that in a physiological point of view the livers of all vertebrate 
animals are composed of lobules, but in a strictly anatomical sense this term must be 
restricted to the livers of the pig and Polar bear. 
