AND DEVELOPMENT OF THE LIVER. 
125 
that I have obtained any satisfactory results ; a better prospect of success is I be- 
lieve afforded by the mode of examination I have already described, in which actual 
recognition of structure, and not appearance only, is accepted as decisive evidence 
of the presence of the duct. Before proceeding to describe the results of my dissec- 
tions of the ducts, I may state what appears to me to be an unexceptionable conclu- 
sion drawn from injection of the hepatic ducts in the Pig. Here, when a successful 
injection has been made in the double mode so successfully employed by Mr. Bowman, 
the lobules are seen to be definitely marked out by yellow lines or tracts, corresponding 
to and exactly occupying the “ fissures” and “ spaces.” In several beautiful specimens 
thus prepared, the yellow line presents a most defined edge, and does not trench in 
the slightest degree upon the interior of the lobule ; from this I cannot but conclude 
that no tubular duct penetrates the secreting structure ; for were such the case, it is 
impossible that the injection should not, to some extent at least, have coloured the 
substance of the lobule. Hitherto I believe no particular description has been given 
of the structure of the minute branches of the hepatic duct ; the larger ones are 
known to have a columnar epithelium resting on a subjacent basement membrane, 
which is strengthened by an investing layer of fibrous tissue. In the minute branches, 
which seem to be approaching their termination, and which sometimes can be isolated 
and examined in the most satisfactory manner, the epithelial particles are remarkably 
modified; they can scarcely be said to exist as separate individuals, but rather their 
nuclei, which are often large and distinct, are set close together in a subgranular or 
homogeneous basis-substance. In ducts where this condition of epithelium exists, 
there is seldom any distinct trace of basement membrane, the margin, though suffi- 
ciently even, yet exhibiting the bulging outlines of the component nuclei; still less is 
there any proper fibrous coat, though the ducts may be more or less involved in the 
filamentary expansions of the capsule of Glisson. Ducts of this character have usually 
a diameter of about iwo^h of an inch ; they can be sometimes followed for a consi- 
derable distance, without being seen to give off any branches, or to diminish much in 
calibre. Their mode of termination is various ; several have been distinctly seen to 
terminate by rounded and closed extremities, which have nearly the same diameter 
as the duct itself ; others seem to lose their tubular character, their nuclei become 
less closely set together, and the uniting substance more faintly granular and indefi- 
nite ; the duct in short gradually ceases, losing all determinate structure. In some of 
rather minute size, 3-2^0 o oth of an inch in diameter, the exterior form remains 
distinct, but the canal is almost obliterated by the close approximation of the nuclei 
of the opposite walls. These structures now described I believe to be truly the 
terminal branches of the hepatic duct, from which they certainly originate ; they seem 
gradually to lay aside the several component tissues of the larger ducts, the fibrous 
coat blending with the ramifications of Glisson’s capsule, the basement membrane 
imperceptibly ceasing, and the epithelium being resolved at last into its simple fun- 
damental nuclei. The above account has been taken chiefly from examination of 
