392 
DR. LIONEL BEALE ON THE 
and Lophius. In Plate XV. figs. 32, 33, 34 & 35, some of the ducts and portions of 
the network are represented. The mode of branching of the ducts, and an anasto- 
mosis, is shown in fig. 33. Even in the very fatty liver of the cod, I once traced the 
continuity of the ducts and the wide tubular network distended with cells containing 
oil and free oil-globules. 
In injecting the livers of fish it is necessary to dilute the injecting fluid with weak 
spirit, or it will not penetrate to the finest branches. Often the particles of the 
injection accumulate in some of the finer ducts, forming what appears to be a rounded 
and slightly dilated extremity, for the further continuity of the tube cannot in all 
cases be seen. Indeed so perfect is the resemblance, that it is only by examining 
numerous different specimens that one becomes convinced of the fallacy. 
In all four classes of vertebrata, I have seen both in injected, and also in uninjected 
specimens, the communications between the finest ducts and the cell-containing net- 
work. Of the nature of this continuity there can, I think, be no doubt. I cannot 
conceive any other explanation of the facts I have observed, or of the appearances I 
have copied from my preparations. The observations upon uninjected specimens, 
shown in Plate XV. figs. 18, 20 &21, were made in 1854, many months before I had 
succeeded in injecting the ducts. 
In all vertebrate animals which I have examined, the duct becomes much narrowed 
just before it becomes continuous with the tubes of the network in which the secret- 
ing cells lie. The arrangement of the most minute ducts varies somewhat in different 
animals, as has been described. In some they form a network of very narrow tubes, 
continuous with those in which the liver-cells are contained ; in others these com- 
munications are excessively few in number; while in some, I do not think they exist 
at all. But I would not express myself positively upon this point, for I feel persuaded 
that in the most perfect injection which I have yet made, the tninute ducts have not 
all been injected, and from a cursory examination of these preparations alone, only a 
very imperfect idea of the number of the ducts or of the beauty of their arrangement 
and relation to the other structural elements of the liver in the natural state of the 
organ, can be formed. 
Diameter of the finest ducts . — The diameter of the finest ducts can only be obtained 
approximatively ; for when not injected, they can only be demonstrated distinctly in 
fortunate specimens, and aie probably somewhat narrower than during life. When 
it)jected, on the other hand, they are usually distended, and sometimes to a very 
considerable extent. 
In the pig, the smallest branches containing a little injection are not more than 
the-gTj-ooth of an inch in diameter; in the human subject, about ^ 5^0 q th ; in the seal, 
- 3 o-o-(jth ; in sotne fishes, not more than -gTroofh. 
The diameter of the cavity of the tube and the total diameter of ducts of different 
sizes are shown in the following Table: — 
