ARRANGEMENT OF THE BILIARY DUCTS. 
391 
communicating' at intervals with each other (cell-containing network), were seen 
separated by wide clear spaces (capillaries) intervening between them. In this liver the 
very fine ducts were injected to a greater extent than can be effected usually, and a 
network of anastomosing branches round the portal vein is shown in the drawing. 
Even in this specimen the injection has not entered many of the small branches of 
the duct. The injection ran very readily, and in some places distended the tubes of 
the cell-containing network to a very great extent, in which case of course the cleat- 
intervening space (capillary) was obliterated. 
Birds . — In the fowl and in the turkey, the ducts form a network continuous with 
the network in which the liver-cells lie; but the tubes are of much less diameter 
than those of the latter. I have been able to trace the continuity in the livers of 
the two birds above referred to, by injection. The abundance of epithelium in the 
ducts of most birds forms a great obstacle to the passage of the injection, and the 
excessive thinness of the capillary vessels prevents the preliminary injection of much 
water without rupture. 
In the chick of tlie fifteenth and also in that of the twenty-first day, the continuity 
between the ducts and cell-containing network is shown in Plate XV. figs. 29 & 30. 
Reptiles . — In the newt {Triton cristatus), the course of the ducts, in an uninjected 
specimen, is shown in fig. 31. The tubes in which the hepatic cells lie were much 
stretched and pressed in these specimens. I have not yet been able to inject the 
ducts of the newt or frog. 
I have succeeded in making a good injection of the ducts of the adder, and was 
enabled to trace their continuity with the wide tubes containing the liver-cells. The 
large branch of the portal vein is surrounded with a plexus of ducts. 
Fishes . — The greatest difficulties presented themselves in the investigation of the 
anatomy of the ducts in this class. The ducts become exceedingly narrow before 
they join the very wide tubes of the network containing the cells. 1 have not been 
able to harden the liver sufficiently to obtain very thin sections, and in tearing out 
the finer ducts they always break otF in the narrow part. 
Numerous attempts at injecting the liver failed altogether in consequence of the 
vessels rupturing when the water was thrown in. Another source of great incon- 
venience is the frequent occurrence of entozoa and their ova. In consequence of the 
tubes being almost always full of cells containing oil, and free oil-globules, it is 
difficult to obtain a specimen for examination which is not rendered obscure by the 
escape of numerous cells into the fluid in which the preparation is placed. 
In the common flounder, the connexion between the ducts and cell-containing 
network has been demonstrated in an uninjected specimen. In this specimen the 
secreting tubes were much shrunken and of less diameter than usual, a circumstance 
to which the distinctness of their outline is due, 
I have injected the ducts and a part of the cell-containing network of the sturgeon 
3 F 2 
