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evidently contained in the interior of tubes, but the membrane of which their walls are composed, is of such extreme tenuity that its outline can only be distinctly traced as a sharp line, in some situations.

a. Transverse branch, connecting two tubes.
Magnified 110 diameters.

These two figures were photographed directly from the drawings, which were originally traced upon paper with the aid of the neutral tint glass reflector. The tubes represented in fig. 55 fit into the meshes between the capillaries represented in fig. 54. These two drawings taken together seem to establish in the most decided manner the presence of a tube of delicate basement membrane, quite distinct from the walls of the vessels, in which the liver cells are contained. The author has still in his possession the preparations from which these drawings were taken.

Fig. 56.-Portion of cell-containing network from a fœtal calf, to show that the tubes may contain two or three rows of cells at an early stage of development.

Magnified 180 diameters.

Fig. 57.-Tubes of cell-containing network from a fœtal snake containing

several rows of cells.

Magnified 150 diameters.

Fig. 58.-Part of the cell-containing network of the dog's liver, in which the branches are parallel with each other, altered by being soaked for some time in a dilute alcoholic solution of caustic soda. A few cells are still seen apparently entire, but the greater number are fused together as it were, and the tubes are principally occupied with a highly refracting substance in which numerous oil globules are seen.

c. A tube stretched and separated from its neighbours showing its basement membrane and contents.

Magnified 180 diameters.

Fig. 59. Small portions of tubes of cell-containing network of the horse. Magnified 180 diameters.

Fig. 60.-Portion of cell-containing network from the liver of a girl.

Fig. 61.-Portion of cell-containing network of human foetus at the point of entrance of a small branch of the portal vein as it is about to divide into capillaries. The meshes of the cell-containing network at this point are much wider than at a greater distance from the circumference of the lobule, in consequence of the vessels being larger. The outline of the capillaries and of the tubes of the network are distinctly seen in this preparation, and are separated by a perfectly transparent material.

Magnified about 150 diameters.

Fig. 62.-Portion of cell-containing network of the hedgehog.
Magnified 180 diameters.

Fig. 63.-Portion of cell-containing network of the Guinea-pig.

Fig. 64. Small branches of duct and their connexion with cell-containing network. From the sturgeon. Injected with Prussian blue.

Magnified 35 diameters.

b. Portion of cell-containing network much distended with oil globules.
From the sturgeon.

c. Small branch of duct at its junction with one of the large tubes.
x. Remnants of capillary vessels.

Magnified 200 diameters.

Fig. 65.-Branches of duct and cell-containing network from the frog-fish (Lophius piscatorias).

d. Ducts injected with Prussian blue. Natural size.

efi. Portions of cell-containing network.

g h k. Minute ducts and branches to network. The shading shows the extent to which the injection has passed.

7. Portion of trunk of small duct showing epithelium in its interior.

m. Portion of duct with epithelium in its interior. The walls are com-
posed of an outer layer of longitudinal fibres, and an inner layer con-
sisting of circular fibres, probably muscular.
eghiklm. Magnified 150 diameters.

Fig. 66.-Ducts and cell-containing network, from the liver of the


a. Small duct with branches.

bcde. Smaller branches continuous with cell-containing network, with a few crystals in the interior of the one marked b.

f. Part of tube of network.

g. Capillaries of lobule much contracted and irregular from the mode of
preparing the specimen.

h. Tubes of cell-containing network with biliary matter precipitated
in the form of a highly refractive substance, in the interior. In many
situations the mass has broken, and the fragments have become sepa-
rated from each other by a short interval, the tube of basement mem-
brane having remained entire, as represented at ¿.
Magnified 150 diameters.

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