196 



MANUAL OF HISTOLOGY. 



FIG. 87. Capillary bile-ducts of a rabbit, 

 distended by artificial injection : 1, a portion 

 of a lobule ; or, central vein ; 6, 6, interlobular 

 veins ; c, c, bile-ducts ; d, d, blood-capillaries ; 

 e, e, bile-capillaries. 



joined together the calibre of the capillary is markedly in- 

 creased. Sections made parallel to the external surface of the 

 liver, immediately under the capsule, generally cut the central 



vein transversely, and such sec- 

 tions show that the bile-capillaries 

 possess a somewhat radial course 

 (Pig. 87). Human livers can rarely 

 be obtained in a fresh state, and 

 examinations of their bile-capil- 

 laries are therefore attended with 

 difficulty. 



Do the bile-capillaries possess 

 walls of their own f This ques- 

 tion must be answered in the 

 affirmative. In specimens where 

 the bile- capillaries have been in- 

 jected by the natural method, 

 cross sections of such capillaries 

 will demonstrate, with high pow- 

 ers, that there is a dot of blue indigo-carmine surrounded by 

 a distinct circle which is perfectly transparent and in marked 

 contrast to the somewhat yellowish color of the adjoining 

 liver-cells. (See Fig. 88.) It is more difficult to see this in 

 sections which cut the capillaries in their longitudinal diam- 

 eters, but where two or more capil- 

 laries unite this halo is again seen. 

 That this appearance is due to the pres- 

 ence of a true wall seems clear, but all 

 doubts will be dispelled by watching 

 the diffusion which takes place in such 

 a section on the addition of a few drops 

 of water under the cover glass. The 

 indigo-carmine becomes dissolved in 

 the water, forming a deep blue liquid 

 which stains the surrounding cells and 

 vessels of a uniform color. While 

 watching a bile-capillary during the 

 progress of this action it appears to 



stand out more prominently than before, and its walls become 

 more distinct. In a few moments the cells will have become 

 swollen by the imbibition of water, and the picture gradually 



FIG. 88. Liver of the dog. Nat- 

 ural injection of bile - capillaries, 

 showing double contour of the capil- 

 laries, which are only partly filled 

 with injection. Cross sections of 

 the capillaries show a dot of indigo- 

 carmine surrounded by a distinct 

 halo. The woodcut does not show 

 this satisfactorily. In the specimen 

 the lines corresponding to the walls 

 of the capillaries are of the utmost 

 delicacy. Magnified 450 diam. 



