140 ORGANS OF DIGESTION. 



with the capillaries which separate them from each other, are 

 well seen. Here and there" it is observed that an interstitial 

 hole or orifice appears to be formed by the apposition of two 

 semi-circular notches in the border of contiguous cells, or, in 

 other cases, by three cells similarly notched. By comparing 

 these appearances with sections of organs in which the ulti- 

 mate bile ducts are injected, it is seen that the orifices cor- 

 respond to sections of these channels. They possess no special 

 wall, being apparently bounded immediately by the cell-sub- 

 stance. In such preparations the cylindrical epithelium of the 

 interlobular ducts can also be well seen. The bloodvessels 

 should be studied in organs in which the vena portse has been 

 previously injected with gelatin mass ; for which purpose the 

 liver of a rabbit, guinea-pig, or small dog, answers best. The 

 animal having been killed by bleeding, a canula is inserted in 

 the vein, and a ligature placed round the vena cava in the 

 thorax. Before injecting the mass, it is best to send warm 

 half per cent, solution of salt through the organ, till it be- 

 comes colorless. Carmine-gelatin or Prussian-blue-gelatin mass 

 must then be injected in the manner directed in Chapter VI. 

 Before leaving off, the ligature on the cava is tightened, after 

 which a somewhat stronger impulse is given, so as to keep 

 the vessels distended. The vena port ae having been ligatured, 

 the organ is treated as before directed. In such preparations 

 the whole course of the vessels from the interlobular veins, 

 through the capillary sj^stem of each acinus to the intralobular 

 vein, may be studied. If it is desired to inject the hepatic 

 artery and the portal system with different colors, this maybe 

 accomplished by securing a canula at the same time in both 

 vessels ; the nozzle of the one canula being connected with 

 a WoolfPs bottle containing carmine mass, that of the other 

 with a similar bottle containing Prussian blue. The connect- 

 ing tubes leading to the two bottles are adapted, one to each 

 arm of a T tube, the stem of which is in communication with 

 the pressure apparatus, so that the same pressure is exerted at 

 the same time in both bottles. The bile ducts can be injected 

 naturally by the same method which is used for injecting the 

 urinary tubes, or in the ordinary way by the hepatic duct. 

 After ligaturing the cj r stic duct, two per cent, solution of Prus- 

 sian blue can be injected with such success that in parts the 

 capillary bile ducts are filled. The livers that answer best for 

 the purpose are those of mature fo3tuses, puppies, and rabbits. 

 As soon as a successful injection has been obtained (as may be 

 judged of by inspection), it is desirable to inject the portal 

 system with a different color. 



The Spleen. For the study of the elements of the pulp of 

 the spleen it is absolutely necessary to use the organs of ani- 

 mals just killed. Preparations may be made either by scraping 



