THE LIVER ATTD BILIARY APPARATUS. 193 



tinuous subdivision, have at length reached the interlobular 

 canals, in conjunction with the branches of the portal vein and 

 hepatic artery, they send capillary branches within the sub- 

 stance of the lobule, and thus form an intralobular network. 

 These capillary ducts are of extreme delicacy, measuring only 

 from 0.001 to 0.0012 mm. 



In order to demonstrate them fully they should be filled by 

 natural injection. The substance to be employed for this pur- 

 pose is a solution of pure indigo-carmine. The animal serving 

 for injection (rabbit or dog) should be secured in the manner 

 described in the chapter on the Kidney, where all the neces- 

 sary manipulations are fully detailed. The best results are 

 obtained by injecting a cold, saturated solution of indigo- 

 carmine into the external jugular vein, directing the stream 

 toward the periphery (brain) ; 5 or 10 ctgms. are to be injected 

 at intervals of thirty to forty minutes, and the injection con- 

 tinued until from 25 to 50 ctgms. have been used, the amount 

 varying according to the size of the animal. It takes a longer 

 time for the elimination of indigo-carmine through the capillary 

 bile-ducts than for the same process by way of the renal tubules, 

 and a larger amount of solution will therefore have to be em- 

 ployed. As soon as large quantities of the indigo solution have 

 been injected into the jugular vein, the animal becomes uncon- 

 scious and there is a decrease of temperature ; hence, it should 

 be covered over with layers of cotton-batting. After a variable 

 time (three to twelve hours) the animal is killed in the follow- 

 ing manner : The abdomen is opened and the canula of a large 

 syringe filled with absolute alcohol secured in the lumen of the 

 portal vein ; the inferior vena cava is then cut across above the 

 entrance of the hepatic vein, and the piston of the syringe 

 pushed home. The liver, which before was of a uniform blue 

 color, now presents a marbled appearance, not unlike that of 

 malachite. 



Or, the portal vein may be injected with the writer's carmine- 

 glycerine, the vena cava having been divided as above. In 

 either case the liver is to be removed at once and placed in a 

 vessel containing absolute alcohol, and while immersed in that 

 fluid cut into small fragments. Sections may then be made in 

 a few hours. 



The arrangement of the bile-capillaries differs in different 

 animals. In the rabbit, for instance, they lie between the ad- 



