226 PRACTICAL HISTOLOGY. 



thus driven out, and only pure injecting fluid begins 

 to pass, this vein is occluded near the diaphragm by 

 the second thread. The pressure in the injecting 

 bottle is then slowly raised, but should not even at 

 the utmost exceed three inches of mercury, for this 

 amount of pressure will cause all the bloodvessels to 

 be quite fully distended, and will effect a very con- 

 siderable consequent enlargement of the organ ; more 

 might cause rupture and extravasation. After the 

 lapse of a few minutes, to allow of the complete fill- 

 ing of all the bloodvessels, a second ligature is tied 

 round the portal vein close to the liver to prevent 

 the return of the still fluid injection, and the canula 

 is cut out from the portal vein (the pressure in the 

 apparatus having first been removed), and the body 

 put into a cold place so as to permit the gelatine to 

 solidify. It is well to hasten the process by pouring 

 cold water iced if possible over the liver. When 

 the injecting material is entirely set, the organ is 

 removed and cut into pieces, which are placed in 

 weak spirit (half water) for twenty-four hours. They 

 are then put into stronger spirit, and in forty-eight 

 hours more in the strongest. In three or four days 

 sections may be made (in two directions as with the 

 uninjected organ), and mounted, after passing 

 through oil of cloves, in dammar. It is better not 

 to stain them. 



During the whole process, the greatest care must 

 be taken not to handle the liver more than can 

 possibly be helped, for it is very readily scratched 

 or ruptured, and any such accident would tend to 

 permit the escape of the fluid injection. This warn- 

 ing applies with equal, if not greater, force to the 

 operation next to be described ; that namely, of 

 filling the bile-ducts. 



Preparation 3. The bile-ducts are injected with 

 Berlin blue solution, 2 per cent., the mercury appa- 

 ratus (Fig. 30) being used. The solution, although 

 fluid in the cold, should nevertheless be employed 

 warm, as it is then less likely to excite contraction 



