102 THE MICROSCOPE. 



fluid should be used. The pieces are then placed in dilute alcohol 

 for a day or two, and then in alcohol of full strength for two or 

 three days longer. Sections can be made now without trouble, 

 and stained with haematoxylin. Sections should be made in 

 at least two directions. First, parallel to the surface, in order 

 to cut the intralobular veins across, and show the arrange- 

 ment of the lobular plexus of capillaries and their relation 

 to the liver cells. Second, vertical to this surface, showing the 

 intralobular veins along their length, and their terminations in the 

 sublobular vein. These vessels are seen to much better advantage 

 in injected specimens. The liver of the rabbit or cat is especially 

 suitable for injection. The animal should be killed by bleeding. A 

 branch of the artery, or portal or hepatic vein, or branch of a duct 

 may be injected, or several of these may be injected at the same 

 time with different colored mixtures. As in the case of many of 

 the vessels of the different organs, so here especially will it be wise 

 to make a slit through the walls of the vessel in a longitudinal direc- 

 tion, and insert the pipe into this rather than into the opening of the 

 cut end of a vessel. In this way a pipe can be inserted into a vessel 

 scarcely larger than the pipe itself. To inject the portal vein 

 thoroughly, first a solution of salt should be injected in order to 

 wash out the blood. 



To inject the biliary passages, the pipe of the injecting appara- 

 tus is secured in the common bile duct, and slight pressure em- 

 ployed. The Prussian blue mixture is satisfactory here, and as soon 

 as a few of the lobules are seen colored by the blue, the duct should 

 be tied, and that part of the organ placed in Midler's fluid, after- 

 wards in spirits, and finally stained slightly with hsematoxylin, 

 cleared in oil of cloves, and mounted in dammar. 



BRAIN. 



Two methods are quite useful for examining fresh brain. Each 

 of these methods has its advantages. 



The first method "will be found in full in the September number 

 of the Monthly Microscopical Journal, vol. XVI, page 105, by Bevan 

 Lewis. His method is briefly this: There are three stages of the 

 process. 



1. The preparatory stage, which consists in making as thin 

 vertical sections as possible of the gray matter. The specimen is 



