XXVI.] LIVER. 293 



The bile-capillaries appear as a black polygonal network on a yellow ground. 

 It is rare, I find, to have the whole thickness of the tissue equally well 

 stained. Only a thin layer on the surface shows the capillaries well, but the 

 result is excellent. I find that the sections keep for a long time if they are 

 mounted under a cover-glass. 



15. Glycogen in Liver-Cells. (a.) The animal must be well fed, e.g., rabbit, 

 with carrots, and six hours or so thereafter it is killed. As glycogen is soluble 

 in, or is at least extracted from, the liver by water, small pieces of the liver 

 must be hardened in alcohol. In a section placed in a weak iodine solution 

 or Lugol's solution (p. 93), the glycogen granules in the cell protoplasm 

 are stained of a port-wine colour. In sections of liver sometimes one sees 

 vacuoles from which the glycogen granules have been washed out. 



(b. ) Harden the liver of a well-fed frog in osmic acid, make thin sections, 

 and irrigate with iodine. The granules of glycogen in the hepatic protoplasm 

 are stained brownish. 



16. Reactionfor Iron( Tizzoni's). (.) Select the liver of a young animal, and 

 harden it in alcohol. Place sections in the following fluid, which should be 

 freshly prepared : 



Water 90 cc. 



aer 



Hydrochloric acid (25 per cent.) 

 Ferricyanide of potash (i : 12) 



Mount in balsam. Particles of free iron are coloured blue. Particles of free 

 iron are seen in the spleen, liver, and kidney by this reaction. 



(b.) Zaleski. 1 Harden the liver in 65 per cent, alcohol, then in 96 per cent, 

 alcohol to which a few drops of sulphuretted hydrogen ara added. After 24 

 hours the iron granules assume a green colour. 



17. Injected Human Liver. (a.) For a double injection, and in order to 

 save injection-mass, the plan recommended by Orth is excellent, viz., to pass 

 an elastic catheter as far as it will go into one of the branches of the portal 

 vein, and through it to make the injection. The hepatic vein is treated in 

 the same way. Sections of a well-injected part may be afterwards stained 

 with picro-lithium-carmine. 



(?>.) In a way a natural injection of the liver is obtained by hardening a 

 human liver which is congested, and contains a large amount of blood. Such 

 livers are apt to show pigmentation of the liver-cells and other changes due to 

 disease. 



18. Pigment in Liver. The presence of pigment in the liver-cells or capil- 

 laries is a matter of considerable importance in regard to the question of the 

 destruction of blood-pigment in this organ, or whether the liver acts as a trap 

 for pigment already altered by its passage through the spleen or gastro- 

 mesenteric capillaries. 2 



In winter frogs the liver contains a large amount of black pigment, which 

 lies in the blood-capillaries. 



19. Granular Cells of Ehrlich. Harden the liver (ox, pig) in absolute 

 alcohol. Place sections for 24 hours in Westphal's fluid (p. 67), wash in 

 absolute alcohol (4-6 hours) until all is clear, only the granular cells remaining 

 stained. Balsam. The granular cells ( ' ; Mastzellen ") are reddish violet, 

 and lie in the interlobular connective tissue. 



1 Zcitsch./. Phys. Chem., xiv. p. 274, 1890. 



2 W. Hunter, Brit. Mcd. Jour., Nov., Dec. 1892. 



