97 



LESSON XXII. 



LIVER, TRACHEA, LUNG, AND THYROID. 



(a) Liver Cells. 



Small pieces from the liver of a cat were macerated for 24 hours 

 in llanviers alcohol, and for 2 hours in 0.5% osinic acid. Tease 

 in gum glycerine. 



Study under high power. The liver cells are polyhe- 

 dral in form, and possess a distinct intracellular network. 

 Fat globules, stained black, may be seen in the cells. As 

 a rule a single spherical nucleus is found. Sketch several 

 as seen under high power. 



(b) Injected and Stained Liver. 



The liver of a pig was injected through the portal vein with 

 Berlin blue, hardened in alcohol, stained in borax carmine, 

 embedded in paraffin, and sectioned. Fix and mount in balsam. 



Study under high power. Note that the gland is com- 

 posed of lobules, and injected interlobular branches of the 

 portal vein are seen between them. From these interlobu- 

 lar vessels capillaries pass into the lobule and unite in an 

 intralobular vessel, this emptying into a sublobular vein. 

 The liver cells appear arranged in columns between the 

 capillaries. Sketch two of the lobules, showing the arrange- 

 ment of blood vessels and liver cells as seen under low 

 power. 



(c) Human Liver. 



Small pieces of a human liver were hardened in mercuric chlo- 

 ride, embedded in paraffin, and sectioned. The paraffin was 

 removed from the sections with xylol ; they were then stained in 

 hsematoxylin and eosin, dehydrated, and cleared in oil of berga- 

 rnot. Mount in balsam. Study first under low power. 



In the human liver the hepatic lobules are separated 

 one from the other by only a very small amount of inter- 



