STEUCTURE OF THE LIVEE. 181 



LESSON XXXIII. 



STRUCTURE OF THE LIVER AND PANCREAS. 



1. MAKE sections of liver, pig's and human, from pieces hardened in Mailer's 

 fluid, and study them carefully with a low and high power. Sketch the 

 general arrangement of the cells in a lobule under the low power and under 

 the high power. Make very careful drawings of some of the hepatic cells 

 and also of a portal canal. 



2. To observe the glycogen and the iron-containing pigment within the 

 liver-cells, kill a rabbit (for glycogen preferably about six hours after a full 

 meal of carrots), and at once throw a thin piece of the liver into 90 per 

 cent, alcohol. When well hardened the piece may be embedded in paraffin 

 in the usual way, or sections may be cut with the free hand without embed- 

 ding. Some of the sections so obtained are to be treated with a solution of 

 iodine in potassic iodide : then rapidly dehydrated by alcohol and passed into 

 clove-oil. They may now be mounted in Canada balsam solution. These will 

 exhibit the glycogen within the liver-cells. Other sections are to be treated 

 first with potassic ferrocyanide solution and then with hydrochloric acid : in 

 these many of the pigment-granules will be stained blue (presence of iron). 



3. Study, first of all with the low and afterwards with a high power, a 

 section of the liver in which both the blood-vessels and the bile ducts have 

 been injected. 1 Make a general sketch of a lobule under the low power and 

 draw a small part of the network of bile-canaliculi under the high power. 



4. Tease a piece of fresh liver in serum or salt solution for the study of the 

 appearance of the hepatic cells in the recent living condition. 



5. Stained sections of pancreas from a gland which has been hardened in 

 alcohol. Small pieces of the gland are stained in bulk and the sections 

 mounted in the usual way in Canada balsam. 



Make a sketch under the low power. 



6. Tease a small piece of fresh pancreas in serum or salt solution. Notice 

 the granules in the alveolar cells, chiefly accumulated in the half of the cell 

 which is nearest the lumen of the alveolus, leaving the outer zone of the cell 

 clear. 



Sketch a small portion of an alveolus under a high power. 



THE LIVER. 



The liver is a solid glandular mass, made up of the hepatic lobules. 

 These are polyhedral masses about 1 mm. (-^ inch) in diameter, 

 composed of cells, and separated from one another by connective tissue. 



1 For the method of injecting these, see Course of Practical Histology. They can also 

 be demonstrated in sections of liver which have been prepared by Golgi's method (see 

 Appendix). 



