XII. J GLYCOGEN IN THE LIVER. 9 1 



LESSON XII. 

 GLYCOGEN IN THE LIVER. 



1. Preparation. 



(a.) Feed a rabbit on carrots for a day or longer, or a rat on 

 oats, and five or six hours after the last meal decapitate it or kill 

 it by bleeding. Rapidly open the abdomen, remove the liver, cut one 

 half of it in pieces, and throw it into boiling water slightly acidu- 

 lated with acetic acid. Lay the other half aside, keeping it moist 

 in a warm place for some hours. After boiling the first portion 

 for a time, pound it in a mortar with sand, and boil again. Filter 

 while hot. The filtrate is milky or opalescent, and is a watery 

 solution of glycogen and other substances. The acetic acid co- 

 agulates the proteids, while the boiling water destroys either a 

 ferment in the liver or the liver cells, which would convert the 

 glycogen into grape-sugar. 



(/>.) Brticke's Method. Feed a rabbit on carrots, and after 

 five or six hours kill it by bleeding. Open the abdomen, rapidly 

 remove the liver. Some wash out its blood-vessels with a stream 

 of normal saline. Divide it into two portions. Cut one half as 

 rapidly as possible into small pieces, and throw the pieces into 

 boiling water. 



Boil them, and afterwards pound them in a mortar and boil 

 again. Filter while hot, and observe the opalescent filtrate, which 

 is a solution of glycogen and proteids. The filtrate should flow 

 into a cooled beaker, placed in a mixture of ice and salt. Pre- 

 cipitate the proteids by adding alternately hydrochloric acid and 

 potassio-mercuric iodide (p. 93), until all the proteids are pre- 

 cipitated. Filter off' the proteids, and the opalescent filtrate is an 

 imperfect solution of glycogen. To separate the glycogen. Evapor- 

 ate the fluid to a small bulk, and precipitate the glycogen by 

 adding 96 per cent, alcohol until the solution contains over 60 per 

 cent, of alcohol. The glycogen is precipitated as a white flocculent 

 powder, which is collected on a filter, washed with alcohol and 

 ether, and then dried in an oven at 100 C. (fig. 47). 



(c.) Kiilz's Method. Feed a rabbit for two days on carrots or boiled 

 rice. Five or six hours after the last full meal decapitate it, open the 

 abdomen, rapidly remove the liver (weigh it), cut it quickly into pieces, and 

 throw the latter into a large porcelain capsule (400 cc. water to 100 grams 

 liver) of water boiling briskly. Boil the pieces for about half an hour. Re- 

 move the pieces, rub them up into a pulp in a mortar (this may be aided by 



