MUSCULAR TISSUE. 35 



NON-NITROGENOUS EXTRACTIVES. 

 GLYCOGEN (C ft H 10 5 ) n . 



This polysaccharide, sometimes called animal starch on 

 account of its similarity in function to plant starch, exists 

 wherever living protoplasm is present and is therefore 

 classed as one of the primary constituents of the cell. It is 

 especially abundant in the liver, where it apparently repre- 

 sents the carbohydrate surplus of the organism and in the 

 muscle, where it serves as a ready source of energy. Glyco- 

 gen forms a tasteless white powder, insoluble in alcohol and 

 ether, but forming with water an opalescent solution which 

 is dextrorotatory. It does not reduce metallic oxides in 

 alkaline solution. By the action of hydrolytic agents or 

 enzymes it is converted into maltose and dextrose similarly 

 to starch. 



The common scallop serves as the most convenient and 

 prolific source of glycogen from muscular tissue. By the 

 simple extraction of the tissues with boiling water, slightly 

 acidulated, a solution is obtained for the following reactions: 



(a) Notice the color of the solution. Add 2 drops of the 

 iodine solution to 5 c.c. of the glycogen solution. Warm 

 gently and allow to cool. Note changes. 



(6) Test 5 c.c. of the solution with Fehling's solution. 



(c) To 5 c.c. of the solution add three volumes of 95 per 

 cent alcohol. 



(d) To 5 c.c. of the solution add 5 drops of concentrated 

 HC1 and boil for some minutes. Neutralize cold with NaOH 

 and test with Fehling's solution. What is this reducing 

 substance? How could you prove it? 



(e) To 5 c.c. of the solution add a few drops of filtered 

 saliva, and warm at 40 C. for a few minutes. Notice changes 

 in the solution. Determine the character of the final reducing 

 body formed. 



