366 PHYSIOLOGICAL CHEMISTRY 



formed and this acid reacted with the fuchsin and again produced the original 

 color of the dye. 



11. Experiments on "Dead" Muscle 



1. Preparation of Myosin. Take 25 grams of finely divided lean beef which 

 has been carefully washed to remove blood and lymph constituents and place 

 it in a beaker with 10 per cent sodium chloride. Stir occasionally for several 

 hours. Strain off the meat pieces by means of cheese cloth, filter the solution 

 and saturate it with sodium chloride hi substance. Filter off the precipitate of 

 myosin and make the tests as given below. This filtration will proceed very 

 slowly. Myosin collects as a film on the sides of the filter paper and may be 

 removed and tested before the entire volume of fluid has been filtered. If this 

 precipitate remains for any length of time on the paper in contact with the air 

 it will become transformed into the protean myosan. Test the myosin precipi- 

 tate as follows : 



(a) Solubility. Try its solubility in water sodium chloride, dilute acid and 

 alkali. Is myosin an albumin or a globulin? 



(b) Xanthoproteic Reaction. See page 98. 



(c) Coagulation Test. Suspend a little of the myosin in water in a test- 

 tube and heat to boiling for a few minutes. Now remove the suspended ma- 

 terial and try its solubility in 10 per cent sodium chloride. What property does 

 this experiment show myosin to possess? 



Test the filtrate from the original myosin precipitate as follows : 



(a) Biuret Test. What does this show? 



(b) Place a little of the solution in a test-tube and heat to boiling. At the 

 boiling-point add a drop of dilute acetic acid and filter. Test this filtrate for 

 proteose with picric acid. Is any proteose present? Saturate another portion 

 of the filtrate with ammonium sulphate and test for peptone in the usual way 

 (see page 119). Do you find any peptone? 



From your experiments on "living" and "dead" muscle what are 

 your ideas regarding the proteins of muscle? 



2. Preparation of Glycogen. Grind a few oysters or scallops 1 in a mortar 

 with sand. Transfer to an evaporating dish, add water, and boil for 20 minutes. 

 Note the opalescence of the solution. At the boiling-point faintly acidify with 

 acetic acid. Why is this acid added? Filter, and divide the filtrate into two 

 parts. Test one part of the filtrate as follows : 



(a) Iodine Test. To 5 c.c. of the solution in a test-tube add 5-10 drops of 

 iodine solution and 2-3 drops of 10 per cent sodium chloride. What do you 

 observe? Is this similar to the iodine test upon any other body with which we 

 have had to deal? 



If difficulty is experienced in securing a satisfactory iodine test proceed as 

 follows : Make equal volumes of glycogen solution acid in reaction with hydro- 

 chloric acid.. Boil one solution to hydrolyze the glycogen. Add equal volumes 



1 Glycogen may also be prepared from the liver of an animal which has been fed a high 

 carbohydrate diet for 1-2 days previously. The best yield of glycogen can, however, gen- 

 erally be obtained from scallops. To secure best yield of glycogen the liver, scallops or 

 oysters should be fresh. Canned oysters or scallops may be used if fresh ones are not 

 available. If permitted to stand some glycogen will be converted into glucose. 



