CH. VII.] MEAT. 177 



218. Take 5 cc. of the extract in a test-tube : place the tube 

 in a beaker of water, supporting it by a clamp so that it does not 

 touch the bottom of the beaker. Heat the water with a Bunsen 

 flame and note the temperature in the tube at which distinct 

 coagulation occurs. It is usually at about 47 C. Filter off the 

 coagulum of paramyosinogen and heat again. Another and larger 

 coagulum of myosinogen occurs at 57 C. 



219. Preparation of Myosin. Fresh veal is finely minced in a 

 machine, stirred with a large volume of water for a quarter of an 

 hour, strained through muslin, and the washing process repeated 

 once more. In this way certain proteins and other substances 

 soluble in water are removed. The veal is now collected on muslin, 

 squeezed to remove the water, ground with sand, and extracted 

 with five times its volume of 10 per cent, ammonium chloride for 

 several hours at room temperature. The extract is filtered through 

 muslin, linen, and then coarse filter paper. In this way a crude, 

 viscid solution of myosin is obtained. 



220. Boil a portion of the solution. A heavy coagulum is 

 formed. Wash the coagulum and on it perform the protein colour 

 reactions. They are all obtained. 



221. Pour 100 cc. into a litre of water contained in a tall 

 cylinder ; mix well, and note the precipitation of myosin, due to the 

 reduction in the concentration of salts. 



Allow this to settle, and then pour or pipette off as much of the 

 supernatant fluid as possible. A suspension of myosin in dilute 

 ammonium chloride is thus obtained for the next three experiments. 



NOTE. If this suspension be allowed to stand it slowly becomes con- 

 verted into an insoluble variety. 



222. To a portion add a saturated solution of common salt, 

 drop by drop. The precipitate dissolves. Add solid NaCl to 

 saturation : the myosin is reprecipitated. 



223. To a portion add saturated ammonium sulphate till the 

 precipitate just dissolves. Now add an equal bulk of saturated 

 ammonium sulphate. The myosin is reprecipitated. 



