MUSCULAR TISSUE. 



245 



Separation of Extractives from Muscle. 



i. Creatine. Dissolve about 10 grams of a commercial extract 

 of meat in 200 c.c. of warm water. Precipitate the inorganic 

 constituents by neutral lead acetate, being careful not to add an ex- 

 cess of the reagent. Write the equations for the reactions taking 

 place here. Allow the precipitate to settle, then filter and remove 

 the excess of lead in the warm filtrate by hydrogen sulphide. Filter 

 while the solution is yet warm, evaporate the clear filtrate to a 

 syrup and allow it to stand at least 48 hours in a cool place. Crys- 

 tals of creatine should form at this point. Examine under the 

 microscope (Fig. 77, page 238). Treat the syrup with 200 c.c. of 

 88 per cent alcohol, stir well with a glass rod to bring all soluble 

 material into solution, and then filter. The purine bases have been 

 dissolved and are in the filtrate, whereas the creatine crystals were 

 insoluble in the 88 per cent alcohol and remain on the filter paper. 

 Wash the crystals with 88 per cent alcohol, then remove them and 

 bring them into solution in a little hot water. Decolorize the solu- 



Fic. 79. 



HYPOXANTHINE SILVER NITRATE. 



tion by animal charcoal and concentrate it to a small volume. 

 Allow the solution to cool and note the separation of colorless crys- 

 tals of creatine. Examine these crystals under the microscope and 

 compare them with those reproduced in Fig. 77, page 238. 



2. Hypoxanthine. Evaporate the alcoholic filtrate from the 

 creatine to remove the alcohol. Make the solution ammoniacal 

 and add ammoniacal silver nitrate until precipitation ceases. The 



