CONSTITUENTS OF MUSCLE. 139 



powder as possible in a mortar, whir>h, as well as the pestle, has 

 been cooled below this temperature by standing in a freezing 

 mixture. Subject the mass to a strong pressure, which gives a 

 yellowish liquid. Filter this through muslin at a temperature 

 below freezing. The nitrate is the muscle-plasma. Through the 

 whole process care must be taken to preserve a low temperature 

 to prevent coagulation. 



310. Pour a few drops of the plasma into a dish of the 

 ordinary temperature. It coagulates immediately. 



311. Test the reaction of the plasma to litmus-paper. It 

 is alkaline. 



312. Allow the temperature of the rest of the plasma to 

 rise slowly, and notice that it coagulates at a little above freezing. 

 On standing, a yellowish liquid is pressed out of the clot, as in 

 the case of the coagulum of blood-plasma,. This is muscle-serum. 



313. Try the reaction of the muscle-serum to litmus-paper. 

 It is alkaline. 



314. Prove that the coagulated mass is a globulin (Experi- 

 ments, 98, 99, 100, and 101). 



315. Take about 500 grammes of lean beef, and, after re- 

 moving, as completely as possible, the fat and connective tissue, 

 chop it finely. Add an equal weight of water and heat half an 

 hour on a water-bath to 55 or 60. Filter through muslin, press- 

 ing out the water with the hands. Repeat the extraction with 

 half as much water. Unite the nitrates, and boil to precipitate 

 the albuminous compounds. (Instead of the meat a jar of beef- 

 extract can be used after dissolving in water.) Filter and add lead 

 acetate as long as a precipitate forms, avoiding a great excess. 

 Filter and remove the lead by passing hydrogen sulphid gas into 

 the solution. Filter out the lead sulphid and evaporate the nitrate 

 on the water-bath to 5 or 10 cubic centimeters. Allow the yellow- 

 ish syrupy liquid to stand two or three days in a cool place, when 

 the creatin crystals will separate. Filter, and wash with 88-per- 

 cent, alcohol. Unite the nitrate and the washings and remove the 

 alcohol by evaporation on a water-bath. After cooling make alka- 

 line with ammonia and add an ammoniacal solution of silver 

 chlorid. Filter. The precipitate contains the silver compounds of 

 hypoxanthin, xantMn, and guanln. (The nitrate contains lactic 

 acid. Preserve for testing.) Wash with ammonia and dissolve 



