138 MUSCULAR TISSUE. 



salt of fuchsin, producing a pink or red color. In the resting leg 

 there is no such acid formation and the color remains pale. 



306. Chop finely 20 to 25 grammes of lean meat and 

 extract it for an hour with three times as much cold water, 

 stirring frequently. Filter through muslin and test the 

 filtrate for myogen, an albumin, sometimes called myo- 

 sinogen. It is coagulable and gives the general reactions 

 for albuminous substances (page 37). It is soluble in 

 distilled water and does not precipitate from this solution 

 on dialysis. 



307. Soak the residue from the last experiment in 

 50 to 75 cubic centimeters of 10 per cent, ammonium 

 chlorid solution, filter through muslin and test the filtrate 

 for myosin, a globulin, sometimes called paramyosinogen 

 or musculin. It responds to the globulin tests (page 45) 

 as well as the general reactions for albuminous substances 

 (page 37) and is coagulated by heat. 



308. Mince finely 10 to 15 grammes of fresh muscular tissue 

 and extract it by stirring with water for a few minutes. Warm 

 the filtered solution in a double beaker (Experiment 91). When 

 coagulation occurs filter and keep the temperature constant until 

 no further change is observed, then increase it. Note the tempera- 

 tures at which the different proteins coagulate and report them. 

 This is the method of separation by fractional coagulation. 



309. PREPARATION OF MUSCLE-PLASMA. Kill a frog and 

 immediately wash the blood from the body by passing in through 

 a cannula inserted in the aorta a cold 0.5-per-cent. sodium chlorid 

 solution. The necessary force can be gained by placing the solu- 

 tion in a doubly-tubulated bottle, which can be raised and lowered, 

 and connecting the lower tubulure with the cannula by a small 

 rubber tube. Cut the muscle up as quickly as possible with a cold 

 knife or pair of scissors and freeze it by stirring in a beaker, pre- 

 viously surrounded by a freezing mixture of ice (3 parts) and salt 

 (1 part). It freezes at about 7 C. Then rub it to as fine a 



