MUSCULAR TISSUE 365 



done by opening the abdomen and inserting a cannula into the aorta. Now 

 remove the skin from the lower limbs, cut away the muscles and divide them 

 into very small pieces by means of a meat chopper. Transfer the pieces of 

 muscle to a mortar and grind them with clean sand and a little ice cold 5 per 

 cent magnesium sulphate. Place in an ice-box over night. Filter off the salted 

 muscle plasma and make the following tests : 



(a) Reaction. Test the reaction to litmus, phenolphthalein, and Congo red. 

 What is the reaction of this fresh muscle plasma? 



(b) Fractional Coagulation. Place a little muscle plasma in a test-tube and 

 arrange the apparatus for fractional coagulation as explained on page 104. Raise 

 the temperature very carefully from 3OC. and note any changes which may occur 

 and the exact temperature at which such changes take place. When the first 

 protein (para-myosinogen) coagulates filter it off and then heat the clear filtrate 

 as before, being careful to note the exact temperature at which the next coagula- 

 tion (myosinogen) occurs. There will probably be a preliminary opalescence in 

 each case before the real coagulation occurs. Therefore do not mistake the 

 real coagulation-point and filter ^t the wrong time. What are the coagulation 

 temperatures of these two proteins? Which protein was present in greater 

 amount? 



(c) Formation of the Myosin Clot. Dilute a portion of the plasma with 3 

 or 4 times its volume of water and place it on a water-bath or in an incubator 

 at 35C. for several hours. A typical myosin clot should form. Note the muscle 

 serum surrounding the clot. Now test the reaction. Has the reaction changed, 

 and if so to what is the change due? Make a test for lactic acid. What do you 

 conclude? 



2. Preparation of Muscle Plasma (v. Furth). Remove the blood-free muscles 

 of a rabbit as explained above. Finely divide by means of a meat chopper and 

 grind in a mortar with a little clean sand and some 0.9 per cent, sodium chloride. 

 Wrap portions of the muscle in muslin and press thoroughly by means of a tincture 

 press or lemon squeezer. Filter and make the tests according to the directions 

 given in the last experiment. 



3. "Fuchsin-frog" Experiment. Inject a saturated aqueous solution of 

 Fuchsin " S " into the lymph spaces of a frog two or three times daily for one or 

 two days, in this way thoroughly saturating the tissues with the dye. Pith the 

 animal (insert a heavy wire or blunt needle through the occipito atlantoid mem- 

 brane), remove the skin from both hind legs and expose the sciatic nerve in one of 

 them. Insert a small wire hook through the jaws of the frog and suspend the ani- 

 mal from an ordinary clamp or iron ring. Pass electrodes under the exposed 

 sciatic nerve, and after tying the other leg to prevent any muscular movement, 

 stimulate the exposed nerve by means of make and break shocks from an in- 

 duction coil. The stimulated leg responds by pronounced muscular contrac- 

 tions, whereas the tied leg remains inactive. Continue the stimulation until 

 the muscles are fatigued. The muscular activity has caused the production of 

 lactic acid and this hi turn has reacted with the injected fuchsin to cause a pink 

 or red color to develop. The muscles of the inactive leg still remain unchanged 

 in color. 



The normal color of the Fuchsin " S " when injected was red, but upon being 

 absorbed it became colorless through the action of the alkalinity of the blood. 

 Upon stimulating the muscles, however, as above explained, lactic acid was 



