MUSCULAR TISSUE 347 



HN CO N = C.NH 2 



II II 



H 2 N.C C NH HC C NH 



CH 



CH 



N C H N C N 



GUANINE, CfiHsNsO. ADENINE, CsHsNs. 



2-amino-6-oxypurine. 6 -aminopurine. 



EXPERIMENTS ON MUSCULAR TISSUE 



I. Experiments on "Living" Muscle 



1. Preparation of Muscle Plasma (Halliburton). Wash out the blood vessels 

 of a freshly killed rabbit with 0.9 per cent sodium chloride. This can best be 

 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 105. 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 at 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. Fiirth). 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 Fuch- 

 sin "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 membrane), 

 remove the skin from both hind legs and expose the sciatic nerve in one of them. 



