GENERAL PHYSIOLOGY OF MUSCLE AND NERVE. 163 



infrequently to the frogs hibernating in holes in the banks of ponds. Since cold 

 prevents coagulation without destroying the life of the muscle protoplasm, we 

 can by its aid isolate the living muscle-substance from the nerves, blood- 

 vessels, connective tissue, and sarcolemna of the muscle, but as soon as we 

 begin to analyze it it loses its living structure. This method of obtaining 

 muscle-plasma was introduced by Kuehne 1 in the study of the muscles of frogs, 

 and was later employed with slight modifications by Halliburton 2 for the mus- 

 cles of warm-blooded animals. The blood was washed out of the vessels with 

 a stream of 0.6 per cent, sodium-chloride solution at 5° C. ; the irritable mus- 

 cles were then quickly cut out and frozen in a mixture of ice and salt. The 

 frozen muscle was then cut up fine in the cold, and a yellowish, some- 

 what viscid, and faintly alkaline muscle-plasma was squeezed out. This 

 fluid was found to coagulate in twenty to thirty minutes at a temperature of 

 40° C. ; if the temperature were lower the coagulation was slower. The clot, 

 which was jelly-like and translucent, contracted slowly and in a few hours 

 squeezed out a few drops of serum. The coagulated material formed in the 

 clot is called myosin. It dissolves readily in dilute neutral saline solutions, 

 as a 10 per cent, solution of sodium chloride or a 5 per cent, solution of mag- 

 nesium sulphate, and its saline solutions are precipitated in an excess of water 

 or by saturation with sodium chloride, magnesium sulphate, or ammonium 

 sulphate; it has, in short, the characteristics of a globulin. Chittenden and 

 Cummins state that it has the following composition: C 52.82, H 7.11, N 

 16.17, S 1.27, O 22.03. 



Halliburton, in studying the coagulation of muscle, followed for the sake of 

 comparison the methods which have been employed in the study of coagulation 

 of blood. He found that muscle-plasma, like blood-plasma, is prevented from 

 coagulating not only by cold, but by neutral salt-, such as magnesium sulphate, 

 sodium chloride, and sodium sulphate; and further, that the salted plasma if 

 diluted coagulates. 



The points of resemblance between the coagulation of myosin in the 

 muscle and fibrin in the blood suggest a similar cause, and Halliburton suc- 

 ceeded in obtaining from muscles coagulated by long standing in alcohol a 

 watery extract, which greatly hastened the coagulation of muscle-plasma. 

 He called the substance thus obtained myosin ferment. The extract obtained 

 contained an albumose which was either the ferment or held it in close com- 

 bination. The pure ferment has not been isolated. In the case of coagula- 

 tion of the blood, a proteid of the plasma, fibrinogen, is changed by coagula- 

 tion to fibrin, this change being brought about by the action of the fibrin 

 ferment, for the formation of which calcium is necessary. The calcium 

 does not enter into the chemical change independently, and it can go on in 

 the absence of calcium provided the ferment has been already formed. In 

 the case of coagulation of muscle, two proteids of the muscle plasma, 

 paramyosinogen and myosinogen, are changed by coagulation to myosin, or. 



1 Untersuchungen fibt r das Protoplasma, Leipzig, 1864. 



* Journal of Physiology, 1887, vol. viii. pp. 1 33 202. 



