THE MUSCLE- ALBUMINS. 349 



renders the substance insoluble to a slight extent, but the greater 

 portion is refractory in this respect. 



By acetic acid myogcn is precipitated only in the presence of a 

 neutral salt, but redissolves in an excess of the acid, with the forma- 

 tion of syntonin. The tendency to the transformation into albu- 

 rn i nates is indeed more marked in the case of the soluble muscle- 

 albumins, in general, than with any other forms. Mineral acids are 

 in this respect still more active than acetic acid, and as a conse- 

 quence a precipitation of myogen is observed only when such acids 

 are present in certain proportion. 



Carbonic acid and the salts of the heavy metals precipitate myo- 

 gen only in the presence of a neutral salt. 



Myogen coagulates at a temperature of from 55 to 65 C. It is 

 not precipitated on dialysis. 



When solutions of myogen are kept at a certain temperature, and 

 in the presence of a definite amount of a neutral salt, the substance 

 is gradually transformed into a soluble form of myogen-fibrin, which 

 differs from myogen in the fact that it is thrown down on dialysis, 

 and in its point of coagulation, which lies at 40 C. As has been 

 stated, a certain amount of soluble myogen-fibrin seems to occur pre- 

 formed in the muscle-tissue, and separates out gradually on standing. 

 At 40 C., however, this occurs instantaneously. By coagulation 

 the soluble myogen-fibrin is transformed into the insoluble form, the 

 my og en-fibrin proper. 



The relative amount of myogen, as compared with myosin (see 

 below), which is found in muscle-tissue varies in all probability with 

 different animals. In rabbits, v. Furth observed that myosin repre- 

 sented about 80 per cent, of the total amount of soluble albumins. 



The amount of soluble myogen-fibrin which is included in the 

 above figures is in mammals apparently very small, as only slight 

 coagula are formed when the plasma is heated to 40 C. But in the 

 frog large amounts are manifestly present. In some animals, on the 

 other hand, it is apparently absent. 



Myosin. Myosin is conveniently isolated from muscle-plasma by 

 salting with ammonium sulphate to the extent of 28 per cent. 

 Sodium chloride and magnesium sulphate may also be employed, 

 but it is then necessary to add the salt to saturation. 



The substance is a globulin, and, curiously, contains a consider- 

 able amount of calcium. It is soluble in dilute saline solutions, and 

 is precipitated from these solutions by salting, as just indicated, by 

 passing a stream of carbon dioxide through its solutions, by diluting 

 with water, and on dialysis. It is characterized by its pronounced 

 tendency to coagulate, and, unlike myogen, is rendered almost 

 entirely insoluble on precipitation with alcohol. Like this, it is also 

 readily transformed into syntonin or alkaline albuminate on treating 

 with acids or alkalies ; and here, as there, a precipitation results 

 only if very dilute acids are used. In an excess the precipitate 

 rapidly dissolves. On heating solutions of myosin to 35 C. the 



