540 MUSCLES. 



is sufficient to extract the muscle free from blood, as above directed, 

 with a 6 p. m. common-salt solution. 



Muscle-plasma forms a yellow to brownish-colored fluid with an alka- 

 line reaction. It varies in different animals. Muscle-plasma from the 

 frog spontaneously coagulates slowly at a little above C., but more 

 quickly at the temperature of the body. Muscle-plasma from mammals 

 coagulates slowly, according to v. FURTH, even at the temperature of 

 the room, though only slightly, and it can hardly be considered as a 

 process comparable with the coagulation of the blood. Indeed the ques- 

 tion may be asked whether a true muscle-plasma does exist in warm- 

 blooded animals, or whether the fluid obtained from such muscles 

 exactly represents the plasma of the living muscle. According to KUHNE 

 and v. FURTH the reaction remains alkaline during coagulation, while 

 HALLIBURTON, STEWART and SOLLMANN find that it becomes acid. 

 Earlier investigators held that the clot consists of a globulin called 

 myosin, while v. FURTH claims that it consists of two coagulated 

 proteins, myosin-fibrin and myogen-fibrin. 



The study of the proteins of the muscles, as well as their nomen- 

 clature, has changed markedly in the last few years, and it is questionable 

 whether an essential difference exists between the proteins of the muscle- 

 plasma and the muscle-serum of warm-blooded animals. Nevertheless 

 it is necessary to separately discuss the proteins of the dead muscle as 

 well as those of the muscle-plasma. 



The proteins of the dead muscle are in part soluble in water or dilute 

 salt solutions, and in part are insoluble therein. Myosin and musculin 

 and also myoglobulin and myoalbumin, which exist to a very slight extent 

 and are perhaps only derived from the remaining lymph, belong to the 

 first group, and the stroma substances of the muscle-tubes belong to the 

 second group. 



Myosin was first discovered by KUHNE, and constitutes the principal 

 mass of the soluble proteins of the dead muscle. It is generally considered 

 as the most essential coagulation product of muscle-plasma. The name 

 myosin KUHNE also gives to the mother-substance of the plasma-clot, 

 and this mother-substance forms, according to certain investigators, 

 the chief mass of contractile protoplasm. The findings as to the 

 occurrence of myosin in other organs besides the muscles require further 

 confirmation. The quantity of myosin in the muscles of different animals 

 varies, according to DANiLEWSKY, 1 between 30 and 110 p. m. 



Myosin, as obtained from dead muscles, is a globulin whose elementary 

 composition, according to CHITTENDEN and CuMMiNS, 2 is, on an average, 

 the following: C 52.28, H 7.11, N 16.77, S 1.27, O 22.03 per cent. If the 



1 Zeitschr. f. physiol. Chem., 7. 



2 Studies from the Physiol. Chem. Laboratory of Yale College, New Haven, 3, 115. 



