PROTEINS OF THE MUSCLES. 571 



this way from the rest of the musculin. The myogen exists in the new 

 nitrate and can be precipitated by ammonium sulphate. The musculin 

 may also be removed by adding 28 per cent ammonium sulphate and then 

 precipitating the myogen from the nitrate by saturating with the salt. 



STEWART and SOLLMANN admit of only two soluble proteins in the" muscles. 

 One is the paramyosinogen, which is the same as v. FURTH'S myosin+the soluble 

 myogen fibrin. The other they call myosinogen, which corresponds to v. FURTH'S 

 myogen or to HALLIBURTON'S myosinogen + my oglobulin. It is a typical globulin 

 which coagulates at 50-60 C. The paramyosinogen as well as the myosinogen 

 is readily converted into an insoluble modification, myosin. The myosin of the 

 above investigators is the same as v. FURTH'S myosin fibr in + myogen fibrin, and 

 corresponds, it seems, also to myosin mixed with paramyosinogen (HALLIBURTON) . 

 STEWART and SOLLMANN differ from HALLIBURTON in considering that paramy- 

 osinogen also coagulates and is converted into myosin. According to them 

 myosin is also insoluble in a NaCl solution. 



The views of the various investigators differ so essentially and the 

 nomenclature is so complicated (three different things are designated 

 by the name myosin) that it is extremely difficult to give any correct 

 review of the various opinions. 1 Thorough investigations on this subject 

 are very necessary. 



Myoproteid is a protein found by v. FURTH in the plasma from fish-muscles. 

 It does not coagulate on boiling, is precipitated by acetic acid, and is considered 

 as a compound protein by v. FURTH. 



In connection with v. FURTH'S work, PRZIBRAM has carried on ivestiga- 

 tions on the occurrence of muscle-proteins in various classes of animals. The 

 myosin (v. FURTH) and myogen occur in all classes of vertebrates; the myogen 

 is always absent in the invertebrates. Myoproteid occurs, at least in considerable 

 quantity, only in fishes. In the muscle after cutting the nerve, STEYRER 2 found 

 somewhat more musculin and less myogen in the muscle-juice than in the normal 

 muscle. 



Muscle-pigments. There is no question that the red color of the 

 muscles, even when completely freed from blood, depends in part on 

 haemoglobin. K. MORNER has shown that muscle-haemoglobin is not 

 quite identical with blood-haemoglobin. The statement of MAcMuNN 

 that in the muscles another pigment occurs which is allied to haemo- 

 chromogen, and called myohcematin by him, has not been substantiated, 

 at least for muscles of higher animals (LEVY and MORNER 3 ) . MACMUNN 

 claims that myohaematin occurs in the muscles of insects, which do not 

 contain any haemoglobin. The reddish-yellow coloring-matter of the 

 muscles of the salmon has been little studied. 



1 For these reasons the author is not sure whether he has understood and correctly 

 given the work of the different investigators. 



2 Przibram, Hofmeister's Beitrage, 2; Steyrer, ibid., 4. 



8 See MacMunn, Phil. Trans, of Roy. Soc., 177, part 1, Journ. of Physiol., 8 and 

 Zeitschr. f. Physiol. Chem., 13; Levy, ibid., 13; K. Morner, Nord. Med. Archiv. Fest- 

 band., 1897, and Maly's Jahresber., 27. 



