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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 filtrate 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-)- myoglobulin. 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 fibrin +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 myohcematifi 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.
’See MacMunn, Phil. Trans, of Roy. Soc, 177, part 1, Journ. of Physiol., 8 and
Zeitsehr. f. Physiol. Chem., 13; Levy, ibid., 13; K. Morner, Nord. Med. Archiv. Fest-
band., 1897, and Maly’s Jahresber., 27.
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