Composition of the Myosin of Muscle Tissue. 135 



work of Halliburton,* muscle-clot or myosin is formed from a sub- 

 stance (myosinogen) in the muscle-plasma which coagulates by heat 

 at 47° C. and 56° C, thus indicating that it probably consists of two 

 distinct proteids which coagulate at these temperatures respectively. 

 Further, Halliburton considers that whenever myosin is dissolved in 

 a suitable saline solution, it is at once re-converted into myosinogen, 

 or rather into two proteids which resemble myosinogen in that they 

 have the same heat coagulation temperatures and that they are con- 

 vertible into myosin by dilution of their saline solutions. In salted 

 muscle-plasma, Halliburton recognizes five distinct proteid bodies, 

 distinguishable by fractional heat coagulation, viz : 



47° C, a flocculent, somewhat sticky precipitate. 

 56° C, a more abundant and very sticky precipitate. 

 63° C, a finely flocculent precipitate, not sticky. 

 73° C, a finely flocculent precipitate, not sticky. 

 A non-coagulable albumose. 



Of these, the two proteids coagulating at 47° C. and 56° C, make 

 up the muscle-clot or myosin. 



With these preliminary statements, we proceed to the results ob- 

 tained in our study of the coagulation points of the diff'erent myo- 

 sins, simply prefacing it with the explanation that our experi- 

 ments were performed previous to reading Halliburton's paper. 

 Naturally, the temperature of coagulation offers the simplest and 

 surest means, in conjunction with the determination of composition, 

 of detecting any difierence in the character of the myosins from 

 different sources. And with this as the main object the following 

 experiments were tried. In every experiment, the muscle tissue was 

 chopped quite fine and very thoroughly extracted with water, well 

 thymolized, prior to solution of the myosin with the saline fluid. 



We first demonstrated to our satisfaction that a 5 per cent, ammo- 

 nium chloride solution of myosin invariably coagulates at a lower 

 temperature than a 5 per cent, sodium chloride solution, and further, 

 that the original saline extract of washed muscle shows approxi- 

 mately the same temperature of coagulation as the salt solution of 

 precipitated myosin. 



* Journal of Pli}'siology, vol. viil, p. 14S. 



