30 PROTEIDS. 



coagulate at 47 l (paramysinogen) 63, (myoglobulin) 73, an albumin 

 closely resembling serum-albumin. 



Preparation 2 . (1) Finely chopped muscle-substance is washed 

 rapidly with cold water, to remove serum-albumin and colouring 

 matters (haemoglobin), the residue is squeezed out in linen, and 

 extracted for at least 24 hours with 10 p.c. solution of NH 4 C1 in 

 which myosin is readily soluble. The extract is now filtered first 

 through muslin and then through paper ; the filtrate is a more or less 

 viscid and opalescent solution of myosin. From this the myosin may 

 be prepared in a pure condition by allowing its solution in the 

 ammonium salt to drop into a large excess of distilled water. The 

 myosin gradually settles out in a flocculent mass, which may be further 

 purified by resolution in a minimal amount of neutral salt and re- 

 precipitation by pouring into an excess of distilled water. This 

 purification must be conducted rapidly and at low temperatures, for 

 myosin is somewhat readily altered by the prolonged action of water 

 and becomes insoluble in saline solutions 3 . (2) The finely chopped 

 and washed muscle is divided into two equal portions : to one of these 

 very dilute (deci-normal) hydrochloric acid is carefully added until a 

 distinct acid reaction is obtained as shewn by tropaeolin 00 (see above, 

 p. 17). The two portions are then intimately mixed together, allowed 

 to stand some time, strained through muslin, filtered and the myosin 

 precipitated from the filtrate by careful neutralisation with very dilute 

 alkali or lime-water. 



Apart from the general reactions which characterise myosin as a 

 globulin, it is distinguished by the low temperature (55 56) at which 

 its saline solutions constantly coagulate. It leaves a large ash residue 

 on incineration, consisting chiefly of salts of lime. As already stated, 

 it is converted into an insoluble proteid by the prolonged action of 

 water, and into syntonin by the action of acids. These substances are 

 stated to be capable of reconversion into myosin (see above, p. 17). 

 It is also stated 4 that if myosin is dissolved in NaCl or MgSO 4 (10 and 

 5 p.c. respectively) it yields a renewed clot on mere dilution with 

 water. 



According to Nasse 5 myosin constitutes the anisotropous substance (see above 

 56) of the unaltered muscle-fibre, and the activity of contraction is inversely 

 proportional to the amount of this substance which is present in the fibres of 

 different animals. 



1 Cf. Demant, Zt.f.physiol. Chem. Bd. m. (1879), S. 241; iv. (1880), S. 384. 



2 Danilewsky, Zt.f. physiol. Chem. Bd. v. (1881), 158. 



3 Weyl, Zt.f. physiol. Chem. Bd. i. (1877), S. 77. 



4 Halliburton, loc. cit. p. 148. 



5 "Anat. u. Physiol. d. Muskelsubst." Leipzig, 1882. Biol. Centralb. Bd. n. 

 (1882-2), S. 313. Zt.f.physiol. Chem. Bd. vn. (1882), S. 124. 



