CHEMICAL BASIS OF THE ANIMAL BODY. 1175 



priate methods (see § 56) the muscle-fibres may be broken up 

 and their contents obtained as a viscid slightly opalescent 

 fluid (muscle-plasma), which filters with difficulty and clots 

 at temperatures above 0°. The muscle-plasma may be diluted 

 with solutions of varying strengths of several neutral salts, 

 whereby its clotting may be delayed, and the nature and phe- 

 nomena of the processes involved in the clotting investigated 

 along the lines previously emploj^ed in the elucidation of the 

 phenomena of the clotting of blood-plasma. The more impor- 

 tant facts which have thus been made out may be briefly 

 summarized as follows. Muscle-plasma contains a globulin- 

 forerunner of myosin ('myosinogen') which resembles fibrinogen 

 in coagulating at 56°. This proteid is converted into myosin 

 on the occurrence of clotting by the action of a specific ferment, 

 which is regarded as being closely related to, if not identical 

 with an albumose. The serum, which is left in small quan- 

 tities only after the formation of the clot, contains proteids 

 which coagulate at 47° (paramyosinogen), 63° (myoglobulin), 

 and 73° an albumin closely resembling serumalbumin. 



Apart from the general reactions which characterize 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. It is also stated that if myosin 

 is dissolved in NaCl or MgS0 4 (10 and 5 p.c. respectively) it 

 yields a renewed clot on mere dilution with water. 



Globulins to which the name of myosin is applied are 

 described as occurring in vegetable protoplasm and in the cells 

 of the liver. 



6. Globin. 



When haemoglobin is allowed to undergo decomposition 

 spontaneously by exposure to the air an insoluble proteid is 

 obtained of which very little is known, but to which the name 

 of globin has been given. It appears to be perhaps an outlying 

 member of the globulin class of proteids, but unlike a true 

 globulin is scarcely soluble in dilute acids and imperfectly 

 soluble in alkalis and solutions of sodium chloride. It is con- 

 verted into acid and alkali-albumin by the action of strong 

 acids and alkalis respectively, and is stated to yield no trace of 

 ash on incineration. 



Class IV. Fibrin. 



This proteid is ordinarily obtained by 'whipping ' blood with 

 a bundle of twigs until clotting is complete; the fibrin which 



