CHEMICAL BASIS OF THE ANIMAL BODY. 29 



globulin is one product, this view is not as yet established. Ham- 

 marsten considers it is more probable that the globulin really repre- 

 sents a portion of the fibrin which has gone into solution during 

 its formation, basing his views on the earlier work of Denis 1 who 

 showed that under special circumstances a form of fibrin may be 

 obtained which is soluble in solutions of sodium chloride, the solution 

 coagulating at 60 65 (see below, p. 32). Al. Schmidt holds that 

 Hammarsten's fibrinogen as coagulating at 55 is in reality a sort of 

 modified or " nascent " fibrin and not truly a globulin. 



The viscid secretion of the vesicula seminalis of the guinea-pig is very rich in 

 proteids and possesses the power of clotting. The proteid which it contains is not 

 in all respects a typical globulin, but in many ways it resembles fibrinogen. 

 When dissolved in a little lime-water it coagulates when heated to 55. The 

 secretion itself clots readily and firmly on the addition of a small quantity of the 

 aqueous extract of a blood clot 2 . 



The fibrinogen of invertebrate blood yields fibrin by the action of fibrin ferment, 

 but differs from vertebrate fibrinogen by coagulating at 65 when heated 3 . 



5. Myosin. 



When an irritable contractile muscle passes into rigor, the sub- 

 stance of which the muscle-fibres are chiefly composed undergoes a 

 change, analogous to the clotting of blood-plasma, which results in the 

 formation of a clot of myosin 4 . By appropriate methods (see 59) 

 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. This muscle-plasma may 

 be diluted with solutions of varying strengths of several neutral salts, 

 whereby its clotting may be delayed, and the nature and phenomena 

 of the processes involved in the clotting investigated along the lines 

 previously employed in the elucidation of the phenomena of the clotting 

 of blood-plasma 5 . The more important facts which have thus been 

 made out may be briefly summarised as follows. (Muscle-plasma con- 

 tains 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 fer- 

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

 with an albumose (see below). The serum, which is left in small 

 quantities only after the formation of the clot, contains proteids which 



1 "Nouvelles etudes chimiques etc." Paris 1856, p. 106. " M&noire sur le 

 sang," 1859. 



2 Landwehr, Pfliiger's Arch. Bd. xxm. (1880), S. 538. 



3 Halliburton, Jl. of Physiol Vol. vi. (1884), p. 321. 



4 Kiihne, " Das Protoplasma, " 1864. Lehrbuch, S. 272. 



5 Halliburton, Jl. of Physiol. Vol. vm. (1887), p. 133. 



