30 PROTEIDS. 



is always less than that of the fibrinogen which disappears at the 

 "same time. 1 The Deficit thus observed is at least partly accounted 

 for by the simultaneous appearance of a globulin which coagu- 

 lates, when heated in saline solution, at 64. Although at first 

 sight it seems very tempting to regard the process of fibrin-for- 

 mation from fibrinogen as partaking of the nature of a hydrolytic 

 (?) cleavage of which this globulin is one product, this view is 

 not as yet established. Hammarsten considers it is more prob- 

 able that the globulin really represents a portion of the fibrin 

 \yliich has gone into solution during its formation, basing liis 

 views on the earlier work of Denis, 2 who showed that j ncj,er 

 speciaT~circumstances a form of fibrin may be obtained winch is 

 soluble in solutions of sodium chloride, the solution coagulating 

 at 60 65 (see below, p. 33). AT Schmidt holds that Hain- 

 mars ten'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 pro- 

 teid 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. 8 



The fibrinogen of invertebrate blood yields fibrin by the action of 

 fibrin ferment, but differs from vertebrate fibrinogen by coagulating 

 at 65 when heated. 4 



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 clnf-.fr'npr nf hlnnrl-plnsTna, which results 

 in the formation of a clot, of myosin. 5 By appropriate methods 

 (see 59) the muscle-fibres may be broken up and their contents 

 obiajned as a viscid, slightly opalescent fluid (muscle-plasma), 

 which .filters with Tiifficulty and clots ^at "temperatures above G. 

 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- 



1 Hammarsten, Pfliiger's Arch. Ed. xxx. (1883), Sn. 459, 465, 475. 



2 " Nouvelles e'tndes chimiques, etc." Paris, 1856, p. 106. " Memoire sur le sang," 

 1859. 



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

 < Halliburton, ,11. of Phi/siol. Vol. vi. (1884), p. 321. 



5 Kiihne, " Das Protoplasma," 1864. Lehrbuch,- S. 272. 



