58 SCIENCE PROGRESS 



agulates at 6o°, and an apparently identical fibrinogen in blood- 

 plasma at 56°, the addition of fibrin-ferment to hydrocele fluid 

 at once reduces the coagulation-temperature of this globulin 

 to 56°. Ferment-free hydrocele fluid remains clear when thawed 

 after freezing, whereas it appears turbid if treated in the same 

 way after the addition of ferment. Since the same phenomena 

 are seen when solutions of fibrinogen are employed instead of 

 blood-plasma, it would appear that in the process of coagulation 

 all the fibrinogen does not become fibrin, but a part of this, 

 fibrin-globulin, which is a soluble protein coagulating at 64 , 

 separates out. It is conceivable that, under the influence of 

 thrombin, fibrinogen suffers a hydrolytic change into two bodies. 

 Hammarsten believed that the fibrin-globulin was a remnant 

 of the soluble fibrin, since the relative amounts of fibrin and 

 fibrin-globulin produced by ferment action vary so enormously 

 that a simple hydrolytic process is impossible. Recently 

 Heubner 1 has stated that never more than half the fibrinogen 

 in a liquid becomes fibrin, and inclines to the view that a 

 hydrolytic action is exerted by the ferment. Huiskamp 2 has 

 prepared solutions of fibrinogen by precipitation with sodium 

 fluoride, and found that these, neither by heat nor by coagula- 

 tion with ferment, yield any fibrin-globulin. This product, 

 therefore, is not produced when blood coagulates, but is either 

 pre-existent as such in plasma, or, as a separate body, may 

 be loosely attached to fibrinogen. 



The greater part of the work on the coagulation question 

 since 1880 centres around the first phase of the process — the 

 formation of fibrin-ferment, but it would appear to be of little 

 use in this place to discuss the theories of those whose real 

 work will be remembered for the establishment of incon- 

 trovertible facts. 



5. The Role of Calcium Salts in the Process of Coagulation 



Hammarsten, in 1875, had already recognised that the 

 addition of calcium chloride to solutions of fibrinogen increased 

 the yield of fibrin which could be obtained on coagulation ; 

 but it was essentially a discovery of Reynolds Green, 3 fifteen 

 years later, that calcium salts are absolutely necessary in order 



1 Archiv f. exp. Path. u. Pharmak. xlix. p. 229, 1902. 



2 Zeits.f.physiol. Chemie, xliv. p. 182, 1904. 



3 Journal of Physiol. 1887. 



