58 SCIENCE “PROGEESS 
agulates at 60°, 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! 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? 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 Catcium 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,’ fifteen 
years later, that calcium salts are absolutely necessary in order 
! Archiv f. exp. Path. u. Pharmak. x\ix. p. 229, 1902. 
* Letts. f. physiol. Chemie, xliv. p. 182, 1904. 
3 Journal of Physiol. 1887. 
