256 THE BLOOD. 



of fibrin (DASTRE). The blood constituents that are active in fibrinolysis 

 are still unknown, but they are without doubt of enzymotic nature. 

 It must be mentioned that a strong fibrinolysis takes place in blood 

 after acute phosphorus poisoning ( JACOB Y and others), after extirpation 

 of the liver (NOLF), and also when the coagulability of the blood has been 

 reduced by the injection of proteoses (NoLF, RULOT 1 ). 



A pure fibrinogen solution may be kept at the ordinary temperature 

 until putrefaction begins without showing a trace of fibrin coagula- 

 tion. But if to this solution is added a water-washed fibrin-clot or a 

 little blood-serum, it immediately coagulates, and may yield a perfect 

 typical fibrin. The transformation of the fibrinogen into fibrin requires 

 the presence of another body contained in the blood-clot and in the serum. 

 This body, whose importance in the coagulation of fibrin was first observed 

 by BucHANAN 2 , was later rediscovered by ALEXANDER SCHMIDT^ and 

 designated as fibrin ferment or thrombin. The nature of this enzymotic 

 body has not been ascertained with certainty. Even after careful 

 purification it gives very faint protein reactions and it is a much disputed 

 question whether it is a globulin or a nucleoprotein. It is a fad that 

 powerfully active solutions of thrombin can be obtained that do 

 not give either the reactions for globulins or nucleoproteins. Fibrin fer- 

 ment is produced, according to PEKELHARiNG, 4 by the influence of soluble 

 calcium salts on a preformed zymogen existing in the non-coagulated 

 plasma. SCHMIDT admits the presence of such a mother-substance 

 of the fibrin ferment in the blood, and calls it prolhrombin. The con- 

 version of this mother-substance into thrombin is a very complicated 

 process, which will be discussed under the coagulation of the blood. 

 Thrombin behaves like other enzymes in that the very smallest amount of 

 it produces an action, and its solution becomes inactive on heating. The 

 velocity of coagulation is dependent upon the quantity of thrombin, 

 and indeed a time law has been proposed for the action of thrombin. 

 According to FULD the action of thrombin, at least within certain limits, 

 follows SCHUTZ'S law, and according to STROMBERG the thrombin follows 

 in its action a time law, which at least in the beginning, corresponds to 



1 Jacoby, Zeitschr. f. physiol. Chem., 30; Nolf, Arch, intern, de Physiol., 3, 1905; 

 Rulot, 1. c. 



2 London Med. Gazette, 1845, 617. Cit. by Gamgee, Journal of Physiol., 1879. 



3 Pfltiger's Arch., 6; see also Zur Blutlehre, 1892, and Weitere Beitrage zur Blut- 

 lehre, 1895. 



4 Pekelharing, Verhandl. d. Kon. Akad. d. Wetensch. te Amsterdam, 1892, Deel 1; 

 ibid., 1895, and Centralbl. f. Physiol., 9; Wright, Proc. Roy. Irish Acad. (3), 2; The 

 Lancet, 1892, and On Wooldridge's Method, etc., British Med. Journal, 1891; Lilien- 

 feld, Hamatol. Untersuch. Arch. f. (Anat. u.) Physiol., 1892; Ueber Leukocyten und 

 Blutgerinnung, ibid.', Halliburton and Brodie, Journal of Physiol., 17 and 18; Huis- 

 kamp, Zeitschr. f. physiol. Chem., 32; Pekelharing and Huiskamp, ibid., 39. 



