ix FIBRIN 383 



fibrinogen, mechanically-produced fibrin, and ferment-produced fibrin 

 have the same heat-coagulation temperature, 53-58. 



The necessity of 'fibrin-ferment' for the normal coagulation of 

 bloodplasma is beyond question, but there is no evidence that the 

 change produced by it is chemical. The facts at present known are 

 consistent with the view that the change from fibrinogen to fibrin, 

 however produced, is purely physical in nature, and analogous to the 

 coagulation-change in certain inorganic colloids (Ramsden). 



The observations on which Lilienfeld based his theory of blood- 

 coagulation are of great interest in this connection, as showing that 

 fibrin can be obtained in the absence of any fibrin-ferment or pro- 

 thrombin by the mere addition of calcium chloride to alkaline solutions 

 of fibrinogen poor in sodium chloride. It is maintained by Ramsden 

 that typical fibrin may be obtained in at least four different ways, 

 and that in none of them is there evidence of chemical change : 



(1) By the action of fibrin-ferment on fibrinogen-solutions. 



(2) By the action of appropriate electrolytes Lilienfeld fibrin. 



(3) By the mechanical aggregations and impactions of the surface 



coating of fibrinogen-solutions mechanical fibrin. 



(4) By the spontaneous change of precipitated fibrinogen. 



How the agglutinins and precipitins of the pathologist produce 

 their specific effect on the surface tension of the suspended bacteria or 

 proteid particles in colloid solutions, in virtue of which bacteria or 

 colloid particles clump together or agglutinate, is unknown. If the 

 change in surface tension should prove to be independent of any pre- 

 cedent chemical change in the bacterial envelope or the suspended 

 colloidal particles, it will be possible, Ramsden points out, to regard 

 precipitins, agglutinins, fibrin-ferment, and electrolytes as all playing 

 essentially similar parts in producing precipitation, 'clumping,' or 

 gelation by altering the surface tension of fine particles in suspension. 1 

 Fibrin -ferment might thus be regarded as a specific precipitin for 

 fibrinogen, differing from other precipitins only in the fact that it is 

 developed in the organism in response to the presence of a normal 

 constituent of the blood, whereas the precipitins investigated by the 

 pathologist are produced only in response to the presence of sub- 

 stances which are not normal constituents of the blood. 



Fibrin is a tough, strongly elastic, jelly-like substance. It is very 

 voluminous, as, notwithstanding its small amount, it converts the 

 whole of the blood into a solid. It is denaturalised by heat, alcohol, 

 formaldehyde, 2 and prolonged action of salts. Changed in this way 



1 The author believes all alterations in surface tensions to depend on chemical change. 

 2 A. Benedicenti, Arch. f. (Anat. u.) Physiol. 1897, p. 219. 



