THEORIES OF COAGULATION 



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vessel, and then gradually extending throughout the mass. If a portion of 

 plasma, diluted or not, be whipped with a bundle of twigs or wire during the 

 process of clotting, the fibrin will be obtained as a stringy, insoluble mass, just 

 in the same way as from the entire blood. The resulting fluid no longer 

 retains its powei of spontaneous coagulability and is in fact now a typical 

 serum. 



Theories of Coagulation. It is evident that the blood plasma contains 

 some substance or substances which take part in the formation of fibrin. 

 By numerous investigations it has been found that the direct antecedent of 

 the fibrin is the protein substance, fibrinogen. This fibrinogen exists in the 

 blood plasma at all times, but is somewhat increased under certain condi- 

 tions. The fibrinogen is reacted on by another substance known as thrombin. 

 We shall not present the numerous theories which have been held concerning 

 blood coagulation, many of which have been more or less disproven, but shall 

 try to present the condensed statement of the present explanations of this 



Blood Tissue Cell 



Neutral Salts Fibrinogen Calcium Salts 



(for dissolving 

 fibrinogen) 



Fibrin-globulin 



Thrombok ina se 



Fibrin 

 Morawitz' Schema of Coagulation. 



intricate phenomenon. One may start from the statement that the fibrinogen 

 of the plasma when acted upon by the thrombin, also of the plasma, produces an 

 insoluble substance, fibrin. The chief interest centers around the origin and 

 character of ihefirbinogen, the origin and nature of the thrombin, and the con- 

 ditions which influence its activity. 



The fibrinogen is present in blood plasma of the circulating blood of the 

 body at all times. It can be separated from plasma by various chemical 

 means, and when purified can be made to form fibrin under proper conditions. 

 All observers are agreed that this protein is the immediate precursor of the 

 insoluble fibrin. Its origin in the blood has been traced by Matthews to the 

 disintegration of the white blood corpuscles. 



The thrombin is the substance which reacts on the fibrinogen in the 



