46 FORMATION OF FIBRIN. 



water, and passes through the filter, while the coagulated albumin 

 remains behind (Schmidt). 



In the preparation of fibrinoplastin, the ferment is carried down with it 

 mechanically. The ferment seems to be formed first in fluids outside the body, 

 very probably by the solution of the colourless corpuscles. More ferment is formed 

 in the blood the longer the interval between its being shed and its coagulation. 

 It is destroyed at 80C. 



[Gamgee's Method. Buchanan's "washed blood-clot" (p. 43) is digested in 

 an 8 per cent, solution of common salt. The solution so obtained possesses in an 

 intense degree the properties of Schmidt's fibrin-ferment.] 



Coagulation Experiments. According to A. Schmidt, if the pure 

 solutions of (1) fibrinogen, (2) fibrinoplastin, and (3) fibrin-ferment 

 be mixed, fibrin is formed. The process goes on best at the tem- 

 perature of the body ; it is delayed at ; and the ferment is 

 destroyed at the boiling point. The presence of O seems necessary 

 for coagulation. The amount of ferment appears to be immaterial; 

 large quantities produce more rapid coagulation, but the amount of 

 fibrin formed is not greater. 



The amount of salts present has a remarkable relation to coagulation. 

 Solutions of the fibrin-factors deprived of salts, and redissolved in 

 very dilute caustic soda, when mixed, do not coagulate until sufficient 

 NaCl be added to make a 1 per cent, solution of this salt (Schmidt). 



When blood or blood-plasma coagulates, all the fibrinogen is used 

 up, so that the serum contains only fibrinoplastin and fibrin-ferment; 

 hence, the addition of hydrocele fluid (which contains fibrinogen) to 

 serum causes coagulation. 



According to Hammarsten, fibrin is formed when the ferment is 

 added to a solution of fibrinogen. 



[Hammarsten's Theory Of Coagulation, Hammarsten's researches lead 

 him to believe that fibrinoplastin is quite unnecessary for coagulation. According 

 to him, fibrin is formed from one body, viz., fibrinogen, which is present in plasma 

 when it is acted upon by the fibrin-ferment; the latter, however, has not been 

 obtained in a pure state. Neither he nor Schmidt asserts that this body is of 

 the nature of a ferment, although they use the term for convenience. It is quite 

 certain that fibrin may be formed when no fibrinoplastin is present, coagulation 

 being caused by the addition of calcic chloride or casein prepared in a special way. 

 But, whether one or two proteids be required, in all cases it is clear that a 

 certain quantity of salts, especially of NaCl, is necessary.] 



30. Source of the Fibrin-Factors. 



Al. Schmidt maintains that all the three substances out of which 

 fibrin is said to be formed, arise from the breaking up of colourless 

 blood-corpuscles. In the blood of man and mammals fibrinogen exists, 

 dissolved in the circulating blood as a dissolution product of the 



