18 FIBRIN-FERMENT. [BOOK i. 



certain quantity of neutral salt and water, be reduced to such a 

 condition that it coagulates very slowly indeed, taking perhaps 

 days to complete the process. The addition of a small quantity of 

 the aqueous extract we are describing will however bring about a 

 coagulation which is at once rapid and complete. 



The active substance, whatever it be, in this aqueous extract 

 J exists in small quantity only, and its coagulating virtues are at 

 ' Npnce and for ever lost when the solution is boiled. Further, there 

 .'is no reason to think that the active substance actually enters 

 $ into the formation of the fibrin to which it gives rise ; it seems, 

 \ $J ^ tnout undergoing changes in itself, to act in some way or other 

 N ^/ on the actual fibrin factors (fibrinogen and paraglobulin or one of 

 /vjy\f them) and to convert them or part of them into fibrin. It appears 

 to belong to a class of bodies playing an important part in 

 physiological processes and called ferments, of which we shall have 

 more to say hereafter. We may therefore speak of it as the fibrin- 

 ferment, the name given to it by its discoverer Alex. Schmidt. 



Fibrin-ferment appears to make its appearance in blood soon 

 after it has been shed, and like other ferments is apt to be 

 entangled in and carried down by any precipitates which occur 

 in blood. It is carried down by the plasmine, and hence solutions 

 of plasmine coagulate spontaneously. 



It exists in serum, and is carried down with paraglobulin when 

 that substance is precipitated. And hence arises the serious 

 question whether the coagulating effects of serum or prepared 

 paraglobulin on hydrocele or pericardial fluid are not, after all, due 

 to the ferment present rather than to the paraglobulin. So that 

 two views may be taken of the nature of coagulation. One 1 teaches 

 that fibrin arises from some mutual action of fibrinogen and para- 

 globulin induced by the fibrin ferment ; the other 2 that fibrin is 

 formed through the conversion of fibrinogen alone by the agency 

 of the ferment, paraglobulin either having nothing to do with the 

 matter, or merely assisting by its presence in some indirect way. 



There can be no doubt that fibrinogen is an essential factor, 

 that coagulation cannot take place without it and that it or some 

 part of it actually becomes fibrin. There is equally no doubt that 

 the presence of the fibrin-ferment is absolutely necessary. It is 

 also more than probable that fibrin does not result from the union 

 of fibrinogen arid paraglobulin, since the quantity of fibrin formed 

 is not greater than that of either of these two substances used to 

 produce it. But we still need further light as to the exact nature 

 of the change produced by the ferment, the true characters of the 

 ferment itself, and the part played by paraglobulin. 



In favour of the view that paraglobulin is not concerned in 

 the matter, it is asserted, that fibrinogen cautiously precipitated 

 from plasma by small quantities of sodium chloride so as to obtain 



1 That of Alexander Schmidt, and his pupils and others. 

 " That of Hammarsten, Fredericq and others. 



