CHAP. II.] THE BLOOD. 49 



amount of the ferment, but the rapidity of coagulation is so influenced. 

 The influence of solutions of the fibrin-ferment may be well seen by 

 adding it to dilute solutions of salted plasma. It has been said that 

 blood or plasma which has been prevented from coagulating by the 

 addition of a neutral salt, such as sodium or magnesium sulphate, 

 will coagulate if a sufficient quantity of water be added. The 

 coagulation is, however, under the circumstances not an immediate 

 one. But if to a slowly coagulating mixture of plasma, water, and 

 neutral salt, there be added some of Schmidt's solution of fibrin-ferment 

 the process may be remarkably hastened. 



The Au- In narrating the discoveries of I)r Andrew Buchanan 



thor's Method attention was called to the action of the so-called ' washed 

 solution^ g a blood clot' of that author, in bringing about the coagu- 

 Fibrin-fer- lation of certain fluids ; washed blood clot being really 

 ment 1 . fibriii obtained by washing the coagulum which separates 



from blood when, at the time of being shed, that fluid is mixed with 

 about 10 times its volume of water. As Buchanan pointed out, such 

 fibrin possesses remarkable coagulant power, and, if preserved in weak 

 spirit, will retain that power for many months. 



By digesting Buchanan's washed blood clot in an 8 p.c. solution of 

 common salt, a solution is obtained which possesses in a very intense 

 degree the properties of Schmidt's solution of fibrin-ferment. This 

 solution contains a proteid in solution which possesses all the reactions 

 of a globulin; it is rendered inactive by exposure to temperature 

 of 56 58 C., and when it is saturated with powdered magnesium 

 sulphate. 



The origin of the Fibrin-ferment. 



After the discovery of the so-called fibrin-ferment, Schmidt's 

 views might be stated as follows, though not in his words : In cases 

 where a fluid coagulates spontaneously with the formation of fibrin 

 there must be present the two fibrin-generators and a yet unknown 

 body, the fibrin-ferment, whose presence is, however, essential in order 

 that the two bodies shall associate themselves. 



Where again a liquid does not coagulate spontaneously but does so 

 on the addition of blood or of serum, the absence of coagulation may 

 be due to the absence of ferment, the two fibrin-factor-s being present ; 

 or it may be, and sometimes is, due to the absence of paraglobulin. In 

 the first case coagulation will be induced by the addition of , fibrin- 

 ferment alone, in the latter not until the previous addition of para- 

 globulin. The interaction of the fibrin-factors necessitates, hoivever, the 

 presence' of certain quantities of salts, and especially of sodium chloride. 



According to Schmidt, then, the formation of fibrin is due to the 

 interaction of two bodies under the influence of a ferment. 



1 A. Gamgee, "Some old and new experiments on the Fibrin-ferment." Journal 

 of Physiology, 1879. No. n. 



