THE BLOOD. 67 



contaminated with lecithin and which can hardly be purified with- 

 out decomposing. The method for the detection and quantitative 

 estimation of fibrinogen in a liquid is based on its property of 

 yielding fibrin on the addition of a little blood, of serum, or of 

 fibrin ferment. 



The fibrinogen stands in close relation to its transformation- 

 product, the fibrin. 



Fibrin is the name of that albuminous body which separates on 

 the so-called spontaneous coagulation of blood, lymph, and trans- 

 udations, as also in the coagulation of a fibrinogen solution after the 

 addition of serum or fibrin ferment (see below). 



If the blood is beaten during coagulation, the fibrin separates in 

 elastic fibrous masses. The fibrin of the blood-clot may be beaten 

 to small, less elastic, and not particularly fibrous lumps. The 

 typical, fibrous, and elastic white fibrin, after washing, stands in 

 regard to its solubility close to the coagulable albuminous bodies. 

 It is insoluble in water, alcohol, or ether. It expands in hydro- 

 chloric acid of 1 p. m., as also in caustic potash or soda of 1 p. m., 

 to a gelatinous mass, which dissolves at the ordinary temperature 

 only after several days, but at the temperature of the body it dis- 

 solves more readily but still slowly. The fibrin expands in a 5- 

 10$ solution of common salt or saltpetre, but only dissolves in 

 the presence of contaminating enzymes or by putrefaction. Fibrin 

 decomposes hydrogen peroxide, but this property is destroyed by 

 heating or by the action of alcohol. 



What has been said of the solubility of fibrin relates only to the 

 typical fibrin obtained from the arterial blood of mammalia or man 

 by whipping and washing first with water and with common-salt 

 solution, and then with water again. The blood of various kinds 

 of animals yields fibrin with somewhat different properties and 

 of varying purity, and likewise blood from different parts of the 

 body may yield fibrim with unlike solubilities ( DENIS). 



The fibrin obtained by beating the blood and purified as above 

 described is always contaminated by enclosed blood-corpuscles or 

 remains thereof, and also by lymphoid cells. It can only be obtained 

 pure from filtered plasma or filtered trausudations. For the pure 

 preparation, as well as for the quantitative estimation of fibrin, the 

 spontaneously coagulating liquid is at once, or the non-spontaneously 

 coagulating liquid only after the addition of blood-serum or fibrin 



