ix FIBRIN 381 



The salting- out limits for ammonium sulphate are given by Reye l 

 as lying between 1-7 to 1 '9 and 2 '5 to 2 '8, according to the concentration 

 of the solution. As the lower limit for globulins lies between 2 '7 and 

 3*1, Reye obtains fibrinogen by adding to 100 parts of plasma 40 parts 

 of saturated ammonium-sulphate solution. Magnesium sulphate and 

 sodium chloride 2 salt out fibrinogen even before complete saturation. 

 Hammarsten obtains his pure fibrinogen by the addition of an equal 

 volume of saturated salt-solution to plasma, and obtains in this way a 

 pure preparation, but only in small amounts. Horse's blood is most 

 suitable, but other blood may be used if its coagulation has been pre- 

 vented by the addition of 1 : 1000 of sodium oxalate or sodium fluoride. 

 If one wishes to examine pure coagulated fibrin, it is best to heat 

 blood-plasma very carefully to 56. The fibrin prepared in the usual 

 way by beating blood with twigs always contains cell-remnants, 

 haemoglobin, and large amounts of globulin ; it must, in addition to 

 water, be also washed out very thoroughly with 3 per cent sodium 

 chloride, but it is even then very impure. 



f Precipitated fibrinogen is a tough, very elastic, glutinous body of 

 the consistency of coagulated blood. It becomes even more rapidly 

 insoluble than do all the other globulins, it being quite immaterial 

 whether it be precipitated by water or acids or salts ; this denatural- 

 isation occurs with special rapidity in the presence of lime salts, 1 a 

 phenomenon met with to a certain extent in all albumins. The in- 

 soluble fibrinogen is absolutely distinct from the coagulated fibrin, it is 

 a true denaturalised albumin. 3 Many erroneous statements 3 are due 

 to no distinction having been made between this coagulated fibrinogen 

 fibrin and the readily formed insoluble fibrinogen -lime compound. 

 Even when in solution 3 fibrinogen rapidly deteriorates and becomes 

 uncoagulable if dialysis be prolonged too much. 



Fibrin 



Under the influence of the fibrin-ferment fibrinogen is changed 

 into fibrin. How this is brought about is not known, but whenever 

 fibrin is formed, an albumin, the so-called fibrin -globulin, 4 remains in 

 solution, immaterial whether fibrinogen is coagulated by being warmed 



1 W. Reye, Medical Dissertation, Strassburg, 1898. 



2 0. Hammarsten, Pflagers Arch. /. d. ges. Physiol. 22. 431 (1880). 



3 0. Hammarsten, Zeitschr. /. physiol. Chem. 22. 333 (1896). 



4 0. Hammarsten, Pfl'Agers Arch. /. d. ges. Physiol. 22. 431 (1880) ; 30. 437 

 (1883) ; Zeitschr. /. physiol. Chem. 28. 98 (1899) ; L. Fredericq, Bull, de V Acad. royale 

 de Belgique, 2nd ser. 64. 7 (1877) ; 0. Hammarsten, Zeitschr. /. physiol. Chem. 22. 333 

 (1896). 



