40 FIBRINOGEN. [BOOK I. 



globulin is an alkaline albuminate 1 . According to Hammarsten 

 paraglobulin would be a proteid having the characters of a weak 

 acid 2 . 



2. Fibrinogen. 

 Schmidt's When plasma which has been diluted with ten or 



fifteen times its volume of ice-cold water, and has 

 keen fr ee d from paraglobulin by the action of a long- 

 continued stream of CO 2 , is still further diluted, and 

 again subjected to G0 2 , there separates a second precipitate which 

 is found to consist of a body very closely resembling paraglobulin, but 

 yet possessing certain marked distinctions. This body is denomi- 

 nated fibrinogerij a term which sufficiently indicates that it is pre- 

 sumed to be one, at least, of the precursors of fibrin. 



Unlike paraglobulin, fibrinogen does not exist in the serum 

 which separates from blood olot, but it is present in the liquid found 

 in many serous cavities, as in the pericardium, the peritoneum, the 

 pleurae ; also in the liquid of hydrocele. 



From all these liquids fibrinogen may be separated by the method 

 previously referred to, viz. by dilution with water, and the subsequent 

 action of CO, or instead of passing C0 2 , the liquids may be cautiously 

 neutralized with acetic acid. Fibrinogen may also be precipitated 

 from liquids which hold it in solution by adding common salt. 



Like paraglobulin, fibrinogen is insoluble in pure water, but 

 soluble in water which holds oxygen in solution ; it is soluble in 

 weak solutions of the alkalies, and in solutions of many neutral salts, 

 as in weak solutions of sodium chloride. 



Hammar- The behaviour of fibrinogen to solutions of common 



salt has been studied with care by Eichwald and Ham- 

 marsten 8 , and is so important as to deserve careful 

 consideration, for upon it is based a method of sepa- 

 rating this substance from paraglobulin, and obtaining it in a pure 

 condition from the fluids which contain it. 



Both fibrinogen and paraglobulin are soluble in solutions of sodium 

 chloride which contain 5 8 per cent, of the salt. When however 

 the quantity of salt attains 12 16p.c., fibrinogen is precipitated whilst 

 paraglobulin remains in solution ; the quantity of salt must amount 

 to more than 20 p.c. before any appreciable quantity of paraglobulin is 

 thrown down. 



In order to obtain pure fibrinogen Hammarsten proceeds as 

 follows : 



The blood of the horse is mixed on its issue from the blood- 



1 Heynsius, "Ueber die Eiweissverbindungen des Blutserams und des Huhnerei- 

 weisses," Pfluger's Arcldv, Vol. ix. 514552. 



2 Hammarsten, "Ueber das Paraglobulin," Erster Absclmitt. Pfluger's Archiv, 

 Vol. xvn. (1878) p. 466. 



3 Hammarsten, " Untersuchungen iiber die Faserstoffgerinnung. 5, Ueber eine 

 neue Methode zur Bemdarstelhmg des Fibrinogens aus dem Blutplasma". Nova Acta, 

 Regiae Societatis Scientiarum Upsalensis. Ser. in., Vol. x. 1, p. 31, Separatabdruck. 



