CHAP. II.] THE BLOOD. 37 



the two reagents, it assumes an intensely blue colour. This is due to 

 the oxidation of the resin of guaiacum by the oxygen which the 

 fibrin has liberated from the peroxide. 



Quantity of Human venous blood in health yields from 2 '2 to 



fibrin in the 2 '8 parts of fibrin per 1000, and it is said that arterial 

 blood - yields somewhat more than venous blood. 



The Assumed Precursors of Fibrin in the Liquor Sanguinis. 



1. Serum-Globulin or Paraglobulin. (Schmidt's fibrinoplastic 



substance.) 

 i 



Schmidt'a When plasma is diluted with ten or fifteen times its 



methods of volume of ice-cold water and subjected to the action of 

 Paraglobulin a stream of carbon dioxide 1 , or when it is carefully 

 neutralized with acetic acid, the liquid soon becomes 

 turbid, and deposits after some time a proteid substance to which the 

 above terms have been applied, of which the first indicates its resem- 

 blance to a proteid contained in the crystalline lens to which the 

 name of globulin was long ago ascribed; and the second the property 

 which has been ascribed to it of inducing, under certain circumstances, 

 the separation of fibrin from solutions containing fibrinogen. 



The quantity of dilute acetic acid (25 per cent.) to be added is 

 4 drops for every 10 c.c. of serum diluted with 150 c.c. of H 2 0. 



As the body which is precipitated under these circumstances is 

 not only contained in the plasma but also exists in the serum, the 

 latter much more readily available fluid may be employed for its 

 preparation. 



The same substance it is 2 , which is precipitated when blood serum 

 is subjected to dialysis (see p. 6), a process which may be employed 

 for the quantitative estimation of paraglobulin. With this object a 

 known weight or volume of serum is dialysed for 24 36 hours ; at 

 the end of this time the contents of the dialyser have become turbid, 

 and they are subjected to a current of C0 2 ; the precipitate produced 

 is collected on a filter, washed with water and alcohol and dried. 

 Following this method Schmidt found that 100 c.c. of the serum of 

 ox's blood yielded on an average 0'887 grammes of dry paraglobulin. 



Hammar- ft h as however been shewn by Hammarsten 3 that 



sten's meth ne ither by acetic acid, nor by dialysis and carbonic 



serum^giob^ acid > is paraglobulin fully precipitated : indeed these 



lin. reagents only throw down a small fraction of the 



paraglobulin contained in the serum or plasma. Having discovered 



1 A. Schmidt, " Weiteres iiber den Faserstoff und die Ursachen seiner Gerinnung. 

 1. Die fibrinoplastische Substanz." Archiv f. Anatomic u. Phijs., 1862, p. 429^et seq. ? 



2 A. Schmidt, " Untersuchung des Eiereiweisses und des Blutserum durch Dialyse. 

 Beitrdge zur Anatomic und Physiologie, als Festgabe Carl Ludwig geividmet. Leipzig, 

 1875. Part I., p. 101. 



3 Hammarsten, "Ueber das Paraglobulin," Erster Abschnitt. Pfliiger's Archiv, 

 Vol. xvn. (1878) p. 447 et seq. 



