710 PEOTEIDS. [A PP. 



According to Kuhne 1 and Eiehwald 2 a globulin with properties identical with 

 those just given may be precipitated from dilute serum by the cautious addition of 

 acetic acid. This body is stated by Weyl 3 to be th6 same as paraglobulin (fibrino- 

 plastin), the latter differing from it only by a small admixture of fibrin-ferment. 



2. Paraglobulin (Fibrinoplastin). 



Preparation. Blood-serum is diluted ten-fold with water, and a 

 brisk current of carbonic anhydride is passed through it. The first-formed 

 cloudiness soon becomes, a flocculent precipitate, which is finally quite 

 granular, and may easily be separated by decantation and filtration : it 

 should be washed on the filter with water containing carbonic acid. 



It has usually been stated that paraglobulin may be separated from 

 $erum by saturation with sodic chloride. But Hammarsten 4 has shown 

 that this is only in part true, a considerable portion of the globulin 

 remaining unprecipitated. The separation may however be completely 

 effected by saturation with magnesic sulphate. When determined 

 by this method the amount of paraglobulin in serum is very con- 

 siderable, amounting, in some cases according to Hammarsten, to as 

 much as 4 '5 6 5 p. c. (reckoned on 100 cc. of serum). The quantity 

 seems to vary in different animals, the precipitation being much more 

 complete in serum from ox-blood than in that from the blood of horses. 

 From its solution in dilute sodic chloride, paraglobulin may be pre- 

 cipitated by a current of carbonic anhydride or the addition of exceedingly 

 dilute (less than 1 pro mille) acetic acid. If the acid is strong, the 

 precipitated proteid becomes immediately changed into acid-albumin 

 (Class II. 1 .). In pure water, free from oxygen, paraglobulin is insoluble, 

 but on shaking with air or passing a current of oxygen, solution readily 

 takes place ; from this it may be reprecipitated by a current of carbonic 

 anhydride. Very dilute alkalis dissolve this body without change ; if, 

 however, the strength of the alkali be raised even to 1 p. c. the para- 

 globulin is changed into alkali-albumin (Class II. 2.). 



According to Kiihne and A. Schmidt the solutions of this body in 

 water containing oxygen or in very dilute alkalis are not coagulated on 

 heating. The sodic chloride solutions do however coagulate when 

 heated to 68 70 C. 5 , and if the substance itself be suspended in 

 water and heated to 70 C. it is coagulated. Although insoluble in 

 alcohol, its solutions are with difficulty precipitated by this reagent. 



Paraglobulin occurs not only in blood-serum, but it is also found in 

 white corpuscles, in the stroma of red corpuscles (to some extent at 



1 Lekrb. d. Physiol. Chem. 1868. S. 175. 



2 Beitrdge zur Chem., d. gewebebild. Subst. Berlin, 1873. Hf. i. 



3 Zeitschr.f. Physiol. Chem., Bd. i. (1878) S. 79. 



4 Pniiger's Archiv, Bd. xvn. (1878) S. 446. Bd. xvm. (1878), S. 38. 

 6 Hammarsten, op. cit. 



