258 THE BLOOD. 



the amount of fibrinogen from which the fibrin is derived, and we always 

 find a small amount of protein substance in the solution. It is therefore 

 not improbable that the fibrin coagulation, in accordance with the views 

 first proposed by DENIS, is a cleavage process in which the soluble fibrinogen 

 is split into an insoluble protein, the fibrin, which forms the chief mass, 

 and a soluble protein substance which is produced only in small amounts. 

 We find a globulin-like substance which coagulates at about 64 C. in 

 blood-serum as well as in the serum from coagulated fibrinogen solutions. 

 This substance is called fibrin-globulin by HAMMARSTEN. The investiga- 

 tions of HUISKAMP have shown that this substance is not formed as a 

 cleavage product from pure fibrinogen, but occurs in plasma or in fibrinogen 

 solutions not purified from sodium fluoride or perhaps in loose com- 

 bination with fibrinogen. The view that a cleavage takes place in the 

 coagulation of the fibrinogen has not been supported by these investi- 

 gations. 1 



Opinions are not unanimous in regard to the enzyme nature of throm- 

 bin and the enzymotic formation of fibrin, and there are, indeed, investiga- 

 tors who consider the coagulation as another process. A more thorough 

 discussion of this subject can take place only in connection with the 

 coagulation of the blood. 



Nucleoprotein. This substance, which, as above-mentioned, is considered 

 by PEKELHARING and HUISKAMP as identical with the prothrombin or thrombin, 

 occurs in the blood-plasma as well as in the serum, and is precipitated from the 

 latter with the globulin. It is similar to the globulin in that it is readily soluble 

 in neutral salt solution, and can be completely salted out on saturation with 

 magnesium sulphate, and separates only incompletely on dialysis. It is much 

 less soluble than serglobulin in an excess of dilute acetic acid, and coagulates 

 at 65-69 C. C. G. LIEBERMEISTER 2 found only 0.08-0.09 per cent phosphorus 

 in the nucleoprotein, which indicates that the nucleoprotein was contaminated 

 with other proteins. He also found that the substance was soluble in acetic acid 

 with difficulty, a property which is used by PEKELHARING as an important means 

 of separating the compound proteins from the globulins. 



Serglobulins, also called paraglobulin (KUHNE), fibrinoplastic substance 

 (ALEX. SCHMIDT), serum-casein (PANUM 3 ), occur in the plasma, serum, 

 lymph, transudates and exudates, in the white and red corpuscles, and 

 probably in many animal tissues and form-elements, though in small 

 quantities. They are also found in the urine in many diseases. 



The so-called serglobulin is without doubt not an individual sub- 

 stance, but consists of a mixture of two or more protein bodies which 



^ee Hammarsten, Zeitschr. f. physiol. Chem., 28; Heubner, Arch. f. exp. Path. 

 u. Pharm., 49, and Zeitschr. f. physiol. Chem., 45; Huiskamp, ibid., 44 and 46. 



2 Hofmeister's Beitrage, 8; Pekelharing and Huiskamp, 1. c. footnote 1, page 256. 



'Kiihne, Lehrbuch d. physiol. Chem., Leipzig., 1866-68; Alex. Schmidt, Arch. f. 

 (Anat. u.) Physiol., 1861-62; Panum, Virchow's Arch., 3 and 4. 



