44 THE FIBRIN-FACTORS. 



the former. Schmidt afterwards discovered that these two substances may be 

 present in a fluid, and yet that coagulation may not occur (e.g., occasionally in 

 hydrocele fluid). He supposed, therefore, that blood or blood-serum contained 

 some other constituent necessary for coagulation. This he afterwards isolated 

 in an impure condition and called fibrin-ferment (Gamgee). ] 



Properties of these Substances. Fibrinogen and fibrinoplastin are 



not distinguished from each other by well-marked chemical characters. 

 Still they differ as follows : 



(a.) Fibrinoplastin is more easily precipitated from its solutions than 

 ftbrinogen. 



(I.) It is more readily redissolved when once it is precipitated. 



(c.) It forms when precipitated a very light granular powder. 



(d.) Fibrinogen adheres as a sticky deposit to the side of the vessel. 

 It coagulates at 56C. 



Both substances closely resemble globulin in their chemical composi- 

 tion (Kiihne called fibrinoplastin paraglobuliri), and in their reactions 

 they are not unlike myosin. Like all globulins, they require a trace of 

 common salt for their solution. 



On account of their great similarity, both substances are not usually 

 prepared from blood-plasma. Fibrinogen is prepared from serous trans- 

 udations (pericardial, abdominal, or pleuritic fluid, or the fluid of 

 hydrocele), which contain no fibrinoplastin. Fibrinoplastin is most 

 readily prepared from serum, in which there is still plenty of fibrino- 

 plastin, but no fibrinogen. 



Preparation of Fibrinoplastin. (a.) Dilute blood-serum with twelve 

 times its volume of ice-cold water, and almost neutralise it with acetic 

 acid, [add 4 drops of a 25 per cent, solution of acetic acid to every 

 120 c.c. of diluted serum]; or (b.) pass a stream of carbonic acid through 

 the diluted serum, which soon becomes turbid ; and after a time a 

 fine white powder, copious and granular, is precipitated (Schmidt, 

 18G2). 



[(c.) The serum may be dialysed for a day ; at the end of this time the contents 

 of the dialyser have become turbid, and when a current of COo is passed through 

 them, a precipitate of fibrinoplastin is obtained. Schmidt's fibrinoplastin has 

 also been called SERUM-GLOBULIN (Hammarsten) or PARAGLOBULIN (Kiihue).] 



Schmidt found that 100 c.c. of the serum of ox blood yielded 0'7 to O'S grins.; 

 horse serum, 0"3 to 0'56 grms. of dry fibrinoplastin. Fibrinoplastin occurs not 

 only in serum, but also in red blood-corpuscles, in the fluids of connective tissue, 

 and in the juices of the cornea. 



[((/.) Method of Hammarsten. All the fibrinoplastin in serum is 

 not precipitated either by adding acetic acid or by C0 2 . Hammarsten 

 found, however, that if crystals of magnesium sulphate be added to 

 complete saturation, it precipitates the whole of the serum-globulin, 

 but does not precipitate serum-albumin (Gamgee) ; it seems that in 



