THE FIBRIN-FACTORS. 45 



the ox and horse serum-globulin is more abundant than serum- albumin, 

 while in the dog and rabbit the reverse obtains.] 



Preparation of Fibrinogen. This is best prepared from hydrocele 

 fluid, although it may also be obtained from the fluids of serous 

 cavities e.g., the pleura, pericardium, or peritoneum. It does not 

 exist in blood-serum, although it does exist in blood-plasma, lymph, and 

 chyle, from which it may be obtained by a stream of C0 2 , after the 

 paraglobulin is precipitated, (a.) Dilute hydrocele fluid with ten to 

 fifteen times its volume of water, and pass a stream of C0 2 through it ; 

 or (b.) carefully neutralise it by adding acetic acid, (c.) Add powdered 

 common salt to saturation to a serous transudation, when a sticky 

 glutinous (not very abundant) precipitate of fibrinogen is obtained. 



[Hammarsten and Eichwald find that, although paraglobulin and 

 fibrinogen are soluble in solutions of common salt (containing 5 to 8 

 per cent, of the salt), a saline solution of 12 to 16 per cent, is 

 required to precipitate the fibrinogen, leaving still in solution para- 

 globulin, which is not precipitated until the amount of salt exceeds 

 20 per cent. (Gamgee).] 



Hammarsten found that it may be prepared from blood (of the 

 horse) by first precipitating all the serum-globulin or fibrinoplastin 

 with crystals of magnesium sulphate, and subsequent filtration, which 

 removes the corpuscles ; a clear salted plasma is thus obtained. If to 

 the filtrate a saturated solution of common salt be added, a turbid, 

 flaky, impure precipitate of fibrinogen is obtained. This may be dis- 

 solved in dilute common salt, and again precipitated by a saturated 

 solution of NaCl. 



Properties Of the Fibrin-Factors. They are insoluble in pure water, but 

 dissolve in water containing O in solution. Both are soluble in very dilute 

 alkalies e. g., caustic soda, and are precipitated from this solution by C0 2 . They 

 are soluble in dilute common salt like all globulins but if a certain amount of 

 common salt be added in excess they are precipitated. Very dilute hydrochloric 

 acid dissolves them, but after several hours they become changed into a body 

 resembling syntonin or acid-albumin. 



Fibrinogen dissolved in a weak solution of common salt (1 to 5 per cent.) is 

 re-precipitated on adding water, so that it resembles fibrin. Its solution in 

 common salt coagulates at 52 to 55C. (Hammarsten, Fre"de"ricq). 



[Fre'de'riccL finds that fibrinogen exists as such in the plasma, it coagulates at 

 56C., and the plasma thereafter is uncoagulable (Gamgee).] 



Preparation of the Fibrin-Ferment. Mix blood-serum (ox) with 

 twenty times its volume of strong alcohol, and filter off the deposit 

 thereby produced after one month. The deposit on the filter consists 

 of albumin and the ferment ; dry it carefully over sulphuric acid, and 

 reduce to a powder. Triturate 1 gramme of the powder with 65 c.c.m. 

 of water for ten minutes, and filter. The ferment is dissolved by the 



