. THE FIBRIN-FACTORS. 35 



[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 paraglobulin, 

 which is not precipitated until the amount of salt exceeds 20 per cent.] 



Properties of the Fibrin-Factors. They are insoluble in pare 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 ( 249, III.). Fibrinogen held in solution by common 

 salt coagulates at 52 to 55 C. [Fredericq finds that fibrinogen exists as such in 

 the plasma ; it coagulates at 56 C, and the plasma thereafter is uncoagulable.] 



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

 times its volume of strong alcohol, and after one month filter off the deposit 

 thereby produced. The deposit on the filter consists of coagulated insoluble 

 albumin and the ferment ; dry it carefully over sulphuric acid, and reduce to a 

 powder. Triturate 1 gram of the powder with 65 c.c. of water for ten 

 minutes, and filter. The ferment is dissolved by the water, and passes through 

 the filter, while the coagulated albumin remains behind (Schmidt). 



[(b) Gamgee's Method. Buchanan's " washed blood-clot " (p. 33) is digested in an 8 percent, 

 solution of common salt. The solution so obtained possesses in an intense degree the properties 

 of Schmidt's fibrin-ferment.] 



In the preparation of fibrino-plastin, the ferment is carried down with it mechanically. The 

 ferment seems to be formed first in fluids outside the body, very probably by the solution of 

 the colourless corpuscles. More ferment is formed in the blood the longer the interval between 

 its being shed and its coagulation. It is destroyed at 70 C. Blood flowing directly from an 

 artery into alcohol contains no ferment. It is also formed in other protoplasmic parts 

 (Eauschenbach), e.g., in dead muscle, brain, suprarenal capsule, spermatozoa, testicle (Foa and 

 Pellacani), and in vegetable micro-organisms [e.g., yeast] and protozoa (Grohmann), [so that it 

 would seem to be a general product of protoplasm. As the ferment does not pre-exist in 

 colourless blood-corpuscles, it seems to be formed from some mother-substance in them, the 

 blood-plasma itself decomposing this substance]. 



Coagulation Experiments. According to A. Schmidt, if pure solutions of (1) 

 fibrinogen, (2) fibrino-plastin, and (3) fibrin-ferment be mixed, fibrin is formed. 

 The process goes on best at the temperature of the body ; it is delayed at ; and 

 the ferment is destroyed at the boiling-point. The presence of O seems necessary 

 for coagulation. The amount of the ferment appears to be immaterial ; large 

 quantities produce more rapid coagulation, but the amount of fibrin formed is not 

 greater. 



[Foa and Pellacani find that a filtered watery extract of fresh brain, capsule of the kidneys, 

 testes, and some other tissues, when injected into the blood-vessels of a rabbit, causes 

 coagulation of the blood in the pulmonary circulation and the heart, death being caused by the 

 action of a substance identical with the fibrin-ferment.] 



The amount of salts present has a remarkable relation to coagulation. Solutions 

 of the fibrin-factors deprived of salts, and redissolved in very dilute caustic soda, 

 when mixed, do not coagulate until sufficient NaCl be added to make a 1 per cent, 

 solution of this salt (Schmidt). [Green finds that calcium sulphate brings about 

 coagulation in plasma which shows little or no tendency to clot, while coagulation 

 in its absence is almost or quite prevented.] 



When blood or blood-plasma coagulates, all the fibrinogen is used up, so that the 

 serum contains only fibrino-plastin and fibrin-ferment ; hence, the addition of 

 hydrocele fluid (which contains fibrinogen) to serum causes coagulation. 



[Hammarsten's Theory. Hammarsten's researches led him to believe that 

 fibrino-plastin is quite unnecessary for coagulation. According to him, fibrin is 

 formed from one body, viz., fibrinogen, which is present in plasma when it is acted 

 upon by the fibrin-ferment ; the latter, however, has not been obtained in a pure 



