NATURE OF COAGULATION. 69 



The enzymes or hydrolytic ferments behave in common in the organism 

 in such a manner that they break up the bodies upon which they act into 

 two other substances by taking up water. It, therefore, appears probable that 

 as a result of the action of thrombin decomposition of the fibrinogen into fibrin 

 and a lesser amount of a globulin-body that remains liquid and that Hammarsten 

 has designated fibrin- globulin, takes place, with the taking up of water. 



Demonstration of Fibrinogen C 112 H 168 N 30 SO 35 . Pulverized sodium 

 chlorid is added to lymphatic transudate to the point of saturation. 

 The fluid poured out into the serous sac surrounding the testicle 

 (hydrocele) is especially useful for this purpose. The precipitated 

 fibrinogen is collected upon a filter. This substance is found also in 

 the lymph and in the chyle. 



Saline plasma also is capable of precipitating fibrinogen by admixture of equal 

 volumes of plasma and a concentrated solution of sodium chlorid. For purposes 

 of purification it may then be dissolved rapidly and repeatedly in a dilute 

 8 per cent. solution of sodium chlorid and again precipitated by a concentrated 

 solution of sodium chlorid. The fibrinogen contained in the sodium-chlorid solu- 

 tion is precipitated by addition of water and is rapidly changed so that it 

 resembles fibrin. Fibrinogen in saline solution coagulates at a temperature of 

 from 52 to 55 C. Solutions free from salt do not coagulate if quickly brought 

 to the boiling-point. 



Fibrinogen behaves like globulin. It is soluble in dilute alkalies and it is 

 precipitated from such solutions by the passage of carbon dioxid. It is further 

 soluble in dilute solution of sodium chlorid, while addition of large amounts of 

 sodium chlorid causes its precipitation as a soft, viscous, tough mass. It is 

 dissolved also by dilute hydrochloric acid, although it is soon transformed into a 

 body resembling syntonin (acid albuminate) . In the fresh state it actively 

 decomposes hydrogen dioxid. Its specific rotatory power is 52.2. 



Demonstration of Fibrin-ferment Thrombin. Blood-serum from cat- 

 tle, which contains a larger amount of ferment than the serum of carnivora, 

 is admixed with twenty times its volume of strong alcohol. The result- 

 ing precipitate is collected upon a filter after the lapse of from two to 

 four weeks. It contains the coagulated albumin and the ferment. It 

 is dried over sulphuric acid and reduced to powder. One dram of this 

 powder is stirred for ten minutes in 65 cu. cm. of water. If the mixture 

 is not filtered, (the ferment, dissolved in water, alone passes through 

 the filter. X 



Thrombin is formed from a forerunner, a zymogen, which is present within 

 the leukocytes and is designated prothrombin. Both are soluble with greater 

 difficulty in an excess of acetic acid than globulins. Even small amounts of the 

 ferment may cause coagulation of fluids containing fibrinogen and most readily 

 at a temperature of 40 C. Prothrombin is destroyed at a temperature of 65 , 

 thrombin at a temperature between 70 and 75. The amount of ferment formed 

 in the blood is the 'greater the longer the time that has elapsed between the 

 escape and the coagulation of the blood. Blood flowing directly from the vein in 

 alcohol yields no ferment. 



Coagulation. If the separate solutions (i) of the fibrinogenous sub- 

 stance and (2) of the ferment are admixed fibrin-formation takes place 

 at once. The most favorable temperature for this is that of the body. 

 A temperature of o C. prevents coagulation, while the boiling tem- 

 perature destroys the ferment. The amount of ferment is a matter of 

 indifference. Larger amounts cause more rapid, but not increased, 

 separation of fibrin. For the formation of fibrin the presence of a 

 certain amount of salt in the fluid is requisite one per cent, sodium 

 chlorid. Otherwise the process takes place but slowly and is only 

 partial. The presence of a calcium-salt favors coagulation. If the 



