204 PHYSIOLOGY. 



defined. It is not known if the thrombokinase acts quantitatively 

 or by a ferment action. By coagulation the whole thrombogen 

 material is not used up, for you can find it in the serum, which 

 becomes active by adding the juice of tissues. The greater part of 

 the formed thrombin soon passes into an inactive form, metathrom- 

 bin, but by alkali or acids can again be changed in thrombin. 



The Importance of the Lime Salts in the Formation of the 

 Fibrin-ferment. It was found by Arthus and Pages that if the lime 

 salts were rendered insoluble by oxalates, the blood did not clot. 

 The addition of calcium salts makes the oxalate-plasma clot. Cal- 

 cium fluoride or citrate acts like the oxalate. This showed that the 

 presence of soluble calcium salts is necessary. Hammersten found 

 out that calcium is not necessary in the second stage of the act of 

 coagulation. It is in the first stage, in the formation of the fibrin- 

 ferment, that the presence of a soluble calcium salt is involved. 

 Pekelharing and Hammersten have shown that the calcium salts 

 activate a pro-thrombin present in the plasma. 



The Action of the Injection of Fibrin-ferment and the Tissue 

 Juices Into the Blood. As a rule, fibrin-ferment from the serum 

 causes intra- vascular clotting, deadly thrombi. The organism, 

 however, has the power to make small quantities of the fibrin-fer- 

 ment inactive. 



The juices of tissues, tissue extracts, often cause in rather small 

 doses extensive intra-vascular clots, which chiefly originate in the 

 right heart. 



In that peculiar hereditary disease of males only, haemophilia, 

 there is a want of coagulation. Morawitz and Lossen found in blood 

 drawn from the veins of a haemophilic that it took two hours to clot, 

 that the addition of calcium chloride did not accelerate coagulation, 

 that fibrinogen was normal in amount, and that the addition of 

 thrombokinase clotted the blood like it does normal blood in one 

 minute. The serum of the haanophilic contains more fibrin-ferment 

 than normally exists. Hence, the trouble in these cases seems to 

 be a want of thrombokinase. 



A condition known as luffy coat occurs when blood coagulates 

 very slowly. It is most readily seen in horses' blood, being caused 

 by the more rapid sinking of the red corpuscles in slow coagulation, 

 thus leaving the upper stratum to consist of a layer of fibrin and 

 white corpuscles. This whitish layer is elastic, has some resistance, 

 is more or less opaque, and has therefore been designated the buffy 

 coat. 



