COAGULATION OF THK BLOOD. C21 



and these have also, although only in the presence of lime salts (if the author 

 understands LOEB), a direct coagulating action upon fibrinogen. According to 

 LOEB the tissue coagulins do not act as kinases in the invertebrates, and he also 

 finds it improbable that they would act as kinases in the vertebrates. Under 

 favorable conditions the combined blood and tissue coagulins are more active 

 than the sum of the individual action. That this is due to an activation by a 

 kinase, which is a possible explanation, has, in LOEB'S opinion, not been proved. 



The coagulins of the blood are, as above stated, according to LOEB, different 

 from the tissue coagulins. The latter are for different classes of animals so 

 adapted that they bring about a quicker coagulation in the blood of certain classes 

 of animals than do the bther class. The erythrocytes of mammalia (cat, dog, rabbit) 

 contain, on the contrary, according to LOEB and FLEISHER x coagulins of such a 

 specific adaptability that it is possible to differentiate between the blood corpuscles 

 of different kinds of mammalia or, if the erythrocytes are known, to detect an 

 unknown plasma. 



Opinions are strikingly at variance in regard to the mode of action 

 of the tissue constituents which accelerate coagulation, and their nature 

 also is entirely unknown, hence great confusion exists on the whole in 

 this subject. 



If we accept the fact that thrombokinase does not occur in the plasma, 

 but is produced under the influence of a foreign body acting as an excitant, 

 it is rather difficult to understand why the plasma obtained from blood 

 collected in a paraffined vessel and quickly and strongly centrifuged, 

 and which is perfectly free from form-elements, should remain fluid for 

 a long time in a paraffined vessel while it coagulates in an ordinary glass 

 vessel. NOLF has tried by his theory to explain this difficulty, as well 

 as the action of the alcohol-soluble zymoplastic substances (ALEX. 

 SCHMIDT). 



According to NoLF 2 the following bodies take direct part in the 

 coagulation of the blood, namely: Fibrinogen, thrombogen (formerly 

 called hepatothrombin by him) thrombozym ( = thrombokinase of MORA- 

 WITZ) and lime salts. The coagulation of the blood, according to him, 

 is a different process from the coagulation of a fibrinogen solution by 

 thrombin. While in this last case the thrombin is the substance exciting 

 coagulation, in the other case the thrombin is a product of the coagu- 

 lation, as suggested by WOOLDRIDGE. In the coagulation of the plasma, 

 according to NOLF we have a mutual precipitation of the three above- 

 mentioned colloids fibrinogen, thrombogen and thrombozym, all three 

 of which are contained in the fibrin clot. This latter has correspondingly 

 no constant composition, but varies according to the relative propor- 

 tions of these three colloids. In the presence of only a little fibrinogen 

 thrombin is produced from the three colloids (in the presence of lime 

 salts) ; in the presence of abundance of fibrinogen, on the contrary, fibrin 



1 Loeb and Fleisher, Bioch. Zeitchr. 28. 



2 Arch, internat. de Physiol., 6, Fasc., 1, 2, and 3 and 7 and 9. 



