308 THE BLOOD. 



they would act as kinases in the vertebrates. Under favorable condi- 

 tions 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, is, in LOEB'S opinion, not proven. 



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

 from the tissue coagulins. The first show no specific action, i.e., between inver- 

 tebrates and vertebrates. The tissue coagulins, on the contrary, have by their 

 action upon the blood a certain specificity, at least in animals widely separated 

 from one another. 



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 1 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 fibrinogeri 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 proportions 

 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 is formed. 

 Thrombin is a fibrin incompletely saturated with fibrinogen, and in the 

 coagulation of fibrinogen with thrombin the still unsatisfied affinities 

 of the latter are saturated (" La thrombine d'A. Schmidt n'est pas autre 

 chose que la fibrine insuffisamment pourvue de fibrinogne. Dans la 



1 Arch, internal . de Physio!., 6, Fasc., 1, 2 and 3. 



