COAGULATION OF THE BLOOD. 647 



of the circulation : for when he connected a dead 

 tube at the temperature of the body, with the ex- 

 tremity of a divided artery of a living animal, the 

 blood sent into it remained fluid while kept in 

 motion by the heart's action. 



Some have ascribed the process of coagulation 

 to the escape of carbonic acid, and others to the 

 loss of nervous influence, or to the death of the 

 blood. But it is now fully established, that it is 

 not prevented by the presence of carbonic acid, 

 nor when placed in vacua. And that it is not 

 owing to the loss of vitality, is evident from the 

 fact, that in the latter stages of the most malig- 

 nant diseases, the blood remains fluid after death. 

 What then is the rationale of coagulation ? To 

 this important query Physiologists have hitherto 

 offered no satisfactory reply ; and Dr. John Davy 

 observes, that it must still be regarded as " one 

 of the many mysteries of nature" that " all we 

 know is, that from a fluid state, the fibrin be- 

 comes solid, entangling a portion of red particles 

 and serum." (Anat. and Physiological Researches, 

 vol. ii. p. 2.) 



The leading facts connected with the theory 

 of coagulation may be reduced to the following 

 propositions : 



1 . That the contractile power of the blood when 

 removed from the body, like that of the muscular 

 fibres, is in proportion to the quantity of respira- 

 tion, mean healthy temperature, and aggregate 



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