THEORY OF COAGULATION. 655 



power of the blood are more expressive of disease, 

 than any other part of the animal economy. 

 (Treatise on the Blood, &c. vol. i. p. 135.) But 

 he was wholly mistaken in supposing that co- 

 agulation is prevented in cases of sudden death 

 from lightning, violent emotions of the mind, 

 the more active poisons, and exhaustion from ex- 

 cessive muscular exertion, as has been recently 

 proved by the accurate researches of Dr. John 

 Davy. 



At the same time, it is certain from the experi- 

 ments of Hewson, that the coagulating power of 

 the blood is diminished in all cases of congestion, 

 intermittent fever, pneumonia, consumption, rheu- 

 matism, and various other modifications of dis- 

 ease, by which the general forces of life are seri- 

 ously impaired, and that the process is delayed 

 in such cases, for ten, twenty, thirty, or even 

 ninety minutes. It is very much protracted in 

 cases of apoplexy, epilepsy, concussion of the 

 brain, suffocation, strangulation, violent emotions 

 of fear, and other depressing passions,* or what- 



* It is very well known, that in cases of fright, the powers of 

 life are remarkably diminished. That this is owing to partially 

 suspended respiration, on which the vital properties of the blood 

 depend, is evident from the coldness of the extremities, langour 

 of the circulation, paleness of the skin, and darkness of the blood, 

 when drawn from a vein. In all such cases, the voluntary power 

 of the brain is more or less impaired by the shock, and its com- 

 mand over the lungs so far diminished, that their chemical func- 

 tion is greatly interrupted, when they fail to arterialize the blood 



