THE BLOOD. 15 



blood is due, have never as yet been satisfactorily explained 

 and determined. Some have conceived that it resulted from 

 the escape of a vital air or essence. Much has been said and 

 written upon this " vital principle," and, it seems to me, with 

 very little profit. It would be more philosophical, I think, 

 to regard animal life not as an essence, or ether, but as the 

 complex operation of nicely adjusted scientific adaptations 

 and principles. According to this view, the human frame in 

 health would be comparable (and yet, withal, how incom- 

 parable is it !) to a finely -balanced machine, in which action 

 and reaction are proportionate, and in disease disproportion- 

 ate, the injury to the machine being equivalent to the dis- 

 proportion between the two forces. * 



The coagulation of the blood, in some degree, doubtless 

 depends upon the operation of the following causes, each con- 

 tributing in a greater or lesser degree to the result ; namely, 

 the cessation of nervous influence, the abstraction of caloric, 

 the exercise of chemical affinity between the particles of 

 fibrin, and, lastly, a state of rest : between motion and life a 

 very close connexion appears to exist, f 



Formation of the Clot. 



A portion of blood having been abstracted from the 

 system, and allowed to remain for a few minutes in a state 

 of quiescence, in a basin or other suitable vessel, soon mani- 

 fests a change of condition. This consists in the separation 

 of the fibrin and globules of the blood, which go to form the 

 clot, from the serum, which holds in solution the various salts 

 of the blood. In this way a rude and natural analysis is 

 brought about; the fibrin, being heavier than the serum, 

 falls to the bottom, and, by reason of its coherence and con- 



* It is hoped that the preceding brief remarks will not expose the 

 writer to the charge of being a Materialist ; between animal life and mind 

 an essential distinction exists. 



f " Fresh blood if exposed to a very low temperature freezes, and may 

 in that state be preserved, so as to be still susceptible of coagulation when 

 thawed." MULLER. 



