DR. PHILIP ON THE NATURE OF DEATH. 189 



We cannot be surprised that the inanimate agents which are incapable of any 

 change that unfits them for their office, should at length effect a permanent change in 

 the vital parts on which they operate, of all parts of nature the most changeable. 

 Hence the death of old age. 



The sensorial functions we have seen fail first, because their organs are removed from 

 the immediate action of the inanimate agents which still excite the organs to which 

 they are directly applied ; but for the same reason, it is in the latter, the organs of 

 the nervous and muscular systems, that the decay begins. Their powers are gradually 

 impaired by the operation of the inanimate agents which excite them, and the sen- 

 sorial powers, as appears from all the phenomena of our decay, only fail in conse- 

 quence of their failure ; but as a certain vigour is necessary to render the latter ca- 

 pable of maintaining the sensorial functions, these necessarily cease before the total 

 extinction of those which maintain them. 



IN the forms of violent death which have been considered, the offending cause 

 makes its impression on the organs of the sensitive, in those which remain to be con- 

 sidered, on the organs of the vital system. 



IT is evident from what has been said of the nature and relations of the functions of 

 the living animal, that there is one class of the causes of death which is necessarily 

 confined to the vital organs. On them, we have seen, the inanimate agents on the 

 operation of which life depends, make their impression. Those which impress the 

 organs of the sensitive system excite only the functions by which our intercourse with 

 the external world is maintained, and consequently may cease to operate without at 

 all endangering life. But the withdrawal of the agents which excite the vital organs 

 as certainly proves fatal as the loss of power in these organs themselves. 



The operation of such causes is too simple to require any comment. It is evident 

 that the want of food must destroy the digestive and other assimilating functions ; 

 that of air, the functions of the lungs ; and the loss of blood, to a certain extent, 

 those of the heart and blood-vessels. 



THE other causes which belong to the forms of death I am now to consider, 

 operate in a manner analogous to the offending causes which make their impression 

 on the organs of the sensitive system ; for although the vital organs are not subject to 

 the same species of exhaustion with those of the sensitive system*, like them they 

 may be debilitated either by the excess of the stimulant, or the more direct, effect of 

 the agent, according to the degree in which it is applied. The excitement of fever 

 terminates in debility of the heart and blood-vessels, or where the cause is more 

 powerful, as we see in the worst forms of typhus, it may directly impair their powers ; 



* See my paper on Sleep in the Philosophical Transactions for 1833. 



