170 DR. PHILIP ON THE NATURE OF DEATH. 



power under all circumstances not being- essential to them, they are not so immedi- 

 ately essential to life as to be comprehended in the term vital functions, according to 

 its usual acceptation. 



When the animal no longer feels and wills, his breathing ceases and he is, accord- 

 ing to the common acceptation of the term, dead, although his body still retains its 

 other powers, which, while they last, prevent its obeying the laws of inanimate na- 

 ture* ; but the changes which after this take place, of course no more affect the indi- 

 vidual than if they took place in any other mass of matter. 



In inquiring into the physiological nature of what is called death, therefore, it is to 

 the ceasing of the sensorial functions alone that the attention must be directed. Thus 

 the subject divides itself into two parts ; the final loss of the sensorial functions, which 

 in common language has obtained the name of Death ; and absolute death, that is^ 

 the loss of all the functions, which we shall find in the more perfect animals is the 

 necessary consequence of the loss of the sensorial functions. 



The latter functions, as I have already had occasion to point out in my paper on the 

 Nature of Sleep, published in the first part of the Philosophical Transactions for 1833, 

 belong to those parts of the brain and spinal marrow which are associated with the 

 nerves of the sensitive system, and which, it appears, from another paper which the 

 Society did me the honour to publish in the same part of the Transactions, are the 

 only active parts of the sensorial system ; those on which the power of all its other 

 parts depends. To them, therefore, we must look for the immediate cause of failure 

 when the functions of the sensitive system, whether temporarily or finally, fail. It is 

 here we found that the immediate cause of sleep exists ; and it appears, from what has 

 just been said, that to the same parts we must look for the immediate cause of what is 

 called death. 



The state which immediately precedes the last act of dying, then, according to the 

 common acceptation of the term, and sleep, depend on a failure of function in the 

 same organs. In what, then, consists the difference of these states ? The most evident 

 is, that the one is a temporary, the other a final failure ; and it will appear, that in 

 the only death which can strictly be called natural, the state of the sensitive system 

 which immediately precedes death differs from its state in sleep in no respect but 

 in degree. 



The cause of sleep, as appears from the paper above referred to, is uniformly the 

 same, — a diminished excitability of the sensitive parts of the brain and spinal mar- 

 row, in consequence of the action of the ordinary stimulants of life ; but a loss of 

 excitability in those parts we shall find is never the sole cause of death, and often 

 makes no part of its cause. In sleep we have seen that the sensitive parts of the brain 

 and spinal marrow regain their functions in consequence of the continued vigour of 

 the vital system, by which their excitability is restored. To render the exhaustion 

 which constitutes sleep permanent, therefore, the powers of this system also must fail ; 



* Experimental Inquiry, Part II. chap. xi. 



