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4. <f On the Powers on which the Functions of Life depend in the more 

 perfect Animals, and on the Manner in which these Powers are asso- 

 ciated in their more complicated results." By A. P. W. Philip, M.D., 

 F.R.S. 



This paper is divisible into three portions. In the first, the author 

 considers the functions and seat of each of the powers of the living 

 animal j in the second, the nature of each power; and in the third, 

 the manner in which they are associated in the more complicated re- 

 sults which constitute life. 



Of these powers the simplest is the muscular, which consists 

 merely in a contractile power residing in the muscular fibre itself: 

 and various experiments are referred to in proof that it depends ex- 

 clusively on the state of this fibre, and in no degree on that of the 

 nervous system, which some physiologists have regarded as the real 

 seat of this power : for, instead of being recruited, it is exhausted by 

 the action of the nervous system upon it, as it is by other stimulants. 



The next power considered is that of the nervous system, properly 

 so called, in contradistinction to the sensorial system. The result of 

 an extensive series of experiments made with a view to establish the 

 exact line of distinction between these two systems, is that the func- 

 tions of the nervous power are as remarkable for their complexity as 

 that of the muscular power is for its simplicity. With regard to the 

 nervous power it is shown that its functions (all of which are capable 

 of existing after the sensorial power is withdrawn, and all of which 

 fail when the nervous power is withdrawn,) are the following : 1 . The 

 excitement of the muscles of voluntary motion in all their actions 5 



2. The occasional excitement of the muscles of involuntary motion 5 



3. The maintenance of the process by which animal temperature is 

 maintained 5 4. The maintenance of the various processes of secre- 

 tion ; 5. The maintenance of the processes of assimilation. It farther 

 appears, from several experiments, that the seat of the nervous power 

 is exclusively in the brain and spinal cord j not, however, in any par- 

 ticular part, but in the whole extent of these organs, from the upper- 

 most surface of the former to the lowest portion of the latter j with 

 the exception only that the lower portions of the spinal cord partake 

 less of this power than the rest. It appears also that the nerves are 

 only the medium of conveying the influence of the above-mentioned 

 organs j and their ganglions and plexuses are only the means of com- 

 bining the power of all the parts of these organs ; such combination 

 being shown to be necessary to the due excitement of the muscles of 

 involuntary motion, and for the maintenance of the functions of secre- 

 tion and assimilation. 



The remaining powers of the living animal are the sensorial powers, 

 and the powers of the living blood. The first of these classes of powers 

 has its seat, not in the whole brain and spinal cord, as is the case with 

 the nervous power, properly so called, but in certain parts of them ; 

 these parts being, in man, almost wholly confined to the brain 5 while 

 in some animals they extend also to a considerable portion of the 

 spinal cord. The functions of the sensorial powers are those strictly 

 termed mental, of which sensation and volition are the simplest, and 



