/o the Agency of the Nerves. 115 



But, on the other hand, even if we admit the galvanic nature 

 of nervous actions*, it does not follow from these experiments 

 that they are essential to secretion ; for the effect of the gal- 

 vanism, applied in these experiments of Dr. Philip, may be 

 merely to counteract a noxious influence resulting from the 

 division of the nerves, not to restore a salutary one. 



I shall first state the considerations which seem to me to 

 render it probable that the actions of nerves are not galvanic, 

 and afterwards those which seem to me to shew, that even if 

 nervous actions be galvanic, still they cannot be necessary to 

 secretion. 



I. It is not, of course, intended to deny, t,hat a certain degree 

 of galvanic action may be excited by the contact of nerve and 

 muscle, or of nerve and gland ; that these substances stand re- 

 lated to each other as the zinc and copper of a galvanic trough 

 do. What is doubted is, not the presence of the cause assigned, 

 but its adequacy both in degree of intensity, and in kind of 

 agency, to the explanation of the phenomena, and that for the 

 following reasons : 



1. If the changes in the nerves, which precede the contraction 

 of muscles irritated through their nerves, be of the nature of 

 galvanism, and if it be by galvanising the muscles that all the 

 stimuli applied to nerves excite these motions, we must suppose 

 galvanism to be excited, from time to time, to an intense degree, 

 in nerves aird muscles, without the aid of any chemical agent, 

 and without any change in the chemical constitution of these parts 

 taking place either during or after the evolution of the galvanism. 

 Now it is quite clear, that in tracing the physical changes pro- 

 duced by mind on body upwards to their source, we must ulti- 

 mately arrive at some physical change which is inexplicable ; 

 and this ultimate inexplicable change may just as well be of the 

 nature of galvanism as of any other nature. I do not there- 

 fore urge it as an argument against nervous actions being gal- 



* In this paper I use the term " nervous actions", as a short expression 

 for those unknown chanjfes in the nervous system, which are presumed to 

 take place on various occasions in the living body, without presuming to offer 

 an opinion as to the nature of these changes. 



I 2 



