114 Alison on the T/ieori/ ascribing Secretion 



3. The action of nerves on muscles is similar to that which 

 is exercised by galvanism on muscles. 



From these facts it is concluded, that what has been called 

 nervous influence or energy is in all cases galvanism, and from 

 them, taken in connexion with the facts just noticed, of the 

 cessation of secretion on the division of tlie nerves supplying 

 certain secreting organs, a strong presumption is thought to 

 arise, that secretion is owing to a galvanic action propagated 

 along the nerves, and is to be numbered with the other well- 

 known chemical effects of galvanism. 



In regard to secretion, a still stronger argument in favour of 

 this theory is adduced by Dr. Wilson Philip. He found, that 

 when the secretion in the stomachs, either of rabbits or dogs, 

 is suspended by cutting the eighth pair of nerves, it may be 

 restored by applying galvanism, and the ordinary changes may 

 be effected by the help of this agent, on the food previously taken 

 into the stomach. 



It is obvious, however, C taken for granted that all sources of 

 fallacy in these experiments were avoided, ) that even this fact 

 admits very readily of a different explanation. It may be said 

 that the secretion in the stomach does not depend on its nerves, 

 but is liable to be influenced through them ; that the shock of 

 the division of the nerves acted as a powerful sedative, and sus- 

 pended the secretion, but that the stimulus of the galvanism 

 was sufficient to restore it. 



It is obvious also, that if this last explanation be admitted, 

 these experiments of Dr. Philip must be regarded as furnishing a 

 decisive argument against the dependance of secretion upon the 

 nervous system. For here we have the nervous influence cut 

 off, and yet secretion going on. On the supposition that the 

 nervous influence is really essential to secretion, this can only 

 be explained by supposing the galvanic influence, which is sub- 

 stituted for it, to be really the same thing. 



If, therefore, we can make it probable, that the changes 

 which occur in the nervous system are not galvanic actions, we 

 need go no farther, after these experiments, in order to shew 

 that the nervous system is not necessary to secretion. 



