Secreting Power uf Animals. "1?63 



According to this view of the subject, which has always ap- 

 peared to me the only correct one, when we prove that afte- 

 deranging the functions of a secreting surface by di\iding its 

 nerves, we can restore its healthy state by galvanism, we prove 

 the identity of this power with that on which secretion depends ; 

 and that secretion depends on the nervous power, the facts just 

 laid before the reader, as far as I am able to judge, appear suf- 

 ficiently to evince. 



The experiment alluded to in the above passages quoted 

 from Dr. Alison's paper, even by his admission, being an experi- 

 mentum crucis of the identity of galvanism and the secreting 

 power, must, except on the supposition that secretion does not 

 depend on the nervous influence, do away all that he says re- 

 pecting our not being able to point out how galvanism is ex- 

 cited, or how it effects so great a variety of changes in the 

 animal body. We must of course admit that our knowledge 

 of this principle is very limited*; but we see nothing in the 

 phenomena of the nervous influence, on the supposition that it 

 is galvanism, more extraordinary than many analogous facts. 

 How is electricity collected and subjected to the will of electric 

 animals, so that they cannot only evolve it at pleasure, but ac- 

 cording to M. Humboldt's experiments, direct it to any particular 

 part of the body. How does it happen, that the electricity of 

 the gymnotus, which is strong enough to deprive a horse of 

 power, cannot affect the nicest electrometer ? Can any one 

 who has read the experiments of Sir James Hall on the various 

 results obtained under different circumstances by the agency of 

 caloric, even on the same substances, and those few in num.ber, 



• When Dr. Alison, towards the end of his paper, accuses me of sup- 

 porting one hypothesis by another, he forgets that what I say on the sub- 

 ject under discussion is thrown out as a mere suggestion, namely, that on 

 the supposition of the nervous influence being galvanism the difficulties 

 stated are explicable : on the supposition of its being something no-where 

 «")ti8ting, but when formed by the brain and spinal marrow, they wre wholly 

 inexplicable ; referring, however, to future investigations for any knowledge 

 that may be acquired on the subject. I allude chiefly to the phenomena 

 of th" foftiis previous to the formation of any part of the brain and spinal 

 marro'.v. 



