to the Agency of the Nerves. 123 



Now this frothy mucus, found not only in the air-cells, but 

 in the bronchia, in a quantity so much greater than natural, as 

 to be the cause of death, — what is it but a secretion ? If it be 

 denied that the fluid which is effused on the membrane lining 

 the bronchia and air-cells be a secretion, it is not worth 

 while to dispute about the word ; but it appears to me obvious, 

 that it is a formation from the blood, so much akin to the forma- 

 tion of the stomachic juice that the two must depend upon the 

 same principles. And when we find, in the experiments in 

 question, that the division of the eighth pair of nerves, which 

 supply equally thelungs and the stomach, diminishes or destroys 

 the production of the one of these fluids, and increases that of the 

 other, it is surely preposterous to conclude, that these experi- 

 ments demonstrate the necessity of an influence, derived from 

 the nerves, to secretion in general. 



There is a series of experiments by Mr. Brodie, {Philosophical 

 Transactions for 1812, p. 378,) intended to prove, that in an 

 animal which has been either killed by decapitation, or stupified 

 by poison, in such a manner as apparently to suspend all the 

 functions of the nervous system, the evolution of carbon still 

 goes on at the lungs, to an equal extent as in a healthy animal, 

 when artificial respiration is employed. To this evolution of 

 carbon, Mr. Ellis has given the name of secretion ; and although 

 I do not pretend to decide whether that name is applied with 

 perfect propriety in this instance, I take leave to observe, that 

 this process, thus proved to go on notwithstanding the division, 

 or destruction of the functions of the nerves supplying the 

 organ concerned in it, is considered by that distinguished phy- 

 siologist so nearly akin to secretion as to deserve the same 

 name. Its continuance, therefore, even independently of the 

 increase of the formation of mucus, in these circumstances, 

 must be regarded as a very strong argument against the depen- 

 dance of secretion on nervous influence. 



Having thus considered the different arguments in favour of 

 the supposition of that dependance, 1 think we may fairly say 

 not only that there is no proof of it in the wtitings of physiolo- 

 gists, but that there is strong evidence against it. I need 



