to the Agency of the Nerves. Ill 



logous to that, which these mental acts or afTections had been 

 wont to produce. 



The opinion, that secretion is dependent on nervous in- 

 fluence or energy has been maintained by different authors ; but 

 the best arguments in favour of it are those which have been 

 lately stated by Sir Everard Home*, Dr. Wollastonf, Mr. 

 Brodie t, and Dr, Wilson Philip §. 



Of these the most important is derived from the observa- 

 tions of the two last authors, on the effect of dividing the 

 eighth pair of nerves, on the secretions of the stomach. 

 Dr. Philip found, that no change takes place on food that 

 has been recently taken into the stomachs of rabbits, on which 

 this operation is performed, even when they live twenty-six 

 hours after the' operation, implying that the gastric juice 

 had not been secreted. This is confirmed by the observation of 

 older experimenters, that in animals killed by the division of 

 the eighth pair of nerves, the contents of the stomach are found 

 putrid : the effect, I presume, of their remaining some time at 

 the temperature of the internal parts of the body, without being 

 acted on by a chemical solvent. (See Haller, Experiences sur les 

 parties sensibles et irritables, No. 182 and 185.) And Mr. 

 Brodie found that the ordinary effect of arsenic, to produce an 

 increase of the mucous and watery secretions of the stomach and 

 intestines, is prevented from taking place, by dividing, either 

 those nerves in the neck, or the branches of them which supply 

 the stomach on the lower part of oesophagus \\. From these 

 experiments, these authors conclude, that the secretions of the 

 stomach, and other parts, are dependant on an influence 

 derived from their nerves. 



According to the principle above laid down, the facts just 



• I'hUosophical Transactions for 1809. 



t Philosophical Magazine for 1809. 

 ' t Philosophical Transactions for 1814, p. 102. 



^ Expl. Inquiry, &c., p. 119, et seq. 



II He had previously found the secretion of urine to cease after the 

 spinal cord is divided in the neck, or the head removed, both in rabbits 

 and dogs; notwithstanding that the circulation is kept up by artificial re 

 Bpiralion. See Philosophical Transactions for 1811. 



