ACTION OF POISONS. 127 



doubt that in many respects these two forces 

 bear a considerable resemblance to each other. 

 The generation of the nervous power as a con- 

 sequence of the circulation of arterial blood in 

 the grey matter of the brain and spinal chord ; 

 the instantaneous transmission of it through 

 the nerves ; sometimes affecting the secretions, 

 and causing the blood to undergo changes in 

 its chemical composition in the various glands, 

 at other times exciting violent contractions of 

 the muscles, these things are very analogous 

 to the effects produced by a voltaic battery ; and 

 there seems to be no reason, d priori, why the 

 resemblance should not extend still further, nor 

 why the evolution of heat should not be one of 

 the results of the operation of the nervous power 

 as it is of electricity. 



NOTE B. (Page 43.) 



In my papers on the mode in which death 

 is produced by poisons, I have stated various 

 circumstances which led me to the conclusion 

 that poisons which are applied to wounded sur- 

 faces produce their effect by passing into the 

 circulation ; and that certain mineral poisons 

 when introduced into the alimentary canal, have 

 a similar mode of operation. There is no doubt 



