6 On the Effects df Opuim 



minished, or exhausted by the apphcation of 

 external powers, which had no effect upon the 

 nervous system, and that it was, to use the 

 words of Dr. John Brown, ' d« • appHed to his 

 principle of Excitability, '^ Una toto eorpore 

 et indivisa proprietas.'* 



To ascertain how far some of these opinions 

 were consistent with the laws of the animal 

 economy, I instituted a set of experiments, 

 which formed the subject of an inaugural dis- 

 sertation, published in the year 1790. It apr 

 peared to me in consequence of that investiga- 

 tion, that several of the above-mentioned 

 opinions, viz. That opium did not act upon 

 the nervous system ^ , that it acted upon the 

 blood; that its effects could be extended by 

 means of the one and indivisible property of 

 irritability, had been founded upon reasons 

 which were very unsatisfactory. 



This publication being calculated principally 

 for the meridian of Edinburgh, was confined to 

 that place, and the question, taken in a general 

 point of view, was left undetermined. 



Since that time I find, from the perusal of a 

 work, called " Medical Extracts," written by 

 a gentleman of some ability, but of more 

 imagination than judgment; that the opiT 

 nions of Fontana are not only sanctioned by 

 respectable authority, but are considered as 



