GENERAL VIEW OF THE FUNCTIONS. 25 



traction totally independent of the will : the heart is said to feel 

 (physiology has no proper term for the idea, but excitability 

 would answer the purpose) the stimulus of the blood, and, without 

 our influence, forthwith contracts ; the lacteals to feel the stimulus 

 of the chyle without our knowledge, and they then propel it 



miasmata. It in some cases destroys its own power in future, as is exemplified 

 in those diseases which occur usually but once during life. 



These observations on rare and frequent agency may relate to agency in general 

 or by particular agents. A very high or low excitement may influence the effects 

 of all subsequent stimuli ; but the rare or frequent application of a particular 

 agent in less intensity may influence its own effects only, as is exemplified in 

 the acquired capability of smoking or taking snuff, while other vapours or powders 

 affect no less than usual. 



While moderate excitement is necessary to maintain action and excitability, 

 and excitement by one stimulus, within due limits, augments the effects of an- 

 other, violent excitement wears out the power, and, very violent, may suddenly 

 destroy life altogether : according to the verses, 



Nutritur ventis, ventis extinguitur ignis, 

 Lenis alit flammas, grandior aura necat. 



Dr. John Brown, seizing the undeniable general facts respecting the effect of 

 rare or frequent application upon the power of stimuli, and naming all agents 

 stimuli, founded a system of pathology and practice at once absurd and destruc- 

 tive. (Elementa Medicince.} Exhaustion, from excess of stimulus, he termed 

 direct debility ; torpor, from deficiency of stimulus, indirect debility ; and how- 

 ever inflammatory a disease, if it arose from a stimulus, it was to be treated by 

 violent stimuli, to prevent the excitability from falling too low. 



In the first place, he abused the word stimulus, by confounding it with the 

 word agent, forgetting what has been just advanced respecting the peculiar pro- 

 perties of every agent, that some depress, and thus, though agents, are not 

 stimuli ; and some affect different parts differently ; and some have a specific 

 power upon certain parts and certain diseases, and against other agents. 



In the second place, he forgot what has been just said respecting the necessity 

 of a certain degree of excitement to maintain excitability ; the effect of one sti- 

 mulus, within due limits, of increasing the effect of others ; and the fact of a 

 stimulus producing so much excitement, that morbid sensibility occurs, far less 

 stimulus than was at first applied causing ten times the effect, and this being 

 reducible only by lessening all stimuli, the temperature, the quantity of blood, 

 &c., and stimulating distant parts. He forgot, also, the effect of sympathy and 

 specific action. 



His error was in keeping in view some general laws, which all know and 

 acknowledge, to the exclusion of others of at least equal importance. 



