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CHAP. VI. 



VEGETABLE POISONS. 



SECTION I. 



Preliminary Observations. 



J\ POISON may be defined to be any substance which, when 

 applied to tlte animal frame externally or internally, injures or de- 

 stroys it, by exciting morbid action. This definition, we allow, is 

 extensive ; but the diversified nature of the substances that fall 

 within the meaning of the term, and the multiform mode of their 

 action, prevent us from being able to limit it within narrower 

 bounds. Poisons may, therefore, be contemplated under the four 

 classes of animal, vegetable, mineral, and hallituous. At the two 

 last we have already occasionally glanced, in various chapters of I he 

 first book of the present work ; the more curious of the animal 

 poisons will fall within the scope of the ensuing book ; and we have 

 only, in the division before us, to notice those that belong to the 

 vegetable world. 



Preliminarily, however, we will observe, that most of the sub- 

 stances properly called poisonous, are only so in certain doses; for 

 below this point in the general scale, many of them form the most 

 active and consequently the most valuable medicines of the dispen- 

 satory. There are nevertheless some poisons which are deleterious 

 and even fatal in the smallest quantities imaginable, and which are 

 hence never administered medicinally; such are those of hydrophobia 

 and the plague. There are other poisons, again, which are inno- 

 cent when taken into the stomach, but which prove deleterious when 

 applied to the lungs, or to an abraded surface j thus carbonic acid 

 is continually swallowed with fermented liquors with impunity, and 

 the poison of the viper may be taken in the same manner : whilst 

 inspiring carbonic acid kills, and the poison of the viper inserted into 

 the flesh often proves fatal. 



