18 MEDICINAL PROPERTIES OP PLAXTS. 



a few solitary families, but from all that compose the veget- 

 able kingdom. 



Arguments for He commences with establishing the general proofs, that the 

 medicinal properties of plants are analogous to their external 

 forms. In fact no one will question, that the properties of 

 medicines depend on their physical constitution or chemical 

 composition: but in organized bodies the nature of a produc- 

 tion is determined by the form of the organs, since the same 

 aliments, digested by different beings, afford different results; 

 consequently the productions bear some relation to the forms. 

 This reasoning is applicable to the vegetable kingdom, though 

 its classification is not derived from the organs of nutrition, 

 but from those of reproduction; for the natural classes deduced 

 from one function necessarily agree with those deduced from 

 another function. 



Observations These general inferences are confirmed by the observation, 



pending to con- t j^ herbivorous animals frequently avoid or seek all the 



Arm it. • n J 



plants of the same family: that those, which seem deter- 

 mined to feed only on a single plant, frequently submit to eat 

 plants of the same genus, or of the same family : and that para- 

 sitic plants, particularly funguses, display the same preference 

 for certain genera, or certain families. To this may be ad- 

 ded, that several foreign drugs, which were formerly supposed 

 to be the production of a single plant, have been found oa 

 inquiry to be furnished by several species of the same genus; 

 and that with respect to indigenous simples it is no new thing, 

 for species of the same genus to be substituted for each other. 

 And we may observe, the narratives of travellers inform us, 

 that plants of the same family are often employed for similar 

 purposes in countries remote from each other. 



Y«t many ex- Notwithstanding these assertions however, which the au- 



ceptions. thor supports by several examples, it cannot be denied, thai 



vegetables very closely allied present very striking anomalies. 

 In order to estimate the real weight of these, the author takes 

 a review of the rules of comparison between forms and pro- 

 perties, and this is the part of his work that displays most 

 novelty. 



Resembtance &• ^ n tne ^ rst P^ ace " e observes, that, though M«e arrange 



in some fami- S p ec ies under genera, genera under families, and families u li- 

 lies ©f plants 7- , 



