MEDICINAL PROPERTIES OF PLANTS. 19 



der classes, in a uniform manner, the groups are far from be- closrr than 



» i „,, . others, 



ing separated from each other in an equal degree 1 hus in 



certain families plants differ from each other by slight modifi- 

 cations only, while in others they are distinguished by more 

 important characteristics. The analogy between their proper- 

 tics may be presumed to be proportional to the analogy of 

 their structure. 



2. Secondly, it is contrary to the spirit of the method, to Similar organs 



„. c ... only and simi- 



compare the properties ot a given organ, or a given juice, j ar : u j ceg 



with those of another organ, or another juice. This however should becom- 



is one of the most frequent causes, that have led to mistakes P are " 



on the question. In this discussion the author introduces by 



the way some new views respecting the structure of bulbs, 



the body of which he proves to be in reality an abortive 



stalk, and not a root. 



3. The circumstances of the age of a plant, the season in Adventitious 



which it is gathered, the soil in which it has grown, and the c i rc,, " lstances . 

 Y o * should be simi- 



d eg ree -of light to which it has been exposed, are so many lar. 



causes of crrour, that are to be avoided in the comparison. 



4. Unequal mixtures or unequal combinations of different Principles 

 principles are found in the organs or juices of certain fami- equulv" 63 '""^ 

 lie.s; and in these families several of the most apparent ano-' or combined. 

 malics occur. 



5. In the comparison of properties, we should pay at ten- Modes of pre- 



tion to the difference that may exist in the mode of extracting P araUJn ;il!er 



J . & properties. 



and preparing a drug; for these circumstances frequently 



have as much influence on their properties as their intrinsic 



nature. 



6. 'We should -exclude from the comparion the mechanical Accidental 



... . . . - . . , qualities must 



or accidental properties, that arise From circumstances inde- be excluded. 



pendent of the true nature of substances. 



7- Above all we should most scrupuously attend not to the Not the paiti- 

 ,„ c iL ;• .. • '. c , . , ,. cular result but 



result ot the application ot a. medicine, but to its mode ot act- general mode 



ing; for medicines similar in reality act differently according OI * action to be 



i i-i i- i i • . • • • regarded. 



to the oigan to which they are applied, or tne casein which 



they are administered, and the contrary. 



After laying down those principles th-e author takes a view 



of all the families, that compose the vegetable- kingdom ; and 



details live properties of all ihe plants that belong to them. 



C 2 including 



