CHARACTERS USED IN CLASSIFICATION. 
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RULES. 
1st. All botanical classification results from an examination and 
comparison of plants. 
2d. Every organic distinction which establishes between indi- 
viduals any resemblance , or any difference , is a character ; 
that is, a sign, by which they may be known and distin- 
guished. 
3d. The presence of an organ, its different modification and 
its absence, are so many characters. 
4th. The presence of an organ furnishes positive characters, 
its absence negative characters. 
Positive characters offering means of comparison, shew 
the resemblances and differences which exist between indi- 
viduals ; those plants in which these characters present but 
slight differences, should be collected in groups ; those in 
which these characters differ more sensibly, should be sep- 
arated ; here we follow strictly the laws of the mind. But 
negative characters as they allow no comparison can only 
be employed to separate individuals, and never to bring 
them together. 
When we say that plants have seeds with one or two 
cotyledons ; that they have monopetalous or polypetalous 
flowers, and are provided with stamens and pistils, we 
point out particulars, where visible and striking resemblan- 
ces may be observed ; these characters then, are positive, 
since they are founded or something real. 
When we say that some plants are destitute of co- 
tyledon, corolla, stamens or pistils, we do not establish 
any real basis for the foundation of a comparison. If we 
wish to separate plants with monopetalous corollas, from 
such as have polypetalous corollas, this single character 
establishes at once, the difference which exists between the 
two groups, and the resemblance, which exists between the 
individuals of each group. Thus positive characters pos- 
sess a great advantage over negative ones ; the latter should 
never be employed when the former can be used ; and in 
proportion, as positive characters can be substituted for 
negative, the science of botany will be perfected. 
Positive characters can only be founded upon evident 
facts, and never upon a presumption of the existence of 
facts, derived from analogy. For it is contrary to true 
Found by examination and comparison of plants — Resemblances and dif- 
ferences are characters — Positive character — Negative character — Positive 
character used in grouping flowers — Negative characters in separating 
them — Advantage of positive characters over negative — Characters founded 
only upon positive facts. 
