132 
CHARACTERS USED IN CLASSIFICATION. 
and qualities, and appear evidently as distinct tribes. If the whole 
of the vegetable kingdom could thus be distributed into natural 
classes, the study of Botany would be much simplified ; but it has 
already been remarked, that there are many plants which cannot be 
thus arranged, and no principle has yet been discovered for system¬ 
atic arrangement which bears any comparison to the Artificial Sys¬ 
tem. This system may be compared to a dictionary ; though by its 
use we do not at first find the name for which we seek, and then 
learn its definition, as we do in dictionaries of terms; but we first 
learn some of the characters of a plant, and with these as our guide, 
we proceed to find the name. Having ascertained the botanical 
name, we can easily find to what natural family a plant belongs, 
and thus learn its habits, medicinal use, and other important par¬ 
ticulars. The natural method may be considered as the grammar 
of botany ; for between this, and the artificial system, the same re¬ 
lation exists, as between the grammar and dictionary of a lan¬ 
guage ; it w T ould be idle to attempt to decide on their comparative 
merits, since both are essential to science. 
As the subject of classification is so important to a knowledge of 
botanical science, we will now consider the general principles on 
which it depends. 
Rules . v 
1st. All botanical classification results from an examination and 
comparison of plants. 
2d. Every organic distinction which establishes betv'een individuals 
any resemblance , or any difference , is a character; that is : a sign by 
which they may be known and distinguished. 
3d. The presence of an organ , its different modification and its ab¬ 
sence^ are so many characters. 
4th. The presence of an organ furnishes positive characters , its ab¬ 
sence negative characters. 
Positive characters offering means of comparison, show the re¬ 
semblances and differences which exist between individuals ; 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 separated ; 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 pro¬ 
vided with stamens and pistils, we point out particulars where visible 
and striking resemblances may be observed; these characters , then, 
are positive, since they are founded on something real. 
When we say that some plants are destitute of cotyledon, corolla, 
stamens or pistils, we do not establish any real basis for the founda¬ 
tion of a comparison. If we wish to separate plants with monope¬ 
talous 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 individ¬ 
uals of each group. Thus positive characters possess a great ad¬ 
vantage over negative ones ; the latter should never be employed 
Artificial system of arrangement compared to a dictionary—First learn the charac¬ 
ters, then the name—The natural method considered as the grammar of botany— 
Mention the first four rules which are given for classification—Positive and negative 
characters—Give illustrations of these characters, with their uses—Advantage of pos¬ 
itive characters over negative. 
