CHAKACTEES USED IN CLASSIFICATION. 125 



^ongs, and thus learn its habits, medicinal use, and other important particulars. 

 The natural method may be considered as tlie grammar of botany ; for between 

 this and the artificial system the same relation exists as between the grammar 

 and dictio7iari/ of a language : it would be idle to attempt to decide on their com- 

 parative merits, since both are essential to science. 



158. Hides for classifications — All hotanical classification rer 

 suits from an examination and comparison of plants. 



JEoery organic distinction which establishes between individu- 

 als any resemblance, or any diffekence, is a character / that 

 is. a sign hy which they may he known and distinguished. 



The presence of an organ., its different modification., and its 

 ahsence., are so many characters. 



The presence of an organ furnishes positive characters — its 



ABSENCE, NEGATIVE CHARACTERS. 



159. Positive characters offering means of comparison, show 

 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 \h.2^i jplants hm)e seeds vnth one or two 

 cotyledons / that they have monopetalous or jpolyjpetalous flow- 

 ers., and are provided with stamens and pistils., we point out 

 particulars where visible and striking rese'tnblances may he ob- 

 served ,' these characters., then, a7'e 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 foundation of a comparison. If we wish to separate 

 plants with monopetalous corollas from such as have polypet- 

 alous corollas, this single character establishes, at once, the 

 difference which exists between the two groups, and the resem,- 

 hlance which exists between individuals of each group. Thus, 

 positive characters possess 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 substi- 

 tuted for negative, the science of botany will be perfected. 

 Positive characters can only be founded upon evident facts., 

 and never upon 2^ presmnption of the existence of facts., derived 

 from analogy ; for it is contrary to true philosophy to suffer 

 hypothetical reasoning to usurp the place of direct observation 



* These rules are chiefly translated from Mirbel's " Elemens de Botanique." 



The natural method considered as the grammar of botany.— 158. Rules for cdassification.— 159. Posi- 

 tive and negative characters— Advantage of positive characters over negative — Positive characters 

 founded only upon e\-ident facts. 



