CHARACTERS USED IN CLASSIFICATION. 133 



when the former can be used ; and in proportion as positive cha- 

 racters can be substituted for negative, the science of botany will 

 oe 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 philosophy, to suffer hypothetical 

 reasoning to usurp the place of direct observation of facts. 



5th. Positive characters are constant or inco7istant. All seeds pro- 

 duced by plants of the same species have the same structure ; all 

 plants which grow from these seeds produce other seeds, similar to 

 those from which they have had their origin ; of course the charac- 

 ters derived from the structure of these seeds are constant. But 

 among these plants some are large and others small ; some may 

 have white corollas, some red, or blue ; some are more fragrant than 

 others ; of course, size, colour, and odour, offer inconstant characters, 



6th. All real science in Botany must rest upon constant characters ; 

 therefore, these characters are much more important than the others. 



7th. Constant characters may be isolated or coexistent. The petals 

 of the RANUNCULUS acris, (butter-cup,) have a nectary in the form of 

 a scale ; this character, although constant, is isolated, for it is not 

 necessarily connected with any other characteristic trait. The calyx 

 of the campanula rotundifolia, (blue-bell,) adheres to the germ ; the 

 germ must of necessity be simple, or without divisions, and the co- 

 rolla and stamens attached to the interior of the calyx. The cha- 

 racter of the adherence of the calyx to the germ, brings in its train 

 several other characteristics ; it is then coexistent ; and is more im- 

 portant than the isolated character. 



8th. Two orders of characters are derived from the two great divi-,. 

 sions of vegetable organs ; those of vegetation and reproduction. The 

 characters of reproduction are numerous and often coexistent ; ons 

 character serving as an index to many others. 



It is seldom that plants which resemble each other in their charac- 

 ters of reproduction, differ much in their characters of vegetation. 

 For example ; all plants which have four didynamous* stamens, at- 

 tached to a monopetalous- labiate corolla, and four seeds lying un- 

 covered in a monophyllous calyx, have an angular stem and opposite 

 leaves. On the contrary, it frequently happens that plants which re- 

 semble each other by the characters of vegetation, differ by those 

 of reproduction. Labiate and caryophyllous plants agree in having 

 their leaves opposite, and yet there is no resemblance in their flow- 

 ers. This consideration alone, would seem sufficient for establish- 

 ing the superior importance of the characters of reproduction over 

 those of vegetation. The seed unites in itself the characters both of 

 reproduction and vegetation. The embryo is the commencement of 

 the new plant, and ix offers us the first characters of vegetation ; but 

 its situation in the fruit, the number, form, and consistence of its en- 

 velope, are characters which belong to fructification. 



In separating or bringing together plants, we should, as far as 

 possible, make use of prominent characters which the eye can see 

 without the help of the microscope ; but if experience teaches us 

 that the characters most constant and proper for the explanation of 

 physiological phenomena can only be discovered by such aid, it is 



* That is, two long and two short stamens. 



Positive characters founded only upon evident facts— What is the fifth rule 7 — The 

 sixth?— The seventh 7— The eighth 7— Characters of reproduction more important 

 than those of vegetation- In what cases should we make use of characters invisible 

 to the naked eye 7 



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