354 LINNiEUS AND THE JUSSIEUS 



class ; thus kindred plants may be separated, or plants 

 of no near kindred united. Tournefort was led by his 

 artificial system to unite the cinquefoil with Ranunculus, 

 and to separate columbine. Linnaeus was led in the 

 same way to unite Colchicum with sorrel, and to 

 separate Persicaria. The natural system, though less 

 facile than an artificial one, avoids these blots ; all the 

 organs of the flower are taken into account, and no 

 genera are separated by an arbitrary definition. A. L. 

 de Jussieu proceeds to investigate the Ranunculaceae. In 

 order to complete his task he would have to determine 

 the characters of the family, and also to fix its place in 

 the series ; but for the present he limits himself to the 

 discovery of the characters, which are first enumerated 

 without selection. Some are constant, others more or 

 less variable ; each may occur by itself in other families, 

 but the combination of all is peculiar to Ranunculaceae, 

 and constitutes its essential character. The characters 

 of the different families are not always drawn, Jussieu 

 goes on to explain, from the same organs, though logic 

 would seem to require that this rule should be strictly 

 observed.^ 



Some few families of flowering plants, Jussieu says, 

 are so plainly marked out in nature that they are 



1 So Linnseua : — " Quas in uno genere ad Genus stabiliendum valent, minime 

 idem in altero neoessario prsestant." {Phil. Bot., §169.) "The conflict 

 between natural classification and logic is apparent only. Logicians say that 

 in classifying books, for instance, you may take any property you please, 

 subject, size, &o., as tlie basis of your arrangement, but having made your 

 choice, you must adhere to it for all divisions of the same rank. Naturalists 

 seem to say something dififerent, for they are agreed that what they call 

 •single-character classifications,' in which one property is adhered to through- 

 out, are unnatural. The fact is that a natural classification always rests 

 upon one and the same property, viz. affinity, i.e. relative nearness of descent 

 from some common ancestor. Every natural classification, like every logical 

 classification, proceeds upon a single basis, and the failure of the single-character 

 classifications is due to their replacing affinity by some definition." (Miall, 

 Hist, of Biology, p. 126.) 



