CtASSII^lCATiOX. 



471 



KuleraWe they may be, do not point to 

 ulterior unknown ditferences, would 

 be to replace classes with more by 

 classes with fewer attributes in coni- 

 njon, and would be subversive of the 

 Natural Method of Classification. 



Accordingly all natural aiTange- 

 ments, whether the reality of the dis- 

 tinction of Kinds was felt or not by 

 their framers, have been led, by the 

 mere pursuit of their own proper end, 

 to conform themselves to the distinc- 

 tions of Kind, so far as these had been 

 ascertained at the time. The Species 

 of Plants are not only real Kinds, but 

 are probably, all of them, real lowest 

 Kinds, infimoi species; which, if we 

 vera to subdivide, as of course it is 

 open to us to do, into sub-classes, 

 the subdivision would necessarily be 

 founded on definite distinctions, not 

 pointing (apart from what may be 

 known of their causes or effects) to 

 any difference beyond themselves. 



In so far as a natural classification 

 is grounded on real Kinds, its groups 

 are certainly not conventional : it is 

 perfectly true that they do not depend 

 npon an arbitrary choice of the natu- 

 ralist. But it does not follow, nor, I 

 conceive, is it true, that these classes 

 are determined by a tj^^*, and not by 

 characters. To determine them by a 

 type woiald be as sure a way of missing 

 the Kind, as if we were to select a set 

 of characters arbitrarily. They are 

 <letermined by characters, but these 

 are not arbitrary. The problem is, 

 to find a few definite characters which 

 point to the multitude of indefinite 

 one.s. Kinds are Classes between 

 which there is an impassable barrier ; 

 and what we have to seek is, marks 

 whereby we may determine on which 

 side of the barrier an object takes its 

 place. The characters which will best 

 do this should be chosen : if they are 

 also important in themselves, so much 

 the better. When we have selected 

 the characters, we parcel out the ob- 

 jects according to those characters, 

 and not, I conceive, according to re- 

 semblance to a type. We do not com- 

 ix>se the species Ranunculus acris of 



all plants which bear a satisfactor}' 

 degree of resemblance to a model 

 buttercup, but of those which possess 

 certain characters selected as marks 

 by which we might recognise the pos- 

 sibility of a common parentage ; and 

 the enumeration of those characters 

 is the definition of the species. 



The question next arises, whether, 

 as all Kinds must have a place among 

 the classes, so all the classes in a na- 

 tural arrangement must be Kinds 'i 

 And to this I answer, Certainly not. 

 The distinctions of Kinds are not 

 ninnerous enough to make up the 

 whole of a classification. Very few 

 of the genera of plants, or even of the 

 families, can be pronounced with cer- 

 tainty to be Kinds. The great dis- 

 tinctions of Vascular and Cellulai', 

 Dicotyledonous or Exogenous and 

 Monocotyledonous or Endogenous 

 plants, are perhaps differences of 

 kind ; the lines of demarcation which 

 divide those classes seem (though 

 even on this I would not pronounce 

 positively) to go through the whole 

 nature of the plants. But the differ- 

 ent species of a genus, or genera of 

 a family, usually have in common 

 only a lin)ited number of characters. 

 A Rose does not seem to differ from 

 a Rubus, or the Umbelliferse from 

 the Ranunculacese, in much else than 

 the characters botanically assigned to 

 those genera or those families. Un- 

 enumerated differences certainly do 

 exist in some cases ; there are families 

 of plants which have peculiarities of 

 chemical composition, or yield pro- 

 ducts having peculiar effects on the 

 animal economy. The Cruciferae and 

 Fungi contain an unusual proportion 

 of nitrogen ; the Labiatae are the chief 

 sources of essential oils, the SolaneaR 

 are very commonly narcotic, &c. In 

 these and similar cases thei-e are pos- 

 sibly distinctions of Kind ; but it is 

 by no means indispensable that there 

 should be. Genera and Families may 

 be eminently natural, though marked 

 out from one another by properties 

 limited in number, provided those 

 properties are important, and tlie 



