CLASSIFICATION. 439 



the sul)ilivi.sion would necessarily be founded upon definite disllnttiona, 

 not poiiitintT (apiut from what may be known of their causes or effects) 

 to any dift'erenco beyond themselves. 



In so far as the natural dassitication is grounded upon real Kinds, 

 its jj^'oups are certainly not conventional ; INIr. Wliewell is quite right 

 in atlirming that they do not depend upon an arbitrary choice of the 

 naturalist. But it does not follow, nor, I conceive, is it true, that 

 these classes are determined by a type, and not by characters. To 

 determine them by a type would be as sure a way of missing the Kind, 

 as if we were to select a set of characters arbitrarily. They are deter- 

 mined by characters, but which are not arbitrary. The problem is, to 

 find a k\v definite characters which point to the multitude of indefinite 

 ones. Kinds are Classes between which there is an impassil)lc bar- 

 rier ; and what we have to seek is, marks whereby we may determine 

 on which side of the banier an object takes its place. The characters 

 which will best do this are what should be chosen : if they are also 

 important in themselves, so much the better. When we have selected 

 the characters, we parcel out the objects according to those characters, 

 and not, as Mr. Wliewell seems to suppose, according to resemblance 

 to a type. We do not compose the species Ranunculus acris, of all 

 plants which bear a satisfactory degree of resemblance to a model-but- 

 tercup, but of tliose which possess certain characters selected as marks 

 by which we might recognize the possibility 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 natural arrangement must 

 be Kinds ] And to this I answer, certainly not. The distinctions 

 of Kind are not numerous enough to supply the whole basis of 

 a classification. Very few of the genera of plants, or even of the 

 famiUes, can be pronounced with certainty to be Ivinds. The gi'cat 

 distinctions of Vascular and Cellular, Dicotyledonous or Exogenous 

 and Monocotyledonous or Endogenous, are perhaps differences of 

 Kind : the lines of demarkation 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 different species of a genus, or 

 genera of a family, usually have in common only a limited number of 

 characters. A Rosa does not seem to differ from a Rubus, or the 

 Umbcllifera3 fi-om the Ranunculacea?, in much else than the characters 

 botanically assigned to those genera or those families. Unenumcratcd 

 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 Cruciferai 

 and Fungi contain an unusual proportion of azote ; the Labiata; are the 

 chief sources of essential (fils, the Solancce are very commonly narcotic, 

 &c. In these and similar cases there are possibly distinctions of Kind ; 

 but it is by no means indispensable that there should be. Genera and 

 Families may be eminently natural, though inarkcd out from one 

 another by properties limited in number ; provided those ])ropertio8 

 be important, and the objec^ts contained in each genus or family re- 

 semble each other more than they resemble anything which is excluded 

 from the genus or family. 



After the recognition and definition, then, of the infima species, the 

 next step is to arrange these infirncc sjjecies into larger groups : making 



