I 



CLASSIFICATION. 389 



on a flat surface. If we imagine a laurel-bush to be squashed 

 flat by a horizontal plane descending upon it, we shall see 

 that sundry of the upper branches and twigs which were 

 previously close together will become remote, and that the 

 relative positions of parts can remain partially true only 

 with the minor branches. The reader must therefore expect 

 to find some of the zoological divisions which in the order of 

 nature are near one another, shown in the table as quite 

 distant. 



§ 101. While the classifications of botanists and zoologists 

 have become more and more natural in their arrangements, 

 there has grown up a certain artificiality in their abstract 

 nomenclature. When aggregating the smallest groups into 

 larger groups and these into groups still larger, they have 

 adopted certain general terms expressive of the successively 

 more comprehensive divisions; and the habitual use of these 

 terms, needful for purposes of convenience, has led to the 

 tacit assumption that they answer to actualities in Nature. 

 It has been taken for granted that species, genera, orders, 

 and classes, are assemblages of definite values — ^that every 

 genus is the equivalent of every other genus in respect of its 

 degree of distinctness; and that orders are separated by 

 lines of damarcation which are as broad in one place as 

 another. Though this conviction is not a formulated one, 

 the disputes continually occurring among naturalists on 

 the questions, whether such and such organisms are specifi- 

 cally or generically distinct, and whether this or that pecu- 

 liarity is or is not of ordinal importance, imply that the 

 conviction is entertained even where not avowed. Yet that 

 differences of opinion like these arise and remain unsettled, 

 except when they end in the establishment of sub-species, 

 sub-genera, sub-orders, and sub-classes, sufficiently shows 

 that the conviction is ill-based. And this is equally shown 

 by the impossibility of obtaining any definition of the degree 

 of difference which warrants each further elevation in the 

 hierarchy of classes. 



