THE NATURE OF SPECIES 



than one species and several subspecies. Systematic botanists 

 and zoologists have been divided into two schools — the 

 "Splitters" and the "Lumpers." The "Splitters" establish 

 species on differences which the "Lumpers" treat as mere 

 individual and inconstant variations. Darwin represented 

 Asa Gray, the famous American botanist, as a Splitter, and 

 Sir Joseph Hooker, of Kew, as a Lumper. Herbert Spencer, 

 in 1852, estimated that the number of species must amount 

 to at least ten millions. The Splitters would multiply that 

 number many times. 



There has been no agreement as to what characteristics 

 should be regarded as of specific rank — that is, as sufficient 

 to justify a naturalist in founding a species — and as to what 

 are of a lower systematic value. For example, there has been 

 a long-continued controversy whether man is one species or 

 whether the European, the Negro, and the Mongolian are 

 distinct species. This difficulty has been partly overcome in 

 practice by the introduction of minor units of classification, 

 which have been called subspecies, and the subspecies have 

 been divided into varieties, and these into subvarieties, and 

 these in turn into races and subraces. The divisions are thus 

 numerous, and the grounds for them are indefinite. Different 

 groups of plants and animals have different grades of spe- 

 cific subdivision, according to the abundance of their mem- 

 bers, or their variability, or the attention they have attracted. 

 Thus the Flora of France uses in some genera six subdivisions 

 lower than the genus. British botanists adopt more subdi- 

 visions of species in roses and brambles than in less variable 

 plants. Some species of British land snails, such as the com- 

 mon Helix nemoralis, have undergone indefinite subdivision. 



The extent to which experts differ as to whether certain 

 variations are distinctive of species, varieties, or races shows 

 that there are no such fixed limits to species as the pre- 



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