340 DARWINISM TO-DAY. 



naeus knew them to be compound ideas in a great number 

 of instances, and increasing knowledge has shown that the 

 same rule prevails in other instances. To-day the vast ma- 

 jority of the old systematic species are known to consist of 

 minor units. These minor entities are called varieties in sys- 

 tematic works. However, there are many objections to this 

 usage. First, the term variety is applied in horticulture and 

 agriculture to things so widely divergent as to convey no 

 clear idea at all. Secondly, the subdivisions of species are 

 by no means all of the same nature, and the systematic 

 varieties include units the real value of which is widely 

 different in different cases. Some of these varieties are in 

 reality as good as species, and have been 'elevated,' as it is 

 called, by some writers, to this rank. This conception of the 

 elementary species would be quite justifiable, and would at 

 once get rid of all difficulties, were it not for one practical 

 obstacle. The number of the species in all genera would be 

 doubled and tripled, and as these numbers are already 

 cumbersome in many cases, the distinction of the native 

 species of any given country would lose most of its charm 

 and interest. 



"In order to meet this difficulty we must recognise two 

 sorts of species. The systematic species are the practical 

 units of the systematists and florists, and all friends of wild 

 nature should do their utmost to preserve them as Linnaeus 

 has proposed them. These units, however, are not really 

 existing entities ; they have as little claim to be regarded 

 as such as the genera and families have. The real units 

 are the elementary species ; their limits often apparently 

 overlap and can only in rare cases be determined on the 

 sole ground of field-observations. Pedigree-culture is the 

 method required and any form which remains constant and 

 distinct from its allies in the garden is to be considered as 

 an elementary species." 



With regard to varieties de Vries has the following to 



