Theories of Evolution 11 



double meaning. One of them is the systematic 

 species, which is the unit of our system. But 

 these units are not at all undivisible. Long 

 ago Linnaeus knew them to be compound ideas 

 in a great number of instances, and increasing 

 knowledge has shown that the same rule pre- 

 vails in other instances. Today the vast ma- 

 jority of the old systematic species are known 

 to consist of minor units. These minor en- 

 tities are called varieties in systematic 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. 



