Theories of Evolution 11 



double meaning. One is the systematic species, 

 which is the unit of our system. But these 

 units are by no means indivisible. Long ago 

 Linnaeus knew them to be compound in a great 

 number of instances, and increasing knowledge 

 has shown that the same rule prevails in other 

 instances. Today the vast majority of the old 

 systematic species are known to consist of minor 

 units. These minor entities are called varieties 

 in systematic works. However, there are many 

 objections to this usage. First, the term vari- 

 ety 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 svstematic varieties include 

 units the real value of which is widely differ- 

 ent in different cases. Some of these vari- 

 eties 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. 



