1 68 EVOLUTION OF TO-DAY. 



species which has been introduced has flourished, and 

 has caused more or less extinction of the native 

 tribes. The people have a saying illustrative of 

 this. " As the white man's rat has driven away the 

 native rat, as the European fly drives away our 

 own, and the clover kills our fern, so will the Maori 

 disappear before the white man himself." All such 

 instances, which are numerous enough, show that 

 species are not created especially for the locality 

 they inhabit, since many localities are better adapted 

 to other animals than those which now inhabit 

 them, and since some species flourish better in other 

 localities than those in which they are found. Cli- 

 mate is a factor in regulating distribution, but since 

 like habitats may possess unlike fauna and unlike 

 habitats possess like fauna, it is evident that the 

 influence of climate is only secondary. 



Laws of Distribution which would Follow from the 

 Descent Theory. 



All that can be expected from evidence on this 

 subject is that the distribution of animals is such as 

 would have resulted if the descent theory were true, 

 and this will, of course, be only an indirect argu- 

 ment. Let us then first notice certain laws of dis- 

 tribution which the evolution theory demands and 

 without which it cannot stand. 



(i) It follows from the descent theory that allied 

 species should inhabit neighboring localities. If 

 species are simply exaggerated varieties, and genera 

 exaggerated species, it would follow that they must 

 have a regular distribution. A given species must 



