The Making of Species 



ditions are comparatively uniform, nevertheless 

 it boasts of no fewer than fifteen out of the thirty- 

 seven known species of cormorant. A possible 

 explanation of this phenomenon may be found 

 in the comparatively easy conditions under which 

 cormorants live in New Zealand. 1 Under such 

 circumstances mutants may be permitted by 

 natural selection to survive, whereas in other 

 parts of the world such mutants have not been 

 able to hold their own. 



Prof. Bateson has likened natural selection 

 to a competitive examination to which every 

 organism must submit. The penalty for failure 

 is immediate death. The standard of the ex- 

 amination may vary with the locality. 



Isolation, then, is a very important factor in 

 the making of species, for without it, in some 

 form, the multiplication of species is impossible. 



Let us, in conclusion, briefly summarise what 

 we now know of the method in which new species 

 are made. We have studied the various factors 

 of evolution variation and correlation, heredity, 

 natural selection, sexual selection, and the other 

 kinds of isolation. How do these combine to bring 

 new species into being, and to establish the same ? 



Let us first consider the factor known as 

 natural selection, since this is the one on which 



1 Hutton and Drummond record other examples of this in the 

 valuable work entitled The Animals of New Zealand. 



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