" Natural Selection " 59 



will be no evolution, unless, by some cause or other, 

 portions of the species are isolated, because, in the 

 long run, the mutations will neutralise one another." 

 They then suppose " that natural selection comes 

 into play," and endeavour to prove that in this case 

 " the result of natural selection would be to accelerate 

 evolution, by weeding out certain classes of individuals, 

 and preventing them breeding with those it has 

 selected." On the other hand, they point out that 

 " natural selection would tend to diminish the number 

 of species which have arisen through mutation, 

 inasmuch as it weeds out many mutants which would 

 not have perished had their survival been determined 

 by lot." This is very interesting, but inconclusive ; 

 surely it is not unjust to say it is more metaphysics 

 than science ; it is speculation, and not fair deduction 

 from the observed phenomena of nature. They admit 

 that " natural selection does not make new species. 

 These make themselves, or rather originate in accord- 

 ance with the laws of variation," and finally we have 

 the following assertion : " The real makers of species 

 are the inherent properties of protoplasm and the 

 laws of variation and heredity. We seem to be 

 tolerably near a solution of the problem of the causes 

 of the survival of any particular mutation. This, 

 however, is merely a side issue. The real problem is 

 the cause of variations and mutations, or, in other 

 words, how species originate. At present our know- 

 ledge of the causes of variation and mutation is 

 practically nil. We do not even know along what lines 

 particular mutations occur. We have yet to discover 

 whether mutating organisms behave as though they had 

 behind them a force acting in a definite direction." 



No one can dispute that " the makers of species are 

 the inherent properties of protoplasm." That is a 

 truism — an axiom of science. But we are still at the 



