22 THE SURVIVAL OF THE UNLIKE. [l, 



themselves exactly as "one of the chief inconsistencies in 

 the prevalent conception of the nature of organisms." 

 "While the doctrine of mutability of species has gener- 

 ally taken the place of immutabilitj'," he writes, "the 

 proposition that like produces like in organic generation 

 is still generally, and I suppose almost universally, 

 accepted. It therefore becomes necjessary to suppose 

 that variation is exceptional, and that some reason for 

 the accumulation of variation is necessary to account for 

 the great divergencies seen in different species. * * * * 

 The search has been for some cause of the variation; it 

 is more probable that mutability is the normal law of 

 organic action, and. that permanency is the acquired 

 law." I do not suppose that Professor Williams makes 

 definite variation an inherent or necessary quality of 

 organic matter, but that he conceives this matter to 

 have had no original hereditary power, and that its 

 form and other attributes in succeeding generations liave 

 been moulded into the environment, and that the bur- 

 den of proof is thrown upon those who assume that 

 life -matter was endowed with the property that like nec- 

 essarily produces like. At all events, this last is my own 

 conception of the modification of the lines of ascent. 



This conception of the unstable constitution of the 

 original forms of life is by no means novel, but it ap- 

 pears to have been held most freely by those thinkers 

 who are not themselves professed biologists. One of 

 the best statements of it which I know is that of E. P. 

 Powell in his powerful book, "Our Heredity from 

 God." "But Nature never fails to remind us," he says, 

 "that heredity is only a slowly established tendency, and 

 that permutation is the original tendency in nature; for, 

 if you succeed in bi-eaking up an established order or 



