Preface. vii 



evolved, is natural selection, or the survival of 

 the fittest (that is, the presence of a general 

 tendency to vary indefinitely, coupled with the 

 gradual accumulation and intensification of such 

 variations as happened to be favourable to the 

 organism), either coupled or not with sexual 

 selection. 



The hypothesis of evolution in general, and 

 the special Darwinian form of it, stand on very 

 different bases, and require very different modes 

 of treatment. It is the object of this work to 

 show, that while Darwinism proper is impro- 

 bable, evolutionism in any form is as yet un- 

 proved ; while, on the other hand, the more we 

 investigate the facts of inheritance, the more we 

 are compelled to regard differences so slight, 

 that they would usually be considered casual 

 variations, as within the limits of our existing 

 knowledge strictly permanent. 



The animal kingdom only is spoken of in this 

 treatise, as I have no knowledge of plants. The 



