146 Permanence and Evolution. 



colour of flowers in a way which it does not lie 

 within the province of this work to criticize, yet 

 even he is compelled to admit that the brilliant 

 colouration of such large classes, as sea-slugs, 

 sea anemones, etc., cannot thus be accounted 

 for. On the whole, I consider that Allen has 

 failed to make out his case with any probability, 

 and that there is no reason to think he has 

 removed any of the difficulties attaching to 

 sexual selection. 



To continue the subject, none of the evolu- 

 tionists who are not Darwinians proper have 

 attempted to give much systematic detail to 

 their views. Sometimes the direct effects of 

 known conditions (temperature, moisture, etc.) 

 have been called in to fill up the deficiency, but 

 these effects are so plainly incapable of pro- 

 ducing the complex results we find, that much 

 time need not be spent in discussing them. 

 There is not really any evidence that colour is 

 permanently affected by climatic change ; geo- 



