Permanence and Evolution. 137 



changes of the land- and sea- line, the extinction, 

 local or entire, of many forms, all changes con- 

 nected with the spread of man, must have 

 greatly altered the surroundings of every form 

 now existing. Considering this, it seems likely 

 that the type would prove more obstinate than 

 its external conditions. 



It may also be not unfairly argued that Dar- 

 win's theory of sexual selection is not very con- 

 sistent with his general principles. In the first 

 place, it is said that (bright or conspicuous) 

 " colour being dangerous, ought not to exist in 

 nature," and there is no doubt that, cceteris 

 paribuSy dull colour is an advantage in harm- 

 less animals, by concealing them from their 

 natural enemies in animals of prey, by hiding 

 their approaches from their victims ; to which 

 it has been answered that only those forms are 

 bright-coloured which have some other means of 

 protection. But granting this, still, on Dar- 

 winian principles, strains which were dull- 



