Of each of these principles I may give a simple example. Supposing a species of bird with a soft slender beak to be placed on an island, where the only food they could obtain was fruit enclosed in a hard or tough shell or covering. Supposing some birds accidentally possessed of a beak that was shorter and stouter than the others', these would be able to break open the shell and get at the fruit, while the others would starve. Some of the descendants of the birds with the stout beaks would inherit the same peculiarity, and in the course of several generations there would thus arise a species with short and strong, perhaps curved, beaks just fitted to live on fruits of the kind described. In a similar way the webbed feet of birds that swim were developed by their aquatic habits. And so with the long slender toes of the waders, which are so well fitted for walking over floating aquatic plants. Of the other principle, sexual selection, a familiar example is the bright and showy colouring of the male birds of many species: the females of their species, as they need protection while helplessly sitting on their eggs, are dull-coloured like the bark of trees or the sand, among which their nests lie hid. Some of the Himalayan pheasants exhibit this peculiarity to a marked degree. Originally, it is said, the male bird, which was more brightly coloured than the rest, got mated more easily by the preference shown to him for his bright colour. The question is, can we suppose all this to go on, by self-caused laws and concurrence of circumstances, without a pre-existing design for the forms to reach or an external guidance in the processes? CHAPTER VI. _THE MARKS OF CREATIVE INTELLIGENCE IN THE EVOLUTION OF ORGANIC FORMS_.