Chap. VI.] ORGANS OF EXTREME PERFECTION. 143 



of the Grallatores are formed for walking over swamps and floating 

 plants? — the water-hen and landrail are members of this order, 

 yet the first is nearly as aquatic as the coot, and the second nearly 

 as terrestrial as the quail or partridge. In such cases, and many 

 others could be given, habits have changed without a corresponding 

 change of structure. The webbed feet of the upland goose may be 

 said to have become almost rudimentary in function, though not 

 in structure. In. the frigate-bird, the deeply scooped membrane 

 between the toes shows that structure has begun to change. 



He who believes in separate and innumerable acts of creation 

 may say, that in these cases it has pleased the Creator to cause a 

 being of one type to take the place of one belonging to another 

 type ; but this seems to me only re-stating the fact in dignified 

 language. He who believes in the struggle for existence and in the 

 principle of natural selection, will acknowledge that every organic 

 being is constantly endeavouring to increase in numbers ; and that 

 if any one being varies ever so little, either in habits or structure, 

 and thus gains an advantage over some other inhabitant of the 

 same country, it will seize on the place of that inhabitant, however 

 different that may be from its own place. Hence it will cause him 

 no surprise that there should be geese and frigate-birds with webbed 

 feet, living on the dry land and rarely alighting on the water • 

 that there should be long-toed corncrakes, living in meadows in- 

 stead of in swamps ; that there should be woodpeckers where hardly 

 a tree grows ; that there should be diving thrushes and diving 

 Hymenoptera, and petrels with the habits of auks. 



Organs of extreme Perfection and Complication. 

 To suppose that the eye with all its inimitable contrivances for 

 adjusting the focus to different distances, for admitting different 

 amounts of light, and for the correction of spherical and chromatic 

 aberration, could have been formed by natural selection, seems, 

 I freely confess, absurd in the highest degree. When it was first 

 said that the sun stood still and the world turned round, the 

 common sense of mankind declared the doctrine false ; but the old. 

 saying of Vox populi, vox Dei, as every philosopher knows, cannot 

 be trusted in science. Keason tells me, that if numerous gradations 

 from a simple and imperfect eye to one complex and perfect can 

 bo shown to exist, each grade being useful to its possessor, as is 

 certainly the case ; if further, the eye ever varies and the variations 

 be inherited, as is likewise certainly the case ; and if such varia- 

 tions should be useful to any animal under changing conditions of 

 life, then the difficulty of believing that a perfect and complex eye 



