How Theories are Manufactured 89 



the Flamingo is anything but an instance of quiet 

 coloration. 



Again, take the large family of the Ducks. The 

 habits and food of all are much the same, yet how 

 extraordinary are the varieties of their colouring ! The 

 Mallard's head is green, the Pochard's chestnut, the 

 Teal's chestnut with a peculiar green patch, the Shel- 

 drake's is black, the Gadwall's grey. The Scoter wears 

 a nearly uniform suit of sable, the Harlequin is spotted 

 and striped, in accordance with his name. One duck 

 is long-tailed, another is pin-tailed, a third is tufted. 

 Most have a green speculum on the wing, in some it is 

 white, others have none at all. How construct an ex- 

 planation to reconcile all these varieties with the fitness 

 of things ? Who standing on the Bass, and seeing the 

 myriad flocks of Gannets sailing above, around, and 

 beneath, can imagine that the delicate shade of buff 

 with which their heads are tinged is a consequence of 

 their acquaintance with herrings and gurnets? The 

 Jackdaw lives a life much like that of Rooks. How has 

 his family and not theirs picked up a taste for a grey 

 hood? The brilliant Yellow-hammer, bright as a 

 Canary, is first cousin to the dingy Bunting, and lives in 

 the same cornfields. The Pied Wagtail differs little in 

 its habits from those whose prevailing hue is yellow. 

 The Swallow has a red patch on the throat, and the 

 House Martin a white patch on the back, though both 

 lead the same life, and hawk after the same flies in 

 fact, so endless are the vagaries of plumage, that it would 

 seem as feasible an undertaking to construct a phil- 

 osophy of Paris fashions by computation of the planets, 

 as to find an explanation of those of birds merely from 

 the circumstances of their life. No one will, of course, 

 deny that the circumstances in which they live have 

 something, or rather very much, to do with their style of 

 dress. We should not, on any theory, expect those who 

 breed in -open fields to be so brilliantly coloured as to 

 attract the attention of every marauding Hawk or Stoat. 

 No doubt Natural Selection would come into play to 



