1 THE ORIGIN OF SPECIES' gi 



fundamental fact of the existence in nature of numerous 

 and indefinite variations, the whole theory of natural 

 selection is ultimately built up. In illustrating by ex- 

 ample the immense variability of domesticated creatures, 

 Darwin lays great stress upon the case of pigeons, 

 with which he was familiar from his long experience as 

 a breeder and fancier in his own home at Down. 

 Naturalists are almost universally of opinion that all 

 the breeds of domestic pigeons, from the carrier to the 

 tumbler, from the runt to the fantail, are alike descended 

 from the wild rock pigeon of the European coasts. The 

 immense amount of variation which this original species 

 has undergone in domestication may be seen by com- 

 paring the numberless breeds of pigeon now exhibited 

 at all our poultry shows with one another. 



But variation gives us only half the elements of 

 the ultimate problem, even in the case of domestic 

 kinds. For the other half, we must have recourse to 

 human selection, which, by picking out for seed or breed- 

 ing purposes certain specially favoured varieties, has pro- 

 duced at last all the purposive or intentional diversity 

 between the different existing stocks or breeds. In 

 these artificially produced domestic races we see every- 

 where special adaptations to man's particular use or 

 fancy. The dray-horse has been fashioned for purposes 

 of strength and sure-footedness in draught, the race- 

 horse for purposes of fleetness in running. In the fox- 

 hound, man has encouraged the special properties that 

 tend to produce a good day's hunting ; in the sheep- 

 dog, those that make for the better maintenance and 

 safety of a herd. The cauliflower is a cabbage, with 

 specialised and somewhat abortive flower-heads j the 



