24 EVOLUTION OF TO-DAY. 



and ease upon animals. No child is precisely like 

 its parents. The man of the nineteenth century 

 is very different from the man of 2000 B. C. The 

 European is very unlike the African. Variations 

 do occur, then, and may (by being transmitted from 

 generation to generation) give rise to races. Among 

 animals and plants it is everywhere recognized that 

 there are species and varieties, and all of the varie- 

 ties of a species are understood as having descended 

 from the same ancestor. Indeed, the commonly 

 recognized distinction between species and varieties 

 has been, until evolution modified it, that varieties 

 are descended from the same parent, while species 

 are not thus genetically related. Nor will any one 

 attempt to deny that the variations which may thus 

 arise may be very great, equalling, or sometimes even 

 exceeding, the amount of difference between species. 

 Compare the English dray-horse with the racer, the^ 

 short-horned with the long-horned cattle, the do- 

 mestic hog with the wild boar remembering all the 

 time that we have here simple varieties. The vari- 

 ous breeds of domestic pigeons differ among them- 

 selves so much that, if found in a state of nature, 

 they would be ranked as different species, as differ- 

 ent genera, or in some cases as different families, so 

 great is the difference between them. The fan-tail 

 has more tail feathers than any other known bird, 

 and this is a tolerably constant feature among birds. 

 The swollen crop of the pouter pigeon is absolutely 

 unique, and yet all breeds of pigeons are simple 

 variations, and no one is inclined to deny that they 

 are derived from the same ancient common ancestor. 



