232 DARWINISM STATED BY DARWIN HIMSELF. 



pair of progenitors. With our domestic animals a new 

 race can readily be formed by carefully matching the 

 varying offspring from a single pair, or even from a single 

 individual possessing some new character ; but most of 

 our races have been formed, not intentionally from a 

 selected pair, but unconsciously, by the preservation of 

 many individuals which have varied, however slightly, in 

 some useful or desired manner. If in one country stronger 

 and heavier horses, and in another country lighter and 

 fleeter ones were habitually preferred, we may feel sure 

 that two distinct sub-breeds would be produced in the 

 course of time, without any one pair having been sepa- 

 rated and bred from in either country. Many races have 

 been thus formed, and their manner of formation is 

 closely analogous to that of natural species. We know, 

 also, that the horses taken to the Falkland Islands have, 

 during successive generations, become smaller and weaker, 

 while those which have run wild on the Pampas have ac- 

 quired larger and coarser heads ; and such changes are 

 manifestly due, not to any one pair, but to all the indi- 

 viduals having been subjected to the same conditions, 

 aided, perhaps, by the principle of reversion. The new 

 sub-breeds in such cases are not descended from any sin- 

 gle pair, but from many individuals which have varied in 

 different degrees, but in the same general manner ; and 

 we many conclude that the races of man have been simi- 

 larly produced, the modifications being either the direct 

 result of exposure to different conditions, or the indirect 

 result of some form of selection. 



