410 THE CAUSES OF THE 



XI 



breed of sheep, the wool of which was inferior to 

 that of the Merino, was gradually allowed to 

 die out. 



You see that these facts illustrate perfectly well 

 what may be done if you take care to breed from 

 stocks that are similar to each other. After having 

 got a variation, if, by crossing a variation with the 

 original stock, you multiply that variation, and then 

 take care to keep that variation distinct from the 

 original stock, and make them breed together, 

 then you may almost certainly produce a race whose 

 tendency to continue the variation is exceedingly 

 strong. 



This is what is called " selection " ; and it is by 

 exactly the same process as that by which Seth 

 Wright bred his Ancon sheep, that our breeds of 

 cattle, dogs, and fowls are obtained. There are 

 some possibilities of exception, but still, speaking 

 broadly, I may say that this is the way in which 

 all our varied races of domestic animals have arisen ; 

 and you must understand that it is not one 

 peculiarity or one characteristic alone in which 

 anhmls may vary. There is not a single peculiarity 

 or characteristic of any kind, bodily or mental, in 

 which offspring may not vary to a certain extent 

 from the parent and other animals. 



Among ourselves this is well known The sim- 

 plest physical peculiarity is mostly reproduced, I 

 know a case of a woman who has the lobe of one 

 of her ears a little flattened. An ordinary obser- 



