HEREDITARY VARIATION 79 



shape, in which some variation or change may not take 

 place, which, by selective breeding, may become perpetuated, 

 and form the foundation of, and give rise to, a new race. 



If you carry in your mind's eye these four varieties of 

 pigeons, you will bear with you as good a notion as you 

 can have, perhaps, of the enormous extent to which a 

 deviation from a primitive type may be carried by means 

 of this process of selective breeding. 



