St. P.crnard 

 Eskimo 

 Poodle 



Dachshund 



German mastiff 

 .English bloodhouud 



Pointer 



Bulldog 



Greyhound 



Newfoundland 



Shepherd 



Spitz 



Fig. 408. — Artificial Selection. Its effects in causing varieties in one species. 

 Which of the dogs is specialized for speed ? Driving cattle ? Stopping cattle ? 

 Trailing by scent? Finding game ? Drawing vehicles? Going into holes? 

 1 [oil ;e pet ? Cold weather ? In Mexico there is a hairless dog specialized for hot 

 climates. The widely differing environments under various forms of domestica- 

 tion cause " sports" which breeders are quick to take advantage of when wishing 

 to develop new varieties. Professor De Vrics by cultivating American evening 

 primroses in Europe has shown that a sudden change of environment may cause 

 not only varieties but new species to arise. 



224 



