THE SCIENCE OF LANGUAGE. 63 



very slow process, when some species 

 manage to prolong their languishing ex- 

 istence for a long time yet in sheltered 

 or isolated places." This happens with 

 languages in the mountains ; I merely 

 call your attention to the Basque in the 

 Pyrenees, which is the ruins or remnants 

 of an idiom which can be proved at one 

 time to have been widely spread ; the 

 same phenomenon may be observed in 

 the Caucasus and elsewhere. 



" If any group has once been extin- 

 guished it can never appear again, because 

 a chain in the link of generation has 

 been broken." 



"This explains how the extension of 

 dominant species which admit of the 

 greatest variation, peoples the earth in 

 the course of time with other forms of 

 life, closely related though modified; and 

 how these generally succeed in supplant- 



