2IO FOOT-NOTES TO EVOLUTION. 



months' sleep. These little trees are the Lapps of forest 

 vegetation. 



All natural history is full of similar cases of modifi- 

 cations. Everywhere there is the most perfect adapta- 

 tion of life to its conditions. But this adaptation must 

 come about through the survival of those organisms 

 fittest to live under the conditions, while the unfit die 

 out and leave no progeny. But fitness is a relative 

 term ; for in many cases, as with the Norwegian dwarf 

 birches, the deformed or stunted may be the only ones 

 fitted to survive. An advantage ever so slight must in 

 the long run conquer. 



The arctic birches serve as one illustration only of 

 the spread and change of organisms in the face of bar- 

 riers apparently insurmountable. I can 



rossing e ^^^ enter into details as to the many 



barriers. . ,.,.,..,, 



ways m which mdividuals manage to 



cross the barriers which usually limit the species. These 

 ways are as varied as the creatures themselves, and in- 

 finitely more varied than the barriers. By the long- 

 continued process of adjustment to circumstances, with 

 the incessant destruction of the unadapted, the various 

 organisms have become so well fitted to their surround- 

 ings as to give rise to the popular impression that each 

 species now inhabits that part of the world best fitted 

 for its occupation. Yet the very reverse of this must 

 be true, for in the growth of any species it is these 

 features of adaptation which are the last to appear. 

 If the history of the individual is an epitome of the 

 history of the group to which the individual belongs, 

 then adaptive characters appearing late in the growth 

 of the individual must have appeared late in the his- 

 tory of the group. They are the last changes made 

 in the organism — mere after-thoughts in the work of 

 creation. 



