ORGANIC EVOLUTION 67 



for existence between nations, as in the struggle for 

 existence between individual organisms, natural selec- 

 tion favors those variations beneficial to the nation, 

 and that nation will best survive, which can best main- 

 tain its people in intellect, freedom, prosperity and 

 patriotism. The United States is so far ahead of most 

 nations in these requirements that there is no doubt of 

 her perpetuation. It is done by the natural selection 

 of variations favorable to the social organism. 



The facts above given regarding the favorable im- 

 provements in physical form made by immigrants to 

 this country, caused by environment, will apply also to 

 the geographical distribution of all organisms in space, 

 in different degrees. New environment causes a varia- 

 tion in the form of organisms, and especially in the 

 offspring they produce in the new habitat. 



From the very limited number of examples of 

 geographical distribution given above, it can readily be 

 seen why naturalists have made so free use of its 

 significant illustrations. It has undoubtedly been a 

 large factor in producing those variations, which being 

 perpetuated by means of that most important factor 

 inheritance, have eventually evolved into new species. 



