DEVIOUS PATHS 



the "migratory species evince a greater amount of 

 individual variation than do non-migrating species " 

 because they are subject to more varying conditions 

 of food and climate. I think we may say, then, if 

 there were no struggle for life, if uniformity of 

 temperature and means of subsistence everywhere 

 prevailed, there would be little or no variation and 

 no new species would arise. The causes of variation 

 seem to be the inequality and imperfection of things ; 

 the pressure of life is unequally distributed, and 

 tliis is one of Nature's ways that accounts for much 

 that we see about us. 



