CHAPTER III 

 THE CHOICE AND FIXATION OF VARIATIONS 



WE have now seen that every living object is unlike 

 every other. In plants, even every branch is unlike any 

 other branch. We have endeavored to discover some of 

 these universal differences. We have found that they 

 are intimately associated with the welfare of the type or 

 species, inasmuch as they appear, for the most part, 

 to be the means of fitting the plant to live in the conditions 

 in which it is placed. But we have also seen that there 

 are more individuals than can find a place to live. How, 

 then, does nature choose the best from the poorest (or, 

 rather, the fit from the unfit), and, having chosen them, 

 how does she endeavor to fix them or to make them more 

 or less stable ? 



"This preservation of favorable individual differences 

 and variations, and the destruction of those which are 

 injurious, I have called Natural Selection or the Survival 

 of the Fittest." This is the philosophy which was pro- 

 pounded by Darwin, and which will carry his name to the 

 last generation of men. It looks simple enough. Those 

 forms which are best fitted to live, do live, because they 

 crowd out the others. Yet, this simple principle of 

 natural selection was the first explanation of the process 

 of evolution that seemed to be capable of interpreting 



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