NATURAL SELECTION 121 



occurrence; he can only preserve and accumulate such as 

 do occur. Unintentionally he exposes organic beings to 

 new and changing conditions of life, and variability | 

 ensues; but similar changes of conditions might and do 

 occur under nature. Let it also be borne in mind how 

 infinitely complex and close-flttmg are the mutual rela- . 

 tions of all organic beings to each other and to their \ 

 physical conditions of life; and consequently what in- '■ 

 finitely varied diversities of structure might be of use 

 to each being under changing conditions of life. Caa 

 it, then, be thought improbable, seeing that variations 

 useful to man have undoubtedly occurred, that other 

 variations useful in some way to each being in the great 

 and complex battle of life, should occur in the course of 

 many successive generations ? If such do occur, can we 

 doubt (remembering that many more individuals are born 

 than can possibly survive) that individuals having any 

 advantage, however slight, over others, would have the 

 best chance of surviving and of procreating their kind? 

 On the other hand, we may feel sure that any variation 

 in the least degree injurious would be rigidly destroyed. 

 This preservation of favorable individual differences and 

 variations, and the destruction of those which are injuri- 

 ous, I have called Natural Selection, or the Survival of 

 the Fittest. Variations neither useful nor injurious would 

 UQ^Joe affected by ^natural selection, and would be left 

 either a fluctuating element, as perhaps we see in certain 

 polymorphic species, or would ultimately become fixed, 

 owing to the nature of the organism and the nature of 

 ._the_cond iti ons. 



Several writers have misapprehended or objected to 

 the term Natural Selection. Some have even imagined 



— SCIENCK — 6 



