1 8 FOOT-NOTES TO EVOLUTION. 



inheritance from their common ancestry. The differ- 

 ences have come about through various natural influ- 

 ences, chief among which is the competition in the 

 struggle for existence between individuals and between 

 species, whereby those best adapted to their surroundings 

 live and reproduce their kind. Any advantage of the 

 individual, no matter how small, must be a help in its life 

 struggle. This advantage inherited becomes the gain of 

 the species. The various influences connected with this 

 struggle were summed up in the comprehensive term of 

 "natural selection," or, as Mr. Herbert Spencer has 

 termed it, "the survival of the fittest." The latter term 

 is, however, only half as large as the former, because " the 

 survival of the existing " is in many regards a factor as 

 potent as the actual survival of the fittest. To be on the 

 ground is a factor not less important in determining sur- 

 vival than to have a special fitness for the conditions of 

 life. The epithet " natural " in natural selection is also 

 of vital importance as distinguished on the one hand from 

 " artificial," or produced by human agency, and on the 

 other hand from "supernatural," or produced by un- 

 knowable agencies. " Fitness " in this sense of course 

 means simply the power to win in the particular kind of 

 contest that may be in question, no moral element and 

 no element of general progress being necessarily in- 

 volved. The term " natural selection " originated from 

 the use of the word "selection " by breeders of animals 

 to indicate the process of " weeding out " by which they 

 improve their herds. For the method by which in 

 Nature a new species is brought into existence seems 

 to be precisely parallel to that by which we may arti- 

 ficially produce a new breed of cows or of dogs, a new 

 race of pigeons, or a new variety of roses. The record of 

 man's work in the creation of species covers some of the 

 most glorious of human achievements, none the less won- 



