66 ORGANIC EVOLUTION CONSIDERED 



of destroying most organic beings that are produced 

 before they arrive at the age of maturity. 



The supply of food being insufficient to support all 

 of the organic beings that are produced, a struggle to 

 obtain that food is perpetually going on, in which the 

 great majority, being necessarily unsuccessful, perish. 

 Everywhere in the organic world is perpetual compe- 

 tition, warfare, a " struggle for existence," in which, 

 other things being equal, the weaker perish. 



A second fact in the theory of natural selection is 

 that the offspring closely resemble the parents. 



A third fact is that the offspring are never exactly 

 like the parents. The variation from the parent 

 form may be in shape, size, color, and, in fact, in an 

 endless number of respects. 



It is claimed by Darwin that the variation at any 

 one time is, as a rule, extremely small; so small, in 

 fact, that it would not be noticeable. 



Again, it is claimed that if any variation is useful 

 to the individual possessing it, if it enables it the bet- 

 ter to compete with its kind and with other organisms 

 for food, or if it gives it an advantage in escaping 

 from its enemies, or an advantage in any other 

 respect over others of its species, then it will survive, 

 while those less favored will perish. 



It is further claimed that the useful variation will 

 be propagated, so that the offspring of the individual 

 which possesses the favorable variation will stand a 

 better chance of surviving than those that have not 

 favorably varied. In this way, therefore, Nature is 

 continually selecting the forms that are best able to 

 compete with other organisms for existence. To ex- 

 press this process Mr. Darwin has used the expression 

 "Natural Selection," and Herbert Spencer the ex- 

 pression " Survival of the Fittest." 



It is further claimed by Darwin, and by evolution- 



