84 FOOT-NOTES TO EVOLUTION. 



"not indiscriminate, but it will first and mainly com- 

 prise those individuals least able to resist attack." 



This is the essential fact upon which rests Herbert 

 Spencer's law of "the survival of the fittest." At the 

 same time the survival of the fittest does not tell the 

 whole story of natural selection. But a small part of 

 the actual characters of animals and plants can be 

 traced directly and solely to the principle of utility. 

 The survival of the existing likewise is a large element 

 in the great process of natural selection. Thus, a water 

 bird has webbed feet. The webbing is useful in swim- 

 ming. Its presence is due to its utility. The survival 

 of the fittest in water birds may mean the survival of 

 the best swimmer, and the best swimmer is the one with 

 the most useful webbing. But a character quite as per- 

 sistent may be a perfectly useless one, as a special ar- 

 rangement of the plates on the tarsus, or the flattening 

 of a single claw. This may have in itself no utility at 

 all. Its presence may not be due to the survival of the 

 fittest. It persists because such a character was pos- 

 sessed by some ancestor. It has been retained through 

 heredity. The nails must have some form, the plates 

 some arrangement, the wing coverts some colour. This 

 ancestral form or colour is as good as some other would 

 be. Hence comes its persistence, which is simply a sur- 

 vival of the existing, no question of relative fitness being 

 involved. 



From the "survival of the existing" arises the per- 

 sistence of those forms which actually inhabit a given 

 district whether they be ideally the fittest or not. By 

 such means the faunae of isolated regions are perpetu- 

 ated, the barriers of land or sea or climate excluding 

 them from competition with the " fitter" organisms that 

 may inhabit other regions. " Possession is nine points 

 of the law " of organic survival, as it is said to be else- 



