36 FOOT-NOTES TO EVOLUTION. 



Stages of incompleteness before the organ is finished. 

 Each of these stages finds a more or less perfect repre- 

 sentation in the adult condition of some animal of less 

 complexity. The long-continued " survival of the fittest " 

 brings these organs to a greater and greater perfection. 

 But by the side of these creatures with the most complex 

 organs will be found those in which the development of 

 some particular part may be less and less complete. 

 An organ highly developed in one animal may be quite 

 rudimentary and imperfect in some other animal whose 

 superior fitness may be in some other direction. Thus 

 fitness for underground life relieves the mole from the 

 need of good eyes. Skill to live by his wits relieves 

 man from the need of the monkey's power to climb 

 trees. Somewhere in the animal kingdom we may find 

 each degree of each organ's development. These or- 

 gans in their varying degrees of complexity corre- 

 spond more or less perfectly to the 



The individual general stages of development of the 



repeats the his- . , .,..,, , . 



. , ,, same organ in the mdividual of the 

 tory of the race. ° 



highest type. The record of the devel- 

 opment of the individual is in a way the recapitulation 

 of the past history of its species. " The physical life of 

 the individual is an epitome of the history of the group 

 to which it belongs." Thus the embryonic life of man 

 corresponds, so far as we can trace it, to the history of 

 that branch of the group of vertebrates which has cul- 

 mmated in man. Each individual lives over again the 

 life of the race. " Under each grave lies a world his- 

 tory,"* says a German proverb. This fact is, however, 

 no mysterious or meaningless law. It is simply a natural 

 result of the processes of heredity. Heredity repeats 

 that which has been, and natural selection suppresses 



* " 



Unter jedem Grab liegt eine Weltgeschichte," 



