502 THE INDIVIDUAL AND THE RACE: 



about them; or, if this be impossible I would have him 

 take the best and most irrefragable of human theories, 

 and let this be the raft upon which he sails through life 

 not without risk, as I admit, if he cannot find some 

 word of God which will more surely and safely carry him." 



SUMMARY. 



Heredity, the genetic relation between ancestors and descendants, 

 between the race and the individual, has to be considered as a condi- 

 tion of racial evolution and as a factor in determining the personal 

 life. 



Heredity is the relation of organic continuity between successive 

 generations, securing the persistence of resemblance between off- 

 spring and their parents, between progeny and their ancestors, 

 and is sustained by the continuance of a specific dynamic organisa- 

 tion of which the germ-cells are usually the vehicle. The natural 

 inheritance includes all that the organism is or has to start with 

 in virtue of its hereditary relation, and is to be distinguished from 

 extra-organismal legacies, such as Man's social heritage; from the 

 results of ante-natal influence as in most mammals and flowering 

 plants; and from exogenous modifications directly due to peculiar- 

 ities in ' nurture '. Nurture includes all manner of extrinsic in- 

 fluences, environmental, nutritional, and functional. Development 

 is the realisation of the inheritance in appropriate nurture. 



Heredity is not so much a factor in, as a condition of evolution. 

 It involves arrangements which secure the persistence of a specific 

 dynamic organisation holding fast that which is good. This is 

 effected by the continuity of the germ-plasm. Nevertheless it admits 

 of the emergence and of the entailment of the new. It serves or 

 tends to prevent the transmission as such of individual somatic 

 modifications either for good or ill. The question arises in what 

 way the personal life counts in evolution. 



Although there is not at present any convincing evidence of the 

 transmission of individual modifications as such or in any representa- 

 tive degree, it should be noted that some may serve as variational 

 stimuli; that some may serve as adaptive screens saving the in- 

 dividual until germinal variations in the same direction may emerge 

 and establish themselves; and that it is in the personal life, often 



