NURTURE AND NATURE 7 



US in our difficulties with regard to what makes for, 

 and what mars national fitness. Indeed we venture 

 to go further and to assert that much of the canon 

 of social conduct and moral action as it has existed 

 in the past and as it widely exists at the present will 

 be found inadequate or even antisocial, when we 

 understand more fully the manner in which legislation, 

 social custom, and philanthropy (in the old sense) 

 tend to modify the biological factors on which human 

 progress so largely has depended. 



There is no one having any biological know- 

 ledge who would refuse to admit the enormous part 

 played by environment in modifying living forms. 

 This modification, however, is of two kinds : 



(a) A change in the somatic characters of the 

 individual following upon his transfer to different 

 surroundings or his treatment to different conditions 

 of nurture ; this environmental change in the indi- 

 vidual appears to be more marked in plants than in 

 animals. If it is in any case persistent after the off- 

 spring of the individual have returned to the original 

 environment, most biologists would assert that a 

 germinal change of some kind, an unrecognized 

 selection of germ plasm, has taken place in the 

 original individual. 



(d) A change in the germ characters of the 

 race, owing to the environment selecting for survival 

 a certain differential class of individuals, and their 

 somatic characters thus becoming more frequent and 

 possibly dominant in the population owing to the 

 strength of heredity. 



Now we are not in any way concerned with a 



