HEREDITY AND ' PTTYSTCAL DEOENKRATrnN \):^ 



children of our cities, and that heredity is not a 

 factor m the production of their wretched physique, 

 but that their environment is all-important and all- 

 effective, the demonstration is to be welcomed and 

 recognised by those who are striving to end a state 

 of things which is amongst the many scandals of our 

 civilisation. ^ 



It appears to me that, both on A priari and a 

 posteriori grounds, we may exclude the action ol" 

 heredity in this matter. 



The a posteriori grounds for ignoring heredity are 

 as follows. In the first place, none of the actual 

 evidence adduced is in any way in favour of the view 

 that this is a progressive change — i.e. a change pro- 

 gressively increasing from one generation to another. 

 Dr. Leslie Mackenzie, of Edinburgh, is one of the first 

 living authorities on this matter. He says that by 

 racial deijfeneration he understands the transmissit)n 

 of weakness and disease from one generation to 

 another, whereas the results of his inquiries have 

 been to show that, in the overwhelming majority of 

 cases, there was nothing which would have pre- 

 vented the children from growing up healthy and 

 fit had they been reared in a better environment. 



The a priori argument against the reference of 

 this "physical degeneration" to the action of heredity 

 is even more important. The majority of those wlio 

 have asserted the occurrence of a progressive change 

 appear completely to ignore the fundamental prin- 

 ciples of the evolutionary biology. They make no 

 allusion to the fact that their assertions run directly 

 counter to the law of natural selection. Those who 

 assert that there is a progressive degeneration occur- 



