RATIONAL LIFE 305 



animal, that the laws of heredity applicable to animal 

 life, and to his animal life, exactly as to any other, 

 prove inadequate, and in some senses inapplicable, 

 when their transference to human life as a whole 

 is attempted. We shall rirst seek to trace the appli 

 cation of physical laws to the fullest extent; and 

 shall thus seek to show wheiv and when their limits 

 of application are reached. 



The physical nature of man comes within sweep of 

 the laws of heredity applicable to all organism. This 

 is scientifically the most obvious position, and, on 

 this account, it has the smallest number of scientific 

 perplexities attached. The development of the or 

 ganic life in man, from the fertilisation of the egg 

 onwards, takes place under conditions analogous with 

 the development of all organism. There is in each 

 case the fusion of two hereditary tendencies/ showing 

 themselves clearly after birth. The persistence of 

 physical inheritance is manifest in every family of 

 the race. A vigorous parentage gives a vigorous 

 family : a feeble parentage the reverse. Disregard of 

 conditions of health will spread an enfeebled life to 

 the succeeding generation. Crowding of population 

 in the great centres, life in an exhausted atmosphere, 

 work in cramped or constrained position, and circula 

 tion through the atmosphere of deleterious matter, 

 inevitably lower physical vigour, which must tell on 

 the physique of the population. An active life, spent 

 largely in the open air, with advantages otherwise 

 from residence in rural districts, will show opposite 

 results, notwithstanding disadvantages from restricted 

 quantity, and little variety, of food. The laws of 

 heredity carry forward these results. 



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