HEREDITY AXD "PHYSICAL DE(JKNKllATION " 9? 



ordinary ignorance — that the infants die because 

 they are too degenerate to Hve. On the other hand, 

 we know that a child which has survived the vicissi- 

 tudes of intra-uterine life, and the dangerous episode 

 of birth, has already given proofs of vitality, and that 

 in ahuost every case there is no inherent (i.e. in- 

 herited) reason why it should die. We know, 

 furthermore, from the comparative death-rates of 

 breast-fed and non-breast-fed children, and from all 

 the other relevant considerations, that extraneous 

 circumstances (i.e. the conditions of the environ- 

 ment) determine the overwhelming majority of these 

 deaths. The infantile mortality is not a proof of 

 failing national physique, but of the miserable in- 

 efficiency of the national conscience. The infantile 

 mortality, and the wretched physique of certain 

 classes of the people, are both consequences of the 

 same causes, viz. the abominable environment 

 which we provide for only too many of the nation's 

 children. 



Let us now consider three causes which, as I 

 believe, have been falsely assigned in explanation of 

 physical deterioration, each of these causes involving 

 an assertion in heredity. 



The first of these assertions is that the conlinuous 

 increase of the average age of marriage is partly 

 responsible for the facts. In this country the 

 average age of men at marriage is now very nearly 

 28 J years, as compared with 28 years a generation 

 ago. During the same period the average age of 

 women at marriage has increased from about 25 

 years and 8 months to 26 years and ?> months. Ihit, 

 even apart from the fact thai the chango is so 



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