io8 



between the right and left sides of the heart, in the auricles, 

 (and which should commence to close so soon as the child 

 commences to respire), remaining open, is a condition 

 sometimes, if not frequently observed. 1 



Such are but a few of the intra-uterine factors of 

 individuality, from which it will be seen that every unborn 

 child may have its health in after-life more or less 

 influenced by agencies to , which it is subjected within 

 the womb of its mother, independently of heredity, and 

 that natural variability which interacts with hereditary 

 predisposition. So refined, indeed, are the influences thus 

 exerted over the unborn, whilst in the maternal womb, that 

 every abnormal throb of her heart every abnormal vibration 

 of her nervous system, is participated in by her unborn 

 child, whether harmfully or favourably, and may leave 

 impressions to which it may be subject during the entire 

 period of its existence. And thus we see that the differen- 

 tiation of individuals depends, not only on heredity 

 and co-existing variability, but may receive independent 

 impulses during uterine existence from agencies external 

 to, and beyond the sphere of both. These being in no 

 proper sense hereditary (although contributing to the 

 individuality of the children), I shall not now further refer 

 to them, but shall proceed, as briefly as possible, to consider 

 those diseases in which heredity is not only a potent, but an 

 essential element. 



At the outset I may ask why is it that no two cases are 

 exactly alike in any disease ? And I, unhesitatingly, reply, 

 owing to variability in the original inherited strength, or the 

 acquired weakness of different organs and tissues. This 

 question and answer really contain my argument, as in a 



1 Ibid. 



