HUMAN LONGEVITY. 127 



What, however, clearly pertains to our subject, is the fact 

 of longevity being hereditary, and running in particular 

 families and lines of descent. Where the organs, serving to 

 the great animal functions respiration, circulation, nutri- 

 tion, and secretion are sound, and conveyed as such from 

 one generation to another, an average prolongation of life will 

 occur as the natural effect. All this is fully confirmed to us 

 by common observation. Every group of tombstones indeed 

 tells a true tale, in this respect, of what lies underneath. 

 Before the Titanic power of steam had given the speed and 

 vehemence of the race-horse to our manner of travelling, we 

 can remember the time when we used to loiter through the 

 country churchyard while horses were changed, or dinner 

 prepared, at the road-side inn. Here, in its simplest but 

 most touching form, may well be learnt the truth of which 

 we are speaking. On one family group of gravestones are 

 recorded the many early deaths which give evidence of feeble 

 or diseased family constitution ; while another group, 

 close at hand, tells in its dates the history of sound native 

 temperament and prolonged age from parents to offspring. 

 Considering the various collateral influences ever at work, 

 we have often been surprised by the uniformity of this result. 

 But these external influences are in fact continually tending 

 to restore the balance ; and do in the end retrieve that ave- 

 rage in which all anomalies and inequalities finally merge. 

 Intermarriage among different families, in successive gene- 

 rations, is obviously the natural provision against such 

 inequalities. They sometimes, however, continue long ; and 

 occasionally assume very singular and morbid aspects ; where, 

 from some cause of local or social limitation, intermarriages 

 are confined to a small community without due admixture 

 from without. This natural correction then, very little aided 

 by human prevision, is a providential one ; illustrated by 

 analogies in other parts both of the animal and vegetable 



