AN ESSAY ON LONGEVITY. 93 



potential longevity being dependent on structure 

 (as pointed out early in the essay), and the various 

 races of men not exhibiting constancy in structural 

 character, we cannot expect that the various races 

 should exhibit anything like an approach to specific 

 potential longevity.' This, too, the more so, remem- 

 bering the delicacy of the quantity, and its liability 

 to fluctuation with small influences. We have, on 

 the contrary, every reason to believe that a man of 

 'English race and a man of Fuegian race, who by 

 gradual change in the condition of their ancestors 

 (for sudden change is likely to act injuriously by 

 its mere suddenness ^) should be living side by side, 

 would live to the same period of time, that is, have 

 the same potential longevity. But it is true enough 

 that either the Fuegian would be no longer a Fue- 

 gian, for he would have abandoned the habits and 

 conditions of life which are his peculiarities, or the 

 Englishman would have ceased to be an Englishman 

 by similar metamorphosis. Buffon, a man of really 

 great insight and philosophical spirit, says : — ' The 

 man who does not die of accidental causes reaches 

 everywhere the age of ninety or one hundred years. 

 If we reflect that the European, Negro, Chinese, 

 and American, the civilized man, the savage, the 



' Dr. Kane, the -American Arctic explorer, and his companions, after 

 residing three years in a high latitude, experienced the most severe 

 injury from the summer heat of the Northern States, and eventually 

 Dr. Kane died from the exhaustion and prostration so produced. — 

 ' Wynn's American Statistics ' (^Influence of Locality on Disease). 



