94 EX VIRIBUS VIVIMUS. - 



rich, the poor, the dweller in cities and in the 

 country, differing so much from each other in some 

 respects, all resemble each other in having the same 

 allotment, the same interval of time to pass from 

 birth to death ; that the variations of race, climate, 

 food, conveniences, have nothing to do with the dura- 

 tion of life, — we shall discover that the duration of 

 life does not depend on habits, customs, nor on the 

 quality of food. Nothing can change the physical 

 laws which regulate the number of our years.' ^ 

 Buffon does not bring forward adequate data to 

 support his statements, and we cannot admit the 

 truth of his assertion in its entirety. But we have 

 seen reason to believe that hereditarily the power of 

 life in all men (within a few generations) is the same, 

 disease, habits, and customs being dependent on ex- 

 ternal conditions, and thus longevity is rendered sub- 

 ject to external rather than internal causes, in the 

 case of man ; though with these varying external 

 conditions are correlated small structural variations, 

 which may make the longevity, in a certain sense, 

 appear to be dependent on structure, so intimately 

 bound up, so closely corresponding and reciprocal 

 are structure and habit, even when dominated by 

 such an organ as man's brain. 



What we are concerned with, then, in the various 

 kinds of man, is not variation in hereditary longevity, 



' Vol, ii. p. 76, quoted by Flourens, p. 52. 



