116 HUMAN LONGEVITY. 



Adaptations, partly of bodily textures, partly of aliment 

 in each case the effect of these physical conditions come 

 into action here, and restore that parity which appears to be 

 the natural law for the species. 



But it may be asked, What then, rejecting this doctrine, is 

 the true natural term of human life ? Or is there any which 

 can be strictly designated as such ? The question is a simple 

 and definite one. The answer cannot easily be rendered so. 

 It might seem probable indeed primd facie that in the case 

 of Man - single in species and presumably derived from a 

 single stock there should exist some middle term of natural 

 age, marking the destined duration of his being on earth, 

 apart from all those incidents, physical or moral, which crowd 

 upon and affect his existence. But these incidents are so 

 numerous and varied, so obscure often in their origin and 

 progress, yet so constantly blending themselves, as we shall 

 see hereafter, with the hereditary constitution of families and 

 communities, that all sagacity is at fault in seeking to deduce 

 and strictly to define such natural term of life. The most 

 copious and accurate registers fail us here ; and we are forced 

 to regard it in some sort as an abstract conception incapable 

 of being expressed, otherwise than approximately, by any 

 simple number. If called upon to state this approximation, 

 we might perhaps seek to rest it on the venerable record of 

 ' three-score years and ten ; ' with a leaning, however, to the 

 belief that this is rather below the true mark. Blumenbach, a 

 great authority on such subjects, rated the period at eighty 

 years. But under no circumstances can we admit the Century 

 of years which M. Flourens has pleased himself by assigning 

 to life ; or allow the force of the arguments by which he 

 seeks to substantiate his doctrine. 



Dismissing then this particular question suggested by the 

 work before us, we may invite our readers to other parts of 

 the interesting subject of human longevity. And first there 



