EX VIRIBUS VIVIMUS. 



Man himself, in his civiHzed form, is continually- 

 bringing his intelligence to bear on his own longevity, 

 thus changing conditions as no other organism can, 

 and consequently in his case normal and absolute 

 potential longevity are merged. It is the develop- 

 ment of unprecedented and overpowering intelligence 

 which interferes in the case of man, and separates 

 him in this as in other matters so greatly from other 

 organisms. His intelligence enables him to take 

 many precautions with advancing years ; it leads him 

 to form communities and organizations in which the 

 active and young protect and minister to the aged. 

 This great peculiarity in man, and the more than 

 specific differences of condition which his all-adapting 

 brain renders possible in various groups of individuals 

 with less than specific difference of structure, makes 

 it desirable to consider him apart from the rest of 

 the organized world in such a matter as longevity. 



When man exerts the greatest care to protract 

 the life of certain organisms, he yet finds that death 

 will come and limit the period. There is a limit to 

 absolute potential longevity clearly enough in many 

 organisms, and this limit, which may be termed an 

 inherent' one, must of course act in limiting normal 

 potential longevity. What is it that constitutes this 

 limit, are all organisms subject to it, and how does 

 it become inherent t It appears that in some orga- 

 nisms we cannot clearly say from observation that 

 there is such an inherent limit ; in fact, their absolute 



