THE DEVELOPMENT OF ORGANISMS 803 



ultimate limit, either for the past or the future. All that we can 

 scientifically say is that there are few well-established instances of 

 a greater human longevity than 104 years. Sir George Cornewall 

 Lewis did good service (1862) in destructively criticising numerous 

 alleged cases of centenarianism, the occurrence of which he at first 

 regarded as quite unproved; but even he finally admitted that men 

 do sometimes reach a hundred years, and that some have reached 

 one hundred and three or four. Thus witness M. Chevreul, a grand 

 old man if ever there was one. The famous cases of Thomas Parr, 

 Henry Jenkins, and the Countess of Desmond, said to be 152, 169 

 and 140 respectively, were ruled out of court by Mr. Thoms, who 

 edited Notes and Queries at the time when Sir G. C. Lewis's whole- 

 some scepticism created much stir. As man is a slowly varying 

 organism, as regards physical characters at least, it is extremely 

 unlikely that his longevity was ever much greater than it is now. 

 Monsters in age and monsters in size are alike incredible. 



Metchnikoff was one of the few modern biologists who dealt 

 generously with biblical and other old records of great human 

 longevity. He apparently thought there has been some misunder- 

 standing in regard to Methuselah's 969 years or Noah's 595, but he 

 accepted the great ages of 175, 189, and 147 years ascribed to 

 Abraham, Isaac, and Jacob. But early age-reckonings seem to have 

 been in lunar months; which would bring down Methuselah to 

 seventy-five : and statistics of longevity are by the admiring juniority 

 of their observers and recorders peculiarly liable to exaggeration, as 

 we can see around us to this day. Similarly, he accepted the 185 years 

 with which St. Mungo, of Glasgow, has been credited. And as he was 

 generous in regard to the past, he was hopeful in regard to the future, 

 believing that a more careful and temperate life, as well as an 

 enlightened recognition of the disharmonies of our bodily frame, may 

 bring about a time when man will no longer, as Buff on says, "die 

 of disappointment", but attain everywhere "a hundred years". 

 "Humanity", Metchnikoff said, "would make a great stride towards 

 longevity could it put an end to syphilis, which is the cause of one- 

 fifth of the cases of arterial sclerosis. The suppression of alcoholism, 

 the second factor great in the production of senile degeneration of 

 the arteries, will produce a still more marked extension of the term 

 of life. Scientific study of old age and of the means of modifying 

 its pathological character will make life longer and happier." He 

 also quotes the theoretically simple conclusion of Pfiiiger's essay on 

 "The art of prolonging human life" — "Avoid the things that are 

 harmful, and be moderate in all things". 



A fact of interest is the statistical evidence that such a subtle 

 character as "longevity" (that is to say, a tendency to a certain 

 lease of life, be it long or short) is heritable like other inborn char- 

 acters; though it rests, of course, to some extent with the individual 



