METCHNIKOFF AND TOLSTOI 41 



"death" before we have really run out our lease of 

 life. 



Human beings die most abundantly in the earliest 

 years of life. Statistics show that at birth the chance 

 or expectation of life is only 45 years, whilst at 10 years 

 old you may expect to live to be 6 1. At 30 you have 

 not a much better chance you will probably, if you are 

 what is called a " healthy" life, die when you are 65. But 

 if you survive to be 50 you may expect, if you have not 

 any obvious disease or signs of " break up," another twenty- 

 years, and will probably die at 70 ; surviving to 60, you 

 may expect, if you are what passes for " healthy," to live 

 to 73. Now, it is especially with regard to life after 40 or 

 50 years of age that Metchnikoff is interested. Those who 

 have survived the special dangers and difficulties of youth, 

 and have arrived at this mature age, ought to be able to 

 realise much more frequently than they do something like 

 the full " lease of life." There seems to be no reason why 

 they should not avoid the usual rapid " senile changes " 

 or weakness of old age, and survive, as a few actually 

 do, to something like 100. The causes of >( senile 

 change " and the way to defeat their operation are what 

 Metchnikoff is studying. Hardening of the walls of the 

 arteries set up by certain avoidable diseases contracted 

 in earlier life, and by the use of alcohol (not only to the 

 degree which we call " drunkenness," but to such a degree 

 as to make one depend on it as a " pick-me-up "), is an 

 undoubted cause of that weakness and liability to succumb 

 to other diseases which is so general after 50 years of age. 

 The causes which produce hardened arteries can be 

 avoided. Another cause of senile changes is declared by 

 Metchnikoff, to arise from the continual absorption of 

 poisonous substances produced by the decomposition of 

 partially digested food in the lower bowel or large intestine. 

 This is at present the chief subject of his study. It is to 



