﻿LENGTHEITING 
  OF 
  HUMAN 
  LIFE 
  FISHER 
  551 
  

  

  LIFE 
  CELLS 
  IMMORTAL 
  

  

  The 
  fifth 
  reason 
  for 
  suspecting 
  that 
  our 
  previous 
  notions 
  of 
  a 
  life 
  

   limit 
  are 
  wrong 
  is 
  that 
  modern 
  biology 
  finds 
  the 
  life 
  cells 
  and 
  many 
  

   tissues 
  potentially 
  immortal. 
  This 
  is 
  perhaps 
  the 
  most 
  sensational 
  

   conclusion 
  which 
  science 
  has 
  ever 
  reached. 
  Yet, 
  according 
  to 
  Pearl 
  

   in 
  his 
  excellent 
  book, 
  The 
  Biology 
  of 
  Death 
  (18), 
  Loeb 
  and 
  Carrel 
  

   and 
  others 
  have 
  demonstrated 
  its 
  truth 
  beyond 
  reasonable 
  doubt. 
  

  

  NO 
  NATURAL 
  DEATH 
  FOUND 
  

  

  Woodruff, 
  of 
  Yale, 
  found 
  no 
  natural 
  death 
  in 
  a 
  culture 
  of 
  Paror 
  

   meciuTTh 
  in 
  8,500 
  generations, 
  equal 
  to 
  250,000 
  years 
  of 
  human 
  life, 
  

   and 
  the 
  culture 
  was 
  going 
  as 
  well 
  at 
  the 
  end 
  as 
  at 
  the 
  beginning. 
  

   Morgan, 
  of 
  Columbia, 
  found 
  1/250 
  of 
  a 
  worm 
  {P. 
  maculata) 
  will 
  

   regenerate 
  and 
  be 
  " 
  younger 
  " 
  than 
  the 
  original. 
  Carrel 
  has 
  kept 
  the 
  

   cells 
  of 
  a 
  chicken 
  embryo's 
  heart 
  alive 
  for 
  many 
  years 
  by 
  washing 
  

   out 
  the 
  poisons 
  generated 
  in 
  the 
  life 
  process 
  and 
  protecting 
  against 
  

   infection 
  and 
  food 
  deficiency. 
  

  

  All 
  of 
  these 
  studies 
  are 
  wonderfully 
  suggestive 
  for 
  the 
  future, 
  

   although 
  they 
  are 
  for 
  the 
  present 
  far 
  beyond 
  the 
  range 
  of 
  any 
  prac- 
  

   tical 
  application. 
  

  

  It 
  would 
  seem 
  that 
  biologists 
  are 
  gradually 
  surrendering 
  the 
  idea 
  

   of 
  any 
  natural 
  death, 
  or 
  life 
  span 
  (19), 
  and 
  reaching 
  instead 
  the 
  idea 
  

   that 
  all 
  death 
  is 
  accidental. 
  

  

  This 
  change 
  of 
  view, 
  if 
  it 
  comes 
  about, 
  will 
  be 
  revolutionary. 
  

   Hitherto 
  we 
  have 
  taken 
  for 
  granted 
  a 
  natural 
  cycle 
  of 
  life 
  with 
  its 
  

   various 
  phases 
  located 
  at 
  more 
  or 
  less 
  definite 
  intervals 
  — 
  birth, 
  

   puberty, 
  maturity, 
  climacteric 
  in 
  females, 
  and 
  death 
  — 
  all 
  spaced 
  in 
  a 
  

   due 
  relationship 
  to 
  each 
  other. 
  But 
  when 
  we 
  attempt 
  to 
  put 
  it 
  in 
  

   figures 
  we 
  find 
  f 
  ai' 
  less 
  indication 
  of 
  a 
  natural 
  age 
  for 
  death 
  than 
  of 
  

   the 
  other 
  milestones 
  in 
  life, 
  such 
  as 
  puberty, 
  for 
  instance. 
  The 
  age 
  of 
  

   puberty 
  varies 
  but 
  little 
  in 
  any 
  one 
  species 
  and 
  the 
  variation 
  from 
  

   the 
  mode 
  follows 
  the 
  usual 
  frequency 
  distribution. 
  If 
  mortality 
  

   followed 
  such 
  a 
  law, 
  it 
  would 
  center 
  about 
  some 
  mode 
  such 
  as 
  three- 
  

   score 
  years 
  and 
  ten. 
  But 
  it 
  does 
  not 
  do 
  so 
  very 
  definitely. 
  

  

  Even 
  Pearson, 
  the 
  greatest 
  apostle 
  of 
  chance 
  in 
  biology, 
  could 
  find 
  

   no 
  such 
  law 
  except 
  by 
  superposing 
  (21) 
  five 
  frequency 
  distributions, 
  

   and 
  Pearl 
  (18), 
  who, 
  if 
  anyone, 
  should 
  be 
  sympathetic 
  with 
  Pear- 
  

   son's 
  point 
  of 
  view, 
  regards 
  this 
  as 
  an 
  artificial 
  fitting 
  of 
  curves 
  and 
  

   not 
  the 
  interpretation 
  of 
  any 
  fundamental 
  biological 
  tendencies. 
  The 
  

   frequency 
  curve 
  is 
  realized 
  to 
  some 
  extent 
  for 
  individual 
  diseases 
  and 
  

   disease 
  groups, 
  as 
  Arne 
  Fisher 
  has 
  emphasized. 
  

  

  Metchnikoff 
  (22) 
  assumed 
  that 
  while 
  to-day 
  all 
  deaths 
  are 
  acci- 
  

   dental, 
  whether 
  due 
  to 
  the 
  invasion 
  of 
  a 
  bullet, 
  a 
  poison, 
  or 
  a 
  germ, 
  

   if 
  we 
  could 
  safeguard 
  against 
  these 
  we 
  should 
  reach 
  a 
  natural 
  death 
  

   at, 
  say, 
  125 
  years 
  of 
  age. 
  

  

  