﻿280 
  ANNUAL 
  EEPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1929 
  

  

  wroBg, 
  it 
  becomes 
  sick, 
  and 
  if 
  the 
  defect 
  is 
  not 
  corrected 
  the 
  animal 
  

   dies. 
  Every 
  individual, 
  after 
  hving 
  for 
  a 
  time 
  that 
  differs 
  greatly 
  for 
  

   different 
  animals, 
  but 
  that 
  is 
  of 
  more 
  or 
  less 
  the 
  same 
  duration 
  for 
  

   every 
  species, 
  will 
  unavoidably 
  be 
  affected 
  by 
  defects 
  of 
  metabolism 
  

   and 
  will 
  die 
  a 
  so-called 
  natural 
  death. 
  

  

  POWER 
  OF 
  REPRODUCTION 
  CONTROLLING 
  THE 
  PRESERVATION 
  OF 
  A 
  RACE 
  

  

  The 
  preservation 
  of 
  a 
  race 
  is 
  dependent 
  on 
  the 
  ability 
  of 
  the 
  organ- 
  

   isms 
  composing 
  it 
  to 
  reproduce. 
  Usually 
  this 
  ability 
  is 
  conjoined 
  

   with 
  the 
  phj^sical 
  development 
  of 
  the 
  individual, 
  which 
  may 
  be 
  divided 
  

   into 
  three 
  stages. 
  The 
  first 
  stage 
  is 
  the 
  period 
  of 
  greatest 
  growth, 
  

   when 
  the 
  income 
  of 
  the 
  body 
  is 
  much 
  greater 
  than 
  its 
  expenditure. 
  

   The 
  stage 
  continues 
  until 
  physical 
  maturity 
  is 
  reached, 
  when 
  some 
  

   kind 
  of 
  equilibrium 
  between 
  income 
  and 
  expenditure 
  is 
  established, 
  

   which 
  is 
  maintained 
  throughout 
  the 
  reproductive 
  period. 
  With 
  the 
  

   passing 
  of 
  the 
  period 
  of 
  reproduction 
  metabohsm 
  decreases 
  and 
  the 
  

   individual 
  gradually 
  loses 
  vitality. 
  This 
  general 
  statement 
  may 
  not 
  

   be 
  correct 
  for 
  every 
  organism 
  or 
  race, 
  but 
  as 
  the 
  expression 
  of 
  a 
  gen- 
  

   eral 
  principle 
  it 
  may 
  be 
  sufficiently 
  correct. 
  

  

  DECREASE 
  OF 
  REPRODUCTION 
  IN 
  HIGHER 
  AND 
  MORE 
  SPECIALIZED 
  

  

  ANIMALS 
  

  

  The 
  relation 
  between 
  reproduction 
  and 
  individual 
  life 
  is 
  not 
  

   invariably 
  so 
  simple. 
  For 
  no 
  apparent 
  reason 
  a 
  strong, 
  healthy 
  

   individual 
  may 
  be 
  incapable 
  of 
  reproduction. 
  The 
  power 
  of 
  repro- 
  

   duction 
  also 
  may 
  not 
  be 
  completely 
  lost; 
  it 
  may 
  be 
  only 
  decreased, 
  

   as 
  it 
  is 
  when 
  the 
  number 
  of 
  births 
  is 
  small, 
  or 
  when 
  the 
  percentage 
  

   of 
  male 
  births 
  in 
  a 
  species 
  or 
  race 
  is 
  much 
  higher 
  than 
  that 
  of 
  female 
  

   births. 
  This 
  phenomenon 
  may 
  be 
  considered 
  the 
  beginning 
  of 
  

   sterility. 
  We 
  do 
  not 
  know 
  the 
  real 
  cause 
  of 
  sterility 
  that 
  is 
  not 
  

   produced 
  by 
  some 
  evident 
  abnormality.- 
  It 
  has 
  been 
  suggested 
  that 
  

   insanity 
  provokes 
  sterility 
  in 
  the 
  fourth 
  generation. 
  Too 
  close 
  

   interbreeding 
  may 
  gradually 
  develop 
  into 
  steriiitj'-, 
  and 
  if 
  the 
  stock 
  

   is 
  not 
  reinvigorated 
  with 
  new 
  blood 
  it 
  will 
  bring 
  about 
  the 
  complete 
  

   extinction 
  of 
  a 
  race, 
  though 
  the 
  correctness 
  of 
  this 
  statement 
  has 
  been 
  

   questioned 
  or 
  denied 
  by 
  some 
  biologists. 
  It 
  has 
  been 
  observed 
  that 
  

   in 
  the 
  first 
  generation 
  interbreeding 
  gives 
  offspring 
  of 
  high 
  grade. 
  

   In 
  this 
  way 
  a 
  breed 
  of 
  setters 
  of 
  high 
  quality, 
  but 
  of 
  short 
  longevity, 
  

   was 
  obtained. 
  The 
  breed 
  began 
  to 
  die 
  out 
  so 
  quickly 
  that 
  the 
  breeder 
  

   witnessed 
  the 
  gradual 
  extinction 
  of 
  his 
  product. 
  

  

  Sterility, 
  even 
  in 
  its 
  first 
  stage, 
  in 
  no 
  way 
  shows 
  a 
  low 
  degree 
  of 
  

   advancement 
  of 
  a 
  species. 
  Indeed, 
  prolification 
  may 
  decrease 
  with 
  

   advancement, 
  either 
  through 
  a 
  diminishing 
  number 
  of 
  offspring 
  or 
  

   an 
  increasing 
  period 
  of 
  gestation 
  and 
  maturity. 
  Man 
  has 
  the 
  rather 
  

  

  