﻿4 
  Descent 
  

  

  comparative 
  sciences 
  compels 
  us 
  to 
  accept 
  the 
  

   idea. 
  To 
  deny 
  it, 
  is 
  to 
  give 
  up 
  all 
  oppor- 
  

   tunity 
  of 
  conceiving 
  Nature 
  in 
  her 
  true 
  form. 
  

  

  The 
  general 
  features 
  of 
  the 
  theory 
  of 
  descent 
  

   are 
  now 
  accepted 
  as 
  the 
  basis 
  of 
  all 
  biological 
  

   science. 
  Half 
  a 
  century 
  of 
  discussion 
  and 
  in- 
  

   vestigation 
  has 
  cleared 
  up 
  the 
  minor 
  points 
  and 
  

   brought 
  out 
  an 
  abundance 
  of 
  facts; 
  but 
  they 
  

   have 
  not 
  changed 
  the 
  principle. 
  Descent 
  with 
  

   modification 
  is 
  now 
  universally 
  accepted 
  as 
  the 
  

   chief 
  law 
  of 
  nature 
  in 
  the 
  organic 
  world. 
  In 
  

   honor 
  of 
  him, 
  who 
  with 
  unsurpassed 
  genius, 
  and 
  

   by 
  unlimited 
  labor 
  has 
  made 
  it 
  the 
  basis 
  of 
  

   modern 
  thought, 
  this 
  law 
  is 
  called 
  the 
  " 
  Dar- 
  

   winian 
  theory 
  of 
  descent. 
  ' 
  

  

  Darwin's 
  second 
  contribution 
  to 
  this 
  attain- 
  

   ment 
  was 
  his 
  proof 
  of 
  the 
  possibility 
  of 
  a 
  phys- 
  

   iological 
  explanation 
  of 
  the 
  process 
  of 
  descent 
  

   itself. 
  Of 
  this 
  possibility 
  he 
  fully 
  convinced 
  his 
  

   contemporaries, 
  but 
  in 
  indicating 
  the 
  particular 
  

   means 
  by 
  which 
  the 
  change 
  of 
  species 
  has 
  been 
  

   brought 
  about, 
  he 
  has 
  not 
  succeeded 
  in 
  securing 
  

   universal 
  acceptation. 
  Quite 
  on 
  the 
  contrary, 
  

   objections 
  have 
  been 
  raised 
  from 
  the 
  very 
  out- 
  

   set, 
  and 
  with 
  such 
  force 
  as 
  to 
  compel 
  Darwin 
  

   himself 
  to 
  change 
  his 
  views 
  in 
  his 
  later 
  writings. 
  

   This 
  however, 
  was 
  of 
  no 
  avail, 
  and 
  objections 
  

   and 
  criticisms 
  have 
  since 
  steadily 
  accumulated. 
  

  

  Physiologic 
  facts 
  concerning 
  the 
  origin 
  of 
  

  

  