﻿224 
  Retrograde 
  Varieties 
  

  

  various 
  facts, 
  given 
  in 
  former 
  lectures 
  and 
  how 
  

   it 
  may 
  be 
  of 
  use 
  in 
  our 
  further 
  discussions. 
  

  

  It 
  is 
  obvious 
  that 
  the 
  differences 
  between 
  ele- 
  

   mentary 
  species 
  and 
  varieties 
  on 
  the 
  one 
  hand, 
  

   and 
  between 
  the 
  positive 
  and 
  negative 
  varieties 
  

   as 
  distinguished 
  above, 
  are 
  quite 
  comparable 
  

   with 
  our 
  theoretical 
  views. 
  For 
  we 
  have 
  seen 
  

   that 
  varieties 
  can 
  always 
  be 
  considered 
  as 
  hav- 
  

   ing 
  originated 
  by 
  an 
  apparent 
  loss 
  of 
  some 
  

   quality 
  of 
  the 
  species, 
  or 
  by 
  the 
  resumption 
  of 
  

   a 
  quality 
  which 
  in 
  allied 
  species 
  is 
  present 
  and 
  

   visible. 
  In 
  our 
  exposition 
  of 
  the 
  facts 
  we 
  have 
  

   of 
  course 
  limited 
  ourselves 
  to 
  the 
  observable 
  

   features 
  of 
  the 
  phenomena 
  without 
  searching 
  

   for 
  a 
  further 
  explanation. 
  For 
  a 
  more 
  com- 
  

   petent 
  inquiry 
  however, 
  and 
  for 
  an 
  understand- 
  

   ing 
  of 
  wider 
  ranges 
  of 
  facts, 
  it 
  is 
  necessary 
  to 
  

   penetrate 
  deeper 
  into 
  the 
  true 
  nature 
  of 
  the 
  im- 
  

   plied 
  causes. 
  

  

  Therefore 
  we 
  must 
  try 
  to 
  show 
  that 
  elemen- 
  

   tary 
  species 
  are 
  distinguished 
  from 
  each 
  other 
  

   by 
  the 
  acquisition 
  of 
  new 
  qualities, 
  and 
  that 
  

   varieties 
  are 
  derived 
  from 
  their 
  species 
  either 
  

   by 
  the 
  reduction 
  of 
  one 
  or 
  more 
  characteristics 
  

   to 
  the 
  latent 
  state, 
  or 
  by 
  the 
  energizing 
  of 
  dor- 
  

   mant 
  characters. 
  

  

  Here 
  we 
  meet 
  with 
  a 
  great 
  difficulty. 
  Hither- 
  

   to 
  varieties 
  and 
  subspecies 
  have 
  never 
  been 
  

   clearly 
  defined, 
  or 
  when 
  they 
  have 
  been, 
  it 
  was 
  

  

  