﻿Stability 
  and 
  Real 
  Atavism 
  175 
  

  

  hitherto 
  observed, 
  seed-reversions 
  must 
  be 
  said 
  

   to 
  be 
  extremely 
  rare. 
  Or 
  rather 
  cases 
  which 
  

   are 
  sufficiently 
  certain 
  to 
  be 
  relied 
  upon, 
  are 
  

   very 
  rare, 
  and 
  perhaps 
  wholly 
  lacking. 
  Most 
  

   of 
  the 
  instances, 
  recorded 
  by 
  various 
  writers, 
  

   are 
  open 
  to 
  question. 
  Doubts 
  exist 
  as 
  to 
  the 
  

   purity 
  of 
  the 
  seeds 
  and 
  the 
  possibility 
  of 
  some 
  

   unobserved 
  cross 
  disturbing 
  the 
  results. 
  

  

  In 
  the 
  next 
  lecture 
  we 
  shall 
  deal 
  in 
  general 
  

   with 
  the 
  ordinary 
  causes 
  and 
  results 
  of 
  such 
  

   crosses. 
  We 
  shall 
  then 
  see 
  that 
  they 
  are 
  so 
  

   common 
  and 
  occur 
  so 
  regularly 
  under 
  ordinary 
  

   circumstances 
  that 
  we 
  can 
  never 
  rely 
  on 
  the 
  

   absolute 
  purity 
  of 
  any 
  seeds, 
  if 
  the 
  impossibility 
  

   of 
  an 
  occasional 
  cross 
  has 
  not 
  been 
  wholly 
  ex- 
  

   cluded, 
  either 
  by 
  the 
  circumstances 
  themselves, 
  

   or 
  by 
  experimental 
  precautions 
  taken 
  during 
  

   the 
  flowering 
  period. 
  

  

  For 
  these 
  reasons 
  cases 
  of 
  atavism 
  given 
  

   without 
  recording 
  the 
  circumstances, 
  or 
  the 
  pre- 
  

   cautions 
  that 
  guarantee 
  the 
  purity 
  of 
  the 
  fertili- 
  

   zation, 
  should 
  always 
  be 
  disregarded. 
  And 
  

   moreover 
  another 
  proof 
  should 
  always 
  be 
  de- 
  

   manded. 
  The 
  parent 
  which 
  yielded 
  the 
  seeds 
  

   might 
  be 
  itself 
  a 
  hybrid 
  and 
  liable 
  to 
  reversions 
  

   by 
  the 
  ordinary 
  laws 
  of 
  the 
  splitting 
  up 
  of 
  hy- 
  

   brids. 
  Such 
  cases 
  should 
  likewise 
  be 
  discarded, 
  

   since 
  they 
  bring 
  in 
  confusing 
  elements. 
  If 
  we 
  

   review 
  the 
  long 
  list 
  of 
  recorded 
  cases 
  by 
  these 
  

  

  