﻿26 
  Descent 
  

  

  from 
  other 
  plants, 
  must 
  be 
  carefully 
  excluded. 
  

   A 
  special 
  lecture 
  will 
  be 
  devoted 
  to 
  this 
  very 
  in- 
  

   teresting 
  source 
  of 
  impurity 
  and 
  of 
  uncertainty 
  

   in 
  ordinary 
  cultures. 
  

  

  Of 
  course, 
  crosses 
  may 
  lie 
  in 
  the 
  proposed 
  

   line 
  of 
  work, 
  and 
  this 
  is 
  the 
  third 
  point 
  to 
  be 
  

   alluded 
  to. 
  They 
  must 
  be 
  surrounded 
  with 
  the 
  

   same 
  careful 
  isolation 
  and 
  protection 
  against 
  

   bees, 
  as 
  any 
  other 
  fertilizations. 
  And 
  not 
  only 
  

   the 
  seed-parent, 
  but 
  also 
  the 
  pollen 
  must 
  be 
  

   kept 
  pure 
  from 
  all 
  possible 
  foreign 
  admixtures. 
  

  

  A 
  pure 
  and 
  accurately 
  recorded 
  ancestry 
  is 
  

   thus 
  to 
  be 
  considered 
  as 
  the 
  most 
  important 
  

   condition 
  of 
  success 
  in 
  experimental 
  plant- 
  

   breeding. 
  Next 
  to 
  this 
  comes 
  the 
  gathering 
  of 
  

   the 
  seeds 
  of 
  each 
  individual 
  separately. 
  Fifty 
  

   or 
  sixty, 
  and 
  often 
  more, 
  bags 
  of 
  seeds 
  are 
  by 
  no 
  

   means 
  uncommon 
  for 
  a 
  single 
  experiment, 
  and 
  

   in 
  ordinary 
  years 
  the 
  harvest 
  of 
  my 
  garden 
  is 
  

   preserved 
  in 
  over 
  a 
  thousand 
  separate 
  lots. 
  

  

  Complying 
  with 
  these 
  conditions, 
  the 
  origin 
  

   of 
  species 
  may 
  be 
  seen 
  as 
  easily 
  as 
  any 
  other 
  

   phenomenon. 
  It 
  is 
  only 
  necessary 
  to 
  have 
  a 
  

   plant 
  in 
  a 
  mutable 
  condition. 
  Not 
  all 
  species 
  

   are 
  in 
  such 
  a 
  state 
  at 
  present, 
  and 
  therefore 
  I 
  

   have 
  begun 
  by 
  ascertaining 
  which 
  were 
  stable 
  

   and 
  which 
  were 
  not, 
  These 
  attempts, 
  of 
  course, 
  

   had 
  to 
  be 
  made 
  in 
  the 
  experimental 
  garden, 
  and 
  

   large 
  quantities 
  of 
  seed 
  had 
  to 
  be 
  procured 
  and 
  

  

  