﻿Polycephalic 
  Poppies 
  389 
  

  

  bility 
  slowly 
  and 
  gradually 
  decreases, 
  to 
  end 
  

   with 
  the 
  definite 
  decision 
  of 
  all 
  further 
  growth 
  

   sometime 
  before 
  the 
  outer 
  form 
  of 
  the 
  organ 
  be- 
  

   comes 
  visible 
  under 
  the 
  microscope. 
  The 
  last 
  

   period 
  of 
  life 
  includes 
  only 
  an 
  expansion 
  of 
  the 
  

   tissues, 
  which 
  may 
  still 
  have 
  some 
  influence 
  on 
  

   their 
  final 
  size, 
  but 
  not 
  on 
  their 
  form. 
  This 
  

   has 
  been 
  definitely 
  arrested 
  before 
  the 
  end 
  of 
  

   the 
  sensitive 
  period, 
  and 
  ordinarily 
  before 
  the 
  

   commencement 
  of 
  that 
  rapid 
  outgrowth, 
  which 
  

   is 
  usually 
  designated 
  by 
  the 
  name 
  of 
  growth 
  as 
  

   contrasted 
  with 
  evolution. 
  

  

  Within 
  the 
  seed 
  the 
  evolution 
  of 
  the 
  young 
  

   plant 
  manifestly 
  depends 
  upon 
  the 
  qualities 
  

   and 
  life-conditions 
  of 
  the 
  parent 
  plant. 
  The 
  

   stronger 
  this 
  is, 
  and 
  the 
  more 
  favorable 
  circum- 
  

   stances 
  it 
  is 
  placed 
  under, 
  the 
  more 
  food 
  will 
  be 
  

   available 
  for 
  the 
  seed, 
  and, 
  the 
  healthier 
  will 
  be 
  

   the 
  development 
  of 
  the 
  embryo. 
  Only 
  well- 
  

   nourished 
  plants 
  give 
  well-nourished 
  seeds, 
  and 
  

   the 
  qualities 
  of 
  each 
  plant 
  are 
  for 
  this 
  reason 
  

   at 
  least 
  partly 
  dependent 
  on 
  the 
  properties 
  of 
  

   its 
  parents 
  and 
  even 
  of 
  its 
  grandparents. 
  

  

  From 
  these 
  considerations 
  the 
  inference 
  is 
  

   forced 
  upon 
  us 
  that 
  the 
  apparently 
  hereditary 
  

   differences 
  which 
  are 
  observed 
  to 
  exist 
  among 
  

   the 
  seeds 
  of 
  a 
  species 
  or 
  a 
  variety 
  and 
  even 
  of 
  a 
  

   single 
  strain 
  or 
  a 
  single 
  parent-plant, 
  may 
  for 
  

   a 
  large 
  part, 
  and 
  perhaps 
  wholly, 
  be 
  the 
  result 
  

  

  