﻿Production 
  of 
  Double 
  Floivers 
  507 
  

  

  even 
  if 
  the 
  plants 
  are 
  very 
  strong 
  and 
  healthy, 
  

   has 
  no 
  such 
  effect. 
  But 
  even 
  here 
  it 
  remains 
  

   doubtful 
  whether 
  it 
  applies 
  to 
  the 
  period 
  before 
  

   or 
  after 
  the 
  internal 
  mutation. 
  On 
  the 
  other 
  

   hand 
  success 
  is 
  not 
  at 
  all 
  to 
  be 
  relied 
  upon, 
  nor 
  

   is 
  the 
  work 
  to 
  be 
  regarded 
  as 
  easy. 
  The 
  in- 
  

   stances 
  of 
  double 
  flowers 
  said 
  to 
  be 
  obtainable 
  

   at 
  will, 
  are 
  too 
  rare 
  in 
  comparison 
  with 
  the 
  

   number 
  of 
  cases, 
  where 
  the 
  first 
  indication 
  of 
  

   them 
  was 
  found 
  accidentally. 
  

  

  Leaving 
  all 
  these 
  doubtful 
  points, 
  which 
  will 
  

   have 
  to 
  be 
  cleared 
  up 
  by 
  further 
  scientific 
  in- 
  

   vestigation, 
  the 
  high 
  degree 
  of 
  variability 
  re- 
  

   quires 
  further 
  discussion. 
  It 
  may 
  be 
  considered 
  

   from 
  three 
  different 
  points 
  of 
  view 
  according 
  

   to 
  the 
  limit 
  of 
  the 
  deviation 
  from 
  the 
  average, 
  

   to 
  the 
  dependency 
  on 
  external 
  conditions 
  and 
  to 
  

   periodicity. 
  It 
  seems 
  best 
  to 
  take 
  up 
  the 
  last 
  

   two 
  points 
  first. 
  

  

  On 
  a 
  visit 
  to 
  a 
  nursery 
  at 
  Erfurt 
  I 
  once 
  in- 
  

   spected 
  an 
  experiment 
  with 
  a 
  new 
  double 
  varie- 
  

   ty 
  of 
  the 
  common 
  blue-bottle 
  or 
  blue 
  corn-flow- 
  

   er. 
  The 
  plants 
  were 
  dependent 
  on 
  the 
  weather 
  

   to 
  a 
  high 
  degree. 
  Bad 
  weather 
  increased 
  the 
  

   number 
  of 
  poorly 
  filled 
  flower-heads, 
  while 
  

   warm 
  and 
  sunny 
  days 
  were 
  productive 
  of 
  beau- 
  

   tiful 
  double 
  flowers. 
  The 
  heads 
  that 
  are 
  borne 
  

   by 
  strong 
  branches 
  have 
  a 
  greater 
  tendency 
  to 
  

   become 
  double 
  than 
  those 
  of 
  the 
  weaker 
  ones, 
  

  

  