﻿Production 
  of 
  Double 
  Flowers 
  511 
  

  

  send 
  me 
  such 
  a 
  curious 
  flower. 
  One 
  half 
  of 
  it 
  

   was 
  completely 
  double, 
  while 
  the 
  other 
  half 
  was 
  

   entirely 
  single, 
  bearing 
  normal 
  and 
  fertile 
  sta- 
  

   mens 
  in 
  the 
  ordinary 
  number. 
  

  

  The 
  same 
  halfway 
  doubling 
  is 
  recorded 
  to 
  

   occur 
  among 
  composites 
  sometimes, 
  and 
  from 
  

   the 
  same 
  source 
  I 
  possess 
  in 
  my 
  collection 
  a 
  

   head 
  of 
  Pyretlirum 
  roseum, 
  bearing 
  on 
  half 
  of 
  

   its 
  disk 
  elongated 
  corolla 
  tubes, 
  and 
  on 
  the 
  

   other 
  half 
  the 
  small 
  disk-florets 
  of 
  the 
  typical 
  

   species. 
  

  

  It 
  is 
  a 
  current 
  belief, 
  that 
  varieties 
  are 
  im- 
  

   proved 
  by 
  continued 
  culture. 
  I 
  have 
  never 
  been 
  

   able 
  to 
  ascertain 
  the 
  grounds 
  on 
  which 
  this 
  con- 
  

   viction 
  rests. 
  It 
  may 
  be 
  referred 
  either 
  to 
  the 
  

   purity 
  of 
  the 
  race 
  or 
  to 
  the 
  complete 
  develop- 
  

   ment 
  of 
  the 
  varietal 
  character. 
  In 
  the 
  first 
  case 
  

   it 
  is 
  a 
  question 
  of 
  hybrid 
  mixtures 
  from 
  which 
  

   many 
  young 
  varieties 
  must 
  be 
  freed 
  before 
  be- 
  

   ing 
  placed 
  on 
  the 
  market. 
  But 
  as 
  we 
  have 
  al- 
  

   ready 
  seen 
  in 
  a 
  former 
  lecture, 
  this 
  requires 
  

   only 
  three 
  or 
  four 
  years, 
  and 
  afterwards 
  the 
  

   degree 
  of 
  purity 
  is 
  kept 
  up 
  to 
  the 
  point 
  which 
  

   proves 
  to 
  be 
  the 
  most 
  suitable 
  for 
  practical 
  

   purposes. 
  The 
  complete 
  development 
  of 
  the 
  

   varietal 
  character 
  is 
  a 
  question 
  restricted 
  to 
  

   ever-sporting 
  varieties, 
  since 
  in 
  white 
  flowers 
  

   and 
  other 
  constant 
  varieties 
  this 
  degree 
  is 
  va- 
  

   riable 
  in 
  a 
  very 
  small 
  and 
  unimportant 
  meas- 
  

  

  