﻿616 
  Mutations 
  

  

  normal 
  parents 
  were 
  in 
  reality 
  hybrids 
  between 
  

   the 
  type 
  and 
  the 
  laciniated 
  form, 
  and 
  simply 
  

   split 
  according 
  to 
  Mendel's 
  law. 
  This 
  hy- 
  

   pothesis 
  is 
  partly 
  founded 
  on 
  general 
  consider- 
  

   ations 
  and 
  partly 
  on 
  experiments 
  made 
  by 
  my- 
  

   self 
  with 
  the 
  cut-leaved 
  celandine, 
  previously 
  

   alluded 
  to, 
  which 
  I 
  crossed 
  with 
  the 
  type. 
  The 
  

   hybrids 
  repeated 
  the 
  features 
  of 
  the 
  species 
  and 
  

   showed 
  no 
  signs 
  of 
  their 
  internal 
  hybrid 
  con- 
  

   stitution. 
  But 
  the 
  following 
  year 
  one-fourth 
  

   of 
  their 
  progeny 
  returned 
  to 
  the 
  cut-leaved 
  

   form. 
  If 
  the 
  same 
  thing 
  has 
  taken 
  place 
  in 
  the 
  

   case 
  of 
  London's 
  maples, 
  but 
  without 
  their 
  

   hybrid 
  origin 
  being 
  known, 
  the 
  result 
  would 
  

   have 
  been 
  precisely 
  what 
  he 
  observed. 
  

  

  Broussonetia 
  papyrifera 
  dissecta 
  originated 
  

   about 
  1830 
  at 
  Lyons, 
  and 
  a 
  second 
  time 
  in 
  1866 
  

   at 
  Fontenay-aux-Koses. 
  The 
  cut-leaved 
  hazel- 
  

   nuts, 
  birches, 
  beeches 
  and 
  others 
  have 
  mostly 
  

   been 
  found 
  in 
  the 
  wild 
  state, 
  as 
  I 
  have 
  already 
  

   pointed 
  out 
  in 
  a 
  previous 
  lecture. 
  A 
  similar 
  

   variety 
  of 
  the 
  elder, 
  Sambucus 
  nigra 
  laciniata, 
  

   and 
  its 
  near 
  ally, 
  Sambucus 
  racemosa 
  laciniata, 
  

   are 
  often 
  to 
  be 
  seen 
  in 
  our 
  gardens. 
  They 
  have 
  

   been 
  on 
  record 
  since 
  1886 
  and 
  come 
  true 
  from 
  

   seed, 
  but 
  their 
  exact 
  origin 
  seems 
  to 
  have 
  been 
  

   forgotten. 
  Cut-leaved 
  walnuts 
  have 
  been 
  known 
  

   since 
  1812; 
  they 
  come 
  true 
  from 
  seed, 
  but 
  are 
  

   extremely 
  liable 
  to 
  vicinism, 
  a 
  nuisance 
  which 
  is 
  

  

  