﻿Unbalanced 
  Crosses 
  267 
  

  

  standing 
  between 
  two 
  allied 
  types, 
  may 
  be 
  con- 
  

   sidered 
  to 
  have 
  originated 
  by 
  a 
  cross. 
  Surely 
  

   a 
  wide 
  field 
  for 
  abuse 
  is 
  opened 
  by 
  such 
  an 
  as- 
  

   sertion, 
  and 
  it 
  is 
  quite 
  a 
  common 
  habit 
  to 
  con- 
  

   sider 
  intermediate 
  forms 
  as 
  hybrids, 
  on 
  the 
  

   grounds 
  afforded 
  by 
  their 
  external 
  characters 
  

   alone, 
  and 
  without 
  any 
  exact 
  knowledge 
  of 
  their 
  

   real 
  origin 
  and 
  often 
  without 
  knowing 
  anything 
  

   as 
  to 
  their 
  constancy 
  from 
  seed. 
  All 
  such 
  ap- 
  

   parent 
  explanations 
  are 
  now 
  slowly 
  becoming 
  

   antiquated 
  and 
  obsolete, 
  but 
  the 
  cases 
  adduced 
  

   by 
  Kerner 
  seem 
  to 
  stand 
  this 
  test. 
  

  

  Kerner 
  designates 
  a 
  willow, 
  Salix 
  ehrhart- 
  

   iana 
  as 
  a 
  constant 
  hybrid 
  between 
  Salix 
  alba 
  

   and 
  S. 
  pentandra. 
  Rhododendron 
  intermed- 
  

   ium 
  is 
  an 
  intermediate 
  form 
  between 
  the 
  hairy 
  

   and 
  the 
  rusty 
  species 
  from 
  the 
  Swiss 
  Alps, 
  R. 
  

   hirsutum 
  and 
  R. 
  fernigineum, 
  the 
  former 
  grow- 
  

   ing 
  on 
  chalky, 
  and 
  the 
  other 
  on 
  silicious 
  soils. 
  

   Wherever 
  both 
  these 
  types 
  of 
  soil 
  occur 
  in 
  the 
  

   same 
  valley 
  and 
  these 
  two 
  species 
  approach 
  

   one 
  another, 
  the 
  hybrid 
  R. 
  intermedium 
  is 
  pro- 
  

   duced, 
  and 
  is 
  often 
  seen 
  to 
  be 
  propagating 
  itself 
  

   abundantly. 
  As 
  is 
  indicated 
  by 
  the 
  name, 
  it 
  

   combines 
  the 
  essential 
  characters 
  of 
  both 
  par- 
  

   ents. 
  

  

  Linaria 
  italic 
  a 
  is 
  a 
  hybrid 
  toad-flax 
  between 
  

   L. 
  genistifolia 
  and 
  L. 
  vulgaris, 
  a 
  cross 
  which 
  I 
  

   have 
  repeated 
  in 
  my 
  garden. 
  Drosera 
  obovata 
  

  

  