﻿618 
  Mutations 
  

  

  seedlings 
  of 
  the 
  typical 
  species 
  in 
  a 
  single 
  in- 
  

   dividual. 
  This 
  was 
  transplanted 
  into 
  the 
  Jar- 
  

   din 
  des 
  Plantes 
  at 
  Paris, 
  where 
  it 
  flowered 
  and 
  

   bore 
  seeds 
  in 
  1865. 
  It 
  must 
  have 
  been 
  partly 
  

   pollinated 
  by 
  the 
  surrounding 
  normal 
  repre- 
  

   sentatives 
  of 
  the 
  species, 
  since 
  the 
  seeds 
  yielded 
  

   only 
  one-fourth 
  of 
  true 
  offspring. 
  This 
  propor- 
  

   tion, 
  however, 
  has 
  varied 
  in 
  succeeding 
  years. 
  

   Briot 
  remarks 
  that 
  the 
  monophyllous 
  bastard- 
  

   acacia 
  is 
  liable 
  to 
  petaloid 
  alterations 
  of 
  its 
  

   stamens, 
  which 
  deficiency 
  may 
  encroach 
  upon 
  

   its 
  fertility 
  and 
  accordingly 
  upon 
  the 
  purity 
  of 
  

   its 
  offspring. 
  

  

  Broom-like 
  varieties 
  often 
  occur 
  among 
  trees, 
  

   and 
  some 
  are 
  known 
  for 
  their 
  very 
  striking 
  re- 
  

   versions 
  by 
  buds, 
  as 
  we 
  have 
  seen 
  on 
  a 
  previous 
  

   occasion. 
  They 
  are 
  ordinarily 
  called 
  pyramidal 
  

   or 
  fastigiate 
  forms, 
  and 
  as 
  far 
  as 
  their 
  history 
  

   goes, 
  they 
  arise 
  suddenly 
  in 
  large 
  sowings 
  

   of 
  the 
  normal 
  species. 
  The 
  fastigiate 
  birch 
  was 
  

   produced 
  in 
  this 
  way 
  by 
  Baumann, 
  the 
  Abies 
  

   concolor 
  fastigiata 
  by 
  Thibault 
  and 
  Keteleer 
  at 
  

   Paris, 
  the 
  pyramidal 
  cedar 
  by 
  Paillat, 
  the 
  analo- 
  

   gous 
  form 
  of 
  Wellingtonia 
  by 
  Otin. 
  Other 
  in- 
  

   stances 
  could 
  easily 
  be 
  added, 
  though 
  of 
  course 
  

   some 
  of 
  the 
  most 
  highly 
  prized 
  broom-like 
  trees 
  

   are 
  so 
  old 
  that 
  nothing 
  is 
  known 
  about 
  their 
  

   origin. 
  This, 
  for 
  instance, 
  is 
  the 
  case 
  with 
  the 
  

   pyramidal 
  yew-tree, 
  Taxus 
  baccata 
  fastigiata. 
  

  

  