﻿Mutations 
  in 
  Horticulture 
  623 
  

  

  mulated 
  in 
  preceding 
  generations. 
  An 
  interest- 
  

   ing 
  case 
  is 
  afforded 
  by 
  a 
  sterile 
  variety 
  of 
  corn, 
  

   which 
  originated 
  some 
  time 
  ago 
  in 
  my 
  own 
  pedi- 
  

   gree-cultures 
  made 
  for 
  another 
  purpose, 
  and 
  

   which 
  had 
  begun 
  with 
  an 
  ear 
  of 
  1886. 
  The 
  first 
  

   generation 
  from 
  the 
  original 
  seeds 
  showed 
  noth- 
  

   ing 
  particular, 
  but 
  the 
  second 
  at 
  once 
  produced 
  

   quite 
  a 
  number 
  of 
  sterile 
  plants. 
  The 
  sterility 
  

   was 
  caused 
  by 
  the 
  total 
  lack 
  of 
  branches, 
  includ- 
  

   ing 
  those 
  bearing 
  the 
  pistillate 
  flowers. 
  The 
  

   terminal 
  spikes 
  themselves 
  were 
  reduced 
  to 
  

   naked 
  spindles, 
  without 
  branches, 
  without 
  flow- 
  

   ers 
  and 
  even 
  almost 
  without 
  bracts. 
  

  

  In 
  some 
  individuals, 
  however, 
  this 
  negative 
  

   character 
  was 
  seen 
  to 
  give 
  way 
  at 
  the 
  tip, 
  show- 
  

   ing 
  a 
  few 
  small 
  naked 
  branches. 
  Of 
  course 
  it 
  

   was 
  impossible 
  to 
  propagate 
  this 
  curious 
  form, 
  

   but 
  my 
  observations 
  showed 
  that 
  it 
  sprang 
  into 
  

   existence 
  from 
  known 
  ancestors 
  by 
  a 
  single 
  step 
  

   or 
  sudden 
  leap. 
  This 
  leap, 
  however, 
  was 
  not 
  

   confined 
  to 
  a 
  single 
  specimen; 
  on 
  the 
  contrary 
  

   it 
  affected 
  40 
  plants 
  out 
  of 
  a 
  culture 
  of 
  340 
  

   individuals. 
  The 
  same 
  phenomenon 
  was 
  re- 
  

   peated 
  from 
  the 
  seeds 
  of 
  the 
  normal 
  plants 
  in 
  

   the 
  following 
  year, 
  but 
  afterwards 
  the 
  mon- 
  

   strosity 
  disappeared. 
  

  

  The 
  Italian 
  poplar 
  affords 
  another 
  instance. 
  

   It 
  is 
  considered 
  by 
  some 
  authors 
  as 
  a 
  distinct 
  

   species, 
  Populus 
  italica, 
  and 
  by 
  others 
  as 
  a 
  

  

  