﻿622 
  Mutations 
  

  

  culture, 
  more 
  than 
  a 
  century 
  ago, 
  as 
  isolated 
  

   monstrous 
  individuals. 
  They 
  come 
  true 
  from 
  

   seed, 
  but 
  show 
  deviations 
  from 
  time 
  to 
  time 
  

   which 
  seem 
  to 
  be 
  intimately 
  linked 
  with 
  their 
  

   abnormal 
  characters. 
  Apetalous 
  flowers 
  may 
  

   be 
  considered 
  as 
  another 
  form 
  of 
  monstrosity, 
  

   and 
  in 
  Salpiglossis 
  sinuata 
  such 
  a 
  variety 
  with- 
  

   out 
  a 
  corolla 
  made 
  its 
  appearance 
  in 
  the 
  year 
  

   1892 
  in 
  the 
  nursery 
  of 
  Vilmorin. 
  It 
  appeared 
  

   suddenly, 
  yielded 
  a 
  good 
  crop 
  of 
  seed 
  and 
  

   was 
  constant 
  from 
  the 
  outset, 
  without 
  any 
  sign 
  

   of 
  vicinism 
  or 
  impurity. 
  

  

  In 
  several 
  cases 
  the 
  origin 
  of 
  a 
  variety 
  is 
  ob- 
  

   scure, 
  while 
  the 
  subsequent 
  historical 
  evidence 
  

   is 
  such 
  as 
  to 
  make 
  an 
  original 
  sudden 
  appear- 
  

   ance 
  quite 
  probable. 
  Although 
  these 
  instances 
  

   offer 
  but 
  indirect 
  evidence, 
  and 
  will 
  sooner 
  or 
  

   later 
  lose 
  their 
  importance, 
  it 
  seems 
  desirable 
  

   to 
  lay 
  some 
  stress 
  on 
  them 
  here, 
  because 
  most 
  of 
  

   these 
  cases 
  are 
  very 
  obvious 
  and 
  more 
  striking 
  

   than 
  purely 
  historical 
  facts. 
  Sterile 
  varieties 
  

   belong 
  to 
  this 
  heading. 
  Sometimes 
  they 
  bear 
  

   fruit 
  without 
  kernels, 
  sometimes 
  flowers 
  with- 
  

   out 
  sexual 
  organs, 
  or 
  even 
  no 
  flowers 
  at 
  all. 
  In- 
  

   stances 
  have 
  been 
  given 
  in 
  the 
  lecture 
  on 
  

   retrograde 
  varieties; 
  they 
  are 
  ordinarily 
  as- 
  

   sumed 
  to 
  have 
  originated 
  by 
  a 
  leap, 
  because 
  it 
  is 
  

   not 
  quite 
  clear 
  how 
  a 
  loss 
  of 
  the 
  capacity 
  for 
  the 
  

   formation 
  of 
  seeds 
  could 
  have 
  been 
  slowlv 
  accu- 
  

  

  