﻿Elementary 
  Species 
  in 
  Nature 
  61 
  

  

  and 
  hence 
  has 
  no 
  fertilizing 
  power. 
  But 
  the 
  

   young 
  ovaries 
  do 
  not 
  need 
  such 
  fertilization. 
  

   They 
  are 
  sufficient 
  unto 
  themselves. 
  One 
  may 
  

   cut 
  off 
  all 
  the 
  flowers 
  of 
  a 
  head 
  before 
  the 
  open- 
  

   ing 
  of 
  the 
  anthers, 
  and 
  leave 
  the 
  ovaries 
  

   untouched, 
  and 
  the 
  head 
  will 
  ripen 
  its 
  seeds 
  

   quite 
  as 
  well. 
  The 
  same 
  thing 
  occurs 
  in 
  the 
  

   hawkweeds. 
  Here, 
  therefore, 
  we 
  have 
  no 
  ferti- 
  

   lization 
  and 
  the 
  extensive 
  widening 
  of 
  the 
  varia- 
  

   bility, 
  which 
  generally 
  accompanies 
  this 
  pro- 
  

   cess 
  is, 
  of 
  course, 
  wanting. 
  Only 
  partial 
  or 
  

   vegetative 
  variability 
  is 
  present. 
  Unfertilized 
  

   eggs 
  when 
  developing 
  into 
  embryos 
  are 
  equiva- 
  

   lent 
  to 
  buds, 
  separated 
  from 
  the 
  parent-plant 
  

   and 
  planted 
  for 
  themselves. 
  They 
  repeat 
  both 
  

   the 
  specific 
  and 
  the 
  individual 
  characters 
  of 
  

   the 
  parent. 
  In 
  the 
  case, 
  of 
  the 
  hawkweed 
  and 
  

   the 
  dandelion 
  there 
  is 
  at 
  present 
  no 
  means 
  of 
  

   distinguishing 
  between 
  these 
  two 
  contrasting 
  

   causes 
  of 
  variability. 
  But 
  like 
  the 
  garden- 
  

   varieties 
  which 
  are 
  always 
  propagated 
  in 
  the 
  

   vegetative 
  way, 
  their 
  constancy 
  and 
  uniformity 
  

   are 
  only 
  apparent 
  and 
  afford 
  no 
  real 
  indication 
  

   of 
  hereditary 
  qualities. 
  

  

  In 
  addition 
  to 
  these 
  and 
  other 
  exceptional 
  

   cases, 
  seed-cultures 
  are 
  henceforth 
  to 
  be 
  con- 
  

   sidered 
  as 
  the 
  sole 
  means 
  of 
  recognizing 
  the 
  

   really 
  existing 
  systematic 
  units 
  of 
  nature. 
  All 
  

   other 
  groups, 
  including 
  systematic 
  species 
  and 
  

  

  