﻿600 
  Mutations 
  

  

  which 
  of 
  course 
  would 
  have 
  remained 
  concealed 
  

   if 
  its 
  multiplication 
  had 
  been 
  checked 
  in 
  the 
  or- 
  

   dinary 
  way. 
  

  

  Many 
  species 
  have 
  had 
  occasion 
  to 
  invade 
  new 
  

   regions 
  and 
  cover 
  them 
  with 
  hundreds 
  of 
  thou- 
  

   sands 
  of 
  individuals. 
  First 
  are 
  to 
  be 
  cited 
  

   those 
  species 
  which 
  have 
  been 
  introduced 
  from 
  

   America 
  into 
  Europe 
  since 
  the 
  time 
  of 
  Colum- 
  

   bus, 
  or 
  from 
  Europe 
  into 
  this 
  country. 
  Some 
  of 
  

   them 
  have 
  become 
  very 
  common. 
  In 
  my 
  own 
  

   country 
  the 
  evening-primroses 
  and 
  Canada 
  flea- 
  

   bane 
  or 
  Erigeron 
  canadensis 
  are 
  examples, 
  and 
  

   many 
  others 
  could 
  be 
  given. 
  They 
  should 
  be 
  

   expected 
  to 
  vary 
  under 
  these 
  circumstances 
  in 
  

   a 
  larger 
  degree. 
  Have 
  they 
  done 
  so? 
  Mani- 
  

   festly 
  they 
  have 
  not 
  struck 
  out 
  useful 
  new 
  char- 
  

   acters 
  that 
  would 
  enable 
  their 
  bearers 
  to 
  found 
  

   new 
  elementary 
  species. 
  At 
  least 
  none 
  have 
  

   been 
  observed. 
  But 
  poor 
  types 
  might 
  have 
  

   been 
  produced, 
  and 
  periods 
  of 
  mutability 
  might 
  

   have 
  been 
  gone 
  through 
  similar 
  to 
  that 
  which 
  is 
  

   now 
  under 
  observation 
  for 
  Lamarck's 
  evening- 
  

   primrose 
  in 
  Holland. 
  

  

  From 
  this 
  discussion 
  we 
  may 
  infer 
  that 
  the 
  

   chances 
  of 
  discovering 
  new 
  mutating 
  species 
  are 
  

   great 
  enough 
  to 
  justify 
  the 
  utmost 
  efforts 
  to 
  

   secure 
  them. 
  It 
  is 
  only 
  necessary 
  to 
  observe 
  

   large 
  numbers 
  of 
  plants, 
  grown 
  under 
  circum- 
  

   stances 
  which 
  allow 
  the 
  best 
  opportunities 
  for 
  

  

  