﻿Double 
  Adaptations 
  439 
  

  

  tween 
  these 
  two 
  alternatives, 
  many 
  writers 
  

   have 
  tried 
  to 
  decide, 
  by 
  transplanting 
  their 
  

   specimens 
  after 
  some 
  time 
  in 
  the 
  garden, 
  into 
  

   arid 
  or 
  sandy 
  soil, 
  in 
  order 
  to 
  see 
  whether 
  they 
  

   would 
  resume 
  their 
  alpine 
  character. 
  

  

  Among 
  the 
  systematists 
  who 
  tested 
  plants 
  in 
  

   this 
  way, 
  Nageli 
  especially, 
  directed 
  his 
  atten- 
  

   tion 
  to 
  the 
  hawkweeds 
  or 
  Hieracium. 
  On 
  

   the 
  Swiss 
  Alps 
  they 
  are 
  very 
  small 
  and 
  ex- 
  

   hibit 
  all 
  the 
  characters 
  of 
  the 
  pure 
  alpine 
  type. 
  

   Thousands 
  of 
  single 
  plants 
  were 
  cultivated 
  by 
  

   him 
  in 
  the 
  botanical 
  garden 
  of 
  Munich, 
  partly 
  

   from 
  seed 
  and 
  partly 
  from 
  introduced 
  root- 
  

   stocks. 
  Here 
  they 
  at 
  once 
  assumed 
  the 
  

   tall 
  stature 
  of 
  lowland 
  forms. 
  The 
  identical 
  

  

  i 
  

  

  individual, 
  which 
  formerly 
  bore 
  small 
  rosettes 
  

   of 
  basal 
  leaves, 
  with 
  short 
  and 
  unbranched 
  

   flower-stalks, 
  became 
  richly 
  leaved 
  and 
  often 
  

   produced 
  quite 
  a 
  profusion 
  of 
  flower-heads 
  on 
  

   branched 
  stems. 
  If 
  then 
  they 
  were 
  trans- 
  

   planted 
  to 
  arid 
  sand, 
  though 
  remaining 
  in 
  the 
  

   same 
  garden 
  and 
  also 
  under 
  the 
  same 
  climatic 
  

   conditions 
  they 
  resumed 
  their 
  alpine 
  charac- 
  

   ters. 
  This 
  proved 
  nutrition 
  to 
  be 
  the 
  cause 
  

   of 
  the 
  change 
  and 
  not 
  the 
  climate. 
  

  

  The 
  latest 
  and 
  most 
  exact 
  researches 
  on 
  this 
  

   subject 
  are 
  due 
  to 
  Bonnier, 
  who 
  has 
  gone 
  into 
  

   all 
  the 
  details 
  of 
  the 
  morphologic 
  as 
  well 
  as 
  

   of 
  the 
  physiologic 
  side 
  of 
  the 
  problem. 
  

  

  