﻿Double 
  Adaptations 
  443 
  

  

  come 
  as 
  small 
  as 
  on 
  the 
  Alps. 
  Continuous 
  elec- 
  

   tric 
  light 
  had 
  very 
  curious 
  effects; 
  the 
  plants 
  

   became 
  etiolated, 
  as 
  if 
  growing 
  in 
  darkness, 
  

   with 
  the 
  exception 
  that 
  they 
  assumed 
  a 
  deep 
  

   green 
  tinge. 
  They 
  showed 
  more 
  analogy 
  with 
  

   the 
  arctic 
  than 
  with 
  the 
  alpine 
  type. 
  

  

  The 
  influence 
  of 
  the 
  soil 
  often 
  produces 
  

   changes 
  similar 
  to 
  that 
  of 
  climate. 
  This 
  was 
  

   shown 
  by 
  the 
  above 
  cited 
  experiments 
  of 
  Na- 
  

   geli 
  with 
  the 
  hawkweeds, 
  and 
  may 
  easily 
  be 
  

   controlled 
  in 
  other 
  cases. 
  The 
  ground-honey- 
  

   suckle 
  or 
  Lotus 
  corniculatus 
  grows 
  in 
  Holland 
  

   partly 
  on 
  the 
  dry 
  and 
  sandy 
  soil 
  of 
  the 
  dunes, 
  

   and 
  occasionally 
  in 
  meadows. 
  It 
  is 
  small 
  and 
  

   dense 
  in 
  the 
  first 
  case, 
  with 
  orange 
  and 
  often 
  

   very 
  darkly 
  colored 
  petals, 
  while 
  it 
  is 
  loose 
  and 
  

   green 
  in 
  the 
  meadows, 
  with 
  yellower 
  flowers. 
  

   Numerous 
  analogous 
  cases 
  might 
  be 
  given. 
  On 
  

   mountain 
  slopes 
  in 
  South 
  Africa, 
  and 
  especial- 
  

   ly 
  in 
  Natal, 
  a 
  species 
  of 
  composite 
  is 
  found, 
  

   which 
  has 
  been 
  introduced 
  into 
  culture 
  and 
  is 
  

   used 
  as 
  a 
  hanging 
  plant. 
  It 
  is 
  called 
  Othonna 
  

   crassifolia 
  and 
  has 
  fleshy, 
  nearly 
  cylindrical 
  

   leaves, 
  and 
  exactly 
  mimics 
  some 
  of 
  the 
  crassu- 
  

   laceous 
  species. 
  On 
  dry 
  soil 
  the 
  leaves 
  become 
  

   shorter 
  and 
  thicker 
  and 
  assume 
  a 
  reddish 
  

   tinge, 
  the 
  stems 
  remain 
  short 
  and 
  woody 
  and 
  

   bear 
  their 
  leaves 
  in 
  dense 
  rosettes. 
  On 
  moist 
  

   and 
  rich 
  garden-soil 
  this 
  aspect 
  becomes 
  

  

  