﻿54 
  INTRODUCTION 
  TO 
  BOTANY 
  

  

  which 
  is 
  covered 
  with 
  a 
  clear, 
  sticky 
  fluid. 
  When 
  a 
  small 
  in- 
  

   sect 
  touches 
  one 
  of 
  the 
  sticky 
  knobs, 
  it 
  may 
  be 
  held 
  fast, 
  and 
  

   in 
  that 
  case 
  the 
  hairs 
  at 
  once 
  begin 
  to 
  close 
  over 
  it. 
  The 
  insect 
  

   soon 
  dies 
  and 
  usually 
  remains 
  for 
  many 
  days, 
  while 
  the 
  leaf 
  

   pours 
  out 
  a 
  juice 
  by 
  which 
  the 
  soluble 
  parts 
  of 
  the 
  insect 
  

   are 
  digested. 
  The 
  liquid 
  containing 
  the 
  digested 
  portions 
  is 
  

   absorbed 
  by 
  the 
  leaf 
  and 
  contributes 
  an 
  important 
  part 
  of 
  

   the 
  nourishment 
  of 
  the 
  plant, 
  while 
  the 
  undigested 
  fragments, 
  

   such 
  as 
  legs 
  and 
  wing 
  cases, 
  remain 
  on 
  the 
  surface 
  of 
  the 
  

   leaf 
  or 
  may 
  drop 
  off 
  after 
  the 
  hairs 
  let 
  go 
  their 
  hold 
  on 
  the 
  

   captive 
  insect. 
  The 
  pitcher 
  plants 
  have 
  cylindrical, 
  liquid- 
  

   containing 
  leaves, 
  with 
  inner 
  hairs 
  so 
  arranged 
  that 
  insects 
  

   get 
  into 
  the 
  leaves 
  very 
  easily 
  and 
  get 
  out 
  with 
  great 
  dit'ti- 
  

   culty, 
  if 
  at 
  all. 
  The 
  leaves 
  of 
  the 
  Venus' 
  s-fly 
  trap 
  close 
  

   so 
  quickly 
  that 
  they 
  sometimes 
  catch 
  insects 
  which 
  may 
  

   come 
  in 
  contact 
  with 
  them. 
  

  

  PROBLEMS 
  

  

  1. 
  Which 
  are 
  greener, 
  leaves 
  which 
  are 
  densely 
  shaded 
  or 
  those 
  

   which 
  are 
  exposed 
  to 
  the 
  sun 
  ? 
  What 
  makes 
  the 
  difference 
  ? 
  

  

  2. 
  Will 
  alcohol 
  dissolve 
  the 
  chlorophyll 
  more 
  quickly 
  from 
  densely 
  

   shaded 
  or 
  from 
  openly 
  exposed 
  leaves 
  ? 
  Why 
  ? 
  

  

  3. 
  Under 
  what 
  conditions 
  could 
  a 
  field 
  of 
  corn 
  lose 
  water 
  to 
  the 
  soil 
  

   instead 
  of 
  securing 
  water 
  from 
  the 
  soil 
  ? 
  

  

  4. 
  What 
  would 
  be 
  the 
  effect 
  upon 
  animal 
  life 
  if 
  green 
  plants 
  should 
  

   manufacture 
  no 
  more 
  food 
  than 
  they 
  consume 
  in 
  their 
  own 
  growth? 
  

  

  5. 
  Leaves 
  often 
  give 
  a 
  strong 
  starch 
  reaction 
  in 
  the 
  late 
  afternoon 
  

   and 
  none 
  in 
  the 
  early 
  morning'. 
  Can 
  you 
  account 
  for 
  this? 
  

  

  6. 
  It 
  was 
  found 
  by 
  some 
  students 
  that 
  a 
  corn 
  plant 
  elongates 
  about 
  

   four 
  times 
  as 
  much 
  between 
  6 
  P.M. 
  and 
  A.M. 
  as 
  between 
  (5 
  A.M. 
  and 
  

   6 
  P.M. 
  Can 
  you 
  account 
  for 
  this 
  fact? 
  

  

  7. 
  Fields 
  of 
  grain 
  are 
  often 
  more 
  or 
  less 
  wilted 
  at 
  noon 
  on 
  hot 
  

   summer 
  days 
  and 
  regain 
  their 
  turgor 
  at 
  night 
  even 
  when 
  no 
  rain 
  has 
  

   fallen. 
  Can 
  you 
  account 
  for 
  this 
  fact? 
  

  

  8. 
  In 
  trying 
  to 
  kill 
  plants 
  in 
  the 
  lawn 
  or 
  trees 
  in 
  the 
  cultivated 
  

   fields 
  people 
  sometimes 
  put 
  salt 
  upon 
  the 
  roots 
  or 
  stumps. 
  What 
  is 
  the 
  

   botanical 
  explanation 
  of 
  this 
  practice? 
  

  

  