﻿THE 
  PLANT 
  AS 
  A 
  WORKING 
  MACHINE 
  

  

  6. 
  The 
  work 
  of 
  plants. 
  Plants 
  

   must 
  have 
  materials 
  for 
  their 
  

   nutrition 
  just 
  as 
  truly 
  as 
  animals 
  

   do. 
  It 
  does 
  not 
  follow, 
  however, 
  

   that 
  the 
  same 
  kinds 
  of 
  food 
  mate- 
  

   rial 
  are 
  needed 
  or 
  that 
  they 
  are 
  

   secured 
  or 
  handled 
  in 
  ways 
  that 
  

   correspond 
  to 
  those 
  found 
  among 
  

   animals. 
  As 
  a 
  rule, 
  animals 
  eat 
  

   plants 
  or 
  animals 
  that 
  have 
  used 
  

   plants 
  as 
  food. 
  Occasionally, 
  as 
  

   we 
  shall 
  see 
  later, 
  seed 
  plants 
  may 
  

   use 
  animals 
  as 
  food 
  material, 
  and 
  

   it 
  is 
  generally 
  known 
  that 
  such 
  

   plants 
  as 
  bacteria 
  and 
  molds 
  may 
  

   live 
  upon 
  animals. 
  Green 
  plants 
  

   may 
  secure 
  water 
  and 
  carbon 
  

   dioxide, 
  and 
  from 
  them 
  they 
  may 
  

   make 
  foods, 
  such 
  as 
  sugar 
  and 
  

   starch. 
  They 
  may 
  use 
  these 
  as 
  

   food 
  or 
  may 
  combine 
  them 
  with 
  

   other 
  substances 
  and 
  thus 
  make 
  

   foods, 
  such 
  as 
  proteins, 
  that 
  are 
  

   more 
  complex 
  than 
  sugar 
  and 
  

   starch. 
  It 
  is 
  also 
  one 
  of 
  the 
  con- 
  

   spicuous 
  and 
  important 
  facts 
  of 
  

   plant 
  life 
  that 
  much 
  surplus 
  plant 
  

   food 
  is 
  stored 
  in 
  grains 
  and 
  fruits, 
  

   and 
  this 
  stored 
  food 
  may 
  serve 
  

   as 
  nutrient 
  material 
  for 
  man 
  and 
  

   the 
  lower 
  animals. 
  Indeed, 
  many 
  

   people 
  find 
  that 
  their 
  chief 
  inter- 
  

   est 
  in 
  plant 
  life 
  is 
  due 
  to 
  the 
  

   possibility 
  of 
  securing 
  and 
  using 
  

   this 
  surplus 
  stored 
  plant 
  food 
  as 
  

   found 
  in 
  such 
  things 
  as 
  the 
  grains 
  

  

  FIG. 
  3. 
  An 
  indian-corn 
  plant 
  with 
  

   roots, 
  stem, 
  leaves, 
  and 
  flowers 
  

  

  Two 
  kinds 
  of 
  flowers 
  are 
  formed, 
  

   one 
  in 
  the 
  ear 
  (e), 
  fnmi 
  which 
  the 
  

   silk 
  (s) 
  protrudes, 
  and 
  the 
  other 
  in 
  

   the 
  tassel 
  at 
  the 
  tip 
  of 
  the 
  plant. 
  

   Special 
  brace 
  roots 
  (b.r) 
  are 
  some- 
  

   times 
  formed 
  

  

  