﻿100 
  

  

  LNTEODUCTION 
  TO 
  BOTANY 
  

  

  em 
  

  

  starch, 
  and 
  oil 
  are 
  highly 
  valuable 
  for 
  human 
  food, 
  and 
  so 
  is 
  

   sugar, 
  which 
  occurs 
  in 
  small 
  quantities 
  in 
  all 
  the 
  bread 
  grains 
  

   and 
  in 
  considerable 
  amounts 
  in 
  the 
  best 
  varieties 
  of 
  sweet 
  corn. 
  

  

  The 
  selection 
  and 
  cultivation 
  of 
  plants 
  

   like 
  the 
  grains, 
  which 
  contain 
  much 
  digest 
  

   ible 
  f 
  ood 
  in 
  a 
  concentrated 
  form, 
  and 
  which 
  

   may 
  retain 
  their 
  food 
  value 
  for 
  some 
  years 
  

   with 
  little 
  loss, 
  marked 
  a 
  long 
  step 
  upward 
  

   in 
  the 
  civilization 
  of 
  the 
  human 
  race. 
  

  

  151. 
  The 
  seed 
  coat. 
  The 
  seed 
  coat 
  is 
  

   more 
  or 
  less 
  efficient 
  in 
  protecting 
  its 
  con- 
  

   tents 
  from 
  mechan- 
  

   ical 
  injury, 
  such 
  as 
  

   crushing, 
  and 
  in 
  

   many 
  cases 
  it 
  pro- 
  

   tects 
  the 
  more 
  per- 
  

   ishable 
  materials 
  

   within 
  it 
  from 
  de- 
  

   cay. 
  Before 
  germi- 
  

   nation 
  can 
  begin, 
  

   a 
  certain 
  amount 
  

   of 
  moisture 
  must 
  

   usually 
  soak 
  into 
  

   the 
  seed, 
  either 
  

   through 
  the 
  gen- 
  

   eral 
  surface, 
  as 
  in 
  

   most 
  seeds, 
  or, 
  in 
  

   such 
  hard-shelled 
  

   seeds 
  as 
  (lie 
  coco- 
  

   nut, 
  hickory 
  nut, 
  

   walnut, 
  and 
  but- 
  

   ternut, 
  through 
  a 
  thin 
  or 
  soft 
  place 
  in 
  the 
  wall. 
  Usually 
  the 
  

   little 
  opening 
  in 
  the 
  ovule, 
  known 
  as 
  the 
  micropyle 
  (fig. 
  119, 
  ni), 
  

   remains 
  in 
  the 
  seed 
  and 
  serves 
  to 
  admit 
  moisture. 
  

  

  The 
  coats 
  of 
  many 
  seeds 
  have 
  wings 
  or 
  outgrowths 
  of 
  hairs 
  

   which 
  aid 
  in 
  their 
  dispersal. 
  Other 
  modifications 
  in 
  the 
  coats 
  

  

  Fio. 
  143. 
  Grain 
  and 
  seedling 
  of 
  corn 
  

  

  .1, 
  lengths 
  ise 
  section 
  of 
  grain; 
  /?, 
  the 
  embryo 
  re- 
  

   moved; 
  < 
  ', 
  seedling; 
  en, 
  endosperm 
  : 
  rm, 
  embryo; 
  r.s, 
  

   Sheath 
  covering 
  tip 
  of 
  rudimentary 
  root 
  : 
  .vc, 
  scut 
  ell 
  inn, 
  

   or 
  absorbing 
  eoty 
  ledon 
  : 
  /-/, 
  plumule; 
  x/i, 
  slieath-like. 
  

   leaf 
  in 
  which 
  the 
  first 
  foliage 
  leaves 
  are 
  inclosed: 
  r, 
  

   first 
  root, 
  springing 
  from 
  within 
  r.x: 
  /-'later-formed 
  

   roots 
  arising 
  from 
  other 
  parts 
  of 
  the 
  grain 
  

  

  