﻿166 
  INTRODUCTION 
  TO 
  BOTANY 
  

  

  by 
  the 
  plant 
  for 
  the 
  purpose 
  of 
  digesting 
  or 
  rendering 
  soluble 
  

   such 
  plant 
  foods 
  as 
  require 
  digestive 
  action 
  before 
  they 
  can 
  be 
  

   absorbed 
  by 
  the 
  tissues 
  of 
  the 
  \onng 
  seedling. 
  

  

  The 
  most 
  familiar 
  ease 
  of 
  action 
  of 
  enzymes 
  on 
  a 
  large 
  

   scale 
  is 
  the 
  malting 
  of 
  barley, 
  in 
  which 
  the 
  starch 
  of 
  the 
  grain 
  

   is 
  converted 
  into 
  a 
  sugar 
  by 
  diastase. 
  It 
  is 
  said 
  that 
  diastase 
  can 
  

   change 
  ten 
  thousand 
  times 
  its 
  own 
  bulk 
  of 
  starch 
  into 
  sugar. 
  1 
  

  

  158. 
  Propagation 
  due 
  to 
  seeds. 
  Annual 
  plants 
  evidently 
  owe 
  

   their 
  continued 
  existence 
  to 
  the 
  growth 
  of 
  new 
  crops 
  from 
  the 
  

   seed. 
  If 
  every 
  grain 
  of 
  Indian 
  corn 
  in 
  the 
  world 
  were 
  to 
  be 
  

   consumed 
  during 
  some 
  winter, 
  com 
  plants 
  could 
  not 
  again 
  be 
  

   grown. 
  Many 
  bulb- 
  and 
  tuber-bearing 
  perennials 
  could 
  con- 
  

   tinue 
  to 
  propagate 
  their 
  kind 
  for 
  an 
  indefinitely 
  long 
  period 
  

   without 
  seeds. 
  Some 
  herbs, 
  such 
  as 
  the 
  common 
  field 
  sorrel, 
  

   and 
  many 
  shrubs 
  and 
  trees, 
  such 
  as 
  rosebushes, 
  black 
  locusts, 
  

   and 
  silver-leaved 
  poplars, 
  reproduce 
  themselves 
  abundantly 
  

   by 
  buds 
  formed 
  on 
  the 
  roots, 
  but 
  most 
  trees, 
  and 
  especially 
  

   nearly 
  all 
  conifers, 
  such 
  as 
  the 
  pines, 
  spruces, 
  and 
  firs, 
  are 
  

   usually 
  propagated 
  only 
  by 
  seeds. 
  

  

  People 
  in 
  general 
  hardly 
  recognize 
  the 
  wonderful 
  capacity 
  

   of 
  seeds 
  for 
  carrying 
  on 
  plant 
  life 
  under 
  extremely 
  adverse 
  con- 
  

   ditions. 
  Most 
  flowering 
  plants 
  soon 
  die 
  if 
  they 
  are 
  entirely 
  

   deprived 
  of 
  water 
  for 
  a 
  few 
  days 
  ; 
  darkness 
  is 
  fatal 
  to 
  them 
  

   and 
  very 
  low 
  temperatures 
  kill 
  many 
  kinds 
  of 
  plants 
  in 
  a 
  few 
  

   minutes; 
  but 
  the 
  seed 
  may 
  be 
  kept 
  for 
  months 
  or 
  years 
  with- 
  

   out 
  water, 
  in 
  absolute 
  darkness 
  and 
  at 
  the 
  lowest 
  temperature 
  

   ever 
  encountered 
  on 
  the 
  earth's 
  surface, 
  and 
  yet 
  remain 
  ready 
  

   to 
  grow 
  as 
  soon 
  as 
  it 
  is 
  exposed 
  to 
  conditions 
  favorable 
  to 
  

   germination. 
  

  

  159. 
  Need 
  of 
  seed 
  dispersal. 
  The 
  successive 
  crops 
  of 
  farm 
  

   and 
  garden 
  annuals 
  are 
  secured 
  by 
  careful 
  seed 
  planting 
  in 
  

   prepared 
  soil. 
  The 
  seeds 
  of 
  wild 
  plants 
  are 
  also 
  sown, 
  on 
  a 
  

   still 
  more 
  extensive 
  scale, 
  by 
  natural 
  agencies. 
  In 
  any 
  coun- 
  

   try 
  the 
  relative 
  numbers 
  of 
  most 
  kinds 
  of 
  wild 
  seed 
  plants 
  

  

  1 
  On 
  digestion 
  and 
  enzymes 
  consult 
  .1. 
  II. 
  Green, 
  An 
  Introduction 
  to 
  Vege- 
  

   table 
  Physiology, 
  Chapter 
  XVI. 
  1'. 
  Blakiston's 
  Son 
  & 
  Co., 
  Philadelphia. 
  

  

  