﻿CHAPTER 
  XIX 
  

   PLANT 
  INDUSTRIES 
  

  

  292. 
  Origin 
  of 
  plant 
  cultivation. 
  In 
  the 
  various 
  chapters 
  of 
  

   this 
  book 
  we 
  have 
  constantly 
  recognized 
  the 
  relation 
  of 
  plants' 
  

   to 
  the 
  common 
  interests 
  of 
  men. 
  It 
  is 
  important, 
  however, 
  

   that 
  special 
  uses 
  of 
  plants 
  in 
  the 
  industries 
  should 
  receive 
  

   separate 
  attention. 
  

  

  In 
  the 
  early 
  stages 
  of 
  civilization 
  plants 
  were 
  used 
  by 
  men 
  

   for 
  food, 
  clothing, 
  and 
  fuel, 
  for 
  the 
  construction 
  of 
  houses 
  

   and 
  boats, 
  and 
  in 
  many 
  other 
  ways. 
  In 
  order 
  to 
  obtain 
  those 
  

   plants 
  that 
  would 
  best 
  serve 
  any 
  of 
  these 
  uses, 
  some 
  obser- 
  

   vations 
  and 
  experiments 
  with 
  plants 
  doubtless 
  had 
  to 
  be 
  made. 
  

   Indeed, 
  primitive 
  people 
  are 
  often 
  well 
  versed 
  in 
  the 
  nature 
  

   of 
  wild 
  plants, 
  so 
  that 
  they 
  know 
  what 
  to 
  select 
  and 
  where 
  

   to 
  find 
  the 
  desired 
  plants 
  in 
  the 
  seasons 
  when 
  they 
  are 
  avail- 
  

   able. 
  Wild 
  plants 
  that 
  were 
  good 
  for 
  food 
  or 
  possibly 
  for 
  

   medicines 
  were 
  cared 
  for 
  early 
  in 
  the 
  history 
  of 
  civilization. 
  

   We 
  can 
  only 
  guess 
  at 
  the 
  ways 
  in 
  which 
  they 
  were 
  first 
  

   watched 
  and 
  protected, 
  but 
  they 
  were 
  cared 
  for 
  by 
  people 
  who 
  

   foresaw 
  a 
  need 
  for 
  the 
  products 
  of 
  these 
  plants 
  when 
  mature. 
  

   With 
  such 
  activities 
  as 
  these 
  agriculture 
  came 
  into 
  existence. 
  

   At 
  this 
  time 
  comparatively 
  little 
  was 
  known 
  of 
  the 
  nature 
  of 
  

   plant 
  life, 
  and 
  therefore 
  early 
  agriculture 
  was 
  relatively 
  simple. 
  

   As 
  more 
  has 
  been 
  learned 
  about 
  plant 
  life, 
  plant 
  products 
  have 
  

   improved 
  in 
  quality 
  or 
  in 
  quantity, 
  or 
  in 
  both. 
  As 
  populations 
  

   become 
  more 
  dense, 
  greater 
  demands 
  are 
  made 
  upon 
  plants 
  

   as 
  a 
  means 
  of 
  supplying 
  adequate 
  food 
  and 
  clothing. 
  

  

  293. 
  Problems 
  of 
  plant 
  industries. 
  Each 
  of 
  the 
  plant 
  indus- 
  

   tries 
  involves 
  two 
  kinds 
  of 
  problems. 
  First, 
  there 
  is 
  the 
  prob- 
  

   lem 
  of 
  carefully 
  applying 
  what 
  science 
  has 
  already 
  discovered 
  

  

  308 
  

  

  