﻿37 
  

  

  and 
  are 
  overlapped 
  by 
  new 
  layers, 
  but 
  the 
  cambium 
  remains 
  living 
  

   throughout 
  the 
  entire 
  life 
  of 
  the 
  tree 
  even 
  if 
  it 
  be, 
  as 
  in 
  the 
  giant 
  

   Redwoods, 
  thousands 
  of 
  years. 
  

  

  Besides 
  forming 
  the 
  regular 
  wood 
  of 
  the 
  tree 
  the 
  cambium 
  also 
  

   grows 
  out 
  over 
  cut 
  places 
  and 
  builds 
  in 
  woody 
  tissues 
  that 
  heal 
  over 
  

   the 
  wounds. 
  It 
  is 
  owing 
  to 
  this 
  fact 
  alone 
  that 
  budding 
  and 
  graft- 
  

   ing 
  are 
  possible. 
  The 
  callus 
  on 
  cuttings 
  and 
  root 
  grafts 
  is 
  another 
  

   evidence 
  of 
  the 
  same 
  phenomenon, 
  for 
  the 
  cambium 
  of 
  the 
  roots 
  of 
  

   a 
  tree 
  is 
  continuous 
  and 
  identical 
  with 
  that 
  of 
  the 
  branches. 
  

  

  The 
  Stock. 
  

  

  The 
  whole 
  practice 
  of 
  successful 
  grafting 
  and 
  budding 
  is 
  the 
  

   proper 
  handling 
  of 
  active 
  cambium. 
  The 
  cambium 
  is 
  the 
  cement- 
  

   ing 
  material 
  that 
  unites 
  stock 
  and 
  scion 
  and 
  unless 
  there 
  is 
  active 
  

   cambium 
  there 
  will 
  be 
  no 
  union. 
  It 
  must 
  be 
  said 
  here 
  that 
  no 
  

   matter 
  how 
  great 
  the 
  future 
  growth 
  of 
  the 
  union, 
  the 
  scion 
  never 
  

   becomes 
  truly 
  united 
  or 
  fused 
  with 
  the 
  stock. 
  The 
  cambium 
  grows 
  

   all 
  over 
  and 
  around 
  the 
  cut 
  parts 
  and 
  cements 
  them 
  together, 
  but 
  

   if 
  the 
  graft 
  union 
  be 
  split 
  open 
  fifty 
  years 
  later, 
  the 
  dead 
  wood 
  of 
  

   the 
  original 
  scion 
  may 
  be 
  found 
  of 
  the 
  original 
  size 
  and 
  in 
  the 
  

   original 
  position. 
  Since, 
  then, 
  successful 
  grafting 
  depends 
  on 
  the 
  

   union 
  of 
  the 
  cambium 
  of 
  the 
  stock 
  with 
  that 
  of 
  the 
  scion, 
  theoretic- 
  

   ally 
  the 
  best 
  time 
  for 
  grafting 
  and 
  budding 
  would 
  be 
  when 
  the 
  cam- 
  

   bium 
  is 
  most 
  active. 
  Actual 
  nursery 
  practice 
  shows 
  that 
  this 
  is 
  

   practically 
  correct, 
  at 
  least 
  as 
  regards 
  the 
  stock. 
  

  

  The 
  ideal 
  stock 
  for 
  propagation 
  purposes 
  is 
  the 
  young 
  seedling 
  

   of 
  one 
  or 
  two 
  years 
  growth. 
  In 
  such 
  a 
  stock 
  all 
  the 
  tissues 
  are 
  new 
  

   and 
  fresh 
  and 
  working 
  to 
  their 
  maximum 
  capacity 
  and 
  the 
  cambium 
  

   is 
  in 
  its 
  most 
  active 
  condition. 
  In 
  top-working 
  old 
  trees 
  it 
  will 
  be 
  

   found 
  that 
  though 
  the 
  branches 
  may 
  appear 
  Adgorous, 
  they 
  are 
  a 
  

   long 
  way 
  from 
  having 
  anything 
  like 
  the 
  active 
  circulation 
  found 
  in 
  

   small 
  seedlings. 
  Buds 
  put 
  in 
  these 
  branches 
  would 
  give 
  a 
  very 
  

   small 
  "live," 
  while 
  the 
  same 
  care 
  on 
  nursery 
  seedlings 
  could 
  be 
  

   counted 
  on 
  giving 
  a 
  high 
  percentage 
  of 
  living 
  buds. 
  In 
  top-work- 
  

   ing, 
  therefore, 
  it 
  is 
  found 
  necessary 
  in 
  order 
  to 
  get 
  the 
  cambium 
  

   sufficiently 
  active, 
  to 
  stub 
  back 
  the 
  branches 
  to 
  mere 
  pollards. 
  This 
  

   cutting 
  back 
  should 
  be 
  done 
  in 
  the 
  winter 
  or 
  dormant 
  season. 
  The 
  

   following 
  growing 
  season 
  will 
  see 
  a 
  dense 
  growth 
  of 
  very 
  vigorous 
  

   shoots 
  trying 
  to 
  repair 
  the 
  injury. 
  See 
  Figure 
  1. 
  These 
  shoots 
  are 
  

   ideal 
  stocks 
  for, 
  on 
  account 
  of 
  their 
  having 
  all 
  the 
  sap 
  from 
  the 
  

   greater 
  root 
  of 
  the 
  mature 
  tree, 
  the 
  cambium 
  will 
  be 
  even 
  more 
  

   active 
  than 
  in 
  the 
  nursery 
  seedling. 
  Often 
  when 
  nursery 
  seedlings 
  

  

  