﻿58 
  i'KOCEEUiNGS 
  UF 
  THE 
  FOURlil 
  ENTOAIO 
  LOGICAL 
  MEETING 
  

  

  back 
  over 
  it. 
  lb 
  was 
  essential 
  tliat 
  the 
  bushes 
  treated 
  should 
  receive 
  

   the 
  usual 
  cultivation, 
  etc., 
  so 
  that 
  a 
  number 
  of 
  the 
  tins 
  were 
  hoed 
  out 
  

   during 
  the 
  season. 
  The 
  tins 
  had 
  this 
  disadvantage, 
  that 
  wherever 
  the 
  

   roots 
  came 
  into 
  contact 
  with 
  the 
  tin 
  the 
  iron 
  of 
  the 
  tin 
  came 
  into 
  ih(; 
  

   reaction, 
  and 
  the 
  roots 
  became 
  covered 
  with 
  a 
  deposit 
  of 
  red 
  oxide 
  of 
  

   iron. 
  Vessels 
  made 
  of 
  glazed 
  earthernware 
  would 
  have 
  been 
  better, 
  but 
  

   they, 
  again, 
  possess 
  the 
  disadvantage 
  of 
  being 
  fragile. 
  In 
  arranging 
  

   the 
  roots 
  in 
  such 
  tins 
  care 
  must 
  be 
  taken 
  that 
  the 
  roots 
  are 
  not 
  in 
  contact 
  

   with 
  the 
  tins 
  at 
  any 
  point, 
  as 
  they 
  will 
  be 
  killed 
  off 
  by 
  this 
  deposition 
  of 
  

   iron 
  oxide. 
  It 
  was 
  further 
  found 
  that 
  care 
  should 
  be 
  taken 
  that 
  the 
  roots 
  

   do 
  not 
  go 
  too 
  far 
  down 
  into 
  the 
  solution, 
  as 
  this 
  latter 
  tends 
  to 
  be 
  more 
  

   concentrated 
  at 
  the 
  bottom 
  than 
  at 
  the 
  top, 
  and 
  may 
  be 
  so 
  strong 
  as 
  

   to 
  kill 
  the 
  root 
  off. 
  The 
  roots 
  chosen 
  for 
  immersion 
  in 
  the 
  solutions 
  should 
  

   be 
  the 
  hne 
  feeder 
  roots. 
  Thicker 
  roots 
  do 
  not 
  grow 
  successfully 
  in 
  these 
  

   solutions. 
  A 
  factor 
  which 
  affected 
  the 
  growth 
  of 
  the 
  roots 
  was 
  the 
  

   degree 
  of 
  acidity 
  or 
  alkalinity 
  of 
  the 
  solution 
  used. 
  Solutions 
  which 
  

   were 
  very 
  definitely 
  acid 
  or 
  alkaline 
  did 
  not 
  allow 
  of 
  root 
  growth, 
  but 
  in 
  

   cases 
  where 
  this 
  solution 
  was 
  neutral, 
  or 
  just 
  faintly 
  acid, 
  a 
  luxuriant 
  

   growth 
  of 
  new 
  roots 
  was 
  obtained. 
  

  

  From 
  one 
  or 
  other, 
  or 
  from 
  different 
  combinations 
  of 
  the 
  above 
  

   causes, 
  many 
  of 
  the 
  experiments 
  were 
  failures, 
  and 
  no 
  root-growth 
  

   occurred 
  inside 
  the 
  tins. 
  In 
  such 
  cases 
  all 
  the 
  solution 
  was 
  left, 
  and 
  none 
  

   of 
  it 
  absorbed, 
  the 
  few 
  exceptions 
  found 
  being 
  explained 
  by 
  soil 
  having 
  

   fallen 
  into 
  the 
  tin, 
  or 
  to 
  its 
  having 
  been 
  struck 
  by 
  a 
  hoe, 
  etc. 
  In 
  all 
  cases 
  

   where 
  root-growth 
  occurred 
  in 
  the 
  tins 
  aU, 
  or 
  nearly 
  all, 
  of 
  the 
  solution 
  

   was 
  taken 
  up. 
  

  

  The 
  successful 
  experiments, 
  however, 
  confirm 
  the 
  results 
  of 
  those 
  

   carried 
  out 
  in 
  1919, 
  and 
  show 
  that 
  potash 
  when 
  taken 
  up 
  by 
  the 
  bush 
  

   via 
  the 
  roots, 
  results 
  in 
  a 
  decreased 
  hability 
  to 
  attack, 
  which 
  is 
  not 
  of 
  

   the 
  same 
  degree 
  under 
  different 
  sets 
  of 
  conditions. 
  The 
  relations 
  bet- 
  

   ween 
  the 
  result 
  and 
  the 
  environmental 
  conditions 
  I 
  have 
  not 
  yet 
  had 
  the 
  

   opportunity 
  to 
  work 
  out. 
  The 
  attempts 
  to 
  increase 
  liability 
  to 
  attack 
  

   by 
  the 
  use 
  of 
  phosphates 
  were 
  fruitless, 
  as 
  the 
  acidity 
  of 
  the 
  phosphoric 
  

   solutions 
  used 
  inhibited 
  root 
  growth. 
  

  

  Much 
  yet 
  remains 
  to 
  be 
  done 
  on 
  these 
  lines, 
  but 
  we 
  do 
  know 
  

   now 
  that 
  bushes 
  can 
  be 
  made 
  resistant 
  to 
  attack 
  by 
  Helopellis. 
  This 
  

   resistance 
  has 
  been 
  brought 
  about 
  by 
  experiments 
  designed 
  to 
  influence 
  

   the 
  composition 
  of 
  the 
  leaf 
  with 
  regard 
  to 
  the 
  proportion 
  of 
  the 
  various 
  

   constituents 
  already 
  present 
  in 
  the 
  leaf, 
  and 
  since 
  our 
  analytical 
  results 
  

   show 
  that 
  this 
  can 
  vary 
  within 
  considerable 
  limits 
  under 
  the 
  conditions 
  

   obtaining 
  in 
  tea, 
  there 
  would 
  appear 
  to 
  be 
  ample 
  grounds 
  for 
  believing 
  

  

  