﻿22 
  W. 
  A. 
  LAMBORN. 
  

  

  ponds 
  on 
  the 
  ' 
  tali 
  ayers 
  ' 
  in 
  which 
  some 
  cheap 
  matter 
  was 
  decomposing, 
  on 
  the 
  lines 
  

   of 
  the 
  big 
  reservoir 
  in 
  the 
  Krian 
  rice-fields." 
  

  

  Inasmuch 
  as 
  the 
  investigations 
  that 
  have 
  been 
  discussed 
  are 
  at 
  an 
  end 
  in 
  the 
  

   Malay 
  States, 
  so 
  far 
  as 
  concerns 
  the 
  writer, 
  it 
  may 
  not 
  be 
  out 
  of 
  place 
  to 
  indicate 
  

   the 
  directions 
  which 
  the 
  enquiry 
  would 
  have 
  taken, 
  had 
  it 
  been 
  resumed 
  by 
  him 
  : 
  — 
  

  

  1. 
  Further 
  data 
  as 
  to 
  the 
  distribution 
  of 
  A. 
  aconitus 
  would 
  have 
  been 
  obtained 
  

   by 
  study 
  limited 
  to 
  unit 
  breeding-places 
  only. 
  

  

  2. 
  The 
  study 
  would 
  have 
  been 
  extended 
  to 
  A. 
  umbrosus 
  with 
  a 
  view 
  to 
  ascertaining 
  

   the 
  factors 
  on 
  which 
  its 
  limitation 
  (in 
  the 
  uplands) 
  to 
  bush 
  pools 
  depends, 
  and 
  the 
  

   influences 
  (as 
  in 
  the 
  instance 
  quoted) 
  which 
  brought 
  about 
  its 
  disappearance 
  on 
  

   clearing. 
  

  

  3. 
  The 
  algal 
  flora 
  of 
  various 
  breeding-places 
  would 
  have 
  been 
  collected 
  and 
  

   submitted 
  to 
  an 
  algologist 
  for 
  determination, 
  and 
  for 
  information 
  as 
  to 
  the 
  conditions 
  

   which 
  determine 
  the 
  presence 
  of 
  the 
  character 
  plants, 
  and 
  enable 
  them 
  to 
  flourish. 
  

  

  4. 
  Full 
  chemical 
  analyses 
  of 
  waters 
  containing 
  the 
  species 
  would 
  have 
  been 
  

   obtained, 
  with 
  further 
  and 
  fuller 
  analyses 
  of 
  fishpond 
  and 
  other 
  waters 
  from 
  which 
  

   A. 
  aconitus 
  is 
  consistently 
  absent. 
  In 
  this 
  connection 
  Dr. 
  A. 
  R. 
  Wellington, 
  the 
  

   Senior 
  Health 
  Officer, 
  to 
  whom 
  were 
  submitted 
  the 
  analyses, 
  suggested 
  the 
  desirability 
  

   of 
  ascertaining 
  the 
  iron 
  content, 
  the 
  salt 
  content, 
  the 
  carbonic 
  acid 
  content, 
  and 
  

   the 
  relative 
  hardness 
  of 
  the 
  various 
  waters. 
  

  

  5. 
  Extended 
  enquiry 
  would 
  have 
  been 
  made 
  as 
  to 
  the 
  factors 
  concerned 
  in 
  the 
  

   entire 
  absence 
  of 
  Anopheline 
  or 
  other 
  Culicid 
  larvae 
  in 
  certain 
  ponds 
  and 
  ditches 
  

   on 
  rubber 
  estates 
  in 
  the 
  neighbourhood 
  of 
  Kuala 
  Lampur. 
  Collections 
  there 
  made 
  

   from 
  time 
  to 
  time 
  were 
  entirely 
  unsuccessful, 
  though 
  Anopheline 
  larvae 
  could 
  be 
  

   obtained 
  near 
  by 
  in 
  abundance. 
  On 
  the 
  assumption 
  that 
  some 
  quality 
  of 
  the 
  water 
  

   might 
  be 
  prejudicial 
  to 
  the 
  larvae, 
  half-grown 
  specimens 
  of 
  various 
  species 
  were 
  

   placed 
  in 
  the 
  water 
  in 
  the 
  laboratory 
  ; 
  many 
  fed 
  up 
  and 
  pupated. 
  It 
  was 
  then 
  

   thought 
  possible 
  that 
  older 
  larvae 
  were 
  able 
  to 
  resist 
  influences 
  which 
  might 
  destroy 
  

   younger 
  ones, 
  and 
  so 
  ova 
  of 
  various 
  Anophelines 
  were 
  placed 
  on 
  the 
  water. 
  They 
  

   duly 
  hatched, 
  and 
  a 
  few 
  larvae 
  matured. 
  As 
  the 
  water 
  from 
  such 
  ponds 
  is 
  usually 
  

   coffee-coloured, 
  owing 
  to 
  the 
  maceration 
  of 
  dead 
  rubber 
  leaves 
  and 
  twigs 
  in 
  it, 
  strong 
  

   infusions 
  and 
  decoctions 
  were 
  made 
  and 
  tested 
  as 
  to 
  their 
  influence 
  on 
  larvae. 
  They 
  

   did 
  not 
  die 
  off 
  in 
  the 
  medium. 
  Algae 
  and 
  water 
  animalcules 
  were 
  poorly 
  represented 
  

   in 
  this 
  water, 
  but 
  at 
  one 
  season 
  two 
  species 
  of 
  tadpoles 
  were 
  abundant, 
  and 
  various 
  

   predacious 
  insects 
  — 
  the 
  larvae 
  of 
  Neuroptera, 
  and 
  some 
  Belostomidae 
  were 
  swarming. 
  

   It 
  was 
  thought 
  that 
  the 
  tadpoles 
  at 
  a 
  late 
  stage 
  of 
  development 
  might 
  prove 
  to 
  be 
  

   carnivorous, 
  but 
  they 
  refused 
  in 
  the 
  laboratory 
  to 
  eat 
  mosquito 
  larvae 
  ; 
  and 
  it 
  was 
  

   then 
  concluded 
  that 
  predacious 
  enemies 
  alone 
  might 
  account 
  for 
  their 
  absence. 
  

   But 
  more 
  probably 
  there 
  are 
  at 
  work 
  other 
  influences 
  which 
  require 
  to 
  be 
  determined. 
  

  

  6. 
  The 
  effect 
  on 
  A. 
  aconitus 
  of 
  the 
  folding 
  of 
  water 
  by 
  the 
  products 
  of 
  vegetable 
  

   decomposition 
  in 
  the 
  laboratory 
  would 
  have 
  been 
  studied 
  with 
  especial 
  reference 
  

   to 
  the 
  influence 
  of 
  gases, 
  marsh 
  gas 
  in 
  particular, 
  in 
  solution. 
  

  

  7. 
  A 
  more 
  directly 
  practical 
  line 
  of 
  investigation 
  would 
  have 
  been 
  the 
  determina- 
  

   tion 
  of 
  the 
  effect 
  of 
  decomposing 
  vegetable 
  matter 
  in 
  solution 
  on 
  A. 
  aconitus. 
  An 
  

   attempt 
  would 
  have 
  been 
  made 
  to 
  cut 
  down 
  to 
  the 
  surface 
  of 
  the 
  water, 
  and 
  to 
  dump 
  

   into 
  it, 
  all 
  the 
  coarse 
  vegetation 
  growing 
  in 
  swamp 
  A, 
  collecting 
  larvae 
  from 
  it 
  

   at 
  intervals 
  for 
  determination. 
  For 
  the 
  further 
  similar 
  treatment 
  experimentally 
  

   of 
  other 
  breeding-places, 
  which 
  do 
  not 
  afford 
  such 
  a 
  plant 
  growth 
  in 
  sufficient 
  quantity 
  

   for 
  thoroughly 
  fouling 
  the 
  water, 
  coarse 
  grass, 
  or 
  the 
  sweepings 
  from 
  rubber 
  estates 
  

   (dead 
  leaves, 
  twigs, 
  hoed-up 
  weeds, 
  etc., 
  which 
  arc 
  usually 
  burnt) 
  would 
  have 
  

   been 
  dumped 
  in 
  ; 
  and 
  in 
  smaller 
  breeding-places, 
  manure 
  from 
  the 
  stables 
  which 
  

   accommodate 
  estate 
  oxen. 
  

  

  