﻿BREEDING-PLACES 
  OF 
  THE 
  ANOPHELINES 
  OF 
  MALAYA. 
  15 
  

  

  " 
  Some 
  of 
  the 
  tanks 
  must 
  certainly 
  be 
  rich 
  in 
  dissolved 
  organic 
  substances 
  owing 
  

   -to 
  the 
  large 
  amount 
  of 
  water-weeds 
  they 
  contain 
  " 
  (p. 
  223). 
  

  

  " 
  The 
  frequent 
  presence 
  of 
  Characeae 
  probably 
  means 
  dissolved 
  carbonate 
  of 
  

   lime 
  " 
  (p. 
  223). 
  

  

  " 
  The 
  conditions 
  of 
  life 
  of 
  the 
  macro-phytic 
  algae 
  are 
  as 
  follows 
  : 
  strong 
  illumin- 
  

   ation 
  ; 
  high 
  temperature 
  of 
  considerable 
  range 
  (varying 
  from 
  6° 
  to 
  10° 
  C.) 
  ; 
  small 
  

   amount 
  of 
  dissolved 
  oxygen 
  in 
  the 
  water 
  " 
  (p. 
  223). 
  

  

  " 
  I 
  think 
  it 
  probable 
  that 
  certain 
  species 
  are 
  able 
  to 
  flourish 
  better 
  in 
  small 
  

   isolated 
  pieces 
  of 
  water 
  than 
  in 
  the 
  large 
  expanse 
  of 
  the 
  waters 
  of 
  the 
  tanks, 
  and 
  

   consequently 
  attain 
  to 
  a 
  degree 
  of 
  development 
  in 
  these 
  pools 
  during 
  the 
  dry 
  season 
  

   which 
  is 
  impossible 
  except 
  in 
  such 
  small 
  collections 
  of 
  water 
  " 
  (p. 
  234). 
  

  

  " 
  It 
  is 
  not 
  easy 
  to 
  understand 
  why 
  the 
  Conjugates 
  play 
  so 
  important 
  a 
  part 
  in 
  

   the 
  pools 
  and 
  ditches, 
  while 
  the 
  Cyanophyceae 
  are 
  subsidiary 
  to 
  them 
  " 
  (p. 
  234). 
  

  

  Elsewhere 
  (p. 
  36) 
  are 
  considered 
  various 
  algae 
  which 
  characterise 
  the 
  " 
  Ferru- 
  

   ginous 
  pools," 
  those 
  which 
  exhibit 
  at 
  the 
  bottom 
  a 
  dense 
  brownish-red 
  deposit 
  of 
  

   ferric 
  hydroxide, 
  which 
  also 
  often 
  constitutes 
  a 
  filmy 
  investment 
  to 
  all 
  the 
  water- 
  

   plants. 
  

  

  In 
  connection 
  with 
  a 
  further 
  paragraph 
  in 
  the 
  same 
  publication 
  discussing 
  the 
  

   periodicity 
  of 
  the 
  algal 
  growths 
  in 
  rice 
  fields 
  (p. 
  242) 
  one 
  may 
  recall 
  the 
  results 
  in 
  

   Java 
  of 
  the 
  Dutch 
  workers, 
  who 
  showed 
  that 
  there 
  is 
  a 
  gradual 
  change 
  in 
  the 
  character 
  

   of 
  the 
  Anopheline 
  fauna 
  as 
  the 
  cultivation 
  of 
  the 
  rice 
  proceeds. 
  The 
  paragraph, 
  

   which 
  may 
  well 
  be 
  pregnant 
  with 
  facts 
  of 
  significance 
  as 
  to 
  the 
  distribution 
  of 
  

   Anopheline 
  larvae, 
  runs 
  as 
  follows 
  : 
  — 
  

  

  " 
  The 
  periodicity 
  of 
  the 
  algal 
  growths 
  in 
  the 
  rice 
  fields 
  would 
  be 
  an 
  interesting 
  

   study 
  and 
  would 
  probably 
  disclose 
  interesting 
  adaptations. 
  It 
  seems 
  that 
  the 
  

   first 
  growth 
  is 
  almost 
  always 
  blue-green 
  and 
  that 
  the 
  green 
  element 
  only 
  appears 
  

   subsequently 
  when 
  the 
  rice 
  and 
  occasional 
  water 
  weeds 
  (especially 
  Characeae) 
  afford 
  

   a 
  certain 
  amount 
  of 
  protection 
  against 
  the 
  strong 
  light. 
  Two 
  fresh 
  rice 
  fields 
  at 
  

   Matale 
  showed 
  practically 
  nothing 
  but 
  blue-green 
  forms, 
  whilst 
  a 
  slightly 
  more 
  

   advanced 
  field 
  at 
  Matara 
  contained 
  abundant 
  Oscillaria 
  intermingled 
  with 
  occasional 
  

   filaments 
  of 
  Spirogyra 
  and 
  Diatoms 
  and 
  Desmids 
  in 
  some 
  numbers. 
  Old 
  rice 
  fields 
  

   often 
  contained 
  only 
  ver} 
  7 
  scanty 
  Cyanophyceae, 
  but 
  in 
  their 
  place 
  quite 
  a 
  rich 
  

   Conjugate 
  and 
  Diatom 
  flora." 
  

  

  No 
  conclusions 
  as 
  to 
  the 
  food 
  preferences 
  of 
  the 
  various 
  Anopheline 
  larvae 
  having 
  

   been 
  satisfactorily 
  determined, 
  some 
  consideration 
  of 
  the 
  question 
  as 
  to 
  the 
  consti- 
  

   tution 
  of 
  waters 
  affecting 
  larval 
  distribution 
  seemed 
  to 
  be 
  called 
  for. 
  Though 
  such 
  

   experimental 
  evidence 
  as 
  has 
  been 
  adduced 
  would 
  seem 
  to 
  show 
  that 
  this 
  has 
  

   little 
  bearing 
  on 
  the 
  matter, 
  the 
  natural 
  evidence 
  would 
  seem 
  strongly 
  to 
  support 
  

   the 
  theory 
  that 
  the 
  absence 
  of 
  A. 
  aconitus 
  is 
  due 
  to 
  pollution, 
  largely 
  of 
  vegetable 
  

   origin. 
  

  

  The 
  swamp 
  water 
  in 
  which 
  A. 
  aconitus 
  was 
  dominant 
  was, 
  relatively 
  to 
  other 
  

   waters 
  in 
  the 
  neighbourhood 
  of 
  Kuala 
  Lam 
  pur, 
  less 
  subject 
  to 
  pollution. 
  Only 
  

   on 
  one 
  side 
  were 
  there 
  houses 
  ; 
  on 
  another 
  was 
  a 
  stream, 
  the 
  periodic 
  rising 
  of 
  which 
  

   ensured 
  at 
  fairly 
  frequent 
  intervals 
  a 
  flooding 
  and 
  wash-out 
  of 
  the 
  whole 
  swamp 
  

   area. 
  The 
  water 
  was 
  never 
  found 
  to 
  emit 
  any 
  odour, 
  and 
  it 
  was 
  fairly 
  clear 
  except 
  

   at 
  flood 
  time. 
  So 
  far 
  as 
  memory 
  serves, 
  there 
  were 
  few, 
  if 
  any, 
  of 
  the 
  large 
  aquatic 
  

   floating 
  plants, 
  which 
  would 
  have 
  been 
  preserved 
  from 
  being 
  washed 
  away 
  by 
  the 
  

   floodings 
  by 
  the 
  coarse 
  grass 
  and 
  reeds 
  abundant 
  in 
  the 
  situation. 
  

  

  The 
  fishpond, 
  on 
  the 
  other 
  hand, 
  was 
  subject 
  to 
  very 
  considerable 
  pollution. 
  

   Some 
  water 
  drained 
  into 
  it 
  after 
  rain 
  from 
  the 
  neighbourhood 
  of 
  Chinese 
  dwellings 
  

   and 
  vegetable 
  plots, 
  which 
  were 
  manured, 
  in 
  accordance 
  with 
  the 
  time-honoured 
  

  

  