﻿BREEDING-PLACES 
  OF 
  THE 
  ANOPHELINES 
  OF 
  MALAYA. 
  21 
  

  

  the 
  bed 
  of 
  the 
  stream. 
  The 
  filaments 
  are 
  much 
  finer 
  than 
  those 
  of 
  the 
  ordinary 
  

   alga 
  that 
  one 
  finds 
  in 
  a 
  pool 
  of 
  clear 
  water 
  in 
  a 
  ravine 
  ; 
  and 
  the 
  felting 
  differs 
  from 
  

   the 
  loose 
  floating 
  tangle 
  of 
  the 
  ordinary 
  alga. 
  When 
  a 
  clear 
  pool 
  containing 
  the 
  

   ordinary 
  floating 
  alga 
  is 
  oiled, 
  the 
  alga 
  dies 
  ; 
  it 
  becomes 
  a 
  dark 
  green 
  mass, 
  in 
  which 
  

   the 
  individual 
  filaments 
  become 
  unrecognisable. 
  In 
  its 
  place 
  appears 
  the 
  felted 
  

   alga, 
  and 
  wherever 
  a 
  ravine 
  is 
  thoroughly 
  oiled 
  this 
  alga 
  appears. 
  It 
  is 
  a 
  test 
  by 
  

   which 
  to 
  know 
  if 
  oiling 
  is 
  properly 
  carried 
  out. 
  Long 
  before 
  I 
  had 
  used 
  oil 
  in 
  ravines 
  

   I 
  had 
  noticed 
  that 
  the 
  presence 
  of 
  the 
  felted 
  alga 
  meant 
  the 
  absence 
  of 
  A. 
  maculatus, 
  

   and 
  I 
  had 
  noticed 
  its 
  association 
  with 
  pollution 
  of 
  the 
  water. 
  For 
  example, 
  on 
  an 
  

   estate 
  there 
  were 
  four 
  ravines, 
  identical 
  as 
  far 
  as 
  the 
  eye 
  could 
  see. 
  At 
  the 
  head 
  of 
  

   one, 
  there 
  was 
  a 
  well 
  where 
  clothes 
  were 
  washed 
  ; 
  that 
  ravine 
  alone 
  contained 
  the 
  

   felted 
  alga. 
  On 
  no 
  occasion 
  was 
  A 
  . 
  maculatus 
  taken 
  in 
  it. 
  In 
  the 
  other 
  three 
  ravines, 
  

   which 
  were 
  not 
  polluted 
  and 
  did 
  not 
  contain 
  the 
  felted 
  alga, 
  the 
  insect 
  flourished. 
  

   Three 
  bungalows, 
  one 
  on 
  each 
  of 
  these 
  ravines, 
  were 
  so 
  malarious 
  that 
  they 
  were 
  

   pulled 
  down 
  ; 
  a 
  bungalow 
  on 
  the 
  other 
  ravine 
  was 
  much 
  less 
  malarious 
  and 
  is 
  still 
  

   inhabited. 
  This 
  was 
  observed 
  before 
  oiling 
  was 
  used 
  in 
  ravines. 
  

  

  " 
  Some 
  ravines 
  are 
  to 
  be 
  found 
  where 
  the 
  felted 
  alga 
  is 
  growing 
  freely, 
  although 
  

   no 
  pollution 
  apparent 
  to 
  the 
  eye 
  takes 
  place 
  and 
  no 
  oiling 
  has 
  been 
  done. 
  On 
  one 
  

   occasion 
  I 
  found 
  the 
  felted 
  alga 
  in 
  a 
  ravine 
  and 
  traced 
  it 
  upwards. 
  The 
  ravine 
  

   branched 
  and 
  the 
  alga 
  followed 
  only 
  one 
  branch, 
  in 
  which 
  it 
  could 
  be 
  found 
  as 
  far 
  

   as 
  a 
  log 
  of 
  newly 
  cut 
  timber 
  lying 
  in 
  the 
  water. 
  Beyond 
  that 
  the 
  alga 
  could 
  not 
  

   be 
  found. 
  I 
  can 
  give 
  no 
  explanation 
  of 
  its 
  appearance. 
  I 
  took 
  possession 
  of 
  a 
  piece 
  

   of 
  the 
  wood. 
  

  

  " 
  In 
  ravines 
  where 
  the 
  pollution 
  is 
  extreme, 
  where, 
  for 
  instance, 
  the 
  whole 
  discharge 
  

   from 
  a 
  rubber 
  factory 
  is 
  poured 
  into 
  a 
  small 
  stream, 
  the 
  aquatic 
  growth 
  will 
  be 
  found 
  

   to 
  differ 
  in 
  different 
  parts 
  of 
  the 
  stream. 
  Nearest 
  the 
  factory 
  the 
  growth 
  may 
  

   consist 
  of 
  dense 
  pendulous 
  fawn-coloured 
  masses 
  composed 
  of 
  colourless 
  filaments, 
  

   containing 
  no 
  chlorophyll 
  ; 
  lower 
  in 
  the 
  ravine 
  this 
  is 
  replaced 
  by 
  the 
  felted 
  alga. 
  

  

  " 
  A 
  full 
  study 
  of 
  the 
  subject 
  is 
  necessary, 
  and 
  may 
  well 
  give 
  us 
  an 
  entire 
  new 
  

   method 
  of 
  controlling 
  malaria." 
  

  

  Dr. 
  Watson's 
  views, 
  which 
  the 
  writer 
  has 
  permission 
  to 
  quote, 
  on 
  the 
  possibility 
  

   of 
  the 
  control 
  of 
  A 
  . 
  aconitus 
  in 
  such 
  a 
  way 
  are 
  contained 
  in 
  a 
  letter 
  of 
  5th 
  December 
  

   1920. 
  

  

  " 
  With 
  regard 
  to 
  A. 
  aconitus, 
  my 
  chief 
  reasons 
  for 
  thinking 
  it 
  does 
  not 
  like 
  decom- 
  

   posing 
  organic 
  matter 
  are 
  epidemiological 
  ; 
  and, 
  as 
  Darling 
  says 
  in 
  his 
  paper 
  ' 
  On 
  

   Experimental 
  Inoculation 
  of 
  Malaria 
  by 
  means 
  of 
  A. 
  ludlowi' 
  (p. 
  315), 
  it 
  is 
  the 
  

   epidemiological 
  evidence 
  in 
  the 
  last 
  analysis 
  which 
  convicts 
  a 
  species 
  and 
  will 
  

   determine 
  the 
  necessity 
  for 
  taking 
  steps 
  against 
  it. 
  

  

  " 
  The 
  first 
  evidence 
  I 
  ran 
  against 
  was 
  its 
  absence 
  from 
  the 
  Krian 
  rice-fields, 
  

   which 
  are 
  free 
  from 
  malaria. 
  The 
  details 
  are 
  in 
  my 
  ' 
  Prevention,'* 
  but 
  it 
  is 
  sum- 
  

   marised 
  at 
  pages 
  21-23 
  in 
  ' 
  Rural 
  Sanitation.' 
  

  

  " 
  The 
  next 
  evidence 
  is 
  its 
  absence 
  from 
  the 
  Coastal 
  Plains 
  — 
  from 
  drains 
  full 
  of 
  

   grass, 
  in 
  which 
  at 
  first 
  sight 
  one 
  might 
  expect 
  it. 
  

  

  " 
  Again 
  it 
  does 
  not 
  occur 
  in 
  the 
  big 
  swamps 
  and 
  valleys 
  where 
  there 
  is 
  mining 
  

   silt. 
  There 
  we 
  get 
  barbirostris, 
  sinensis 
  (= 
  hyrcanus), 
  rossi, 
  fuliginosus, 
  from 
  the 
  

   various 
  breeding-places 
  ; 
  but 
  hardly 
  ever 
  aconitus 
  ; 
  and 
  the 
  malaria 
  rate 
  is 
  low. 
  I 
  

   have 
  used 
  this 
  knowledge 
  for 
  years 
  and 
  have 
  not 
  hesitated 
  to 
  house 
  coolies 
  on 
  the 
  

   edge 
  of 
  mining 
  swamps. 
  

  

  " 
  I 
  have 
  always 
  felt 
  that 
  we 
  could 
  control 
  the 
  malaria 
  of 
  the 
  valley 
  of 
  rice-fields 
  

   by 
  some 
  form 
  of 
  pollution 
  — 
  perhaps 
  by 
  adding 
  some 
  decomposable 
  manure, 
  or 
  by 
  

  

  * 
  " 
  The 
  Prevention 
  of 
  Malaria." 
  

  

  