﻿20 
  W. 
  A. 
  LAMBOKX. 
  

  

  When 
  the 
  nature 
  of 
  this 
  influence 
  determining 
  Anopheline 
  distribution 
  has 
  been 
  

   ascertained, 
  it 
  can 
  hardly 
  be 
  doubted 
  that 
  a 
  method 
  of 
  control 
  of 
  the 
  species, 
  at 
  once 
  

   less 
  expensive, 
  less 
  crude, 
  and 
  more 
  scientific 
  than 
  the 
  constant 
  dumping 
  of 
  valuable 
  

   mineral 
  oil 
  on 
  to 
  the 
  breeding-places, 
  will 
  be 
  at 
  hand. 
  The 
  broad 
  general 
  possibility 
  

   of 
  such 
  a 
  method 
  of 
  control 
  was 
  long 
  since 
  realised 
  by 
  Dr. 
  Watson, 
  and 
  is 
  emphasised 
  

   in 
  his 
  various 
  contributions 
  to 
  the 
  literature 
  dealing 
  with 
  malaria 
  and 
  sanitation 
  

   in 
  the 
  tropics. 
  Thus, 
  Dr. 
  W'atson 
  gives 
  a 
  table 
  showing 
  the 
  presence 
  of 
  the 
  dangerous 
  

   A. 
  maculatus, 
  A. 
  aconitus 
  (albirostris) 
  and 
  A. 
  umbrosus 
  at 
  the 
  foot 
  of 
  the 
  hills 
  forming 
  

   the 
  Bukit 
  Gantang 
  valley 
  in 
  the 
  Malay 
  States, 
  and 
  of 
  A 
  . 
  aconitus 
  and 
  A 
  . 
  umbrosus 
  

   in 
  the 
  rice-fields 
  of 
  the 
  valley, 
  and 
  shows 
  that 
  neither 
  is 
  present 
  in 
  the 
  Krian 
  irrigation 
  

   area.* 
  He 
  then 
  observes 
  : 
  " 
  I 
  suggested 
  that 
  in 
  the 
  future 
  it 
  might 
  be 
  possible 
  to 
  

   eradicate 
  malaria 
  from 
  certain 
  places 
  by 
  altering 
  the 
  composition 
  of 
  the 
  water 
  in 
  

   such 
  a 
  way 
  as 
  to 
  make 
  it 
  uninhabitable 
  for 
  some 
  particular 
  malaria-carrying 
  mosquito. 
  

   It 
  was 
  therefore 
  with 
  the 
  greatest 
  interest 
  that 
  I 
  found 
  in 
  1913 
  that 
  one 
  of 
  the- 
  most 
  

   dangerous 
  malaria-carrying 
  Anopheles 
  which 
  exists 
  had 
  been 
  driven 
  from 
  the 
  rice- 
  

   fields 
  of 
  British 
  Guiana 
  by 
  controlling 
  the 
  water 
  supply. 
  This 
  is 
  one 
  step 
  towards 
  

   what 
  I 
  suggested 
  in 
  1910, 
  in 
  a 
  public 
  lecture, 
  given 
  in 
  Kuala 
  Lampur, 
  in 
  the 
  following 
  

   words 
  : 
  ' 
  But 
  when 
  we 
  came 
  to 
  work 
  out 
  the 
  Anophelines, 
  it 
  was 
  found 
  that 
  different 
  

   species 
  were 
  found 
  in 
  the 
  middle 
  of 
  the 
  swamp 
  from 
  those 
  on 
  the 
  hills. 
  Nature 
  has, 
  

   therefore, 
  carried 
  out 
  a 
  great 
  experiment. 
  There 
  were 
  three 
  groups 
  of 
  Anophelines 
  : 
  

   one 
  on 
  the 
  hills, 
  one 
  on 
  the 
  rice-fields 
  close 
  to 
  the 
  hills, 
  and 
  a 
  third 
  lot 
  in 
  Krian 
  far 
  

   from 
  the 
  hills. 
  Now 
  why 
  do 
  these 
  vary 
  ? 
  Clearly 
  on 
  account 
  of 
  something 
  in 
  the 
  

   water 
  ; 
  and 
  it 
  can 
  be 
  easily 
  imagined 
  that 
  only 
  a 
  small 
  change 
  would 
  assimilate 
  the 
  

   Bukit 
  Gantang 
  water 
  to 
  that 
  of 
  the 
  Krian 
  rice-fields, 
  and 
  then 
  malaria 
  would 
  dis- 
  

   appear 
  from 
  Bukit 
  Gantang 
  too. 
  I 
  believe 
  that 
  in 
  this 
  way 
  a 
  great 
  anti-malaria 
  

   method 
  will 
  be 
  evolved, 
  and 
  I 
  can 
  look 
  to 
  the 
  time 
  when 
  we 
  will 
  be 
  able 
  to 
  play 
  with 
  

   species 
  of 
  Anopheles, 
  say 
  to 
  some 
  " 
  Go," 
  and 
  to 
  others 
  " 
  Come," 
  and 
  to 
  abolish 
  

   malaria 
  with 
  ease, 
  perhaps 
  at 
  hardly 
  any 
  expense. 
  Drainage 
  schemes 
  may 
  become 
  

   things 
  of 
  the 
  past, 
  and 
  future 
  generations 
  may 
  smile 
  to 
  think 
  how 
  their 
  ancestors, 
  

   who 
  thought 
  they 
  were 
  so 
  clever, 
  burned 
  the 
  house 
  to 
  cook 
  the 
  pig.' 
  ' 
  

  

  Dr. 
  Watson 
  remarks 
  further 
  in 
  the 
  same 
  book 
  (p. 
  14) 
  (as 
  to 
  A. 
  maculatus) 
  : 
  " 
  I 
  

   came 
  to 
  the 
  conclusion 
  that 
  unless 
  we 
  could 
  alter 
  the 
  composition 
  of 
  the 
  water 
  in 
  

   these 
  hill 
  streams 
  in 
  such 
  a 
  way 
  as 
  to 
  make 
  it 
  uncongenial 
  to 
  all 
  malaria-carrying 
  

   mosquitos, 
  the 
  only 
  way 
  we 
  could 
  get 
  rid 
  of 
  the 
  insect 
  (and 
  malaria) 
  would 
  be 
  by 
  

   putting 
  the 
  streams 
  underground 
  in 
  pipes." 
  

  

  A 
  paragraph 
  in 
  an 
  unpublished 
  report 
  by 
  Dr. 
  Hacker, 
  dated 
  30th 
  July 
  1917, 
  on 
  

   the 
  distribution 
  of 
  Anopheline 
  larvae 
  on 
  a 
  certain 
  estate 
  in 
  the 
  Federated 
  Malay 
  

   States, 
  may 
  be 
  quoted 
  here, 
  with 
  his 
  kind 
  permission, 
  as 
  having 
  some 
  bearing 
  on 
  

   Dr. 
  Watson's 
  contention. 
  Discussing 
  the 
  suitability 
  of 
  a 
  site 
  proposed 
  for 
  new 
  

   coolie 
  lines, 
  more 
  especially 
  as 
  regards 
  its 
  proximity 
  to 
  breeding-places 
  of 
  A. 
  maculatus, 
  

   he 
  remarks: 
  "The 
  main 
  ravine 
  in 
  front 
  of 
  the 
  site 
  is 
  also 
  a 
  favourable 
  place 
  for 
  

   maculatus, 
  and 
  probably 
  the 
  reason 
  that 
  more 
  breeding 
  was 
  not 
  discovered 
  on 
  this 
  

   visit 
  was'the 
  amount 
  of 
  decaying 
  vegetation. 
  The 
  grass 
  has 
  been 
  cut 
  down 
  and 
  

   allowed 
  to 
  rot 
  in 
  the 
  sand, 
  and 
  whenever 
  it 
  was 
  stirred 
  up 
  it 
  emitted 
  an 
  offensive 
  

   smell. 
  When 
  the 
  water 
  gets 
  clean 
  more 
  breeding 
  will 
  probably 
  occur.'' 
  

  

  By 
  the^courtesy 
  of 
  Dr. 
  Watson 
  the 
  writer 
  had 
  the 
  privilege 
  of 
  reading 
  a 
  portion 
  

   of 
  the 
  manuscript 
  of 
  a 
  forthcoming 
  new 
  edition 
  of 
  his 
  book, 
  "The 
  Prevention 
  of 
  

   Malaria," 
  and 
  is 
  permitted 
  to 
  quote 
  the 
  following 
  paragraphs 
  having 
  further 
  bearing 
  

   on 
  the 
  subject 
  : 
  — 
  

  

  " 
  Previously, 
  I 
  mentioned 
  the 
  appearance 
  of 
  a 
  green 
  slime 
  on 
  the 
  bottom 
  of 
  the 
  

   ravine 
  following 
  on 
  the 
  application 
  of 
  the 
  oil. 
  It 
  consists 
  of 
  an 
  alga, 
  the 
  filaments 
  

   of 
  which 
  are 
  closely 
  felted 
  or 
  matted, 
  and 
  attached 
  to 
  the 
  stones 
  or 
  sand 
  forming 
  

  

  * 
  " 
  Rural 
  Sanitation 
  in 
  the 
  Tropics." 
  1911. 
  

  

  