﻿BREEDING-PLACES 
  OF 
  THE 
  ANOPHELINES 
  OF 
  MALAYA. 
  13 
  

  

  March 
  on 
  malodorous 
  sewage 
  water 
  obtained 
  from 
  the 
  drain 
  of 
  a 
  Chinese 
  house 
  in 
  

   which 
  the 
  larvae 
  of 
  A 
  . 
  vagus 
  had 
  been 
  sparingly 
  obtained 
  ; 
  the 
  other 
  half 
  were 
  placed, 
  

   as 
  a 
  control, 
  on 
  tap 
  water. 
  The 
  eggs 
  hatched 
  on 
  both 
  media, 
  and, 
  entirely 
  contrary 
  

   to 
  expectation, 
  the 
  young 
  larvae 
  on 
  the 
  foul 
  medium 
  did 
  not 
  succumb 
  forthwith, 
  for 
  

   on 
  19th 
  March, 
  eight 
  days 
  after 
  hatching, 
  there 
  were 
  as 
  many 
  as 
  15. 
  Two 
  only 
  

   eventually 
  pupated 
  and 
  emerged. 
  In 
  two 
  similar 
  experiments 
  three 
  larvae 
  out 
  of 
  

   76 
  ova 
  were 
  bred 
  almost 
  to 
  maturity, 
  then 
  dying. 
  But 
  attempts 
  to 
  rear 
  the 
  

   larvae 
  of 
  A 
  . 
  aconitus 
  in 
  water 
  from 
  the 
  fishpond 
  A, 
  in 
  which 
  they 
  were 
  so 
  consistently 
  

   absent, 
  were 
  entirely 
  unsuccessful 
  even 
  when 
  the 
  water 
  was 
  changed 
  daily. 
  The 
  larvae 
  

   hatched, 
  but 
  their 
  numbers 
  gradually 
  dwindled 
  so 
  that 
  usually 
  within 
  a 
  week 
  all 
  had 
  

   perished. 
  For 
  example, 
  on 
  31st 
  December 
  50 
  ova 
  of 
  the 
  Anopheline 
  were 
  trans- 
  

   ferred 
  to 
  this 
  water. 
  By 
  6th 
  January 
  most 
  had 
  hatched, 
  but 
  by 
  8th 
  January 
  all 
  were 
  

   dead 
  in 
  spite 
  of 
  their 
  being 
  transferred 
  daily 
  to 
  a 
  fresh 
  supply 
  of 
  the 
  water. 
  A 
  modifica- 
  

   tion 
  of 
  this 
  experiment 
  consisted 
  in 
  the 
  transfer 
  on 
  6th 
  January 
  of 
  101 
  of 
  these 
  larvae 
  

   which 
  hatched 
  on 
  2nd 
  January 
  and 
  were 
  thriving 
  on 
  Eiiglena-conta.\ning 
  water, 
  to 
  

   the 
  fishpond 
  water. 
  Within 
  two 
  days 
  all 
  were 
  dead. 
  A 
  further 
  modification 
  of 
  the 
  ex- 
  

   periment 
  was 
  the 
  following 
  : 
  — 
  An 
  A 
  . 
  aconitus 
  laid 
  on 
  30th 
  April 
  70 
  ova 
  on 
  water 
  

   from 
  a 
  small 
  muddy 
  pool. 
  The 
  ova 
  were 
  transferred 
  to 
  fishpond 
  water, 
  and 
  the 
  larvae 
  

   hatching 
  on 
  3rd 
  May 
  were 
  then 
  transferred 
  to 
  similar 
  water 
  half-diluted 
  with 
  water 
  

   from 
  a 
  breeding-place 
  natural 
  to 
  the 
  species, 
  and 
  changed 
  daily. 
  By 
  the 
  time 
  they 
  

   were 
  three 
  days 
  old 
  it' 
  was 
  found 
  that 
  fully 
  half 
  were 
  dead, 
  and 
  a 
  note 
  was 
  made 
  that 
  

   the 
  other 
  half 
  were 
  combing 
  their 
  tails 
  with 
  their 
  mouth-brushes 
  (usually 
  a 
  sign 
  of 
  ill- 
  

   health 
  with 
  Anopheline 
  larvae), 
  and 
  that 
  they 
  showed 
  a 
  sluggish 
  response 
  to 
  stimuli, 
  

   though 
  the 
  reaction 
  was 
  quickened 
  on 
  the 
  addition 
  of 
  tap 
  water. 
  By 
  8th 
  May 
  all 
  were 
  

   dead. 
  

  

  Such 
  was 
  the 
  outcome 
  of 
  many 
  experiments 
  on 
  these 
  lines 
  with 
  A. 
  aconitus. 
  But 
  

   unfortunately 
  for 
  the 
  interpretation 
  to 
  be 
  put 
  on 
  them, 
  there 
  was 
  some 
  difficulty 
  also 
  

   in 
  breeding 
  in 
  the 
  fishpond 
  water 
  the 
  larvae 
  natural 
  to 
  it, 
  A. 
  barbirostris 
  in 
  particular, 
  

   and^4 
  . 
  hyrcanus 
  ; 
  but 
  the 
  failure 
  was 
  rarely 
  so 
  complete 
  as 
  with 
  A 
  . 
  aconitus, 
  a 
  few 
  larvae, 
  

   out 
  of 
  large 
  numbers, 
  being 
  invariably 
  reared. 
  But 
  though 
  the 
  collection 
  data 
  and 
  the 
  

   experimental 
  facts 
  are 
  largely 
  in 
  direct 
  conflict, 
  the 
  outstanding 
  facts 
  are 
  the 
  eclectic- 
  

   ism 
  of 
  A. 
  aconitus 
  as 
  to 
  breeding-places 
  and 
  the 
  inability 
  of 
  its 
  larvae 
  to 
  maintain 
  

   themselves 
  in 
  the 
  fishpond 
  water. 
  To 
  account 
  for 
  this, 
  one 
  must 
  suppose 
  that 
  the 
  food 
  

   supply 
  is 
  unsuitable, 
  for 
  the 
  algal 
  flora 
  was 
  markedly 
  different 
  from 
  that 
  in 
  the 
  swamp, 
  

   or 
  that 
  some 
  quality 
  of 
  the 
  water 
  is 
  prejudicial 
  to 
  the 
  larvae. 
  

  

  It 
  was 
  anticipated 
  that 
  by 
  systematic 
  dissections 
  of 
  larvae 
  freshly 
  taken 
  from 
  

   various 
  breeding-places 
  it 
  might 
  be 
  possible 
  to 
  ascertain 
  precisefy 
  the 
  various 
  algal 
  

   forms 
  favoured 
  as 
  food 
  material, 
  and 
  so 
  define 
  one 
  of 
  the 
  main 
  factors 
  determining 
  

   oviposition 
  and 
  larval 
  prevalence. 
  Large 
  numbers 
  of 
  larvae, 
  killed 
  instantly 
  on 
  cap- 
  

   ture 
  by 
  immersion 
  in 
  20 
  per 
  cent, 
  formalin 
  solution, 
  were 
  dissected, 
  and 
  the 
  contents 
  of 
  

   the 
  alimentary 
  canal 
  were 
  examined 
  microscopically 
  ; 
  but 
  without 
  the 
  very 
  special 
  

   knowledge 
  of 
  aquatic 
  plants 
  required 
  it 
  was 
  impossible 
  to 
  arrive 
  at 
  any 
  definite 
  

   determination 
  of 
  the 
  organisms, 
  which 
  were 
  largely 
  in 
  a 
  fragmentary 
  state. 
  

  

  An 
  examination 
  of 
  the 
  excreta 
  of 
  various 
  species 
  of 
  larvae 
  fed 
  in 
  the 
  laboratory 
  on 
  

   Euglena 
  afforded 
  an 
  interesting 
  comparison. 
  So 
  abundant 
  was 
  the 
  organism, 
  and 
  so 
  

   active, 
  that 
  there 
  was 
  no 
  need 
  for 
  the 
  larvae 
  to 
  swim 
  about 
  in 
  search 
  of 
  food, 
  and 
  it 
  

   was 
  usual 
  for 
  the 
  larvae, 
  even 
  of 
  species 
  favouring 
  moving 
  water, 
  A. 
  maculatus 
  and 
  

   A. 
  kanvari 
  for 
  instance, 
  to 
  remain 
  anchored 
  hour 
  after 
  hour 
  at 
  a 
  particular 
  spot, 
  if 
  

   undisturbed, 
  feeding 
  constantly 
  with 
  a 
  steadily 
  accumulating 
  pile 
  of 
  excreta 
  below 
  

   them, 
  often 
  equalling 
  them 
  in 
  bulk. 
  The 
  pellets 
  were 
  readily 
  removed 
  and 
  examined 
  

   microscopically. 
  With 
  most 
  of 
  the 
  Anophelines 
  it 
  was 
  possible 
  to 
  identify 
  with 
  

   certainty 
  the 
  Euglena 
  fragments. 
  But 
  though 
  some 
  success 
  was 
  met 
  with 
  in 
  rearing 
  

   to 
  maturity 
  on 
  the 
  medium 
  a 
  number 
  of 
  small 
  larvae 
  of 
  A. 
  leucosphynts, 
  a 
  bush 
  

   breeder, 
  31 
  out 
  of 
  51 
  affording 
  imagos, 
  total 
  failure 
  was 
  experienced 
  with 
  the 
  larvae 
  

  

  