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  PROCEEDINGS 
  OF 
  THE 
  FOURTH 
  ENTOMOLOGICAL 
  MEETING 
  

  

  ** 
  If 
  direct 
  transmission 
  is 
  the 
  means 
  by 
  which 
  Surra 
  is 
  spread 
  from 
  

   camel 
  to 
  camel, 
  any 
  blood-sucking 
  fly 
  may 
  transmit 
  the 
  disease, 
  and 
  

   considering 
  the 
  number 
  of 
  blood-sucking 
  flies 
  in 
  India 
  and 
  the 
  number 
  

   of 
  reservoirs 
  of 
  Surra, 
  it 
  is 
  difficult 
  to 
  imagine 
  that 
  a 
  single 
  camel 
  could 
  

   have 
  escaped 
  becoming 
  surra-infected. 
  It 
  is 
  probable 
  that 
  the 
  try- 
  

   panosome 
  undergoes 
  a 
  cycle 
  in 
  the 
  fly 
  (and 
  in 
  a 
  particular 
  species 
  of 
  fly 
  

   only), 
  a 
  percentage 
  only 
  of 
  these 
  flies 
  being 
  capable 
  of 
  infecting 
  healthy 
  

   camels 
  — 
  i.e., 
  the 
  cycle 
  is 
  not 
  completed 
  in 
  every 
  one 
  of 
  the 
  flies 
  that 
  

   has 
  fed 
  on 
  blood 
  containing 
  trypanosomes. 
  

  

  " 
  From 
  practical 
  experience 
  there 
  is 
  no 
  doubt 
  that 
  

  

  the 
  most 
  dangerous 
  flies 
  in 
  the 
  spread 
  of 
  Surra 
  from 
  camel 
  to 
  camel 
  

   are 
  the 
  Tabanidse." 
  

  

  Patton 
  (1920) 
  suggests 
  that 
  transmission 
  occurs 
  through 
  the 
  mucous 
  

   membrane 
  of 
  the 
  mouth 
  from 
  Crithidia 
  voided 
  from 
  the 
  rectum 
  of 
  

   Tabanus. 
  

  

  On 
  going 
  over 
  these 
  various 
  papers, 
  the 
  chief 
  point 
  that 
  emerges 
  

   is 
  the 
  very 
  wide 
  difference 
  of 
  opinion 
  held 
  by 
  various 
  investigators 
  

   on 
  almost 
  every 
  point. 
  Some 
  observers 
  declare 
  that 
  transmission 
  is 
  

   purely 
  mechanical, 
  others 
  that 
  a 
  developmental 
  cycle 
  occurs 
  in 
  the 
  

   insect 
  transmitter 
  ; 
  some 
  implicate 
  Stomoxys, 
  others 
  declare 
  that 
  

   Stomoxys 
  is 
  unable 
  to 
  transmit 
  at 
  all 
  ; 
  in 
  fact, 
  there 
  is 
  hardly 
  a 
  statement 
  

   made 
  by 
  one 
  observer 
  that 
  is 
  not 
  directly 
  contradicted 
  by 
  another. 
  

  

  Before 
  considering 
  these 
  views 
  further 
  at 
  this 
  point, 
  we 
  will 
  diverge 
  

   for 
  a 
  short 
  while 
  and 
  run 
  briefly 
  over 
  a 
  few 
  of 
  the 
  more 
  salient 
  facts 
  

   connected 
  with 
  another 
  Trypanosome 
  disease 
  on 
  which 
  a 
  great 
  deal 
  

   of 
  investigatory 
  work 
  has 
  been 
  done. 
  An 
  interesting 
  case, 
  in 
  many 
  

   ways 
  analogous 
  to 
  that 
  of 
  Surra, 
  is 
  furnished 
  by 
  Sleeping 
  Sickness, 
  

   which 
  is 
  happily 
  so 
  far 
  restricted 
  to 
  tropical 
  and 
  subtropical 
  Africa. 
  

   Sleeping 
  Sickness 
  is 
  caused 
  by 
  a 
  Trypanosome, 
  Trypanosoma 
  gambiense, 
  

   which 
  is 
  carried 
  by 
  a 
  biting 
  fly, 
  Glossina 
  palpalis. 
  The 
  distribution 
  

   of 
  this 
  disease 
  was 
  originally 
  restricted 
  to 
  West 
  Africa, 
  where 
  there 
  is 
  

   some 
  evidence 
  that 
  the 
  negro 
  population 
  has 
  acquired 
  a 
  certain 
  degree 
  

   of 
  immunity 
  (more 
  marked 
  in 
  the 
  case 
  of 
  another 
  closely 
  related 
  disease 
  

   produced 
  by 
  Trypanosoma 
  nigeriense, 
  which 
  causes 
  only 
  a 
  mild 
  form 
  

   of 
  disease 
  in 
  man), 
  but 
  when 
  equatorial 
  Africa 
  was 
  opened 
  up 
  the 
  disease 
  

   was 
  carried 
  eastwards 
  to 
  Uganda, 
  where 
  it 
  caused 
  great 
  mortality 
  and 
  

   from 
  its 
  first 
  appearance 
  in 
  1901 
  up 
  to 
  1905 
  killed 
  ofi 
  over 
  200,000 
  

   people, 
  whole 
  villages 
  being 
  depopulated. 
  The 
  species 
  of 
  Glossina 
  

   have 
  a 
  life-history 
  very 
  similar 
  to 
  that 
  of 
  our 
  species 
  of 
  Hippobosca, 
  

   the 
  egg 
  hatching 
  inside 
  the 
  female 
  fly 
  and 
  the 
  larvae 
  being 
  extruded 
  

   i>nly 
  when 
  ready 
  to 
  pupate, 
  pupation 
  taking 
  place 
  in 
  the 
  ground 
  in 
  

   soil 
  which 
  is 
  loose 
  and 
  dry, 
  well 
  shaded 
  but 
  with 
  the 
  surface 
  thoroughly 
  

  

  