﻿PROCEEDINGS 
  OF 
  THE 
  FOURTH 
  ENTOMOLOGICAL 
  MEETING 
  231 
  

  

  ventilated, 
  within 
  a 
  few 
  yards 
  from 
  the 
  water 
  but 
  beyond 
  its 
  reach. 
  

   As 
  such 
  a 
  combination 
  of 
  characters 
  is 
  only 
  to 
  be 
  found 
  in 
  definitely 
  

   limited 
  areas, 
  the 
  distribution 
  of 
  the 
  fly 
  is 
  limited 
  to 
  forested 
  and 
  humid 
  

   country 
  and 
  is 
  often 
  very 
  sharply 
  marked. 
  It 
  has 
  been 
  found 
  in 
  Uganda 
  

   that 
  Trypanosoma 
  gambiense 
  is 
  carried 
  normally 
  by 
  the 
  sHutunga 
  

   antelope 
  {Tragelaphus 
  spekei), 
  which, 
  with 
  other 
  wild 
  animals 
  generally, 
  

   is 
  immune 
  to 
  the 
  effects 
  of 
  the 
  presence 
  of 
  this 
  Trypanosome, 
  which 
  

   has 
  a 
  cycle 
  of 
  development 
  of 
  from 
  18 
  to 
  45 
  days 
  in 
  Glossina 
  palpalis, 
  

   after 
  which 
  the 
  fly 
  is 
  infective 
  whilst 
  it 
  remains 
  alive 
  up 
  to 
  about 
  75 
  

   days 
  ; 
  development 
  takes 
  place 
  in 
  the 
  gut 
  of 
  the 
  fly, 
  whence 
  the 
  

   parasite 
  passes 
  into 
  the 
  salivary 
  glands, 
  and 
  thence 
  into 
  the 
  blood 
  of 
  

   ' 
  its 
  next 
  host. 
  In 
  the 
  case 
  of 
  monkeys 
  infection 
  has 
  been 
  obtained 
  by 
  

   mechanical 
  transmission 
  by 
  means 
  of 
  G. 
  palpalis 
  if 
  the 
  transference 
  

   of 
  the 
  flies 
  from 
  the 
  infected 
  to 
  the 
  healthy 
  animal 
  is 
  instantaneous, 
  

   that 
  is, 
  by 
  " 
  interrupted 
  feeding," 
  but 
  this 
  mechanical 
  transmission 
  

   does 
  not 
  take 
  place 
  if 
  an 
  interval 
  of 
  time 
  elapses 
  between 
  the 
  two 
  

   feedings, 
  and 
  mechanical 
  transmission, 
  though 
  possible, 
  plays 
  a 
  very 
  

   small 
  part 
  in 
  the 
  spread 
  of 
  Sleeping 
  Sickness. 
  When 
  the 
  Glossina 
  

   alights 
  to 
  feed, 
  it 
  selects 
  a 
  suitable 
  place 
  and 
  inserts 
  the 
  proboscis, 
  

   which 
  is 
  then 
  withdrawn 
  slightly 
  and 
  blood 
  is 
  sucked 
  up 
  ; 
  " 
  almost 
  at 
  

   once 
  the 
  excess 
  of 
  fluid 
  is 
  exuded 
  as 
  a 
  bead 
  at 
  the 
  posterior 
  end 
  of 
  

   the 
  body, 
  so 
  that 
  the 
  fly 
  is 
  enabled 
  as 
  it 
  were 
  to 
  have 
  a 
  larger 
  feed 
  of 
  

   corpuscles 
  than 
  if 
  it 
  were 
  compelled 
  to 
  retain 
  all 
  the 
  fluid 
  part." 
  

   (Carpenter, 
  pp. 
  34-35). 
  Even 
  when 
  its 
  natural 
  host, 
  the 
  siiutwnga 
  

   antelope, 
  is 
  present, 
  Glossina 
  palpalis 
  derives 
  only 
  about 
  25 
  per 
  cent, 
  

   of 
  its 
  food 
  from 
  mammalian 
  blood, 
  the 
  remaining 
  75 
  per 
  cent, 
  being 
  

   derived 
  from 
  the 
  blood 
  of 
  non-mammals, 
  mostly 
  lizards 
  and 
  crocodiles. 
  

   The 
  chances 
  of 
  an 
  individual 
  fly 
  being 
  infected 
  with 
  Trypanosoma 
  

   gambiense 
  is 
  therefore 
  minute, 
  for 
  every 
  fly 
  does 
  not 
  feed 
  on 
  a 
  buck 
  

   nor 
  is 
  every 
  buck 
  infected. 
  Also, 
  as 
  Miss 
  Kobeitson 
  has 
  shown, 
  even 
  

   if 
  the 
  buck 
  is 
  infected 
  the 
  Trypanosome 
  is 
  not 
  always 
  in 
  a 
  condition 
  

   ready 
  to 
  multiply 
  in 
  the 
  fly 
  and 
  also 
  every 
  fly 
  that 
  ingests 
  Trypanosomes 
  

   is 
  not 
  a 
  suitable 
  medium 
  for 
  their 
  further 
  development. 
  Carpenter 
  

   found 
  that, 
  in 
  the 
  absence 
  of 
  the 
  natural 
  host 
  (the 
  situtunga 
  antelope), 
  

   as 
  many 
  as 
  5,765 
  flies 
  of 
  Glossina 
  palpalis 
  failed 
  to 
  cause 
  infection 
  

   in 
  a 
  monkey 
  ; 
  whilst 
  in 
  the 
  same 
  locality, 
  three 
  years 
  later, 
  after 
  

   the 
  situtunga 
  antelope 
  had 
  found 
  their 
  way 
  there, 
  " 
  the 
  flies 
  were 
  

   again 
  tested 
  and 
  found 
  to 
  be 
  infected, 
  for 
  after 
  2076 
  had 
  fed 
  upon 
  a 
  

   monkey 
  it 
  showed 
  the 
  Trypanosome 
  in 
  its 
  blood," 
  (Carpenter, 
  p: 
  29). 
  

   A 
  very 
  interesting 
  and 
  suggestive 
  point 
  which 
  Carpenter 
  notes 
  is 
  that 
  

   ' 
  besides 
  Trypanosomes 
  bacilli 
  are 
  often 
  found 
  in 
  countless 
  numbers 
  

   in 
  the 
  gut 
  of 
  the 
  fly, 
  but 
  in 
  a 
  different 
  part. 
  Nevertheless 
  there 
  appears 
  

  

  q2 
  

  

  