﻿20 
  DR. 
  H. 
  LYNDHURST 
  DUKE. 
  

  

  persisted 
  which, 
  for 
  reasons 
  undetermined 
  at 
  present, 
  instead 
  of 
  increasing, 
  

   diminished 
  to 
  the 
  point 
  of 
  absolute 
  disappearance 
  before 
  Hamilton's 
  arrival 
  in 
  1902. 
  

  

  This 
  explanation 
  is 
  compatible 
  also 
  with 
  the 
  apparent 
  irregularity 
  in 
  the 
  effects 
  

   of 
  the 
  disease 
  on 
  fly 
  distribution 
  in 
  different 
  areas. 
  To 
  exert 
  its 
  maximum 
  effect 
  

   the 
  epidemic 
  should 
  arrive 
  during 
  the 
  season 
  when 
  the 
  grass 
  is 
  long. 
  In 
  its 
  passage 
  

   through, 
  the 
  country 
  it 
  may 
  reach 
  certain 
  fly 
  belts 
  when 
  the 
  grass 
  is 
  yet 
  short 
  and 
  the 
  

   game 
  easy 
  to 
  see. 
  In 
  such 
  case 
  the 
  effect 
  on 
  the 
  fly 
  might 
  be 
  less 
  severely 
  felt. 
  The 
  

   tsetse 
  would 
  be 
  better 
  able 
  to 
  follow 
  the 
  migratory 
  movements 
  of 
  the 
  susceptible 
  

   game, 
  and 
  to 
  locate 
  the 
  whereabouts 
  of 
  such 
  relatively 
  immune 
  species 
  as 
  waterbuck, 
  

   impala, 
  and 
  hartebeest, 
  whose 
  distribution 
  is 
  local. 
  

  

  The 
  practical 
  outcome 
  of 
  these 
  observations 
  is 
  that 
  morsitans 
  should 
  be 
  attacked 
  

   during 
  the 
  dry 
  season 
  of 
  the 
  year, 
  when 
  natural 
  conditions 
  are 
  most 
  unfavourable 
  

   to 
  it. 
  The 
  two 
  main 
  indications 
  are 
  : 
  — 
  (1) 
  Destruction 
  of 
  the 
  primary 
  centres 
  

   or 
  foci 
  referred 
  to 
  by 
  Shircore 
  and 
  Fiske 
  by 
  filling 
  in 
  or 
  drainage 
  of 
  the 
  water 
  supply 
  ; 
  

   destruction 
  of 
  game 
  in 
  the 
  vicinity, 
  and 
  careful 
  burning 
  of 
  the 
  grass 
  at 
  the 
  most 
  

   suitable 
  time. 
  (2) 
  Careful 
  control 
  of 
  bush 
  burning 
  so 
  as 
  to 
  obtain 
  the 
  maximum 
  

   effect 
  of 
  the 
  fire 
  ; 
  indiscriminate 
  and 
  patchy 
  burning 
  by 
  natives 
  to 
  be 
  stopped, 
  and 
  

   the 
  fires 
  started 
  and 
  maintained 
  in 
  a 
  systematic 
  manner 
  so 
  as 
  to 
  ensure 
  universal 
  

   burning 
  of 
  the 
  grass. 
  

  

  An 
  observation 
  made 
  by 
  Dr. 
  Sander 
  (14) 
  in 
  German 
  East 
  Africa 
  in 
  a 
  pamphlet 
  

   on 
  tsetses 
  in 
  1905 
  is 
  of 
  interest 
  in 
  this 
  connection. 
  He 
  says 
  that 
  both 
  Europeans 
  and 
  

   natives 
  attribute 
  the 
  increase 
  and 
  spread 
  of 
  tsetse 
  in 
  the 
  area 
  between 
  Tanga 
  and 
  

   Kilimanjaro 
  to 
  the 
  cessation 
  of 
  annual 
  grass 
  fires. 
  The 
  game 
  in 
  this 
  area 
  had 
  

   diminished 
  very 
  greatly. 
  

  

  References. 
  

  

  1. 
  Bull. 
  Ent. 
  Kes., 
  i, 
  p. 
  174. 
  

  

  2. 
  Austen, 
  E. 
  E. 
  Monograph 
  of 
  the 
  Tsetse 
  Flies, 
  p. 
  290. 
  

  

  3. 
  Bull. 
  Ent. 
  Res., 
  ii, 
  p. 
  113 
  et 
  seq. 
  

  

  4. 
  Minutes 
  of 
  Evidence 
  of 
  Departmental 
  Committee 
  on 
  Sleep 
  Sickness 
  ; 
  Question 
  

  

  321. 
  

  

  5. 
  Bull. 
  Ent. 
  Res., 
  ii, 
  p. 
  40. 
  

  

  6. 
  Bull. 
  Ent. 
  Res., 
  ii, 
  p. 
  44. 
  

  

  7. 
  Austen, 
  E. 
  E. 
  Monograph 
  of 
  the 
  Tsetse 
  Flies. 
  

  

  8. 
  Neumann, 
  0. 
  " 
  Elephant 
  Hunting 
  in 
  East 
  Equatorial 
  Africa," 
  pp. 
  141-142. 
  

  

  9. 
  Minutes 
  of 
  Evidence 
  of 
  Departmental 
  Committee 
  on 
  Sleep 
  Sickness. 
  

  

  10. 
  Gibbons, 
  Major 
  A. 
  St. 
  H. 
  " 
  Africa 
  from 
  South 
  to 
  North, 
  through 
  Marotse 
  Land." 
  

  

  11. 
  Jack, 
  R. 
  W. 
  Bull. 
  Ent. 
  Res., 
  v, 
  pp. 
  97-110. 
  

  

  12. 
  Shircore, 
  J. 
  0. 
  Bull. 
  Ent. 
  Res., 
  v, 
  pp. 
  87-90. 
  

  

  13. 
  Fiske, 
  W. 
  F. 
  Report 
  on 
  Preliminary 
  Investigations 
  into 
  the 
  Bionomics 
  of 
  

  

  Glossina 
  morsitans 
  in 
  Uganda. 
  

   14. 
  Minutes 
  of 
  Evidence 
  of 
  Departmental 
  Committee 
  on 
  Sleep 
  Sickness. 
  Mr. 
  G. 
  A. 
  K. 
  

   Marshall; 
  Quest. 
  2020. 
  

  

  