﻿458 
  W. 
  F. 
  FISKE. 
  

  

  These 
  were 
  the 
  principal 
  changes 
  that 
  were 
  taking 
  place 
  in 
  the 
  conditions 
  of 
  life 
  

   for 
  tsetse 
  along 
  the 
  lake 
  shore 
  as 
  a 
  result 
  of 
  the 
  flood 
  tide 
  of 
  1906 
  and 
  subsequent 
  

   low 
  water. 
  At 
  some 
  places 
  the 
  changes 
  were 
  of 
  a 
  very 
  different 
  character, 
  and 
  more 
  

   kinds 
  of 
  changes 
  were 
  progressing 
  than 
  can 
  well 
  be 
  described 
  in 
  detail. 
  In 
  general, 
  

   however, 
  it 
  can 
  be 
  stated 
  that 
  wherever 
  the 
  shore 
  rises 
  very 
  gradually, 
  and 
  most 
  

   particularly 
  at 
  the 
  many 
  points 
  where 
  the 
  gradient 
  is 
  less 
  than 
  1 
  per 
  cent., 
  extra- 
  

   ordinary 
  changes 
  in 
  the 
  conditions 
  of 
  life 
  for 
  tsetse 
  are 
  likely 
  to 
  follow 
  any 
  such 
  

   unusual 
  flood 
  as 
  that 
  of 
  1906. 
  But 
  if 
  the 
  land 
  rises 
  sharply 
  from 
  the 
  water 
  the 
  changes 
  

   may 
  be 
  insignificant, 
  and 
  usually 
  are 
  of 
  no 
  consequence. 
  

  

  In 
  a 
  general 
  way 
  the 
  island 
  survey 
  had 
  shown 
  that 
  the 
  range 
  and 
  density 
  of 
  fly 
  

   must 
  have 
  been 
  profoundly 
  affected 
  by 
  the 
  movement 
  of 
  the 
  water, 
  but 
  the 
  real 
  

   extent 
  of 
  the 
  changes 
  wrought 
  was 
  not 
  appreciated 
  until, 
  in 
  1915, 
  a 
  fly 
  survey 
  was 
  

   made 
  of 
  the 
  Buddu 
  shore. 
  This 
  region 
  had 
  been 
  surveyed 
  in 
  August 
  and 
  September 
  

   1906 
  by 
  Dr. 
  Van 
  Someren, 
  whose 
  reports 
  were 
  in 
  considerable 
  detail, 
  and 
  permitted 
  

   the 
  quite 
  accurate 
  comparison 
  which 
  follows. 
  

  

  XI 
  (c). 
  Increase 
  in 
  Density 
  of 
  Glossina 
  palpalis 
  due 
  to 
  falling 
  of 
  Lake 
  Level. 
  

  

  The 
  lake 
  shore 
  of 
  the 
  district 
  of 
  Buddu 
  was 
  surveyed 
  for 
  fly 
  in 
  1906 
  by 
  Dr. 
  R. 
  

   Van 
  Someren, 
  working 
  under 
  the 
  direction 
  of 
  Dr. 
  A. 
  D. 
  P. 
  Hodges 
  in 
  the 
  Sleeping 
  

   Sickness 
  Extended 
  Investigations. 
  This 
  same 
  shore 
  was 
  surveyed 
  by 
  me 
  in 
  1915, 
  

   and 
  a 
  most 
  extraordinary 
  change 
  in 
  conditions 
  of 
  infestation 
  was 
  found 
  to 
  have 
  

   occurred. 
  Following 
  is 
  an 
  extract 
  from 
  the 
  MS. 
  report 
  of 
  Dr. 
  Van 
  Someren, 
  kindly 
  

   supplied 
  me 
  by 
  Dr. 
  Hodges, 
  paralleled 
  by 
  comments 
  on 
  the 
  present 
  conditions. 
  

  

  Conditions 
  in 
  1906. 
  Conditions 
  in 
  1915. 
  

  

  (Keport 
  of 
  Dr. 
  E. 
  Van 
  Someren.) 
  (Fly 
  Survey.) 
  

  

  "When 
  I 
  came 
  to 
  Bale, 
  a 
  little 
  south 
  

   of 
  Namirembe 
  I 
  found 
  the 
  distribution 
  

   again 
  interesting. 
  

  

  " 
  Northwards 
  from 
  Bale 
  I 
  found 
  the 
  Northwards 
  from 
  Bale 
  the 
  whole 
  coast 
  

   whole 
  coast 
  some 
  3 
  miles 
  up 
  to 
  Namirembe 
  to 
  Namirembe 
  was 
  found 
  infested 
  to 
  the 
  

   devoid 
  of 
  fly, 
  and 
  • 
  from 
  Namirembe 
  for 
  average 
  density 
  of 
  6*3. 
  At 
  Namirembe 
  it 
  

   some 
  further 
  2 
  to 
  1\ 
  miles, 
  roughly, 
  into 
  was 
  very 
  low, 
  but 
  about 
  half 
  a 
  mile 
  beyond 
  

   the 
  Gwamba 
  also 
  with 
  no 
  fly. 
  the 
  landing 
  it 
  began 
  to 
  iucrease 
  rapidly, 
  

  

  until 
  at 
  points 
  from 
  2 
  to 
  2\ 
  miles 
  beyond 
  

  

  it 
  had 
  reached 
  the 
  very 
  high 
  average 
  of 
  

  

  63*5. 
  I 
  have 
  never 
  but 
  twice 
  seen 
  fly 
  

  

  more 
  numerous 
  or 
  more 
  annoying 
  (see 
  

  

  fig. 
  11). 
  

  

  " 
  After 
  this 
  point 
  one 
  meets 
  them 
  at 
  After 
  this 
  point 
  the 
  density 
  rises 
  to 
  yet 
  

  

  first 
  very 
  scantily 
  indeed 
  ; 
  then 
  in 
  in- 
  higher 
  figures 
  (76'5, 
  73*5, 
  89*5, 
  etc.) 
  and 
  

  

  creasing 
  numbers 
  right 
  up 
  to 
  our 
  limit 
  in 
  then 
  falls 
  away 
  to 
  moderate 
  figures 
  (5*3, 
  

  

  the 
  Gwamba 
  some 
  8 
  to 
  10 
  miles 
  from 
  7'5, 
  5*5, 
  etc.) 
  but 
  only 
  to 
  rise 
  again 
  later. 
  

  

  Namirembe. 
  The 
  average 
  for 
  this 
  6 
  to 
  8 
  miles 
  of 
  shore 
  

  

  is 
  the 
  very 
  high 
  one 
  of 
  37*6. 
  

   " 
  For 
  some 
  3 
  miles 
  southward 
  from 
  For 
  some 
  5 
  (not 
  3) 
  miles 
  southward 
  from 
  

   Bale 
  no 
  fly 
  are 
  met 
  with 
  till 
  a 
  small 
  point 
  Bale 
  to 
  Sekwe 
  the 
  shore 
  is 
  continuously 
  

   near 
  the 
  landing 
  place 
  Sekwe 
  (Calcosa) 
  infested, 
  and 
  at 
  3 
  miles 
  (2 
  miles 
  north 
  of 
  

   close 
  to 
  Dumo, 
  where 
  I 
  came 
  across 
  them 
  Kalkosa 
  or 
  Sekwe) 
  is 
  the 
  centre 
  of 
  the 
  

   in 
  small 
  numbers 
  and 
  limited 
  practically 
  Mujuzi 
  Creek 
  colony 
  described 
  on 
  p. 
  387 
  

   to 
  this 
  point. 
  and 
  illustrated 
  by 
  figure 
  5, 
  with 
  the 
  

  

  extreme 
  density 
  of 
  98*0. 
  

  

  