﻿INVESTIGATIONS 
  INTO 
  THE 
  BIONOMICS 
  OF 
  GLOSSINA 
  PALPALIS. 
  463 
  

  

  The 
  narrow 
  outlet 
  to 
  the 
  enormous 
  volume 
  of 
  the 
  lake 
  acts 
  like 
  a 
  choked 
  safety 
  

   valve. 
  Rise 
  in 
  lake 
  level 
  may 
  be 
  very 
  rapid, 
  but 
  fall 
  is 
  more 
  gradual. 
  It 
  seems 
  

   to 
  have 
  required 
  more 
  than 
  a 
  year 
  for 
  the 
  unusual 
  surplus 
  that 
  gathered 
  so 
  

   quickly 
  in 
  1906 
  to 
  find 
  its 
  way 
  through 
  the 
  walls 
  of 
  rock 
  at 
  the 
  source 
  of 
  the 
  

   Victoria 
  Nile. 
  If 
  the 
  outlet 
  were 
  not 
  choked 
  in 
  this 
  manner 
  the 
  level 
  of 
  Victoria 
  

   Nyanza 
  would 
  be 
  somewhat 
  more 
  constant, 
  and 
  the 
  flow 
  of 
  the 
  Victoria 
  Nile 
  

   somewhat 
  more 
  variable. 
  If 
  it 
  were 
  yet 
  more 
  effectually 
  choked 
  the 
  flow 
  of 
  the 
  

   river 
  would 
  be 
  more 
  constant 
  and 
  the 
  level 
  of 
  the 
  lake 
  subject 
  to 
  yet 
  wider 
  

   fluctuations. 
  

  

  XI. 
  (e). 
  The 
  probable 
  Effect 
  of 
  a 
  Dam 
  at 
  the 
  Outlet 
  upon 
  the 
  Tsetse 
  along 
  the 
  

   Shores 
  of 
  Victoria 
  Nyanza. 
  

  

  The 
  outlet 
  to 
  the 
  lake 
  into 
  the 
  Victoria 
  Nile 
  is 
  a 
  superb 
  source 
  of 
  water-power, 
  

   and 
  one 
  of 
  Uganda's 
  great 
  assets. 
  The 
  topography 
  permits 
  its 
  relatively 
  cheap 
  

   development. 
  There 
  is 
  a 
  natural 
  dam, 
  and 
  excellent 
  opportunity 
  for 
  a 
  canal 
  along 
  

   the 
  eastern 
  shore 
  of 
  the 
  river, 
  which 
  does 
  not 
  immediately 
  fall 
  away. 
  But 
  a 
  dam 
  

   would 
  permit 
  a 
  much 
  more 
  complete 
  utilisation 
  of 
  the 
  power 
  that 
  it 
  is 
  as 
  certain 
  

   to 
  be 
  built 
  as 
  that 
  the 
  economic 
  development 
  of 
  the 
  country 
  will 
  continue. 
  

  

  It 
  is 
  neither 
  a 
  high 
  nor 
  a 
  low 
  level 
  of 
  the 
  lake 
  that 
  creates 
  favourable 
  conditions 
  

   of 
  life 
  for 
  tsetse, 
  but 
  a 
  fluctuating 
  level. 
  The 
  rising 
  waters 
  clear 
  away 
  massed 
  

   vegetation 
  and 
  wash 
  clean 
  the 
  breeding 
  grounds 
  ; 
  the 
  falling 
  waters 
  permit 
  the 
  growth 
  

   of 
  new 
  shelter 
  and 
  the 
  breeding 
  of 
  fly 
  in 
  the 
  renovated 
  terrain. 
  Continued 
  growth 
  

   chokes 
  the 
  breeding 
  grounds, 
  and 
  hides 
  them 
  beneath 
  massed 
  vegetation 
  or 
  the 
  

   accumulations 
  of 
  mould. 
  

  

  If 
  a 
  dam 
  at 
  the 
  outlet 
  of 
  the 
  lake 
  could 
  be 
  so 
  constructed 
  as 
  to 
  equalise 
  the 
  level 
  

   of 
  it 
  by 
  permitting 
  more 
  rapid 
  egress 
  of 
  rising 
  waters, 
  it 
  might 
  have 
  a 
  beneficial 
  

   effect 
  in 
  reducing 
  the 
  density 
  of 
  tsetse 
  along 
  its 
  borders. 
  But 
  the 
  object 
  in 
  building 
  

   a 
  dam 
  would 
  be 
  the 
  very 
  opposite 
  ; 
  it 
  would 
  be 
  to 
  equalise 
  the 
  flow 
  of 
  water 
  in 
  the 
  

   power 
  canal 
  and 
  the 
  Victoria 
  Nile, 
  and 
  thus 
  to 
  accentuate 
  the 
  fluctuations 
  of 
  the 
  

   lake. 
  

  

  This 
  might, 
  conceivably, 
  be 
  prejudicial 
  to 
  the 
  fly 
  below 
  the 
  dam, 
  but 
  it 
  would 
  

   be 
  beneficial 
  to 
  fly 
  above 
  it. 
  

  

  It 
  would 
  be 
  delightful 
  if 
  construction 
  of 
  a 
  dam, 
  and 
  utilisation 
  of 
  the 
  water- 
  

   power 
  at 
  the 
  source 
  of 
  the 
  Nile 
  could 
  be 
  urged 
  as 
  a 
  sanitary 
  measure, 
  but 
  unfortunately 
  

   its 
  construction 
  will 
  have 
  the 
  opposite 
  to 
  the 
  desired 
  effect. 
  

  

  