﻿ENTOMOLOGICAL 
  ASPECTS 
  OF 
  AN 
  OUTBREAK 
  OF 
  SLEEPING 
  SICKNESS. 
  323 
  

  

  (3) 
  "Enclosed" 
  Formations. 
  — 
  -These 
  are 
  (a) 
  the 
  broad-leaved, 
  very 
  distinct 
  

   formation 
  of 
  trees 
  and 
  shrubs 
  (Grewia, 
  Sterculia, 
  and 
  many 
  others) 
  that 
  closely 
  fills 
  

   the 
  interstices 
  between 
  the 
  great 
  boulders 
  of 
  the 
  kopjes 
  and 
  (on 
  the 
  island 
  at 
  Musoma 
  

   and 
  the 
  coast 
  opposite, 
  as 
  well 
  as 
  at 
  points 
  on 
  the 
  Mwanza 
  Gulf 
  and 
  elsewhere 
  where 
  

   kopjes 
  are 
  half 
  submerged) 
  comes 
  down 
  to 
  the 
  lake 
  and 
  harbours 
  G. 
  palpalis. 
  This 
  

   formation 
  (PI. 
  xv, 
  fig. 
  2) 
  takes 
  the 
  guise 
  of 
  little 
  rocky 
  islands 
  and 
  archipelagos, 
  

   not 
  thorny 
  and 
  devoid 
  of 
  acacia, 
  dotted 
  through 
  the 
  acacia 
  thorn 
  woodland 
  ; 
  

   (b) 
  the 
  thickets, 
  which 
  are, 
  in 
  part, 
  composed 
  of 
  the 
  densely 
  growing 
  seedlings 
  of 
  

   the 
  savannah 
  trees, 
  and 
  partly, 
  more 
  or 
  less 
  low, 
  dense 
  shrub-thickets 
  (PI. 
  xiii, 
  fig. 
  2), 
  

   in 
  places 
  scattered, 
  in 
  others 
  more 
  massed. 
  Such 
  thickets 
  occur 
  throughout 
  the 
  

   woodland, 
  and 
  with 
  the 
  aid 
  of 
  the 
  sapling 
  thickets 
  (which 
  they 
  invade) 
  are 
  tending 
  

   to 
  cover 
  the 
  entire 
  area 
  with 
  the 
  quite 
  intractable 
  type 
  of 
  tsetse-infested 
  bush 
  that 
  

   occurs, 
  for 
  instance, 
  over 
  great 
  stretches 
  of 
  country 
  between 
  Dar-es-Salaam 
  and 
  

   Morogoro. 
  They 
  often 
  enclose 
  and 
  are 
  overshaded 
  by 
  from 
  one 
  to 
  many 
  large 
  or 
  

   small 
  acacias 
  (as 
  in 
  PI. 
  xii, 
  fig. 
  2), 
  doubtless 
  owing 
  to 
  the 
  fact 
  that 
  the 
  grass 
  in 
  the 
  

   shade 
  of 
  a 
  tree 
  dries 
  later 
  than 
  the 
  grass 
  outside, 
  escapes 
  the 
  weak 
  fires 
  of 
  the 
  early 
  

   months, 
  and 
  allows 
  shrubs 
  and 
  saplings 
  to 
  obtain 
  a 
  start. 
  They 
  comprise, 
  especially, 
  

   species 
  of 
  Grewia 
  and 
  Commiphora, 
  Acacia 
  verek, 
  Guill. 
  & 
  Perr., 
  and 
  in 
  places 
  

   Markhamia 
  lanata, 
  the 
  small-leaved, 
  thorny 
  trailer 
  (Harrisonia 
  abyssinica, 
  Oliv.), 
  

   and 
  (especially 
  in 
  the 
  drier 
  situations 
  and 
  in 
  association 
  with 
  A. 
  spirocarpa) 
  

   Kalanchoe, 
  Aloe, 
  Sanseviera, 
  and 
  much 
  of 
  the 
  fleshy-looking 
  liana 
  (Strophanthus 
  

   sp.) 
  that 
  is 
  shown 
  in 
  Plate 
  xvii, 
  fig. 
  1, 
  and 
  that 
  sometimes 
  coils 
  all 
  over 
  the 
  thicket 
  

   floor 
  and 
  shelters 
  both 
  tsetse 
  and 
  their 
  puparia 
  ; 
  (c) 
  a 
  kind 
  of 
  thicket 
  that 
  

   I 
  found 
  containing 
  flies 
  in 
  small 
  numbers 
  near 
  Zagayu 
  and 
  north 
  of 
  Kahama 
  and 
  that 
  

   occurs 
  here 
  and 
  there 
  throughout 
  the 
  area, 
  and 
  particularly 
  on 
  the 
  margins 
  of 
  certain 
  

   seasonally 
  damp 
  spots, 
  is 
  composed 
  of 
  large, 
  round 
  brakes 
  of 
  a 
  trailing 
  Combretum 
  

   that 
  gives 
  a 
  little 
  the 
  effect 
  of 
  a 
  much-enlarged 
  blackberry 
  bush, 
  and 
  may 
  or 
  may 
  

   not 
  occur 
  in 
  connection 
  with 
  the 
  types 
  of 
  thicket 
  I 
  have 
  referred 
  to 
  already. 
  

  

  Reproduction 
  is 
  only 
  too 
  good. 
  An 
  enormous 
  amount 
  of 
  young 
  growth 
  {Acacia 
  

   and 
  Albizzia 
  especially) 
  is 
  everywhere 
  springing 
  up 
  more 
  or 
  less 
  densely, 
  and 
  unless 
  

   this 
  can 
  be 
  kept 
  down 
  by 
  systematic 
  burning, 
  the 
  whole 
  area 
  will 
  become 
  as 
  thicketed 
  

   and 
  as 
  heavily 
  fly-infested 
  as 
  patches 
  of 
  it 
  now 
  are. 
  I 
  cleared 
  of 
  grass 
  two 
  squares, 
  

   each 
  of 
  nine 
  square 
  yards. 
  In 
  one 
  I 
  counted 
  95 
  young 
  trees, 
  and 
  in 
  the 
  other 
  77. 
  

   These 
  squares 
  were 
  not 
  exceptional, 
  but 
  represented 
  the 
  present 
  position 
  over 
  broad 
  

   patches 
  of 
  country. 
  Some 
  early 
  grass-fires 
  had 
  already 
  taken 
  place 
  at 
  the 
  time 
  of 
  

   our 
  visit 
  and 
  had 
  killed 
  not 
  a 
  twig 
  of 
  these 
  little 
  trees 
  that 
  an 
  October 
  fire 
  would 
  

   have 
  burned 
  to 
  the 
  ground. 
  The 
  results 
  of 
  past 
  ineffective 
  fires 
  were 
  seen 
  in 
  places 
  

   where 
  masses 
  of 
  these 
  small 
  trees 
  were 
  already 
  growing 
  up 
  and 
  forming 
  thickets. 
  

  

  V. 
  The 
  People. 
  

  

  The 
  people 
  generally, 
  for 
  our 
  present 
  purpose, 
  are 
  to 
  be 
  distinguished 
  into 
  (a) 
  

   cattle-keeping 
  cultivators, 
  who 
  live 
  relatively 
  thickly 
  in 
  the 
  cleared 
  areas, 
  and 
  who, 
  

   where 
  near 
  enough, 
  visit 
  the 
  woods 
  for 
  wood, 
  bark 
  rope, 
  water, 
  hunting, 
  fishing, 
  

   young 
  birds 
  and 
  honey, 
  medicines, 
  ancestor 
  worship, 
  and 
  material 
  for 
  the 
  Ifubo 
  

   or 
  silver-leaf 
  dance 
  ; 
  and 
  (b) 
  hunting 
  and 
  fishing 
  cultivators, 
  who, 
  owing 
  to 
  nagana, 
  

   can 
  keep 
  no 
  cattle, 
  and 
  who 
  live 
  in 
  a 
  more 
  scattered 
  fashion 
  in 
  the 
  woodland 
  area 
  itself. 
  

   It 
  is 
  a 
  most 
  interesting 
  point 
  that 
  they 
  have 
  been 
  enabled 
  to 
  do 
  this, 
  as 
  the3^ 
  them- 
  

   selves 
  state, 
  b}r 
  the 
  freedom 
  they 
  have 
  now 
  obtained 
  from 
  the 
  old 
  tribal 
  ra 
  ; 
  ds 
  and 
  

   clan 
  warfare 
  that 
  forced 
  on 
  them 
  the 
  concentration 
  that 
  has 
  usefully 
  cleared 
  so 
  much 
  

   country 
  ; 
  and 
  they 
  have 
  been 
  induced 
  to 
  do 
  so 
  by 
  the 
  loss 
  of 
  their 
  cattle 
  in 
  the 
  epi- 
  

   demics 
  that 
  have 
  accompanied 
  the 
  European 
  regime 
  during 
  the 
  past 
  thirty 
  years. 
  

   Game 
  skins 
  and 
  fish 
  nets 
  may 
  be 
  found 
  in 
  most 
  huts 
  of 
  this 
  section. 
  The 
  fruits 
  of 
  

   Strophanthus 
  eminii, 
  Asch. 
  & 
  Pax., 
  are 
  used 
  for 
  the 
  manufacture 
  of 
  arrow 
  poison 
  by 
  

   every 
  native 
  in 
  these 
  parts 
  and 
  are 
  found 
  lying 
  in 
  the 
  villages. 
  Pits, 
  game 
  nets, 
  and 
  

   heavy 
  iope 
  snares 
  are 
  also 
  employed. 
  Along 
  the 
  whole 
  lower 
  course 
  of 
  the 
  Simiyu 
  

  

  