﻿350 
  W. 
  F. 
  FISKE. 
  

  

  report 
  defined. 
  It 
  contains 
  a 
  mere 
  mass 
  of 
  unapplied, 
  and 
  for 
  the 
  present 
  inapplicable, 
  

   information 
  of 
  no 
  practical 
  value 
  until 
  a 
  decision 
  has 
  been 
  reached 
  on 
  the 
  following 
  

   points 
  : 
  — 
  

  

  (1) 
  Shall 
  the 
  original 
  plan 
  for 
  these 
  investigations 
  be 
  followed, 
  and 
  an 
  experiment 
  

  

  be 
  planned 
  and 
  conducted 
  to 
  test 
  the 
  accuracy 
  and 
  applicability 
  of 
  the 
  

   conclusions 
  reached 
  % 
  

  

  (2) 
  If 
  so, 
  shall 
  the 
  object 
  be 
  — 
  

  

  (a) 
  to 
  exterminate 
  fly 
  and 
  prevent 
  all 
  contact 
  between 
  fly 
  and 
  population, 
  

  

  in 
  accordance 
  with 
  the 
  theories 
  held 
  in 
  1906-07 
  ; 
  or 
  

   (6) 
  to 
  reduce 
  excessive 
  density 
  of 
  fly 
  and 
  to 
  prevent 
  excessive 
  breadth 
  of 
  

   contact 
  between 
  fly 
  and 
  population, 
  in 
  accordance 
  with 
  present 
  practice 
  

   — 
  as 
  in 
  the 
  Bukakata 
  District 
  in 
  1915-16 
  ? 
  

  

  Unfortunately 
  the 
  decision 
  cannot 
  rest 
  on 
  the 
  results 
  of 
  these 
  studies 
  in 
  tsetse 
  

   bionomics, 
  which 
  have 
  only 
  the 
  most 
  indirect 
  bearing 
  upon 
  the 
  point 
  at 
  issue. 
  

   Every 
  bit 
  of 
  information 
  which 
  seemed, 
  even 
  remotely, 
  to 
  bear 
  upon 
  them, 
  and 
  

   which 
  could 
  be 
  gleaned 
  from 
  any 
  available 
  source, 
  was 
  included 
  in 
  a 
  report 
  presented 
  

   in 
  1916, 
  upon 
  which 
  no 
  action 
  has 
  been 
  taken 
  at 
  this 
  date 
  of 
  writing. 
  The 
  one 
  phase 
  

   of 
  tsetse 
  bionomics 
  having 
  any 
  bearing 
  on 
  these 
  points 
  is 
  the 
  fly's 
  choice 
  of 
  hosts 
  

   and 
  host 
  preferences. 
  This 
  is 
  enlarged 
  upon 
  in 
  the 
  following 
  pages. 
  

  

  The 
  methods 
  used 
  in 
  conducting 
  these 
  studies 
  consisted 
  in 
  the 
  main 
  of 
  a 
  " 
  fly 
  

   survey 
  " 
  of 
  the 
  lake 
  shore 
  and 
  islands. 
  This 
  survey 
  was 
  designed 
  to 
  measure 
  

   as 
  accurately 
  as 
  possible 
  all 
  peculiarities 
  and 
  variations 
  in 
  the 
  range 
  of 
  the 
  

   insect, 
  and 
  all 
  variations 
  in 
  its 
  density 
  as 
  they 
  occurred 
  from 
  time 
  to 
  time 
  in 
  

   the 
  same 
  localities, 
  or 
  from 
  one 
  locality 
  to 
  another 
  at 
  the 
  same 
  time. 
  Coincidently 
  

   observations 
  were 
  made 
  and 
  notes 
  kept 
  concerning 
  every 
  factor 
  known 
  or 
  suspected 
  

   to 
  operate 
  in 
  the 
  " 
  natural 
  control 
  ' 
  of 
  range 
  and 
  density, 
  with 
  the 
  object 
  of 
  

   identifying 
  those 
  of 
  major 
  importance, 
  i.e., 
  such 
  as 
  are 
  responsible 
  for 
  easily 
  

   measurable 
  peculiarities 
  in 
  range 
  or 
  variations 
  in 
  density. 
  No 
  attempt 
  was 
  made 
  

   to 
  study 
  specific 
  factors 
  — 
  such 
  as 
  natural 
  enemies 
  — 
  unless 
  they 
  were 
  indicated 
  to 
  

   be 
  of 
  sufficient 
  importance 
  to 
  account 
  for 
  measurable 
  variations 
  in 
  density. 
  By 
  

   this 
  procedure 
  much 
  useless 
  work 
  was 
  avoided. 
  

  

  These 
  methods 
  were 
  especially 
  applicable 
  to 
  studies 
  having 
  as 
  their 
  ultimate 
  

   or 
  practical 
  objective 
  the 
  extermination 
  of 
  the 
  insect. 
  But 
  after 
  the 
  readjustment 
  

   of 
  old 
  ideas 
  and 
  preconceptions 
  of 
  the 
  economic 
  problem, 
  made 
  necessary 
  by 
  the 
  

   discovery 
  that 
  it 
  is 
  practically 
  unnecessary, 
  and 
  even, 
  for 
  economic 
  reasons, 
  unde- 
  

   sirable 
  to 
  undertake 
  extermination 
  of 
  fly, 
  entirely 
  different 
  methods 
  of 
  study 
  were 
  

   demanded. 
  The 
  questions 
  to 
  be 
  answered 
  involved 
  less 
  the 
  range 
  and 
  density 
  of 
  

   tsetse 
  and 
  the 
  factors 
  controlling 
  them 
  than 
  the 
  injuriousness 
  of 
  the 
  tsetse 
  and 
  

   the 
  factors 
  in 
  its 
  control. 
  The 
  injuriousness 
  of 
  the 
  insect, 
  or 
  its 
  injurious 
  status 
  

   in 
  relation 
  to 
  a 
  population 
  occupying 
  the 
  same 
  or 
  adjoining 
  territory, 
  is, 
  in 
  part, 
  

   but 
  only 
  in 
  relatively 
  small 
  part, 
  determined 
  by 
  density 
  of 
  infestation. 
  Factors 
  

   of 
  equal 
  or 
  even 
  greater 
  importance 
  are 
  those 
  which 
  control 
  the 
  frequency 
  of 
  contact 
  

   between 
  flies 
  and 
  persons, 
  and 
  these 
  include 
  the 
  relative 
  abundance 
  of 
  host 
  animals 
  

   {such 
  as 
  crocodiles), 
  the 
  principal 
  occupations 
  of 
  the 
  population, 
  the 
  precise 
  location 
  

   of 
  points 
  of 
  occupation 
  or 
  concourse 
  of 
  the 
  population 
  with 
  respect 
  to 
  colony 
  centres 
  

  

  