﻿354 
  

  

  W. 
  F. 
  FISKE. 
  

  

  Much 
  wider 
  variations 
  in 
  sex 
  ratio 
  between 
  different 
  islands 
  were 
  subsequently 
  

   noted, 
  and 
  the 
  extremes 
  are 
  given 
  in 
  Table 
  II. 
  In 
  all 
  such 
  cases 
  — 
  or 
  at 
  least 
  in 
  

   most 
  of 
  them 
  — 
  explanations 
  for 
  variations 
  in 
  sex 
  ratio 
  must 
  be 
  found 
  in 
  the 
  purely 
  

   local 
  conditions 
  of 
  life, 
  and 
  not 
  in 
  climatic 
  or 
  seasonal 
  differences. 
  

  

  The 
  absolute 
  extremes 
  encountered 
  in 
  the 
  course 
  of 
  the 
  investigations, 
  together 
  

   with 
  the 
  records 
  for 
  all 
  colonies 
  of 
  fly 
  or 
  infected 
  districts 
  in 
  which 
  female 
  percentage 
  

   exceeded 
  45 
  '0 
  are 
  presented 
  in 
  Tables 
  III 
  and 
  IV. 
  

  

  Table 
  II. 
  

   Extreme 
  Range 
  in 
  Variation 
  of 
  Sex 
  Ratio 
  (observed) 
  between 
  different 
  Islands 
  

  

  in 
  Victoria 
  Nyanza. 
  

  

  

  

  

  T»0+0 
  

  

  

  

  Catch 
  of 
  Fly. 
  

  

  

  Ua>TJQ. 
  

  

  Total. 
  

  

  Females. 
  

  

  Kimmi 
  

   Luambu 
  . 
  

   Wema 
  

   Bugovu 
  . 
  

   Ngamba 
  . 
  

   Bugabu 
  . 
  

   Mbugwe 
  . 
  , 
  

   Nkase 
  

  

  

  

  

  January 
  1914 
  

   July 
  1915 
  . 
  

   February 
  1914 
  . 
  

   March 
  1915 
  . 
  

   January 
  1914 
  

   August 
  1914 
  

   September 
  19 
  14 
  

   February 
  1915 
  

  

  

  

  7065 
  

   557 
  

  

  1413 
  

   415 
  

   761 
  

   704 
  

   73 
  

   101 
  

  

  63-5 
  % 
  

  

  44-3 
  % 
  

  

  39-1 
  % 
  

  

  39-0 
  % 
  

  

  7'9 
  % 
  

  

  7'9 
  % 
  

  

  4-1 
  % 
  

  

  3-0 
  % 
  

  

  Table 
  III. 
  

   Absolute 
  Extremes 
  in 
  Sex 
  Ratio 
  as 
  encountered 
  in 
  course 
  of 
  these 
  Investigations 
  

  

  on 
  Islands 
  and 
  Mainland. 
  

  

  

  

  

  Per 
  

  

  

  Locality. 
  

  

  Date. 
  

  

  Catch. 
  

  

  cent. 
  

   Fern. 
  

  

  Kemarks. 
  

  

  Manene 
  Island. 
  . 
  

  

  March 
  1915.. 
  

  

  46 
  

  

  0-0 
  

  

  Largest 
  catch 
  with 
  no 
  females. 
  

  

  Bugaba 
  Beach 
  . 
  . 
  

  

  August 
  1914. 
  . 
  

  

  106 
  

  

  1-9 
  

  

  t 
  Lowest 
  percentage 
  of 
  females 
  in 
  catch 
  

  

  Manene 
  Island. 
  . 
  

  

  March 
  1915.. 
  

  

  107 
  

  

  1-9 
  

  

  / 
  of 
  over 
  100 
  flies. 
  

  

  Bukakata 
  

  

  July 
  1915.. 
  

  

  30 
  

  

  90-0 
  

  

  Largest 
  percentage 
  of 
  females 
  in 
  catch 
  

   of 
  over 
  10 
  flies. 
  

  

  Bale 
  Beach 
  

  

  June 
  1915.. 
  

  

  241 
  

  

  84-6 
  

  

  Largest 
  percentage 
  of 
  females 
  in 
  catch 
  

   of 
  over 
  100 
  flies 
  

  

  Table 
  IV. 
  

   Catch 
  in 
  those 
  Districts 
  on 
  Mainland 
  where 
  Female 
  Percentage 
  averaged 
  45*0 
  

  

  or 
  over 
  for 
  entire 
  District. 
  

  

  District. 
  

  

  Percentage 
  of 
  

   Females. 
  

  

  Mujuzi 
  Creek 
  Colony, 
  Buddu 
  

   Bukakata 
  South 
  Colony, 
  Buddu 
  

   Kaziru 
  District, 
  Buddu 
  

   Kitebo 
  District 
  Mawakotu 
  . 
  . 
  

   G-wamba 
  District, 
  South 
  Buddu 
  

  

  June 
  

  

  1915. 
  . 
  

  

  July 
  

  

  1915.. 
  

  

  July 
  

  

  1915. 
  . 
  

  

  August 
  

  

  1915. 
  . 
  

  

  July 
  

  

  1915. 
  . 
  

  

  1611 
  

  

  298 
  

  

  991 
  

  

  1199 
  

  

  3422 
  

  

  67-6 
  

   51-0 
  

   50-6 
  

   47-5 
  

  

  45-0 
  

  

  