﻿362 
  W. 
  F. 
  FISKE. 
  

  

  for 
  constant 
  vigilance. 
  All 
  the 
  fly 
  boys 
  were 
  on 
  the 
  qui 
  vive, 
  and 
  continually 
  fighting 
  

   off 
  flies, 
  in 
  sharp 
  contrast 
  to 
  complete 
  indifference 
  toward 
  them 
  on 
  the 
  22nd 
  and 
  

   previously." 
  

  

  Undoubtedly 
  more 
  flies 
  would 
  have 
  bitten 
  man 
  on 
  the 
  25th 
  than 
  actually 
  engorged 
  

   upon 
  the 
  pigs 
  that 
  day, 
  and 
  their 
  changed 
  behaviour 
  toward 
  man 
  was 
  equally 
  as 
  

   notable 
  as 
  shown 
  by 
  the 
  table 
  (IX) 
  toward 
  pig. 
  

  

  This 
  experiment 
  of 
  hunting 
  the 
  wild 
  hosts 
  of 
  tsetse 
  was 
  accidentally 
  repeated 
  

   on 
  the 
  peninsula 
  of 
  Neozi 
  on 
  the 
  island 
  of 
  Bugalla 
  (Sesse) 
  where 
  camp 
  was 
  pitched 
  

   in 
  November 
  1914. 
  There 
  was 
  a 
  not 
  heavy 
  or 
  noticeable 
  infestation 
  by 
  tsetse, 
  

   and 
  the 
  principle 
  host 
  of 
  it 
  was 
  situtunga. 
  But 
  no 
  sooner 
  was 
  the 
  camp 
  occupied 
  

   than 
  these 
  animals 
  evacuated 
  the 
  peninsula 
  and 
  were 
  seen 
  crossing 
  the 
  isthmus 
  

   connecting 
  it 
  with 
  the 
  mainland 
  one 
  to 
  two 
  miles 
  distant 
  only 
  a 
  few 
  hours 
  after 
  the 
  

   men 
  began 
  work 
  on 
  the 
  tent 
  and 
  huts. 
  On 
  the 
  following 
  day 
  (Sunday) 
  the 
  behaviour 
  

   of 
  the 
  flies 
  was 
  not 
  notably 
  changed, 
  but 
  on 
  the 
  third 
  day 
  they 
  became 
  so 
  unbearably 
  

   persistent 
  in 
  their 
  attack 
  that 
  (in 
  view 
  of 
  the 
  possibility 
  of 
  human 
  infection 
  from 
  

   their 
  bites) 
  the 
  camp 
  was 
  abandoned. 
  

  

  Such 
  conditions 
  are 
  likely 
  to 
  be 
  produced 
  in 
  almost 
  any 
  fly- 
  infested 
  locality 
  by 
  the 
  

   advent 
  of 
  a 
  temporary 
  population 
  sufficiently 
  large 
  to 
  produce 
  a 
  measurable 
  effect 
  

   upon 
  host 
  animals. 
  They 
  are 
  particularly 
  likely 
  to 
  be 
  created 
  when, 
  as 
  was 
  formerly 
  

   a 
  custom 
  of 
  the 
  natives, 
  temporary 
  fishing 
  camps 
  are 
  located 
  on 
  small 
  islets 
  which 
  

   are 
  otherwise 
  uninhabited. 
  If 
  a 
  person 
  infected 
  by 
  the 
  human 
  parasite 
  is 
  a 
  member 
  

   of 
  such 
  a 
  fishing 
  party 
  conditions 
  will 
  be 
  extremely 
  favourable 
  to 
  the 
  transmission 
  

   of 
  the 
  organism 
  to 
  other 
  members 
  of 
  the 
  expedition. 
  

  

  II 
  (c). 
  Correlation 
  between 
  High 
  Percentage 
  of 
  Females 
  naturally 
  prevailing 
  and 
  

   Persistence 
  of 
  Attack 
  upon 
  Man. 
  

  

  The 
  islands 
  listed 
  in 
  Table 
  X 
  were 
  visited 
  in 
  January 
  and 
  February 
  1914 
  in 
  company 
  

   with 
  Dr. 
  Carpenter. 
  Large 
  collections 
  of 
  fly 
  were 
  made 
  and 
  the 
  average 
  of 
  male 
  

   density 
  and 
  of 
  female 
  percentage 
  recorded 
  for 
  the 
  several 
  observation 
  points 
  on 
  

   each 
  island 
  is 
  also 
  given 
  in 
  the 
  table. 
  Dr. 
  Carpenter 
  and 
  I 
  were 
  agreed, 
  at 
  the 
  close 
  

   of 
  the 
  tour, 
  that 
  the 
  relative 
  persistency 
  of 
  attack 
  by 
  fly 
  upon 
  man 
  was 
  fairly 
  estimated 
  

   as 
  in 
  the 
  table. 
  

  

  The 
  difference 
  between 
  behaviour 
  of 
  fly 
  towards 
  man 
  on 
  Kimmi 
  and 
  Damba, 
  

   respectively, 
  was 
  truly 
  extraordinary— 
  equally 
  as 
  extraordinary 
  as 
  its 
  changed 
  

   behaviour 
  on 
  Lugazi 
  islet 
  following 
  the 
  banishment 
  of 
  its 
  wild 
  hosts. 
  And 
  these 
  

   differences 
  are 
  strikingly 
  correlated 
  with 
  variations 
  in 
  sex 
  ratio, 
  and 
  not 
  at 
  all, 
  or 
  

   only 
  as 
  by 
  accident, 
  with 
  variations 
  in 
  density 
  of 
  infestation 
  (as 
  measured 
  by 
  density 
  

   of 
  active 
  males). 
  

  

  These 
  observations 
  have 
  been 
  many 
  times 
  confirmed, 
  notably 
  by 
  the 
  behaviour 
  

   of 
  flies 
  on 
  Bale 
  fly 
  beach 
  (Table 
  VIII), 
  where 
  the 
  female 
  percentage 
  was 
  84 
  '6, 
  and 
  

   where, 
  despite 
  constant 
  vigilance, 
  the 
  observer 
  was 
  actually 
  bitten 
  about 
  15 
  times 
  

   per 
  hour. 
  This 
  is 
  more 
  times 
  in 
  one 
  hour 
  than 
  he 
  was 
  bitten 
  in 
  more 
  than 
  six 
  weeks 
  

   spent 
  in 
  field 
  work 
  on 
  the 
  islands 
  of 
  Bulago, 
  Kome, 
  Damba, 
  Tavu, 
  Lula 
  and 
  others, 
  

   from 
  1st 
  November 
  to 
  15th 
  December 
  1913. 
  A 
  record 
  was 
  kept 
  of 
  the 
  number 
  of 
  

   bites 
  inflicted 
  during 
  this 
  period 
  and 
  it 
  totalled 
  only 
  9. 
  When 
  the 
  fly 
  is 
  no 
  more 
  

  

  