﻿103 
  

  

  Out 
  of 
  the 
  entire 
  lot 
  of 
  caterpillars 
  (110) 
  fed 
  with 
  unsterilised 
  

   Berkefeld 
  filtrate, 
  28 
  died 
  with 
  typical 
  wilt 
  symptoms. 
  Polyhedral 
  bodies 
  

   were 
  abundant, 
  but 
  there 
  were 
  no 
  bacteria. 
  Other 
  caterpillars 
  died 
  from 
  

   other 
  causes 
  ; 
  the 
  caterpillars 
  dying 
  thus 
  differed 
  from 
  those 
  dying 
  

   of 
  wilt 
  disease 
  in 
  being 
  tough 
  instead 
  of 
  flaccid, 
  and 
  in 
  the 
  absence 
  in 
  

   them 
  of 
  polyhedral 
  bodies. 
  Some 
  of 
  the 
  caterpillars 
  were 
  killed 
  by 
  the 
  

   Tachinid 
  parasite, 
  Compsilura 
  concinnata. 
  A 
  greater 
  number 
  of 
  

   caterpillars 
  (48 
  out 
  of 
  85) 
  died 
  in 
  the 
  experiments 
  with 
  the 
  unfiltered 
  

   virus. 
  This 
  seems 
  to 
  show 
  that 
  the 
  virus 
  is 
  filterable, 
  but 
  with 
  difficulty. 
  

   Among 
  the 
  entire 
  number 
  of 
  controls, 
  162 
  caterpillars, 
  only 
  three 
  died 
  

   of 
  wilt, 
  equivalent 
  to 
  about 
  1*8 
  per 
  cent., 
  a 
  very 
  small 
  percentage, 
  

   which 
  can 
  be 
  overlooked 
  as 
  an 
  experimental 
  error. 
  

  

  The 
  polyhedral 
  bodies 
  have 
  as 
  yet 
  revealed 
  nothing 
  of 
  a 
  parasitic 
  

   nature 
  ; 
  they 
  may 
  be 
  a 
  resting 
  stage 
  of 
  a 
  filterable 
  vegetative 
  form, 
  

   but 
  the 
  authors 
  are 
  rather 
  inclined 
  to 
  regard 
  them 
  as 
  reaction 
  bodies. 
  

   They 
  are 
  possibly 
  products 
  of 
  nuclear 
  digestion, 
  produced 
  by 
  the 
  

   virus 
  invading 
  the 
  nuclei 
  and 
  digesting 
  the 
  chromatin. 
  

  

  One 
  more 
  matter 
  is 
  considered, 
  viz., 
  the 
  question 
  as 
  to 
  whether 
  the 
  

   disease 
  is 
  carried 
  by 
  the 
  air, 
  as 
  is 
  held 
  to 
  be 
  the 
  case 
  by 
  W. 
  Reiff. 
  

   Details 
  are 
  given 
  of 
  the 
  experiments 
  carried 
  out 
  to 
  test 
  this 
  view, 
  and 
  

   the 
  conclusion 
  is 
  that 
  the 
  wind 
  is 
  not 
  an 
  important 
  factor 
  in 
  transport- 
  

   ing 
  the 
  disease, 
  and 
  that 
  infection 
  in 
  nature 
  occurs 
  when 
  caterpillars 
  

   feed 
  on 
  leaves 
  soiled 
  by 
  the 
  juices 
  of 
  dead 
  individuals. 
  

  

  A 
  striking 
  phenomenon 
  observed 
  in 
  all 
  the 
  experiments 
  was 
  the 
  

   large 
  number 
  of 
  moths 
  obtained 
  from 
  caterpillars 
  which 
  had 
  been 
  

   repeatedly 
  infected. 
  This 
  seems 
  to 
  suggest 
  a 
  degree 
  of 
  immunity 
  

   possessed 
  by 
  some 
  of 
  the 
  caterpillars, 
  and 
  agrees 
  with 
  the 
  observations 
  

   in 
  the 
  field, 
  where, 
  in 
  a 
  given 
  locality, 
  the 
  disease 
  raged 
  for 
  several 
  

   weeks, 
  and 
  yet 
  moths 
  were 
  seen 
  later 
  in 
  abundance. 
  

  

  GouGH 
  (L. 
  H.). 
  The 
  Fumigation 
  Campaign 
  of 
  1912-1913. 
  — 
  Agric. 
  

   Jl. 
  of 
  Egypt, 
  Cairo, 
  iii, 
  part 
  1, 
  1913, 
  pp. 
  38-41. 
  

  

  The 
  fumigation 
  with 
  hydrocyanic 
  acid 
  gas 
  in 
  Egypt 
  of 
  citrus 
  trees 
  

   affected 
  with 
  scale-insects 
  was 
  commenced 
  by 
  the 
  Department 
  of 
  

   Agriculture 
  in 
  January 
  1912. 
  Two 
  gardens 
  containing 
  about 
  3,000 
  

   small 
  trees 
  were 
  fumigated 
  with 
  satisfactory 
  results. 
  For 
  the 
  

   fumigation 
  campaign 
  of 
  1913-1914, 
  the 
  equipment 
  consisted 
  of 
  seventy- 
  

   two 
  fumigation 
  sheets, 
  of 
  which 
  thirty 
  were 
  20 
  feet 
  in 
  diameter, 
  thirty 
  

   34 
  feet 
  in 
  diameter, 
  and 
  twelve 
  45 
  feet 
  in 
  diameter. 
  These, 
  except 
  

   five 
  of 
  the 
  largest, 
  had 
  been 
  made 
  at 
  Cawnpore 
  to 
  the 
  pattern 
  given 
  in 
  

   Mr. 
  Woglum's 
  paper 
  (Fumigation 
  of 
  Citrus 
  trees, 
  tJ.S. 
  Bureau 
  of 
  

   Entomology, 
  Bull. 
  90). 
  The 
  cloth 
  used 
  w^as 
  1\ 
  oz. 
  drill 
  ; 
  the 
  dosage 
  

   was 
  calculated 
  from 
  the 
  tables 
  given 
  in 
  that 
  paper, 
  one 
  ounce 
  charges 
  

   being 
  given 
  in 
  every 
  case 
  to 
  allow 
  for 
  the 
  loose 
  texture 
  of 
  the 
  cloth. 
  

   A 
  start 
  was 
  made 
  in 
  October 
  1912, 
  in 
  the 
  garden 
  of 
  H.H. 
  the 
  Khedive, 
  

   at 
  Kubba, 
  the 
  fumigation 
  campaign 
  being 
  carried 
  out 
  by 
  the 
  staff, 
  

   consisting 
  of 
  a 
  European 
  Inspector, 
  and 
  at 
  first 
  seven, 
  but 
  generally 
  

   two, 
  students. 
  The 
  tallest 
  trees 
  fumigated 
  were 
  23 
  feet 
  high, 
  those 
  

   taller 
  being 
  usually 
  too 
  old 
  to 
  be 
  profitable. 
  The 
  balance 
  sheet 
  showed 
  

   a 
  small 
  loss. 
  

  

  