﻿186 
  PROCEEDINGS 
  OF 
  THE 
  FOURTH 
  ENTOMOLOGICAL 
  MEETING 
  

  

  A 
  series 
  of 
  parallel 
  observations 
  was 
  carried 
  out 
  on 
  the 
  effects 
  of 
  a 
  

   few 
  more 
  halogen 
  salts 
  of 
  mercury 
  (HgBrg, 
  Hgig, 
  HgCL 
  and 
  Hglg 
  2KI) 
  ; 
  

   the 
  two 
  soluble 
  salts 
  (HgClg 
  and 
  Hgl2 
  2KI) 
  were 
  much 
  quicker 
  in 
  action 
  

   than 
  the 
  other 
  two. 
  This 
  led 
  to 
  an 
  attempt 
  to 
  find 
  out 
  how 
  far 
  the 
  

   toxicity 
  would 
  increase 
  if 
  HgCl 
  were 
  offered 
  in 
  dissolved 
  condition, 
  and 
  

   for 
  this 
  purpose 
  a 
  more 
  or 
  less 
  neutral 
  solvent 
  was 
  necessary 
  which 
  

   would 
  dissolve 
  the 
  salt 
  without 
  the 
  latter 
  having 
  to 
  undergo 
  any 
  chemical 
  

   transformation. 
  It 
  seemed 
  possible 
  that, 
  in 
  the 
  case 
  of 
  HgCl, 
  such 
  a 
  

   condition 
  could 
  be 
  realized 
  in 
  pepsin 
  which 
  is 
  capable 
  of 
  dissolving 
  the 
  

   salt 
  unchanged. 
  In 
  Graph 
  5 
  it 
  will 
  be 
  seen 
  that 
  some 
  difference 
  was 
  

   observed 
  between 
  the 
  effect 
  of 
  a 
  mixture 
  of 
  pepsin 
  and 
  HgCl 
  and 
  that 
  

   of 
  HgCl 
  only. 
  But 
  in 
  the 
  present 
  state 
  of 
  this 
  inquiry 
  no 
  definite 
  state- 
  

   ment 
  is 
  possible. 
  

  

  With 
  regard 
  to 
  the 
  discrepant 
  results, 
  as 
  shown 
  in 
  the 
  graphs, 
  obtained 
  

   with 
  HgCl, 
  under 
  conditions 
  practically 
  identical, 
  three 
  explanations 
  

   present 
  themselves 
  : 
  

  

  (1) 
  Quicker 
  death 
  might 
  be 
  the 
  result 
  of 
  comparatively 
  debilitated 
  

  

  condition 
  of 
  the 
  larva. 
  It 
  would 
  be 
  hardly 
  profitable 
  to 
  

   discuss 
  this 
  possibility. 
  

  

  (2) 
  As 
  the 
  salt 
  presumbly 
  acted 
  in 
  the 
  solid 
  state, 
  death 
  must 
  have 
  

  

  been 
  dependent 
  on 
  the 
  extent 
  to 
  which 
  the 
  salt 
  particles 
  

   were 
  distributed 
  over 
  the 
  surface 
  of 
  the 
  water. 
  This 
  seems 
  

   to 
  be 
  borne 
  out 
  by 
  the 
  fact 
  that 
  in 
  certain 
  cases 
  the 
  action 
  

   of 
  the 
  salt 
  increased 
  after 
  some 
  days, 
  which 
  was 
  probably 
  

   the 
  result 
  of 
  thorough 
  disruption 
  and 
  consequent 
  distribution 
  

   of 
  the 
  salt 
  particles 
  effected 
  by 
  its 
  prolonged 
  contact 
  with 
  

   water 
  : 
  the 
  fact 
  of 
  a 
  comparatively 
  heavy 
  dose 
  of 
  the 
  salt 
  

   sometimes 
  taking 
  a 
  longer 
  time 
  to 
  kill 
  the 
  larvae 
  gives 
  support 
  

   to 
  this 
  assumption. 
  

  

  (3) 
  It 
  might 
  be 
  the 
  result 
  of 
  variation 
  in 
  atmospheric 
  temperature. 
  

  

  Larvse 
  experimented 
  with 
  in 
  June 
  and 
  July 
  died 
  more 
  quickly 
  

   than 
  those 
  experimented 
  with 
  in 
  November. 
  It 
  will 
  be 
  

   seen 
  that 
  the 
  series 
  of 
  lines 
  with 
  0-001 
  gm. 
  HgCl 
  in 
  Graph 
  1 
  

   are 
  generally 
  much 
  shorter 
  than 
  the 
  corresponding 
  lines 
  in 
  

   Graph 
  4 
  which 
  refers 
  to 
  winter 
  observations. 
  This 
  difference 
  

   can 
  hardly 
  be 
  accounted 
  for 
  by 
  any 
  of 
  the 
  two 
  preceding 
  

   explanations. 
  So 
  far 
  as 
  has 
  been 
  observed 
  by 
  placing 
  the 
  

   larvae 
  in 
  incubators, 
  the 
  thermal 
  factor 
  seems 
  to 
  be 
  of 
  import- 
  

   ance. 
  It 
  is 
  proposed 
  to 
  continue 
  the 
  inquiry, 
  the 
  object 
  being 
  

   not 
  only 
  to 
  find 
  out 
  whether 
  toxicity 
  is 
  governed 
  by 
  tempera- 
  

   ture 
  but 
  also 
  how 
  far 
  the 
  relation 
  between 
  the 
  two 
  approxi- 
  

   mates 
  the 
  formula, 
  t=f 
  (t)^, 
  when 
  t 
  denotes 
  toxicity 
  and 
  

   t^, 
  temperature. 
  

  

  