﻿376 
  jouRNAiy 
  OF 
  the; 
  Washington 
  acadkmy 
  of 
  sciences 
  vol. 
  12, 
  no. 
  16 
  

  

  senile 
  M. 
  papillatus 
  have 
  a 
  decreased 
  efficiency 
  in 
  combating 
  nematode 
  

   pests. 
  

  

  V. 
  I.BNGTH 
  OF 
  IvlFE 
  OF 
  M. 
  PAPILLATUS 
  

  

  Eighteen 
  weeks 
  was 
  the 
  maximum 
  length 
  of 
  life 
  observed 
  for 
  M. 
  

   papillatus 
  in 
  a 
  slide 
  culture; 
  the 
  tube 
  culture 
  method 
  showed 
  the 
  life 
  

   period 
  under 
  more 
  normal 
  conditions 
  to 
  be 
  very 
  much 
  longer. 
  Com- 
  

   pared 
  with 
  the 
  length 
  of 
  life 
  of 
  other 
  nemas, 
  even 
  excluding 
  forms 
  of 
  

   Rhabditis, 
  Diplogaster, 
  Plectus 
  spec, 
  etc. 
  that 
  live 
  on 
  decaying 
  matter, 
  

   this 
  period 
  seems 
  very 
  long, 
  but 
  it 
  may 
  not 
  be 
  exceptional 
  for 
  soil 
  

   nematodes. 
  At 
  the 
  Zoological 
  Station 
  of 
  Cette 
  (France) 
  the 
  senior 
  

   author 
  kept 
  adult 
  marine 
  nematodes 
  alive 
  for 
  a 
  comparatively 
  long 
  

   time, 
  as 
  for 
  example 
  an 
  adult 
  species 
  of 
  Thoracostoma 
  for 
  over 
  thirty 
  

   days. 
  We 
  may 
  therefore 
  conclude 
  that 
  free 
  living 
  nematodes 
  have 
  a 
  

   much 
  longer 
  life 
  period 
  than 
  is 
  usually 
  supposed. 
  

  

  To 
  a 
  certain 
  degree, 
  this 
  fact 
  may 
  compensate 
  for 
  the 
  restricted 
  

   number 
  of 
  eggs 
  of 
  M. 
  papillatus 
  when 
  considering 
  the 
  effect 
  of 
  this 
  

   species 
  on 
  the 
  nema 
  population 
  of 
  the 
  soil 
  and 
  the 
  whole 
  community 
  

   of 
  life 
  therein, 
  as, 
  it 
  means 
  an 
  increase 
  of 
  the 
  efficiency 
  of 
  this 
  species 
  as 
  

   a 
  destructive 
  factor. 
  

  

  VI. 
  FOOD 
  AND 
  FEEDING-HABITS 
  OF 
  M. 
  PAPILLATUS 
  

  

  In 
  working 
  out 
  our 
  problem, 
  a 
  study 
  of 
  the 
  food 
  and 
  feeding 
  habits 
  

   was 
  of 
  the 
  greatest 
  interest. 
  From 
  statements 
  made 
  by 
  the 
  investiga- 
  

   tors 
  already 
  mentioned, 
  it 
  was 
  known 
  that 
  M. 
  papillatus 
  fed 
  on 
  other 
  

   nematodes. 
  It 
  was 
  necessary 
  to 
  discover 
  whether 
  the 
  carnivorous 
  

   habit 
  lasted 
  throughout 
  its 
  life 
  or 
  for 
  only 
  a 
  certain 
  period. 
  To 
  obtain 
  

   these 
  facts 
  was 
  of 
  great 
  importance 
  as 
  they 
  determined 
  largely 
  whether 
  

   M. 
  papillatus 
  can 
  become 
  a 
  really 
  efficient 
  agent 
  in 
  combating 
  nema- 
  

   tode 
  pests. 
  Our 
  experiments 
  along 
  this 
  line 
  confirmed 
  fully 
  what 
  Cobb 
  

   in 
  several 
  papers 
  stated 
  to 
  be 
  true. 
  In 
  our 
  cultures, 
  M. 
  papillatus 
  

   lived 
  exclusively 
  on 
  other 
  nemas, 
  also 
  appearing 
  at 
  times 
  to 
  devour 
  

   small 
  soil 
  particles. 
  The 
  consumption 
  of 
  soil 
  grains 
  seemed 
  to 
  be 
  of 
  

   chief 
  importance 
  in 
  the 
  first 
  larval 
  stage 
  of 
  the 
  animal, 
  and 
  we 
  observed 
  

   likewise 
  in 
  the 
  intestine 
  of 
  adults 
  soil 
  particles 
  of 
  unknown 
  origin. 
  The 
  

   important 
  influence 
  of 
  the 
  presence 
  of 
  soil 
  on 
  our 
  cultures 
  seemed 
  also 
  

   to 
  confirm 
  these 
  observations. 
  

  

  The 
  larval 
  M. 
  papillatus, 
  just 
  hatched 
  from 
  the 
  egg, 
  was 
  very 
  active. 
  

   Its 
  intestine 
  at 
  first 
  was 
  transparent 
  ; 
  the 
  cells 
  of 
  the 
  thin 
  wall 
  at 
  this 
  

   stage 
  were 
  easily 
  seen, 
  and 
  their 
  nuclei 
  as 
  well. 
  But 
  in 
  a 
  suitable 
  

   medium, 
  a 
  few 
  days 
  were 
  sufficient 
  to 
  transform 
  this 
  colorless 
  intestine 
  

  

  