﻿OCT. 
  4, 
  1922 
  STEINER 
  AND 
  HEINLY 
  : 
  CONTROL 
  OF 
  INJURIOUS 
  NEMAS 
  375 
  

  

  D. 
  The 
  adult 
  and 
  senile 
  Mononchus 
  papillatus. 
  — 
  Soon 
  after 
  moulting 
  

   the 
  last 
  time, 
  the 
  mononch 
  began 
  to 
  produce 
  eggs. 
  At 
  this 
  age, 
  the 
  

   nema 
  was 
  extremely 
  voracious. 
  The 
  number 
  of 
  eggs 
  produced 
  

   seemed 
  to 
  be 
  in 
  direct 
  proportion 
  to 
  the 
  number 
  of 
  destroyed 
  and 
  

   devoured 
  nemas. 
  

  

  The 
  maximum 
  duration 
  of 
  &gg 
  production 
  observed 
  was 
  twenty 
  days, 
  

   but 
  further 
  experiments 
  may 
  probably 
  show 
  a 
  longer 
  period. 
  

  

  The 
  period 
  after 
  the 
  cessation 
  of 
  &gg 
  production 
  was 
  called 
  the 
  senile 
  

   stage. 
  It 
  seemed 
  very 
  remarkable 
  that 
  this 
  senile 
  stage 
  was 
  of 
  such 
  

   long 
  duration 
  as 
  compared 
  with 
  the 
  length 
  of 
  the 
  other 
  periods. 
  In 
  

   one 
  case 
  the 
  senile 
  period 
  lasted 
  ten 
  weeks, 
  while 
  the 
  combined 
  length 
  

   of 
  the 
  other 
  periods 
  was 
  only 
  eight 
  weeks. 
  In 
  many 
  hermaphroditic 
  

   nematodes 
  there 
  are 
  long 
  senile 
  stages. 
  The 
  senior 
  author 
  observed 
  

   in 
  cultures 
  of 
  the 
  hermaphroditic 
  Rhabditis 
  elegans 
  Maupas, 
  the 
  length 
  

   of 
  the 
  different 
  life 
  periods 
  to 
  be 
  as 
  follows 
  : 
  

  

  April 
  20 
  — 
  newly 
  hatched 
  larva, 
  — 
  (larval 
  stage 
  lasted 
  two 
  days 
  or 
  

   less) 
  . 
  

  

  April 
  24 
  — 
  first 
  production 
  of 
  eggs, 
  — 
  (egg 
  production 
  stage 
  lasted 
  

   two 
  to 
  three 
  days) 
  . 
  

  

  April 
  26 
  — 
  production 
  of 
  eggs 
  stopped, 
  — 
  (senile 
  stage 
  lasted 
  thirteen 
  

   days) 
  . 
  

  

  May 
  9 
  — 
  death. 
  

  

  Of 
  a 
  life 
  period 
  of 
  eighteen 
  to 
  nineteen 
  days, 
  thirteen 
  were 
  of 
  the 
  

   senile 
  stage, 
  that 
  is, 
  the 
  period 
  after 
  the 
  last 
  fertilized 
  egg 
  was 
  laid. 
  

   The 
  senile 
  stage 
  was 
  therefore 
  two 
  or 
  three 
  times 
  longer 
  than 
  the 
  other 
  

   Hfe 
  periods 
  taken 
  together. 
  The 
  protandric 
  syngonism 
  (Cobb 
  5) 
  

   of 
  these 
  forms 
  is 
  probably 
  the 
  cause 
  of 
  this. 
  If 
  spermatozoa 
  are 
  es- 
  

   sential 
  and 
  only 
  a 
  certain 
  number 
  of 
  spermatozoa 
  are 
  produced, 
  then 
  

   when 
  this 
  supply 
  is 
  exhausted, 
  if 
  the 
  gonads 
  are 
  unable 
  to 
  produce 
  more 
  

   sperms, 
  all 
  subsequent 
  ova 
  will 
  fail 
  of 
  further 
  development, 
  and 
  

   senility 
  begins. 
  

  

  The 
  same 
  thing 
  seems 
  to 
  happen 
  in 
  Mononchus 
  papillatus. 
  The 
  

   comparatively 
  enormous 
  length 
  of 
  the 
  senile 
  stage 
  may 
  be 
  the 
  result 
  

   of 
  the 
  inability 
  of 
  the 
  syngone 
  to 
  produce 
  sperm 
  cells 
  a 
  second 
  time. 
  

   The 
  senile 
  period 
  of 
  ten 
  weeks 
  was 
  observed 
  on 
  a 
  slide 
  culture, 
  and 
  un- 
  

   der 
  more 
  favorable 
  conditions 
  it 
  may 
  last 
  very 
  much 
  longer. 
  

  

  In 
  judging 
  the 
  relationship 
  between 
  Mononchus 
  papillatus 
  and 
  other 
  

   soil 
  nematodes 
  the 
  above 
  facts 
  are 
  of 
  some 
  importance, 
  as 
  the 
  amount 
  

   of 
  food 
  required 
  during 
  the 
  senile 
  stage 
  was 
  very 
  small 
  compared 
  with 
  

   that 
  devoured 
  during 
  the 
  egg-producing 
  period. 
  Consequently 
  all 
  

  

  