﻿OCT. 
  4, 
  1922 
  STEINER 
  AND 
  HEINLY: 
  CONTROL 
  OF 
  INJURIOUS 
  NEMAS 
  373 
  

  

  and 
  females, 
  — 
  males 
  are 
  rare 
  in 
  M. 
  ohtusus 
  and 
  in 
  most 
  of 
  the 
  species 
  

   they 
  have 
  not 
  yet 
  been 
  found. 
  

  

  Hermaphroditism 
  in 
  Mononchus 
  papillatus 
  is 
  of 
  some 
  importance 
  

   in 
  our 
  problem, 
  as 
  every 
  individual 
  is 
  able 
  to 
  reproduce, 
  not 
  being 
  

   dependent 
  upon 
  the 
  presence 
  of 
  the 
  other 
  sex 
  for 
  propagation. 
  This 
  

   may 
  prove 
  of 
  great 
  value 
  in 
  using 
  this 
  species 
  as 
  a 
  means 
  of 
  fighting 
  

   injurious 
  nemas. 
  

  

  B. 
  The 
  egg 
  and 
  the 
  embryonic 
  evolution. 
  — 
  -The 
  spermatozoa 
  in 
  

   M. 
  papillatus 
  are 
  very 
  minute, 
  the 
  ovary 
  producing 
  them 
  early, 
  

   and 
  later 
  on 
  the 
  eggs. 
  Fertilization 
  then 
  takes 
  place. 
  The 
  ovary 
  

   of 
  the 
  nema 
  is 
  syngonic, 
  and 
  the 
  animal 
  a 
  protandric 
  syngone. 
  (See 
  

   Cobb 
  5.) 
  We 
  could 
  not 
  determine 
  the 
  number 
  of 
  sperms 
  produced 
  

   but 
  it 
  is 
  probably 
  rather 
  restricted, 
  as 
  we 
  observed 
  several 
  cases 
  of 
  

   old 
  females 
  that 
  formed 
  eggs 
  (at 
  times 
  depositing 
  them 
  also) 
  , 
  that 
  were 
  

   probably 
  not 
  fertilized, 
  as 
  they 
  never 
  developed. 
  

  

  There 
  were 
  never 
  more 
  than 
  two 
  eggs 
  in 
  one 
  uterus 
  

   at 
  a 
  time, 
  and 
  usually 
  two 
  or 
  three 
  to 
  the 
  individual 
  

   were 
  observed. 
  It 
  was 
  rather 
  a 
  rare 
  occurrence 
  for 
  the 
  

   animal 
  to 
  have 
  four 
  eggs, 
  two 
  in 
  each 
  uterus. 
  The 
  eggs 
  

   were 
  elongated, 
  and 
  appeared 
  smooth 
  shelled 
  in 
  the 
  

   uterus, 
  but 
  when 
  deposited 
  the 
  surface 
  seemed 
  covered 
  ^*^- 
  ^- 
  ^^^ 
  °^ 
  ^'!' 
  

   with 
  protuberances, 
  having 
  the 
  appearance 
  of 
  short 
  ^^^^^^ 
  showing 
  

   ridges, 
  the 
  whole 
  surface 
  having 
  a 
  somewhat 
  lace-like 
  the 
  protuber- 
  

  

  effect. 
  (See 
  Fig. 
  2.) 
  ances 
  on 
  the 
  

  

  If 
  the 
  mononchs 
  lived 
  in 
  an 
  approximately 
  normal 
  ess 
  s 
  e 
  

   condition, 
  an 
  average 
  of 
  two 
  or 
  three 
  eggs 
  was 
  deposited 
  daily. 
  Our 
  

   slide 
  cultures 
  showed 
  a 
  production 
  of 
  two 
  or 
  less, 
  but 
  the 
  tube 
  cultures 
  

   gave 
  higher 
  results, 
  and 
  it 
  may 
  be 
  that 
  under 
  natural 
  conditions 
  in 
  the 
  

   soil 
  the 
  egg 
  production 
  is 
  still 
  higher. 
  

  

  In 
  the 
  slide 
  cultures, 
  the 
  maximum 
  number 
  of 
  eggs 
  deposited 
  by 
  one 
  

   female 
  was 
  twenty-eight 
  in 
  twelve 
  days, 
  the 
  animal 
  then 
  ceasing 
  to 
  

   produce; 
  but 
  in 
  tubes 
  our 
  records 
  showed 
  eighteen 
  eggs 
  produced 
  in 
  

   six 
  days, 
  and 
  forty-one 
  larvae 
  hatched 
  from 
  eggs 
  produced 
  by 
  one 
  fe- 
  

   male 
  in 
  twenty 
  days 
  were 
  also 
  found. 
  The 
  exact 
  number 
  of 
  eggs 
  pro- 
  

   duced 
  may 
  have 
  exceeded 
  this, 
  as 
  even 
  with 
  the 
  most 
  careful 
  inspec- 
  

   tion, 
  eggs 
  and 
  larvae 
  may 
  escape 
  notice. 
  Experiments 
  along 
  this 
  

   line 
  are 
  still 
  being 
  carried 
  on 
  and 
  higher 
  figures 
  may 
  be 
  obtained. 
  

  

  The 
  number 
  of 
  eggs 
  laid 
  by 
  one 
  M. 
  papillatus 
  seems 
  very 
  small 
  when 
  

   compared 
  with 
  that 
  of 
  some 
  other 
  free-living 
  species, 
  as, 
  for 
  instance, 
  

   species 
  of 
  Rhabditis, 
  in 
  which 
  within 
  a 
  few 
  days 
  eight 
  hundred 
  or 
  more 
  

  

  