﻿OCT. 
  4, 
  1922 
  STEINER 
  AND 
  HEINLY 
  : 
  CONTROL 
  OF 
  INJURIOUS 
  NRMAS 
  385 
  

  

  feeding 
  habits 
  have 
  been 
  described 
  in 
  this 
  paper. 
  There 
  are 
  other 
  

   species 
  of 
  nemas 
  with 
  a 
  similar 
  significance. 
  Here 
  is 
  a 
  great 
  field 
  for 
  

   study. 
  Investigations 
  should 
  also 
  be 
  carried 
  on 
  to 
  show 
  more 
  defi- 
  

   nitely 
  the 
  relations 
  of 
  these 
  predatory 
  forms 
  to 
  rotifers, 
  oligochaetes 
  

   and 
  other 
  soil 
  animals. 
  

  

  6. 
  As 
  a 
  factor 
  in 
  the 
  humification 
  of 
  the 
  soil, 
  in 
  transformation 
  and 
  

   removal 
  of 
  all 
  kinds 
  of 
  organic 
  matter, 
  decaying 
  bodies, 
  etc. 
  

  

  ' 
  7. 
  As 
  assisting 
  in 
  the 
  aeration 
  of 
  the 
  soil. 
  We 
  know 
  how 
  very 
  im- 
  

   portant 
  aeration 
  of 
  soil 
  is 
  for 
  the 
  growth 
  of 
  bacteria 
  and 
  all 
  kinds 
  of 
  

   plants. 
  Quite 
  possibly 
  these 
  millions 
  of 
  nematodes 
  living 
  in 
  the 
  soil 
  

   are 
  highly 
  useful 
  aerators. 
  

  

  In 
  order 
  to 
  solve 
  the 
  problem 
  of 
  the 
  relation 
  of 
  soil 
  nemas 
  to 
  soil 
  

   fertility, 
  we 
  require 
  a 
  knowledge 
  of 
  the 
  nema 
  population 
  in 
  the 
  soil 
  

   itself 
  and 
  we 
  also 
  need 
  to 
  know 
  : 
  

  

  1. 
  The 
  composition 
  of 
  the 
  nema 
  population, 
  the 
  species 
  found 
  and 
  

   their 
  numeric 
  representation 
  in 
  all 
  kinds 
  of 
  soil, 
  — 
  ;sandy, 
  humus, 
  

   swampy, 
  dry-soil, 
  hard 
  clay, 
  etc. 
  

  

  2. 
  The 
  horizontal 
  and 
  vertical 
  distribution 
  of 
  nemas 
  in 
  all 
  kinds 
  of 
  

   soil 
  and 
  the 
  reasons 
  for 
  this. 
  

  

  3. 
  The 
  seasonal 
  changes 
  of 
  the 
  different 
  species, 
  the 
  number 
  of 
  spe- 
  

   cies 
  and 
  the 
  number 
  of 
  individuals 
  of 
  each 
  species. 
  

  

  4. 
  The 
  influence 
  of 
  habitat 
  on 
  the 
  nematode 
  population 
  including 
  

   physical, 
  chemical 
  and 
  biological 
  factors 
  found 
  in 
  the 
  habitat. 
  The 
  

   biological 
  factors 
  include 
  kinds 
  of 
  crops 
  and 
  other 
  forms 
  of 
  vegetation 
  

   that 
  may 
  be 
  present. 
  , 
  

  

  The 
  working 
  out 
  of 
  these 
  problems 
  will 
  surely 
  enable 
  us 
  to 
  conclude 
  

   why 
  nema 
  pests 
  are 
  absent 
  in 
  some 
  cases, 
  and 
  why 
  in 
  apparently 
  similar 
  

   conditions 
  they 
  exist 
  in 
  such 
  enormous 
  numbers. 
  A 
  large 
  field 
  is 
  thus 
  

   opened 
  up 
  for 
  investigations, 
  the 
  results 
  of 
  which 
  will 
  be 
  of 
  great 
  im- 
  

   portance 
  to 
  agricultural 
  science. 
  

  

  REFERENCES 
  

  

  1. 
  Berliner, 
  Ernst 
  and 
  Busch, 
  Kurt, 
  "tjber 
  die 
  Ziichtung 
  des 
  Riibennematoden 
  

   {Heterodera 
  schachtli 
  Schmidt) 
  auf 
  Agar." 
  Biol. 
  Centralblatt 
  34: 
  349. 
  1914. 
  

  

  2. 
  Byars, 
  L. 
  p. 
  "Preliminary 
  notes 
  on 
  the 
  cultivation 
  of 
  the 
  plant 
  parasitic 
  nematode, 
  

   Heterodera 
  radicicola." 
  Phytopathology 
  4: 
  323-326. 
  pi. 
  21. 
  1914. 
  

  

  3. 
  Byars, 
  L. 
  P. 
  "The 
  nematode 
  disease 
  of 
  wheat 
  caused 
  by 
  Tylenchus 
  tritici." 
  

   U. 
  S. 
  Dept. 
  Agr. 
  Bull. 
  842. 
  1920. 
  

  

  4. 
  Cobb, 
  N. 
  A. 
  "The 
  Mononchs. 
  A 
  genus 
  of 
  free-living 
  predatory 
  nematodes. 
  

   Contributions 
  to 
  a 
  science 
  of 
  Hematology 
  VI." 
  Soil 
  Science 
  3. 
  1917. 
  

  

  5. 
  Cobb, 
  N. 
  A. 
  "Notes 
  on 
  Nemas. 
  Contributions 
  to 
  a 
  Science 
  of 
  Nematology 
  V." 
  

   Waverly 
  Press, 
  Baltimore, 
  1917. 
  

  

  6. 
  Cobb, 
  N. 
  A. 
  "Nematodes 
  of 
  the 
  slow 
  sand 
  filter 
  beds 
  of 
  American 
  cities. 
  Con- 
  

   tributions 
  to 
  a 
  vScience 
  of 
  Nematology 
  VII." 
  1918. 
  

  

  