﻿Vol. 
  XV. 
  No. 
  12.-B0TANICAL 
  Gazette.-Dec, 
  i89o. 
  

  

  Notes 
  on 
  the 
  development 
  of 
  Tubnliua 
  eyiindrica 
  and 
  allied 
  

  

  species 
  of 
  Ulyxomyeefes. 
  

  

  GEORGE 
  A. 
  REX. 
  

  

  That 
  part 
  of 
  the 
  life 
  cycle 
  of 
  the 
  curious 
  and 
  ever 
  inter- 
  

   eshng 
  Myxomycetes, 
  which 
  includes 
  the 
  formative 
  Plasmod- 
  

   ium 
  and 
  its 
  subsequent 
  stages 
  of 
  development 
  into 
  mature 
  

   sporangia, 
  has 
  been 
  the 
  subject 
  of 
  extensive 
  physiological 
  

  

  J^'u^ 
  the 
  laboratory, 
  but 
  has 
  been 
  as 
  yet 
  but 
  little 
  consid- 
  

   ered 
  by 
  the 
  system 
  atists. 
  

  

  Notwithstanding 
  the 
  anomalous 
  character 
  of 
  the 
  origin 
  

   and 
  development 
  of 
  these 
  marvelous 
  organisms, 
  their 
  gen- 
  

   eric 
  and 
  specific 
  limits 
  are 
  practically 
  well 
  defined 
  and 
  ap- 
  

   parently 
  as 
  stable 
  as 
  in 
  any 
  other 
  natural 
  group. 
  This 
  is 
  

   essentially 
  true, 
  even 
  though 
  the 
  sporangia 
  of 
  the 
  mature 
  

   Myxomycetes 
  manifest 
  a 
  well 
  marked 
  tendency 
  to 
  variation 
  

   lorm, 
  color 
  and 
  structure 
  which 
  seems 
  to 
  characterize 
  

   some 
  genera 
  especially, 
  wdiile 
  only 
  exceptionally 
  found 
  in 
  

  

  f 
  i^'^^^^^^6 
  as 
  this 
  variation 
  is 
  in 
  some 
  cases, 
  it 
  may 
  be 
  

   lound 
  by 
  careful 
  field 
  work 
  or 
  by 
  an 
  analysis 
  of 
  a 
  large 
  

   number 
  of 
  specimens 
  to 
  fall 
  within 
  specific 
  lines, 
  and 
  to 
  be 
  

   aue 
  mainly 
  to 
  local 
  external 
  influences. 
  

  

  Many 
  causes 
  operate 
  to 
  produce 
  these 
  results 
  in 
  the 
  ma- 
  

  

  armth 
  combined 
  with 
  great 
  humidity 
  

   ^eveiop 
  rapidly 
  and 
  multiply 
  with 
  wonderful 
  exuberance, 
  

  

  < 
  using 
  the 
  resulting 
  sporangia 
  to 
  lose 
  their 
  possibly 
  simple 
  

   ma!r 
  ^^^^"^cter 
  and 
  become 
  clustered, 
  distorted 
  or 
  plas- 
  

  

  oaiocarpous 
  in 
  form. 
  Climate, 
  the 
  season 
  of 
  the 
  year, 
  or 
  

   hahit 
  ?^^ 
  ^^^^ 
  practically 
  the 
  same 
  effect, 
  the 
  altitude 
  of 
  

   from 
  ]' 
  ^^^^ 
  ^^^^^ 
  ^ 
  difference 
  in 
  the 
  time 
  of 
  development 
  

   som 
  P^^"^°d^um 
  to 
  maturity, 
  of 
  from 
  twenty-four 
  hours 
  in 
  

   ^ 
  cases 
  to 
  nearly 
  a 
  w^eek 
  in 
  others, 
  with 
  a 
  corresponding 
  

  

  erence 
  in 
  results. 
  

  

  am 
  

  

  into 
  V 
  '^ 
  ^ 
  ^^ 
  ^^^ 
  ^^ys 
  of 
  July 
  and 
  August 
  will 
  erect 
  quick! 
  

   scattered, 
  globose, 
  long-stiped 
  sporangia 
  which 
  ruptur 
  

  

  e 
  

  

  