﻿1890. 
  J 
  BOTANICAL 
  GAZETTE. 
  121 
  

  

  If 
  a 
  full 
  expression 
  of 
  opinion 
  can 
  be 
  had 
  through 
  the 
  journals, 
  or 
  

   otherwise, 
  the 
  Association 
  meeting 
  at 
  Indianapolis 
  will 
  give 
  opportunity 
  

   to 
  arrange 
  plans 
  and 
  efiect 
  an 
  organization. 
  — 
  J. 
  C, 
  A. 
  

  

  Relation 
  oF 
  light 
  to 
  epinastj 
  in 
  Solanum 
  tuberosum.— 
  In 
  his 
  article 
  

   on 
  Epinasty 
  and 
  Hyponasty, 
  in 
  the 
  Annals 
  of 
  Botany 
  (August, 
  1889), 
  Vines 
  

   catalogues 
  certain 
  experiments 
  which 
  indicate 
  that 
  epinasty 
  is 
  stimulated 
  

   in 
  the 
  case 
  of 
  Helianthus 
  annuus 
  rather 
  by 
  absence 
  of 
  light 
  than 
  by 
  its 
  

   presence 
  — 
  thus 
  offering 
  a 
  criticism 
  upon 
  the 
  well-known 
  photo-epinastic 
  

   theory 
  of 
  Detmer. 
  A 
  specimen 
  of 
  Solanum 
  tuberosum 
  growing 
  in 
  the 
  

   plant-house 
  of 
  the 
  University 
  of 
  Minnesota 
  has 
  seemed 
  to 
  present 
  some 
  

   interesting 
  evidence 
  in 
  the 
  same 
  line. 
  A 
  plant 
  of 
  the 
  Solanum, 
  about 
  fif- 
  

  

  r 
  

  

  teen 
  centimeters 
  in 
  height, 
  was 
  exposed 
  to 
  diminished 
  and 
  one-sided 
  il- 
  

   lumination 
  for 
  a 
  period 
  of 
  twenty-four 
  hours 
  and 
  pronounced 
  epinastic 
  

   curvatures 
  resulted. 
  When 
  in 
  the 
  plant-house 
  the 
  shoot 
  and 
  leaves 
  of 
  

   this 
  specimen 
  were 
  growing 
  under 
  the 
  influence 
  of 
  strong 
  direct 
  sun- 
  

   light 
  augmented 
  by 
  reflection 
  from 
  the 
  snow 
  and 
  by 
  the 
  southerly 
  expos- 
  

   ure. 
  When 
  removed 
  from 
  the 
  house 
  the 
  plant 
  was 
  placed 
  in 
  a 
  lecture-room 
  

   lighted 
  by 
  three 
  large 
  windows 
  facing 
  the 
  south. 
  The 
  removal 
  took 
  place 
  

   about 
  three 
  o'clock 
  in 
  the 
  afternoon, 
  and 
  by 
  four 
  o'clock 
  the 
  following 
  

   day 
  the 
  older 
  leaves 
  were 
  turned 
  downward 
  so 
  that 
  the 
  tips 
  touched 
  the 
  

   stem, 
  and 
  at 
  the 
  same 
  time 
  transverse 
  epinastic 
  curvatures 
  had 
  taken 
  

   place, 
  rolling 
  the 
  leaves 
  so 
  that 
  in 
  two 
  cases 
  the 
  margins 
  touched 
  each 
  

   other. 
  The 
  younger 
  leaves 
  were 
  in 
  four 
  cases 
  thrown 
  into 
  helicoid 
  

   curves, 
  reminding 
  one 
  of 
  the 
  circinate 
  vernation 
  in 
  ferns, 
  and 
  in 
  three 
  

   cases 
  turned 
  down 
  against 
  the 
  stem 
  in 
  the 
  same 
  fashion 
  as 
  the 
  mature 
  

   leaves. 
  Contemporaneously 
  the 
  shoot 
  had 
  taken 
  a 
  slanting 
  position 
  to- 
  

   wards 
  the 
  window— 
  from 
  which 
  the 
  plant 
  was 
  distant 
  a 
  little 
  over 
  seven 
  

   feet— 
  and 
  finally 
  made 
  an 
  angle 
  of 
  thirty-five 
  degrees 
  with 
  the 
  perpendic- 
  

   ular. 
  This 
  strongly 
  epinastic 
  and 
  heliotropic 
  position 
  was 
  maintained 
  

   for 
  four 
  days, 
  and 
  at 
  the 
  end 
  of 
  this 
  time 
  the 
  plant 
  was 
  returned 
  to 
  the 
  

   well 
  illuminated 
  green-house 
  where, 
  after 
  twenty-four 
  hours, 
  the 
  leaves 
  

   began 
  to 
  resume 
  their 
  normal 
  position, 
  although 
  the 
  axis 
  remained 
  in 
  a 
  

   heliotropically 
  curved 
  position. 
  After 
  five 
  days 
  had 
  passed 
  the 
  most 
  of 
  

   the 
  leaves 
  were 
  in 
  the 
  ordinary 
  position, 
  and 
  only 
  one 
  of 
  the 
  oldest 
  pre- 
  

   served 
  any 
  marked 
  traces 
  of 
  its 
  stimulated 
  position. 
  The 
  temperature 
  of 
  

   the 
  green-house 
  was 
  constant 
  at 
  about 
  80"* 
  P., 
  while 
  that 
  of 
  the 
  lecture- 
  

   room 
  was 
  variable, 
  running 
  from 
  about 
  60^ 
  F. 
  in 
  the 
  early 
  morning 
  to 
  

   74"" 
  F. 
  in 
  the 
  afternoon. 
  

  

  The 
  behavior 
  of 
  this 
  Solanum 
  would 
  indicate 
  that 
  even 
  a 
  slight 
  

   diminution 
  in 
  illumination 
  permits 
  epinastic 
  curvatures 
  to 
  manifest 
  

   themselves 
  very 
  strongly, 
  but 
  further 
  experiments 
  should 
  be 
  made 
  before 
  

   . 
  It 
  would 
  be 
  possible 
  to 
  refer 
  the 
  position 
  described 
  in 
  this 
  brief 
  note 
  en- 
  

   tirely 
  to 
  the 
  diminished 
  illumination.— 
  Conway 
  Macmillak, 
  University 
  of 
  

   Minnesota. 
  

  

  