﻿16 
  On 
  Occurrence 
  of 
  Multinucleate 
  Cells 
  in 
  Vegetative 
  Tissues. 
  

  

  In 
  Cerebratulus, 
  also, 
  the 
  whole 
  quality 
  of 
  the 
  cytoplasm 
  of 
  the 
  developing 
  

   egg 
  is 
  altered 
  by 
  the 
  escape 
  of 
  nuclear 
  substance 
  into 
  it.* 
  

  

  In 
  several 
  of 
  the 
  plants 
  studied 
  by 
  us, 
  notably 
  in 
  the 
  case 
  of 
  Tropceolum 
  

   majus, 
  nuclear 
  degenerations 
  take 
  place 
  at 
  a 
  very 
  early 
  period 
  whilst 
  mitotic 
  

   divisions 
  of 
  other 
  nuclei 
  are 
  still 
  actively 
  proceeding. 
  It 
  is 
  possible 
  that 
  

   such 
  a 
  process 
  of 
  continuous 
  nuclear 
  dissolution, 
  accompanied 
  by 
  repeated 
  

   nuclear 
  multiplication 
  through 
  the 
  growth 
  and 
  division 
  of 
  the 
  remaining 
  

   nucleus 
  or 
  nuclei 
  of 
  the 
  cell, 
  may 
  contribute 
  to 
  the 
  cytoplasm 
  material 
  which 
  

   is 
  of 
  importance 
  in 
  cell 
  metabolism. 
  

  

  It 
  appears 
  probable, 
  therefore, 
  that 
  in 
  some 
  or 
  in 
  all 
  of 
  the 
  ways 
  mentioned 
  

   above, 
  the 
  multinucleate 
  condition 
  is 
  of 
  direct 
  or 
  indirect 
  value 
  to 
  the 
  plant. 
  

   The 
  multinucleate 
  state 
  may 
  have 
  arisen, 
  in 
  the 
  first 
  place, 
  merely 
  as 
  a 
  

   chance 
  incident 
  in 
  the 
  transition 
  from 
  young 
  to 
  adult 
  tissue, 
  owing 
  to 
  the 
  

   higher 
  susceptibility 
  of 
  the 
  cytoplasm 
  to 
  the 
  altering 
  conditions. 
  But 
  once 
  

   it 
  made 
  its 
  appearance, 
  it 
  would 
  conceivably 
  afford 
  the 
  organism 
  a 
  distinct 
  

   advantage 
  in 
  carrying 
  out 
  the 
  chemical 
  processes 
  associated 
  with 
  growth, 
  and 
  

   might 
  tend 
  to 
  become 
  perpetuated 
  as 
  a 
  definite 
  physiological 
  phase 
  in 
  the 
  

   history 
  of 
  growing 
  members. 
  

  

  EXPLANATION 
  OF 
  PLATE. 
  

  

  (All 
  drawings 
  were 
  made 
  with 
  the 
  aid 
  of 
  a 
  camera 
  lucida. 
  Leitz's 
  2 
  - 
  50 
  mm. 
  oil 
  

   immersion 
  lens 
  was 
  used 
  with 
  various 
  eye-pieces, 
  except 
  in 
  the 
  case 
  of 
  figs. 
  27, 
  28 
  and 
  29, 
  

   in 
  which 
  Zeiss's 
  2 
  mm. 
  oil 
  immersion 
  lens 
  and 
  C.0.6 
  were 
  used. 
  The 
  magnifications 
  

   given 
  below 
  have 
  been 
  reduced 
  to 
  \ 
  in 
  reproduction.) 
  

   Figs. 
  1 
  and 
  2. 
  — 
  Phragmospheres 
  of 
  Zea 
  Mays, 
  L. 
  ( 
  x 
  800.) 
  

  

  Fig. 
  3.— 
  Multinucleate 
  cells 
  from 
  leaf-sheath 
  of 
  Zea 
  Mays 
  seedling, 
  1 
  inch 
  high. 
  ( 
  x 
  800.) 
  

   Fig. 
  4. 
  — 
  Multinucleate 
  cell 
  from 
  stem 
  of 
  Zea 
  Mays, 
  just 
  above 
  first 
  node. 
  ( 
  x 
  800.) 
  

   Fig. 
  5. 
  — 
  Binucleate 
  rudiment 
  of 
  a 
  vessel 
  from 
  the 
  root 
  of 
  Zea 
  Mays, 
  just 
  behind 
  growing 
  

   point. 
  (x800.) 
  

  

  Fig. 
  6. 
  — 
  One 
  degenerating 
  and 
  one 
  functional 
  nucleus 
  in 
  one 
  cell 
  of 
  Zea 
  Mays 
  ; 
  stem 
  

  

  about 
  5 
  mm. 
  above 
  the 
  ninth 
  node. 
  ( 
  x 
  2000.) 
  

   Fig. 
  7. 
  — 
  Nucleus 
  in 
  prophase 
  of 
  division 
  and 
  another 
  in 
  resting 
  state 
  in 
  a 
  cell 
  of 
  

  

  Anthriscus 
  sylvestris, 
  Hoffm. 
  ( 
  x 
  2000.) 
  

   Fig. 
  8. 
  — 
  Cell 
  from 
  stem 
  of 
  Anthriscus 
  sylvestris 
  with 
  one 
  phragmosphere, 
  one 
  nucleus 
  

  

  in 
  anaphase 
  of 
  division, 
  and 
  one 
  nucleus 
  in 
  resting 
  condition. 
  (x800.) 
  

   Figs. 
  9, 
  10, 
  11 
  and 
  12. 
  — 
  Stages 
  in 
  development 
  of 
  phragmosphere 
  of 
  Anthriscus 
  sylvestris. 
  

  

  (X2000.) 
  

  

  Fig. 
  13. 
  — 
  Multinucleate 
  cell 
  from 
  stem 
  of 
  Anthriscus 
  sylvestris. 
  ( 
  x 
  800.) 
  

  

  Fig. 
  14. 
  — 
  One 
  of 
  two 
  nuclei 
  from 
  a 
  cell 
  in 
  the 
  older 
  region 
  of 
  stem 
  of 
  Anthriscus 
  

  

  sylvestris. 
  (x2000.) 
  ' 
  

   Fig. 
  15. 
  — 
  Four 
  nuclei 
  in 
  a 
  cell 
  of 
  second 
  internode 
  of 
  young 
  plant 
  of 
  Anthriscus 
  sylvestris. 
  

  

  Three 
  nuclei 
  are 
  still 
  active 
  and 
  one 
  is 
  degenerating. 
  ( 
  x 
  2000.) 
  

  

  * 
  MacBride, 
  E. 
  W., 
  " 
  Pres. 
  Add. 
  to 
  Section 
  D 
  (Zoology)," 
  ' 
  Brit. 
  Ass. 
  Adv. 
  Sci. 
  Eep., 
  

   86th 
  Meeting,' 
  Newcastle-on-Tyne, 
  pp. 
  403-417 
  (1917 
  for 
  1916). 
  

  

  