﻿Occurrence 
  of 
  Multinucleate 
  Cells 
  in 
  Vegetative 
  Tissues. 
  15 
  

  

  cells 
  of 
  the 
  parasitic 
  Copepod 
  Levnanthropus 
  possess 
  similarly 
  lobed 
  nuclei. 
  

   The 
  Malpighian 
  tubes 
  of 
  insects 
  are 
  also 
  lined 
  with 
  cells 
  possessing 
  lobed 
  

   nuclei. 
  

  

  The 
  so-called 
  " 
  nurse-cells 
  " 
  of 
  many 
  insect 
  ovaries 
  form 
  another 
  striking 
  

   illustration 
  of 
  cells 
  engaged 
  in 
  intense 
  metabolic 
  activity, 
  in 
  which 
  the 
  

   nuclei 
  have 
  enlarged 
  their 
  surface 
  by 
  intricate 
  lobing 
  (Korschelt).* 
  In 
  the 
  

   secretory 
  cells 
  of 
  the 
  mammary 
  gland 
  investigated 
  by 
  Nissenf 
  the 
  same 
  end 
  

   is 
  reached 
  by 
  the 
  actual 
  division 
  of 
  the 
  nucleus 
  into 
  two 
  or 
  three 
  daughter 
  

   nuclei, 
  without 
  an 
  accompanying 
  cell-division 
  at 
  first 
  taking 
  place. 
  

  

  Among 
  plants 
  we 
  also 
  find 
  records 
  in 
  the 
  literature 
  of 
  similar 
  facts. 
  The 
  

   tapetal 
  cells 
  of 
  many 
  stamens 
  form 
  a 
  good 
  instance 
  of 
  this 
  kind. 
  In 
  certain 
  

   pollen 
  grains, 
  at 
  the 
  time 
  when 
  their 
  cytoplasm 
  is 
  undergoing 
  a 
  rapid 
  

   increase 
  in 
  quantity, 
  the 
  tube-nucleus 
  becomes 
  amoeboid 
  in 
  form. 
  

  

  In 
  Utricularia 
  haustoria 
  are 
  formed 
  at 
  both 
  ends 
  of 
  the 
  embryo 
  sac, 
  while 
  

   part 
  of 
  the 
  placenta, 
  near 
  the 
  base 
  of 
  the 
  ovule, 
  becomes 
  modified 
  as 
  a 
  

   nutritive 
  tissue, 
  which 
  is 
  tapped 
  by 
  the 
  micropylar 
  haustorium. 
  In 
  

   U. 
  oligosperma 
  this 
  placental 
  nutritive 
  tissue 
  is 
  immensely 
  developed, 
  and 
  

   shows 
  lobed 
  nuclei 
  and 
  some 
  cells 
  with 
  two 
  nuclei.J 
  Here, 
  again, 
  we 
  find 
  

   the 
  association 
  of 
  lobed 
  nuclei 
  or 
  of 
  several 
  free 
  nuclei 
  with 
  a 
  tissue 
  in 
  

   which 
  active 
  metabolic 
  processes 
  are 
  certainly 
  taking 
  place. 
  

  

  Altogether 
  there 
  is 
  a 
  considerable 
  body 
  of 
  facts 
  all 
  pointing 
  to 
  the 
  import- 
  

   ance 
  of 
  the 
  establishment 
  of 
  as 
  large 
  an 
  area 
  of 
  contact 
  as 
  possible 
  between 
  

   nucleus 
  and 
  cytoplasm 
  during 
  periods 
  of 
  marked 
  metabolic 
  activity. 
  This 
  

   end 
  is 
  attained 
  either 
  by 
  the 
  lobing 
  of 
  a 
  single 
  nucleus 
  or 
  through 
  the 
  

   development 
  of 
  a 
  multinucleate 
  condition. 
  

  

  In 
  another 
  way 
  the 
  establishment 
  of 
  a 
  plurality 
  of 
  nuclei 
  by 
  repeated 
  

   mitotic 
  divisions 
  may 
  aid 
  the 
  interchange 
  of 
  materials 
  between 
  nucleus 
  and 
  

   cytoplasm. 
  At 
  each 
  division 
  the 
  nuclear 
  membrane 
  disappears, 
  and 
  the 
  

   karyolymph 
  mingles 
  directly 
  with 
  the 
  cytoplasm. 
  By 
  this 
  means, 
  materials 
  

   elaborated 
  within 
  the 
  nucleus 
  rapidly 
  pass 
  into 
  the 
  cytoplasm 
  and 
  can 
  be 
  

   utilised 
  in 
  cell 
  metabolism. 
  In 
  this 
  connection 
  we 
  may 
  recall 
  the 
  case 
  of 
  the 
  

   Ascidian 
  Cynthia 
  partita. 
  Here 
  the 
  nuclear 
  sap 
  iu 
  the 
  developing 
  egg 
  

   escapes 
  into 
  the 
  cytoplasm, 
  where 
  it 
  becomes 
  located 
  in 
  a 
  definite 
  region 
  ; 
  in 
  

   the 
  course 
  of 
  development 
  it 
  is 
  confined 
  to 
  certain 
  cells 
  which 
  ultimately 
  

   form 
  the 
  ectoderm. 
  The 
  ectoderm 
  thus 
  " 
  owes 
  its 
  origin 
  to 
  the 
  nuclear 
  sap." 
  

  

  * 
  Korschelt, 
  E., 
  ' 
  Zoologische 
  Jahrbiicher 
  : 
  Abtheilung 
  fur 
  Anatomie 
  u. 
  Ontogenie 
  der 
  

   Thiere,' 
  vol. 
  4 
  (Part 
  I, 
  1889), 
  pp. 
  1-154 
  (1891). 
  

  

  t 
  Nissen, 
  F., 
  ' 
  Archiv 
  f. 
  Mikr. 
  Anat.,' 
  vol. 
  26, 
  pp. 
  337-342 
  (1886). 
  

   \ 
  Merz, 
  M., 
  ' 
  Flora,' 
  vol. 
  84 
  (Erganzungsband), 
  pp. 
  69-87 
  (1897). 
  

  

  