﻿Voi. 
  47 
  

  

  No. 
  8 
  

  

  BULLETIN 
  

  

  OF 
  TH£ 
  

  

  TORREY 
  BOTANICAL 
  CLUB 
  

  

  August, 
  1920 
  

  

  Cell-division 
  of 
  the 
  pollen-mother-cell 
  of 
  Cobaea 
  scandens 
  alba 
  

  

  Wanda 
  Kirkbride 
  Farr 
  

   (with 
  plate 
  14) 
  

  

  SpindJe 
  formation 
  in 
  the 
  pollen-mother-cells 
  of 
  Cobaea 
  scandens 
  

   Cav. 
  was 
  studied 
  by 
  Lawson* 
  In 
  1898. 
  The 
  stages 
  represented 
  

   in 
  his 
  plates 
  extend 
  from 
  the 
  resting 
  pollen-mother-cell 
  to 
  the 
  

   time 
  of 
  nuclear 
  reorganization 
  after 
  the 
  second 
  division. 
  With 
  

   reference 
  to 
  the 
  division 
  c^ 
  the 
  cell 
  the 
  following 
  statements 
  are 
  

   made 
  (pp. 
  177 
  and 
  178): 
  

  

  There 
  is 
  no 
  cell-plate 
  formed 
  until 
  after 
  the 
  second 
  division. 
  ... 
  In 
  fig. 
  24 
  we 
  

   see 
  three 
  daughter-nuclei 
  in 
  the 
  same 
  plane. 
  Bj^ 
  means 
  of 
  the 
  continuous 
  fibers 
  and 
  

   mantle-fibers 
  they 
  are 
  connected 
  with 
  one 
  another. 
  These 
  fibers 
  now 
  occupy 
  almost 
  

   the 
  entire 
  cell-cavity. 
  Cell-plates 
  are 
  now 
  formed 
  in 
  the 
  usual 
  way. 
  Swellings 
  

   appear 
  on 
  the 
  connecting 
  fibers; 
  these 
  increase 
  in 
  size, 
  and 
  finally 
  result 
  in 
  forming 
  

   cell-walls 
  which 
  separate 
  the 
  daughter-cells 
  from 
  one 
  another. 
  

  

  A 
  complete 
  disappearance 
  of 
  the 
  spindle-fibers 
  is 
  shown 
  to 
  take 
  

  

  (/ 
  

  

  The 
  

  

  four 
  nuclei 
  resulting 
  from 
  the 
  second 
  division 
  are 
  arranged 
  tetra- 
  

   hedrally 
  in 
  the 
  mother-cell. 
  Every 
  one 
  of 
  the 
  twenty-four 
  cells 
  

   figured 
  shows 
  evidence 
  of 
  a 
  thickening 
  of 
  the 
  mother-walL 
  

  

  The 
  behavior 
  of 
  the 
  cells 
  in 
  Cobaea^ 
  as 
  reported 
  by 
  Lawson, 
  

   resembles 
  in 
  some 
  respects 
  that 
  of 
  the 
  pollen-mother-cells 
  of 
  

   Nicotiana 
  Tabacum, 
  Primula 
  sine?isisy 
  Tropaeolum 
  majus, 
  and 
  

   certain 
  other 
  dicotyledons 
  in 
  which 
  cell-division 
  was 
  found 
  by 
  C. 
  

   H. 
  Farrt 
  to 
  be 
  accomplished, 
  not 
  by 
  the 
  formation 
  of 
  a 
  cell-plate, 
  

  

  [The 
  Bulletin 
  for 
  July 
  (47: 
  279-324, 
  pL 
  10-13) 
  was 
  issued 
  August 
  9, 
  1920] 
  

   * 
  Lawson, 
  A. 
  A. 
  Some 
  observations 
  on 
  the 
  development 
  of 
  the 
  karyokinetic 
  

  

  spindle 
  in 
  the 
  pollen-mother-cells 
  of 
  Cobaea 
  scandens 
  Cav. 
  Proc. 
  California 
  Acad. 
  

  

  Sci. 
  Hot. 
  III. 
  I: 
  168-188. 
  pL 
  33-36. 
  1898. 
  

  

  t 
  Farr, 
  C. 
  H, 
  Cytokinesis 
  of 
  the 
  pollen-mother-cells 
  of 
  certain 
  dicotyledons. 
  

  

  Mem. 
  N. 
  Y. 
  Bot. 
  Gard. 
  6; 
  253-317. 
  p'. 
  27-29, 
  1916. 
  

  

  325 
  

  

  