﻿568 
  J. 
  B. 
  FARMER 
  AND 
  D. 
  SHOVE. 
  

  

  being 
  once 
  more 
  rejoined 
  after 
  the 
  true 
  reduction 
  has 
  been 
  

   effected. 
  The 
  normal 
  process 
  is 
  again 
  resumed 
  at 
  the 
  spot 
  

   where 
  the 
  divergence 
  first 
  occurred^ 
  and 
  the 
  longitudinal 
  

   fission 
  achieves 
  its 
  logical 
  result 
  in 
  the 
  equatoriii.1 
  plate 
  of 
  

   the 
  homotype 
  division. 
  

  

  EXPLANATION 
  OF 
  PLATES 
  42 
  & 
  43, 
  

  

  Illustrating 
  Prof. 
  J. 
  B. 
  Farmer's 
  and 
  Miss 
  D. 
  Shove's 
  

   paper 
  " 
  On 
  the 
  Structure 
  and 
  Development 
  of 
  the 
  

   Somatic 
  and 
  Heterotype 
  Chromosomes 
  of 
  Trades- 
  

   cantia 
  Virginica," 
  

  

  Somatic 
  Divisions. 
  

  

  Fig. 
  1. 
  — 
  Resting 
  nucleus, 
  chromatin 
  evenly 
  distributed. 
  

  

  Fig. 
  2. 
  — 
  Nucleus 
  siiowing 
  definite 
  strands 
  of 
  liuinwith 
  chromatin 
  granules. 
  

  

  Fig. 
  3. 
  — 
  Linin 
  strands 
  undergoing 
  contraction. 
  

  

  Fig. 
  2a. 
  — 
  Nucleus 
  showing 
  reticulate 
  structures. 
  

  

  Fig. 
  3a. 
  — 
  Breaking 
  down 
  of 
  reticulum, 
  witli 
  shortening 
  and 
  thickening 
  of 
  

   the 
  strands. 
  

  

  Fig. 
  4. 
  — 
  Chromatin 
  granules 
  arranged 
  in 
  single 
  rows 
  in 
  the 
  linin 
  strands, 
  

   and 
  strands 
  in 
  form 
  of 
  spireme. 
  

  

  Figs. 
  5, 
  G.— 
  The 
  linin 
  strand 
  further 
  contracted. 
  

  

  Fig. 
  7. 
  — 
  A 
  transition 
  from 
  above 
  stages 
  to 
  the 
  well-marked 
  polarisation 
  

   figure. 
  

  

  Figs. 
  8, 
  9. 
  — 
  Complete 
  polarisation 
  of 
  loops 
  of 
  spireme 
  strand, 
  each 
  loop 
  

   representing 
  a 
  complete 
  chrosome. 
  

  

  Fig. 
  10.— 
  Tlie 
  loops 
  have 
  lost 
  their 
  polarisation, 
  and 
  are 
  undergoing 
  con- 
  

   traction. 
  The 
  nucleolus 
  has 
  lost 
  tlie 
  greater 
  part 
  of 
  its 
  stainable 
  substance 
  

   when 
  this 
  stage 
  is 
  readied. 
  

  

  Fig. 
  11. 
  — 
  Longitudinal 
  fission 
  clearly 
  marked 
  by 
  the 
  arrangement 
  of 
  

   chromatin 
  in 
  two 
  parallel 
  rows 
  of 
  granules. 
  

  

  Fig. 
  12. 
  — 
  Further 
  contraction, 
  which 
  shows 
  individual 
  chromosomes 
  lying 
  

   at 
  periphery 
  of 
  nucleus; 
  longitudinal 
  fission 
  can 
  be 
  seen. 
  

  

  Fig. 
  13. 
  — 
  The 
  chromosomes 
  are 
  scattered 
  over 
  the 
  largest 
  area 
  they 
  cover 
  

   during 
  their 
  life 
  history. 
  

  

  Fig. 
  13a.— 
  Ditto. 
  

  

  Figs. 
  14, 
  15. 
  — 
  Formation 
  of 
  the 
  equatorial 
  plate. 
  

  

  Fig. 
  16. 
  — 
  Equatorial 
  plate. 
  

  

  