﻿THE 
  MATOTIC 
  PHASE 
  IN 
  ANIMALS 
  AND 
  PLANTS. 
  507 
  

  

  during 
  the 
  earlier 
  stages 
  of 
  the 
  preceding 
  (heterotype) 
  

   mitosis. 
  

  

  When 
  one 
  turns 
  to 
  the 
  first 
  maiotic 
  (heterotype) 
  division 
  

   itself, 
  the 
  case 
  is 
  widely 
  different, 
  and 
  it 
  is 
  a 
  singular 
  as 
  well 
  

   as 
  a 
  somewhat 
  unfortunate 
  circumstance 
  that 
  a 
  genus 
  offering 
  

   such 
  special 
  difficulties 
  in 
  the 
  way 
  of 
  correct 
  interpretation 
  of 
  

   the 
  sequence 
  of 
  changes 
  should 
  have 
  been 
  so 
  constantly 
  and 
  

   often 
  exclusively 
  studied 
  by 
  those 
  who 
  have 
  generalised 
  on 
  

   the 
  events 
  that 
  obtain 
  during 
  the 
  course 
  of 
  the 
  mitosis 
  in 
  

   question. 
  For 
  even 
  in 
  a 
  single 
  anther 
  the 
  temptation 
  to 
  

   regard 
  the 
  series 
  as 
  therein 
  presented 
  as 
  representing 
  a 
  trans- 
  

   itional 
  series 
  of 
  phases 
  has 
  misled 
  some 
  writers. 
  It 
  very 
  

   seldom 
  happens 
  that 
  any 
  such 
  a 
  complete 
  series 
  that 
  embraces 
  

   the 
  critical, 
  but 
  transient, 
  phases 
  can 
  really 
  be 
  so 
  traced; 
  and, 
  

   moreover, 
  some 
  of 
  these 
  important 
  phases 
  are 
  often 
  not 
  easy 
  

   to 
  fix 
  satisfactorily, 
  perhaps 
  just 
  on 
  account 
  of 
  their 
  changing 
  

   character. 
  

  

  As 
  the 
  result 
  of 
  an 
  examination 
  of 
  a 
  very 
  long 
  series 
  of 
  

   preparations, 
  illustrating 
  the 
  processes 
  in 
  a 
  number 
  of 
  species, 
  

   we 
  have 
  been 
  irresistibly 
  driven 
  to 
  the 
  conclusion 
  that 
  the 
  

   evidence 
  for 
  the 
  existence 
  of 
  a 
  transverse 
  (reducing) 
  division 
  

   during 
  the 
  heterotype 
  mitosis 
  is 
  irrefragible, 
  and 
  we 
  think 
  we 
  

   are 
  in 
  a 
  position 
  to 
  explain 
  the 
  sources 
  of 
  the 
  more 
  important 
  

   differences 
  of 
  opinion 
  expressed 
  by 
  others 
  who 
  have 
  worked 
  

   on 
  these 
  plants. 
  

  

  At 
  the 
  conclusion 
  of 
  the 
  last 
  archesporial 
  division 
  of 
  the 
  

   sporogenous 
  tissue 
  the 
  nucleus 
  goes 
  into 
  a 
  state 
  of 
  almost 
  

   complete 
  rest. 
  The 
  chromatin 
  exists 
  as 
  scattered 
  granules, 
  

   though 
  here 
  and 
  there 
  a 
  thread-like 
  arrangement 
  can 
  be 
  seen 
  

   (PI. 
  34, 
  fig. 
  1). 
  The 
  great 
  bulk 
  of 
  the 
  staining 
  matter 
  in 
  

   the 
  nucleus 
  is, 
  however, 
  concentrated 
  in 
  the 
  nucleolus, 
  of 
  

   which 
  there 
  may 
  be 
  one 
  or 
  more 
  in 
  each 
  nucleus. 
  As 
  yet 
  the 
  

   archesporial 
  cells 
  are 
  closely 
  coherent, 
  but 
  as 
  they 
  increase 
  

   in 
  size 
  intercellular 
  spaces 
  begin 
  to 
  appear 
  at 
  the 
  angles 
  

   where 
  several 
  cells 
  meet. 
  About 
  the 
  same 
  time 
  the 
  linin 
  

   becomes 
  more 
  chromatic, 
  and 
  in 
  the 
  majority 
  of 
  cases 
  the 
  

   general 
  impression 
  is 
  conveyed 
  that 
  this 
  increase 
  in 
  chromatin 
  

  

  