﻿Studies 
  on 
  Synapsis. 
  

  

  307 
  

  

  contraction, 
  while 
  the 
  fusion 
  witnessed 
  in 
  the 
  first 
  contraction 
  figures 
  involves 
  

   the 
  reassociation 
  of 
  half 
  chromosomes 
  split 
  in 
  preparation 
  for 
  an 
  arrested 
  

   division 
  in 
  the 
  preceding 
  telophase. 
  The 
  chief 
  issue 
  between 
  the 
  rival 
  

   schools 
  in 
  this 
  case 
  concerns 
  not 
  primarily 
  that 
  suggested 
  by 
  the 
  etymological 
  

   distinction, 
  but 
  the 
  significance 
  of 
  the 
  earlier 
  stages 
  in 
  the 
  meiotic 
  phase. 
  

   The 
  telosynaptists 
  interpret 
  the 
  first 
  contraction 
  in 
  terms 
  of 
  the 
  premeiotic 
  

   prophase, 
  whereas 
  the 
  parasynaptic 
  school, 
  like 
  Gregoire 
  (7), 
  attempt 
  to 
  

   compare 
  it 
  with 
  the 
  bouquet 
  zygotene 
  processes 
  in 
  animals. 
  

  

  In 
  direct 
  opposition 
  to 
  Gregoire, 
  Farmer 
  and 
  Moore 
  (1905) 
  have 
  attempted 
  

   to 
  interpret 
  tne 
  events 
  of 
  the 
  meiotic 
  phase 
  in 
  animals 
  as 
  well 
  as 
  plants 
  in 
  

   terms 
  of 
  the 
  premeiotic 
  prophases. 
  The 
  principal 
  form 
  investigated 
  from 
  this 
  

   standpoint 
  was 
  Periplaneta, 
  Osmunda 
  being 
  one 
  of 
  the 
  forms 
  on 
  which 
  the 
  

   comparison 
  was 
  based. 
  These 
  two 
  authors 
  (8) 
  omit 
  any 
  account 
  of 
  a 
  

   leptotene 
  or 
  zygotene 
  stage 
  : 
  their 
  observations 
  commence 
  with 
  the 
  chromatin 
  

   already 
  present 
  as 
  the 
  reduced 
  number 
  of 
  loops 
  ; 
  so 
  that 
  the 
  earlier 
  events 
  of 
  

   the 
  synaptic 
  processes 
  here 
  described 
  are 
  very 
  different 
  from 
  those 
  set 
  forth 
  

   in 
  Osmunda 
  by 
  Miss 
  Digby 
  (9). 
  According 
  to 
  their 
  statement 
  of 
  the 
  case 
  

   the 
  heterotype 
  chromosomes 
  segment 
  transversely 
  with 
  respect 
  to 
  the 
  line 
  of 
  

   cleavage- 
  in 
  the 
  diplotene 
  stage; 
  and 
  since 
  the 
  homotype 
  division 
  is 
  

   longitudinal, 
  they 
  are 
  forced 
  to 
  conceive 
  the 
  bouquet 
  as 
  a 
  spireme 
  in 
  which 
  

   each 
  segment 
  corresponds 
  to 
  a 
  pair 
  of 
  chromosomes 
  united 
  end-to-end. 
  Thus 
  

   we 
  read 
  : 
  " 
  the 
  spireme 
  thread 
  work 
  tends 
  at 
  first 
  to 
  separate 
  into 
  half 
  as 
  many 
  

   lengths 
  " 
  (as 
  the 
  premeiotic 
  chromosome 
  number). 
  It 
  cannot 
  be 
  questioned 
  

   that 
  Prof. 
  Farmer 
  performed 
  a 
  very 
  great 
  service 
  to 
  cytology 
  in 
  this 
  pioneer 
  

   work 
  by 
  demonstrating 
  a 
  definite 
  relationship 
  between 
  the 
  heterotype 
  and 
  

   normal 
  somatic 
  chromosomes. 
  But 
  in 
  emphasising 
  the 
  similarity 
  between 
  the 
  

   heterotype 
  and 
  premeiotic 
  prophases, 
  and 
  more 
  particularly 
  the 
  resemblances 
  

   of 
  the 
  former 
  in 
  plants 
  and 
  animals, 
  it 
  appears 
  to 
  the 
  present 
  writer 
  that 
  the 
  

   issue 
  has 
  been 
  obscured 
  rather 
  than 
  clarified 
  in 
  certain 
  particulars, 
  so 
  that 
  a 
  

   re-examination 
  of 
  the 
  meiotic 
  phenomena 
  in 
  Periplaneta 
  in 
  the 
  light 
  of 
  

   Miss 
  Digby's 
  discoveries 
  would 
  assist 
  towards 
  a 
  better 
  appreciation 
  of 
  the 
  

   relation 
  of 
  these 
  fundamental 
  processes 
  in 
  animals 
  and 
  plants. 
  Special 
  

   attention 
  has 
  been 
  directed 
  to 
  the 
  study 
  of 
  the 
  premeiotic 
  telophase 
  and 
  its 
  

   bearing 
  on 
  the 
  earlier 
  events 
  of 
  synapsis, 
  a 
  more 
  searching 
  study 
  of 
  the 
  

   genesis 
  of 
  the 
  spindle 
  bivalents 
  in 
  spermatogenesis, 
  and 
  the 
  first 
  account 
  of 
  

   the 
  synaptic 
  events 
  in 
  oogenesis 
  in 
  the 
  same 
  form 
  are 
  here 
  included. 
  

   Together 
  with 
  these 
  observations 
  are 
  recorded 
  conclusions 
  on 
  the 
  relation 
  of 
  

   the 
  plasmosome 
  to 
  yolk 
  -deposition 
  in 
  insects. 
  It 
  is 
  a 
  pleasant 
  duty 
  to 
  

   acknowledge 
  the 
  generous 
  encouragement 
  and 
  helpful 
  criticism 
  offered 
  by 
  

   Prof. 
  Farmer 
  during 
  the 
  course 
  of 
  the 
  investigation. 
  

  

  