﻿322 
  

  

  Mr. 
  L. 
  T. 
  Hogben. 
  

  

  Synapsis. 
  

  

  Farmer 
  and 
  Moore 
  commence 
  their 
  account 
  with 
  maximal 
  contraction. 
  No 
  

   conflict 
  arises 
  therefore 
  between 
  their 
  interpretation 
  of 
  the 
  mode 
  of 
  synapsis 
  

   derived 
  from 
  the 
  formation 
  of 
  the 
  heterotype 
  chromosomes 
  and 
  the 
  processes 
  

   involved 
  in 
  the 
  elaboration 
  of 
  the 
  synaptic 
  bouquet. 
  Morse, 
  on 
  the 
  other 
  

   hand, 
  gives 
  data 
  less 
  detailed 
  but 
  essentially 
  in 
  unison 
  with 
  those 
  already 
  

   described 
  in 
  the 
  early 
  history 
  of 
  the 
  ovarian 
  oocyte. 
  The 
  polar 
  orientation 
  is 
  

   preceded 
  by 
  a 
  tangled 
  leptotene 
  stage, 
  in 
  which 
  the 
  individual 
  filaments 
  are 
  

   only 
  traceable 
  with 
  great 
  difficulty 
  : 
  as 
  polarisation 
  sets 
  in, 
  optical 
  sections 
  

   reveal 
  the 
  presence 
  of 
  about 
  thirty, 
  i.e., 
  the 
  diploid 
  number 
  of 
  threads 
  ; 
  later, 
  

   as 
  described 
  by 
  Farmer 
  and 
  Moore, 
  only 
  sixteen 
  thickened 
  loops 
  are 
  seen. 
  

   Throughout 
  these 
  stages 
  the 
  unpaired 
  accessory 
  is 
  recognised 
  as 
  a 
  fusiform 
  

   body 
  closely 
  applied 
  to 
  the 
  plasmosome, 
  and 
  hence 
  confused 
  with 
  that 
  body 
  

   by 
  Moore 
  and 
  Eobinson 
  (21). 
  Morse 
  does 
  not 
  describe 
  the 
  zygotene 
  stage, 
  

   but 
  concludes 
  from 
  the 
  arrangement 
  and 
  numerical 
  relations 
  of 
  the 
  threads 
  

   before 
  and 
  during 
  maximal 
  contraction 
  that 
  parallel 
  conjugation 
  occurs. 
  In 
  

   good 
  transparently 
  stained 
  preparations 
  evidence 
  of 
  the 
  actual 
  assembling 
  of 
  

   the 
  loops 
  in 
  pairs 
  can 
  nevertheless 
  be 
  traced, 
  though 
  this 
  is 
  admittedly 
  

   difficult, 
  owing 
  to 
  the 
  compact 
  state 
  of 
  the 
  chromatin 
  filaments. 
  Fig. 
  56 
  in 
  

   Farmer 
  and 
  Moore's 
  paper 
  suggests 
  a 
  zygotene 
  stage 
  in 
  which 
  the 
  interspace 
  

   between 
  two 
  diverging 
  loops 
  is 
  too 
  much 
  stained 
  to 
  allow 
  the 
  line 
  of 
  separa- 
  

   tion 
  to 
  be 
  manifest. 
  

  

  In 
  the 
  unravelling 
  of 
  the 
  postsynaptic 
  spireme 
  the 
  diplotene 
  threads 
  

   undergo 
  a 
  very 
  complicated 
  metamorphosis 
  that 
  cannot 
  in 
  the 
  least 
  be 
  

   regarded 
  as 
  a 
  typical 
  meiotic 
  phenomenon 
  : 
  they 
  first 
  become 
  extended 
  and 
  

   later 
  shortened, 
  so 
  that 
  Farmer 
  and 
  Moore 
  speak 
  of 
  a 
  second 
  contraction 
  

   figure. 
  This 
  is 
  not 
  in 
  the 
  strict 
  usage 
  of 
  the 
  phrase 
  " 
  a 
  contraction 
  figure," 
  

   because 
  the 
  threads 
  lie 
  manifestly 
  on 
  the 
  nuclear 
  membrane, 
  though 
  they 
  

   happen 
  to 
  be 
  concentrated 
  towards 
  one 
  pole 
  of 
  the 
  nucleus. 
  At 
  a 
  still 
  later 
  

   stage, 
  as 
  Morse 
  figures, 
  half 
  of 
  the 
  loops 
  are 
  seen 
  at 
  one 
  pole 
  and 
  the 
  

   remainder 
  at 
  the 
  opposite 
  one, 
  this 
  condition 
  being 
  preceded 
  by 
  the 
  division 
  

   and 
  separation 
  of 
  the 
  centrosome 
  in 
  preparation 
  for 
  the 
  ensuing 
  heterotype 
  

   mitosis. 
  

  

  A 
  Sequential 
  Analysis 
  of 
  the 
  Heterotype 
  Complex. 
  

  

  It 
  has 
  been 
  seen 
  in 
  the 
  oocyte 
  that 
  after 
  the 
  dissolution 
  of 
  post-synaptic 
  

   spireme 
  the 
  diplotene 
  loops 
  become 
  straighter 
  and 
  shorter. 
  In 
  the 
  formation 
  

   of 
  the 
  heterotype 
  chromosomes 
  of 
  the 
  male, 
  however, 
  according 
  to 
  Farmer 
  

   and 
  Moore, 
  the 
  loops 
  of 
  what 
  they 
  term 
  second 
  contraction 
  separate 
  and 
  

   immediately 
  unite 
  by 
  their 
  free 
  ends 
  to 
  form 
  ring-like 
  chromosomes 
  which 
  

  

  