﻿318 
  

  

  Mr. 
  L. 
  T. 
  Hogben. 
  

  

  part 
  played 
  by 
  chromatin 
  in 
  the 
  genesis 
  of 
  the 
  oocyte 
  to 
  furnish 
  such 
  

   evidence. 
  Nevertheless 
  the 
  demonstration 
  of 
  the 
  chromatin 
  origin 
  of 
  the 
  

   nuclear 
  granules 
  which 
  appear 
  to 
  be 
  extruded 
  — 
  and 
  the 
  onus 
  of 
  proof 
  lies 
  

   with 
  those 
  who 
  make 
  the 
  affirmation 
  — 
  would 
  not 
  be 
  a 
  fatal 
  blow 
  to 
  Boveri's 
  

   theory 
  ; 
  for 
  those 
  who 
  advocate 
  a 
  structural 
  continuity 
  of 
  substance 
  between 
  

   individual 
  chromosomes 
  do 
  not 
  necessarily 
  conceive 
  chromatin 
  as 
  a 
  static 
  

   constituent 
  of 
  the 
  cell 
  : 
  if 
  the 
  ultimate 
  mechanism 
  of 
  inheritance 
  is 
  conceived 
  

   to 
  reside 
  in 
  the 
  autocatalytic 
  properties 
  of 
  the 
  substance 
  of 
  the 
  chromosomes, 
  

   the 
  elimination 
  of 
  chromatin 
  raises 
  no 
  special 
  objection. 
  A 
  study 
  of 
  the 
  

   conditions 
  under 
  which 
  the 
  cell 
  structures 
  hitherto 
  described 
  as 
  nucleoli 
  are 
  

   formed 
  and 
  their 
  relation 
  to 
  the 
  chromatic 
  organisation 
  of 
  the 
  nucleus 
  would 
  

   perform 
  a 
  genuine 
  service 
  to 
  cytological 
  theory. 
  

  

  Chubb 
  (20) 
  has 
  described 
  the 
  relation 
  of 
  the 
  nucleolus 
  to 
  the 
  deposition 
  of 
  

   yolk 
  in 
  the 
  Echinoderm 
  Antedon 
  ; 
  and 
  in 
  many 
  points 
  his 
  observations 
  

   display 
  similarity 
  to 
  those 
  set 
  forth 
  above 
  : 
  but 
  it 
  must 
  not 
  be 
  inferred 
  that 
  

   the 
  data 
  supplied 
  by 
  the 
  examination 
  of 
  fixed 
  material 
  necessarily 
  furnish 
  a 
  

   faithful 
  facsimile 
  of 
  the 
  actual 
  process 
  as 
  it 
  occurs 
  in 
  the 
  living 
  organism. 
  

   In 
  the 
  absence 
  of 
  further 
  evidence 
  derived 
  from 
  ultramicroscopical 
  examina- 
  

   tion 
  of 
  fresh 
  tissue, 
  it 
  can 
  only 
  be 
  legitimately 
  inferred 
  that 
  a 
  transportation 
  

   of 
  material 
  from 
  the 
  nucleolus 
  is 
  instrumental 
  in 
  the 
  formation 
  of 
  the 
  

   deutoplasmic 
  spheres. 
  It 
  is 
  necessary 
  to 
  state 
  this 
  because 
  of 
  the 
  difficulty 
  

   of 
  imagining 
  the 
  movement 
  of 
  comparatively 
  large 
  bodies 
  in 
  viscous 
  media 
  

   according 
  to 
  such 
  a 
  definite 
  mode 
  of 
  procedure. 
  Whether 
  then 
  the 
  gemmules 
  

   correspond 
  to 
  fluid 
  globules 
  or 
  solid 
  particles 
  of 
  corresponding 
  magnitude, 
  or 
  

   whether 
  they 
  are 
  to 
  be 
  regarded 
  as 
  precipitation 
  products 
  of 
  a 
  diphasic 
  

   colloidal 
  system, 
  cannot 
  be 
  definitely 
  stated. 
  There 
  are, 
  however, 
  two 
  

   considerations 
  which 
  uphold 
  the 
  former 
  alternative, 
  namely 
  : 
  (a) 
  the 
  

   constancy 
  of 
  magnitude 
  exhibited 
  by 
  these 
  bodies 
  after 
  precipitation 
  by 
  a 
  

   variety 
  of 
  reagents 
  (vide 
  infra) 
  ; 
  and 
  (6) 
  correspondence 
  in 
  size, 
  when 
  seen 
  in 
  

   media 
  of 
  apparently 
  different 
  density 
  (nucleolus, 
  karyolymph, 
  and 
  cytoplasm). 
  

  

  The 
  nucleolar 
  particles 
  observed 
  in 
  Periplaneta 
  are 
  not 
  identical 
  in 
  their 
  

   staining 
  reactions 
  with 
  the 
  chromatin 
  network 
  ; 
  but 
  for 
  the 
  reasons 
  stated 
  

   emphasis 
  will 
  not 
  be 
  laid 
  on 
  this 
  point. 
  As 
  regards 
  the 
  logwood 
  dyes, 
  

   Haidenhein 
  after 
  fixation 
  with 
  picroformol-acetic 
  (Bouin), 
  bichromate 
  acetic 
  

   (Tellyesnicsky), 
  chromosmic 
  acetic 
  (Flemming), 
  caused 
  the 
  plasmosome 
  in 
  

   the 
  very 
  young 
  oocyte 
  to 
  stain 
  deeply 
  like 
  the 
  reticulum 
  : 
  in 
  later 
  stages, 
  

   as 
  figured, 
  the 
  chromaticity 
  of 
  the 
  former 
  appears 
  to 
  diminish, 
  giving 
  a 
  

   translucent 
  greyish 
  effect 
  immediately 
  before 
  the 
  formation 
  of 
  the 
  deuto- 
  

   somes. 
  After 
  acid-free 
  fixation 
  — 
  chromosmic 
  (Gatenby) 
  — 
  the 
  plasmosome 
  

   was 
  seen 
  to 
  be 
  deeply 
  chromatic 
  at 
  all 
  stages, 
  when 
  stained 
  with 
  iron 
  

  

  