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  The 
  Properties 
  of 
  Colloidal 
  Systems. 
  

  

  statement 
  of 
  Gaidukov 
  that 
  death 
  is 
  associated 
  with 
  an 
  irreversible 
  coagula- 
  

   tion. 
  It 
  appears, 
  however, 
  from 
  some 
  observations 
  of 
  Kuhne, 
  that 
  the 
  lethal 
  

   gel 
  state 
  begins 
  at 
  a 
  later 
  stage 
  to 
  show 
  Brownian 
  movement 
  again. 
  Kiihne 
  

   interpreted 
  this 
  reappearance 
  as 
  being 
  due 
  to 
  absorption 
  of 
  water. 
  It 
  may 
  

   indicate 
  the 
  commencement 
  of 
  autolysis. 
  Sherrington 
  (1894, 
  p. 
  188), 
  in 
  his 
  

   observations 
  on 
  leucocytes, 
  regarded 
  the 
  appearance 
  of 
  Brownian 
  movement 
  

   as 
  a 
  sign 
  of 
  approaching 
  death. 
  It 
  seems 
  probable 
  that 
  the 
  second 
  stage 
  may 
  

   come 
  on 
  more 
  quickly 
  in 
  these 
  cells 
  than 
  in 
  Amceha. 
  Leucocytes 
  may 
  

   consist 
  of 
  more 
  viscous 
  protoplasm 
  and 
  the 
  granules 
  observed 
  by 
  Sherrington 
  

   may 
  have 
  been 
  too 
  large 
  to 
  show 
  Brownian 
  movement 
  until 
  the 
  post-lethal 
  

   changes 
  had 
  reduced 
  the 
  viscosity 
  of 
  the 
  medium. 
  I 
  have 
  not 
  made 
  any 
  

   observations 
  on 
  these 
  cells. 
  Pus 
  cells, 
  according 
  to 
  Sherrington, 
  show 
  

   Brownian 
  movement 
  of 
  the 
  particles 
  which 
  they 
  contain. 
  

  

  Although 
  many 
  plant 
  cells 
  are 
  very 
  favourable 
  objects 
  for 
  the 
  investiga- 
  

   tion 
  of 
  the 
  movements 
  of 
  protoplasm, 
  I 
  found 
  them 
  less 
  so 
  for 
  the 
  brilliant 
  

   illumination 
  required 
  for 
  the 
  observations 
  of 
  the 
  present 
  paper. 
  The 
  cell 
  

   wall, 
  by 
  its 
  dazzling 
  brightness, 
  renders 
  the 
  detection 
  of 
  changes 
  in 
  the 
  

   protoplasm 
  in 
  contact 
  with 
  it 
  a 
  matter 
  of 
  difficulty. 
  In 
  Nitella, 
  probably 
  

   owing 
  to 
  the 
  relative 
  delicacy 
  of 
  the 
  cell 
  wall, 
  I 
  have, 
  however, 
  been 
  able 
  to 
  

   observe 
  phenomena 
  similar 
  to 
  those 
  in 
  Amoeba. 
  In 
  Spirogyra, 
  the 
  central 
  

   vacuole 
  contains 
  numerous 
  granules 
  in 
  Brownian 
  movement, 
  and 
  I 
  was 
  unable 
  

   to 
  satisfy 
  myself 
  that 
  their 
  movement 
  could 
  be 
  distinguished 
  from 
  that 
  of 
  

   the 
  particles 
  in 
  the 
  protoplasmic 
  layer 
  itself. 
  In 
  the 
  staminal 
  hairs 
  of 
  

   Tradescantia, 
  although 
  one 
  could 
  recognise 
  a 
  cessation 
  of 
  Brownian 
  move- 
  

   ment 
  in 
  the 
  protoplasmic 
  trabecular 
  on 
  stimulation, 
  it 
  would 
  have 
  scarcely 
  

   been 
  possible 
  to 
  feel 
  assured 
  of 
  it 
  without 
  previous 
  acquaintance 
  with 
  its 
  

   appearance 
  in 
  Amceha, 
  for 
  the 
  reason 
  referred 
  to 
  in 
  the 
  case 
  of 
  Spirogyra, 
  

   namely, 
  the 
  presence 
  of 
  particles 
  in 
  the 
  cell 
  sap, 
  on 
  which 
  stimulation 
  has 
  

   no 
  effect. 
  

  

  Summary. 
  

  

  With 
  intense 
  dark-ground 
  illumination 
  it 
  is 
  possible 
  to 
  see 
  that 
  the 
  

   apparently 
  clear 
  pseudopodia 
  of 
  Amoeba 
  are 
  filled 
  with 
  numerous 
  very 
  minute 
  

   particles 
  in 
  Brownian 
  movement 
  ; 
  thus 
  affording 
  further 
  evidence 
  of 
  the 
  liquid, 
  

   hydrosol, 
  nature 
  of 
  simple 
  protoplasm. 
  

  

  By 
  electrical 
  stimulation, 
  this 
  sol 
  can 
  be 
  reversibly 
  changed 
  into 
  the 
  

   gel 
  state, 
  evidenced 
  by 
  the 
  sudden 
  cessation 
  of 
  the 
  Brownian 
  movement. 
  

  

  REFERENCES. 
  

  

  Chambers, 
  Rob., 
  Jr., 
  " 
  The 
  Cell 
  Aster 
  : 
  a 
  reversible 
  gelation 
  phenomenon," 
  ' 
  Journ. 
  

  

  Exp. 
  Zool.,' 
  vol. 
  23, 
  p. 
  483 
  (1917). 
  

   Duclaux, 
  Jacques, 
  ' 
  Comptes 
  rendus,' 
  vol. 
  147, 
  p. 
  13 
  L 
  (1908). 
  

  

  