﻿198 
  

  

  Prof. 
  W. 
  M. 
  Bayliss. 
  

  

  sufficient 
  for 
  our 
  present 
  purpose 
  to 
  call 
  attention 
  to 
  the 
  fact 
  shown 
  by 
  the 
  

   experiment 
  with 
  gamboge 
  given 
  above, 
  namely, 
  that 
  liquid 
  properties 
  cease 
  

   and 
  a 
  fixed 
  structure 
  makes 
  its 
  appearance. 
  

  

  Certain 
  facts 
  noticed 
  by 
  Kiihne, 
  in 
  his 
  experiments 
  on 
  electrical 
  stimula- 
  

   tion 
  of 
  protoplasm, 
  suggest 
  that 
  a 
  reversible 
  change 
  of 
  the 
  kind 
  referred 
  tc- 
  

   may 
  occur 
  in 
  this 
  colloidal 
  system, 
  although 
  Kiihne 
  did 
  not 
  interpret 
  them 
  

   as 
  of 
  such 
  a 
  nature. 
  It 
  is 
  to 
  be 
  remembered 
  that 
  his 
  work 
  was 
  done 
  very 
  

   soon 
  after 
  the 
  publication 
  in 
  1861 
  of 
  Graham's 
  investigations 
  on 
  colloids 
  

   which 
  had 
  not 
  then 
  become 
  a 
  part 
  of 
  common 
  physiological 
  knowledge. 
  An 
  

   observation 
  made 
  by 
  Gaidukov 
  (1910, 
  p. 
  58), 
  in 
  the 
  course 
  of 
  his 
  work 
  oik 
  

   the 
  phenomena 
  shown 
  in 
  living 
  protoplasm 
  by 
  dark-ground 
  illumination,, 
  

   suggests 
  that 
  " 
  spontaneous 
  " 
  changes 
  from 
  sol 
  to 
  gel 
  take 
  place. 
  This- 
  

   observer 
  noted 
  that 
  the 
  movements 
  of 
  the 
  protoplasm 
  in 
  the 
  cell 
  of 
  

   Vallisneria 
  appeared 
  occasionally 
  to 
  become 
  arrested 
  at 
  a 
  spot, 
  while 
  the 
  

   Brownian 
  movement 
  of 
  the 
  particles 
  in 
  it 
  ceased. 
  Presently, 
  the 
  Brownian 
  

   movement 
  became 
  visible 
  again, 
  and 
  immediately 
  afterwards 
  the 
  general 
  

   protoplasmic 
  circulation 
  was 
  resumed. 
  According 
  to 
  Chambers 
  (1917)- 
  

   there 
  is 
  a 
  periodic 
  reversal 
  of 
  the 
  sol 
  to 
  the 
  gel 
  state, 
  and 
  vice 
  versa, 
  in 
  the 
  

   process 
  of 
  cell-division, 
  the 
  greater 
  part 
  of 
  the 
  cell 
  being 
  in 
  the 
  state 
  of 
  gel 
  

   when 
  the 
  aster 
  is 
  fully 
  formed. 
  In 
  fact, 
  the 
  appearance 
  of 
  the 
  aster 
  is 
  

   associated 
  with 
  gelation 
  of 
  the 
  protoplasm. 
  Leblond 
  (1919) 
  describes 
  the 
  

   phenomenon 
  as 
  occurring 
  in 
  conjugation, 
  as 
  well 
  as 
  in 
  cell- 
  division. 
  In 
  

   fact, 
  the 
  occurrence 
  of 
  reversible 
  gelation 
  seems 
  to 
  be 
  a 
  regular 
  condition 
  of 
  

   cell 
  activities. 
  Some 
  observers 
  have 
  described 
  the 
  appearance 
  of 
  a 
  reticular 
  

   structure. 
  But, 
  on 
  account 
  of 
  the 
  ease 
  with 
  which 
  a 
  series 
  of 
  points 
  gives 
  rise- 
  

   by 
  diffraction 
  to 
  network 
  images, 
  care 
  is 
  needed 
  in 
  the 
  interpretation 
  of 
  such 
  

   images. 
  Nevertheless, 
  Hardy 
  (1900) 
  has 
  described 
  the 
  formation 
  of 
  networks 
  

   in 
  moderately 
  strong 
  solutions 
  of 
  gelatin 
  in 
  dilute 
  alcohol, 
  so 
  that 
  there 
  is 
  

   reason 
  to 
  admit 
  the 
  possibility 
  of 
  their 
  production 
  in 
  protoplasm. 
  

  

  The 
  experiments 
  which 
  I 
  made 
  were 
  for 
  the 
  purpose 
  of 
  seeing 
  whether 
  

   this 
  reversible 
  state 
  of 
  gelation 
  could 
  be 
  induced 
  at 
  will 
  by 
  means 
  of 
  

   electrical 
  stimulation. 
  The 
  method 
  used 
  for 
  stimulation 
  was 
  the 
  same 
  as- 
  

   that 
  of 
  Kiihne. 
  Two 
  thin 
  blunt-pointed 
  pieces 
  of 
  platinum 
  foil 
  were 
  

   cemented 
  on 
  a 
  microscope 
  slide, 
  so 
  that 
  there 
  was 
  a 
  gap 
  of 
  about 
  2 
  mm.- 
  

   between 
  the 
  points. 
  A 
  drop 
  of 
  water 
  containing 
  amoebae 
  or 
  other 
  cells 
  was 
  

   placed 
  between 
  the 
  points 
  and 
  a 
  cover-glass 
  dropped 
  on 
  the 
  top. 
  The 
  

   platinum 
  strips 
  can 
  readily 
  be 
  connected 
  to 
  the 
  terminals 
  of 
  the 
  secondary 
  

   coil 
  of 
  an 
  induction 
  apparatus 
  by 
  resting 
  the 
  bared 
  ends 
  of 
  fine 
  copper 
  wire 
  

   on 
  them 
  and 
  placing 
  small 
  weights 
  on 
  these. 
  It 
  was 
  found 
  to 
  be 
  a 
  matter 
  of 
  

   some 
  difficulty 
  to 
  adjust 
  the 
  strength 
  of 
  the 
  stimulus 
  to 
  an 
  appropriate 
  

  

  