﻿THE 
  UNIQUENESS 
  OF 
  LIFE 
  151 
  

  

  another 
  and 
  touch; 
  they 
  actually 
  become 
  pressed 
  and 
  flat- 
  

   tened 
  up 
  against 
  one 
  another. 
  This 
  interesting 
  attraction 
  

   was 
  called 
  by 
  Eoux 
  cytotropism 
  or 
  cytotaxis, 
  and 
  it 
  has 
  been 
  

   observed 
  in 
  other 
  cases. 
  Assheton 
  was 
  particularly 
  concerned 
  

   with 
  the 
  development 
  of 
  the 
  lancelet 
  or 
  Amphioxus, 
  where 
  

   the 
  ovum 
  divides 
  into 
  a 
  hollow 
  ball 
  of 
  cells, 
  which 
  again 
  is 
  

   indimpled 
  or 
  invaginated 
  to 
  form 
  a 
  two-layered 
  sac 
  of 
  cells, 
  

   the 
  gastrula. 
  Assheton 
  sought 
  to 
  show 
  that, 
  if 
  there 
  were 
  

   an 
  attractive 
  force 
  between 
  cell 
  and 
  cell, 
  acting 
  from 
  centres 
  

   represented 
  by 
  the 
  nuclei 
  of 
  the 
  cells, 
  the 
  hollow 
  ball 
  of 
  cells 
  

   would 
  at 
  a 
  certain 
  stage 
  become 
  invaginated. 
  The 
  explana- 
  

   tion 
  of 
  how 
  gastrulation 
  might 
  come 
  about 
  was 
  put 
  forward 
  

   as 
  indirect 
  evidence 
  in 
  favour 
  of 
  the 
  existence 
  of 
  some 
  force 
  

   acting 
  from 
  a 
  centre 
  like 
  gravitation 
  or 
  magnetism 
  or 
  statical 
  

   electricity, 
  but 
  probably 
  of 
  a 
  different 
  nature 
  and 
  with 
  dif- 
  

   ferent 
  laws, 
  and 
  an 
  attribute 
  of 
  living 
  matter 
  alone. 
  Asshe- 
  

   ton 
  meant 
  definitely 
  a 
  kind 
  of 
  physical 
  energy 
  " 
  which 
  could 
  

   be 
  investigated 
  by 
  the 
  ordinary 
  methods 
  of 
  mensuration 
  and 
  

   computation 
  available 
  to 
  the 
  mathematician 
  ". 
  

  

  Herbst 
  made 
  the 
  remarkable 
  observation 
  that 
  if 
  the 
  ova 
  

   of 
  the 
  sea-urchin 
  be 
  allowed 
  to 
  develop 
  in 
  sea 
  water 
  deprived 
  

   of 
  its 
  calcium 
  salts, 
  the 
  blastomeres 
  separate 
  from 
  one 
  an- 
  

   other, 
  instead 
  of 
  adhering. 
  What 
  looks 
  like 
  repulsion 
  be- 
  

   tween 
  two 
  centres 
  is 
  seen 
  in 
  the 
  normal 
  process 
  of 
  cell- 
  

   division, 
  where 
  the 
  incipient 
  daughter-nuclei, 
  while 
  still 
  parts 
  

   of 
  the 
  parent 
  cell, 
  seem 
  to 
  repel 
  one 
  another, 
  and 
  yet 
  imme- 
  

   diately 
  after 
  separation 
  appear 
  to 
  attract 
  one 
  another 
  strongly. 
  

   Assheton 
  suggested 
  that 
  the 
  hypothetical 
  form 
  of 
  energy 
  ex- 
  

   hibits 
  an 
  unceasing 
  recurrence 
  of 
  a 
  bipolar 
  state 
  out 
  of 
  a 
  

   unipolar 
  state. 
  "The 
  attraction 
  and 
  repulsion 
  observed 
  be- 
  

   tween 
  cell 
  and 
  cell 
  are 
  certain 
  of 
  the 
  manifestations 
  of 
  this 
  

   supposed 
  form 
  of 
  energy 
  but 
  probably 
  not 
  by 
  any 
  means 
  

  

  