﻿Miscellaneous. 
  67 
  

  

  off, 
  each 
  on 
  its 
  own 
  account, 
  they 
  remain 
  near 
  the 
  mouth 
  of 
  the 
  

   sporange, 
  each 
  in 
  turn 
  edging 
  its 
  way 
  in 
  between 
  those 
  that 
  have 
  

   already 
  escaped, 
  with 
  its 
  narrower 
  flagellate 
  (anterior) 
  end 
  inwards. 
  

   They 
  thus 
  form 
  a 
  hollow 
  sphere, 
  each 
  zoospore 
  rotating 
  round 
  its 
  

   long 
  axis 
  (radial 
  to 
  the 
  sphere) 
  before 
  encysting 
  in 
  its 
  place. 
  The 
  

   only 
  explanation 
  that 
  will 
  fit 
  these 
  phenomena 
  is 
  that 
  these 
  zoo- 
  

   spores 
  are 
  endowed 
  with 
  a 
  peculiar 
  irritability, 
  in 
  virtue 
  of 
  which 
  

   they 
  tend 
  to 
  place 
  themselves 
  close 
  together 
  side 
  by 
  side, 
  with 
  their 
  

   long 
  axes 
  parallel. 
  This 
  irritability 
  is 
  only 
  exerted 
  at 
  a 
  short 
  dis- 
  

   tance 
  ; 
  for 
  if 
  a 
  zoospore 
  be 
  pushed 
  as 
  little 
  as 
  its 
  long 
  diameter 
  

   away, 
  whether 
  by 
  accident 
  or 
  design, 
  it 
  fails 
  to 
  find 
  its 
  place, 
  but 
  

   swims 
  off 
  to 
  and 
  fro, 
  instead 
  of 
  rotating 
  in 
  situ, 
  before 
  encysting. 
  

  

  In 
  a 
  critical 
  review 
  of 
  a 
  paper 
  by 
  Iiothert, 
  I 
  have 
  given 
  the 
  

   name 
  " 
  adelphotaxy 
  " 
  to 
  this 
  form 
  of 
  irritability, 
  consisting 
  in 
  the 
  

   tendency 
  of 
  spontaneously 
  motile 
  cells 
  to 
  asstone 
  definite 
  positions 
  ivith 
  

   regard 
  to 
  their 
  fellows. 
  

  

  Leaving 
  aside 
  the 
  kindred 
  question 
  of 
  tissue-formation 
  and 
  the 
  

   processes 
  in 
  the 
  embryo-sac 
  of 
  Phanerogams, 
  adelphotaxy 
  is 
  of 
  rare 
  

   occurrence 
  in 
  the 
  Vegetable 
  Kingdom. 
  Two 
  good 
  instances 
  occur 
  

   in 
  the 
  Chlorophytes. 
  In 
  Pediastrum 
  the 
  contents 
  of 
  each 
  cell 
  of 
  

   the 
  flat 
  disk 
  break 
  up 
  into 
  sixteen 
  (or 
  thirty-two) 
  zoospores, 
  which 
  

   swarm 
  in 
  the 
  cell 
  and 
  then 
  unite 
  edge 
  to 
  edge 
  to 
  form 
  a 
  new 
  disk. 
  

   So 
  in 
  each 
  cell 
  of 
  a 
  Hydrodictyon 
  the 
  many 
  thousand 
  zoospores 
  unite 
  

   end 
  to 
  end 
  to 
  form 
  a 
  new 
  network 
  with 
  hexagonal 
  meshes. 
  

  

  In 
  many 
  of 
  the 
  Myxornycetes 
  the 
  plasmodia 
  aggregate 
  together 
  

   before 
  fructification 
  to 
  form 
  the 
  compound 
  masses 
  termed 
  rethalia 
  ; 
  

   possibly 
  even 
  the 
  very 
  formation 
  of 
  plasmodia 
  may 
  be 
  regarded 
  as 
  

   a 
  mode 
  of 
  adelphotaxy. 
  

  

  We 
  may 
  perhaps 
  go 
  a 
  step 
  further 
  and 
  describe 
  the 
  parallel 
  or 
  con- 
  

   verging 
  courses 
  of 
  Fungus 
  liyphai 
  to 
  form 
  mycelium-strings, 
  fruit- 
  

   bodies, 
  and 
  pseudo-parenchyma 
  as 
  extreme 
  cases 
  of 
  adelphotaxy. 
  

  

  I 
  think 
  this 
  principle 
  affords 
  a 
  ready 
  explanation 
  of 
  many 
  cases 
  

   of 
  cellular 
  aggregations 
  in 
  the 
  animal 
  embryo 
  and 
  the 
  formation 
  of 
  

   the 
  spermatophores 
  of 
  many 
  animals, 
  notably 
  Limicolous 
  worms. 
  

  

  The 
  relations 
  of 
  sexual 
  and 
  isogamous 
  union 
  of 
  gametes 
  to 
  adel- 
  

   photaxy 
  are 
  obvious 
  ; 
  for, 
  though 
  in 
  some 
  cases 
  of 
  sexual 
  union 
  

   chemotaxy 
  has 
  been 
  shown 
  by 
  Pfcffer 
  to 
  be 
  involved 
  in 
  bringing 
  the 
  

   active 
  gamete 
  from 
  a 
  distance, 
  that 
  will 
  not 
  cover 
  the 
  actual 
  fusion 
  

   of 
  the 
  two 
  cells. 
  

  

  What 
  may 
  be 
  the 
  mechanism 
  of 
  adelphotaxy 
  it 
  is 
  impossible 
  to 
  

   see 
  at 
  present 
  ; 
  but 
  its 
  existence 
  as 
  a 
  distinct 
  mode 
  of 
  irritability 
  

   must 
  now 
  be 
  recognized, 
  

  

  On 
  the 
  Hersiliidse, 
  a 
  new 
  Family 
  of 
  Commensal 
  Copepoda. 
  

   By 
  M. 
  Eugene 
  Canii. 
  

  

  The 
  author 
  has 
  discovered 
  at 
  Wimereux 
  two 
  new 
  genera, 
  very 
  

   nearly 
  allied 
  to 
  Hersilia 
  and 
  commensals 
  of 
  various 
  Invertebrates, 
  

  

  