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  are 
  found 
  in 
  great 
  numbers 
  without 
  spore-cases, 
  or 
  ' 
  sporangia.' 
  

   When 
  a 
  spore, 
  wafted 
  far, 
  perhaps 
  by 
  the 
  wind, 
  falls 
  on 
  to 
  a 
  suit- 
  

   able 
  moist 
  surface, 
  such 
  as 
  dead 
  wood 
  or 
  dead 
  leaves, 
  the 
  spore-wall 
  

   cracks 
  and 
  the 
  contents 
  creep 
  out 
  into 
  the 
  water 
  as 
  a 
  speck 
  of 
  naked 
  

   protoplasm, 
  termed 
  a 
  ' 
  swarm-cell 
  ' 
  or 
  ' 
  myxamceba.' 
  It 
  contains 
  a 
  

   nucleus 
  and 
  a 
  contracting 
  vacuole 
  ; 
  soon 
  a 
  lash-like 
  flagellum 
  is 
  

   extended, 
  by 
  the 
  aid 
  of 
  which 
  it 
  swims 
  off 
  as 
  an 
  active 
  ' 
  zoospore.' 
  

   The 
  food 
  of 
  the 
  zoospores 
  consists 
  chiefly 
  of 
  bacteria. 
  To 
  catch 
  

   these, 
  delicate 
  sticky 
  processes, 
  ' 
  pseudopodia 
  ' 
  are 
  protruded 
  from 
  the 
  

   posterior 
  end 
  of 
  the 
  zoospore, 
  to 
  which 
  the 
  bacteria 
  adhere, 
  and 
  by 
  

   which 
  they 
  are 
  conveyed 
  into 
  special 
  digestive 
  vacuoles, 
  formed 
  for 
  

   their 
  reception 
  within 
  the 
  cell. 
  Here 
  they 
  are 
  gradually 
  digested, 
  

   while 
  indigestible 
  matter 
  is 
  thrown 
  out. 
  

  

  " 
  The 
  zoospores 
  divide 
  repeatedly 
  by 
  bipartition, 
  each 
  daughter 
  

   zoospore 
  resembling 
  its 
  parent. 
  After 
  a 
  certain 
  number 
  of 
  divisions, 
  

   the 
  flagella 
  are 
  withdrawn, 
  and 
  the 
  cells 
  creep 
  about 
  as 
  ' 
  myxa- 
  

   modae,' 
  which 
  again 
  may 
  divide 
  several 
  times. 
  

  

  " 
  Thus, 
  as 
  Dr. 
  Jahn 
  first 
  discovered, 
  as 
  these 
  myxamoebse 
  unite 
  in 
  

   pairs, 
  and 
  their 
  nuclei 
  fuse 
  into 
  one, 
  they 
  must 
  be 
  regarded 
  as 
  

   gametes, 
  and 
  the 
  body 
  formed 
  by 
  the 
  union 
  of 
  a 
  pair, 
  as 
  a 
  zyr/ote. 
  

   By 
  the 
  recent 
  admirable 
  investigations 
  of 
  Skupienski, 
  further 
  light 
  

   is 
  thrown 
  on 
  the 
  nature 
  of 
  these 
  gametes. 
  He 
  finds 
  that 
  a 
  gamete 
  

   does 
  not 
  fuse 
  indiscriminately 
  with 
  ainj 
  other 
  gamete, 
  but 
  exercises 
  

   a 
  distinct 
  power 
  of 
  selection. 
  He 
  has 
  proved 
  that 
  they 
  are 
  of 
  two 
  

   kinds, 
  and 
  it 
  is 
  only 
  when 
  a 
  pair 
  includes 
  one 
  of 
  each 
  kind 
  that 
  

   fusion 
  takes 
  place. 
  Thus 
  although 
  to 
  our 
  eyes 
  the 
  gametes 
  are 
  

   exactly 
  alike, 
  there 
  exists 
  among 
  them 
  a 
  distinctive 
  suggestion 
  of 
  a 
  

   primitive 
  sexual 
  differentiation. 
  

  

  "A 
  zygote 
  formed 
  by 
  this 
  process 
  of 
  fusion 
  may 
  be 
  distinguished 
  

   from 
  a 
  gamete 
  by 
  its 
  larger 
  size, 
  the 
  larger 
  nucleus, 
  and 
  by 
  a 
  regular 
  

   rhythmic 
  circulation 
  of 
  its 
  more 
  fluid 
  granular 
  contents. 
  It 
  also 
  

   develops 
  the 
  faculty 
  of 
  devouring 
  the 
  myxamoebfe. 
  It 
  increases 
  in 
  

   size 
  by 
  feeding, 
  and 
  also 
  by 
  uniting 
  with 
  other 
  zygotes, 
  or 
  young 
  

   planvindia 
  as 
  they 
  are 
  called. 
  As 
  they 
  grow 
  they 
  spread 
  out 
  in 
  

   search 
  of 
  food 
  in 
  a 
  network 
  of 
  veins 
  through 
  which 
  a 
  torrent 
  of 
  

   circulation 
  may 
  be 
  seen 
  to 
  flow. 
  The 
  current 
  usually 
  continues 
  for 
  

   about 
  a 
  minute 
  and 
  a 
  half 
  in 
  one 
  direction, 
  then 
  stops, 
  and 
  flows 
  

   for 
  the 
  same 
  time 
  in 
  the 
  opposite 
  direction 
  ; 
  this 
  ' 
  tide,' 
  as 
  it 
  may 
  

   be 
  termed, 
  is 
  strongest 
  towards 
  the 
  part 
  where 
  most 
  active 
  feeding 
  

   is 
  taking 
  place. 
  By 
  means 
  of 
  this 
  circulation 
  all 
  parts 
  of 
  the 
  

   Plasmodium 
  are 
  kept 
  in 
  close 
  communication. 
  

  

  " 
  In 
  dry 
  weather, 
  when 
  the 
  moisture 
  needful 
  for 
  the 
  active 
  life 
  of 
  

  

  