﻿372 
  LEONARD 
  ROGERS. 
  

  

  Stage 
  of 
  Development 
  after 
  Forty-eiglit 
  Hours. 
  — 
  

   By 
  tlie 
  end 
  of 
  the 
  second 
  day 
  much 
  more 
  marked 
  changes 
  are 
  

   met 
  with, 
  the 
  principal 
  forms 
  of 
  which 
  are 
  shown 
  in 
  lines 
  IV 
  

   and 
  VIII 
  of 
  the 
  Plate. 
  In 
  the 
  first 
  place 
  there 
  is 
  a 
  still 
  

   further 
  and 
  very 
  marked 
  increase 
  in 
  the 
  size 
  of 
  the 
  organisms 
  

   still 
  affecting 
  especially 
  the 
  macronucleus 
  and 
  the 
  protoplasm, 
  

   as 
  in 
  figs. 
  5 
  and 
  7 
  of 
  line 
  IV. 
  Secondly, 
  and 
  of 
  much 
  greater 
  

   interest, 
  is 
  the 
  appearance 
  of 
  double 
  forms, 
  such 
  as 
  are 
  not 
  

   met 
  with 
  on 
  the 
  first 
  day. 
  These 
  show 
  every 
  degree 
  from 
  

   apposition 
  at 
  one 
  point 
  of 
  their 
  circumference 
  of 
  two 
  of 
  the 
  

   large 
  oval 
  forms, 
  through 
  closer 
  degrees 
  of 
  contact 
  up 
  to 
  

   nearly 
  complete 
  fusion 
  of 
  the 
  two 
  cells. 
  At 
  first 
  I 
  took 
  these 
  

   stages 
  for 
  a 
  method 
  of 
  division, 
  but 
  as 
  a 
  further 
  study 
  showed 
  

   that 
  the 
  latter 
  developments 
  into 
  elongated 
  and 
  flagellated 
  

   forms 
  always 
  takes 
  place 
  in 
  pairs 
  or 
  rarely 
  threes, 
  I 
  have 
  

   come 
  to 
  the 
  conclusion 
  that 
  these 
  early 
  double 
  forms 
  are 
  

   really 
  a 
  kind 
  of 
  conjugation, 
  such 
  as 
  is 
  known 
  to 
  occur 
  in 
  

   other 
  protozoa 
  preparatory 
  to 
  the 
  evolution 
  of 
  new 
  stages 
  

   in 
  their 
  life 
  history. 
  In 
  favour 
  of 
  this 
  view 
  there 
  is 
  also 
  the 
  

   fact 
  that 
  the 
  pairs 
  of 
  large 
  oval 
  organisms 
  during 
  the 
  second 
  

   and 
  third 
  days 
  are 
  found 
  to 
  be 
  in 
  contact 
  with 
  each 
  other 
  in 
  

   very 
  varying 
  positions, 
  and 
  to 
  present 
  no 
  regularity 
  in 
  this 
  

   feature, 
  as 
  is 
  the 
  case 
  with 
  the 
  small 
  spleen 
  forms 
  undergoing 
  

   fission 
  shown 
  in 
  figs. 
  1 
  to 
  4 
  of 
  line 
  I 
  of 
  the 
  Plate. 
  Thus, 
  while 
  

   figs, 
  4 
  and 
  6 
  of 
  line 
  IV 
  show 
  contact 
  of 
  the 
  sides 
  of 
  the 
  oval 
  

   bodies, 
  figs. 
  5 
  and 
  7 
  of 
  line 
  V 
  show 
  apposition 
  of 
  the 
  end 
  

   of 
  one 
  to 
  the 
  side 
  of 
  the 
  other, 
  and 
  similar 
  variations 
  are 
  

   shown 
  in 
  the 
  figures 
  of 
  line 
  VIII. 
  

  

  In 
  addition 
  to 
  the 
  forms 
  showing 
  mere 
  apposition, 
  others 
  

   show 
  more 
  or 
  less 
  complete 
  degrees 
  of 
  fusion 
  of 
  two 
  oval 
  

   forms, 
  as 
  in 
  figs. 
  1, 
  2, 
  and 
  8 
  of 
  line 
  IV, 
  the 
  two 
  macro- 
  and 
  

   micronuclei 
  being 
  each 
  distinctly 
  seen. 
  Further, 
  even 
  on 
  the 
  

   second 
  day, 
  forms 
  approximating 
  to 
  the 
  next 
  stage 
  in 
  the 
  

   development 
  of 
  the 
  organism 
  may 
  be 
  found 
  — 
  namely, 
  an 
  

   elongation 
  of 
  the 
  conjugating 
  forms, 
  as 
  shown 
  in 
  figs. 
  1, 
  6, 
  

   and 
  7 
  of 
  line 
  VIII, 
  — 
  but 
  as 
  a 
  rule 
  these 
  do 
  not 
  appear 
  in 
  any 
  

   numbers 
  until 
  the 
  third 
  day. 
  

  

  