﻿12 
  Merriman: 
  Conjugatiox 
  of 
  Spirogyra 
  terxata 
  

  

  out 
  changes 
  in 
  the 
  length 
  of 
  the 
  filament 
  as 
  a 
  whole 
  but 
  would 
  not 
  

   take 
  into 
  account 
  differences 
  in 
  the 
  two 
  sides 
  of 
  the 
  cell 
  and 
  in 
  the 
  

   extent 
  of 
  the 
  cell 
  walls. 
  

  

  two 
  

  

  cell 
  in 
  each 
  sex 
  were 
  measured 
  in 
  some 
  of 
  the 
  most 
  curved 
  examples. 
  

  

  betw 
  

  

  measurement 
  

  

  the 
  various 
  degrees 
  of 
  bulging 
  of 
  the 
  inner 
  walls 
  where 
  the 
  tube 
  

   emerged 
  made 
  accuracy 
  difficult. 
  When 
  accurate 
  measurements 
  

   were 
  needed 
  to 
  determine 
  the 
  size 
  and 
  position 
  of 
  the 
  various 
  cell 
  

   organs, 
  such 
  as 
  the 
  nuclei 
  and 
  pyrenoids, 
  higher 
  powers 
  and 
  the 
  

   ocular 
  micrometer 
  were 
  used. 
  Measurements 
  of 
  the 
  drawings 
  

   by 
  means 
  of 
  the 
  thread 
  following 
  the 
  curving 
  lateral 
  walls 
  always 
  

   gave 
  figures 
  in 
  excess 
  of 
  the 
  sum 
  of 
  the 
  lengths 
  of 
  the 
  cells 
  measured 
  

   individually. 
  Both 
  of 
  these 
  methods, 
  when 
  so 
  many 
  hundreds 
  

   of 
  cells 
  were 
  examined, 
  involved 
  far 
  less 
  labor 
  than 
  the 
  use 
  of 
  the 
  

   ocular 
  micrometer 
  and 
  gave 
  the 
  same 
  relative 
  proportions 
  in 
  the 
  

   lengths 
  of 
  the 
  cells. 
  

  

  The 
  various 
  measurements 
  obtained 
  in 
  each 
  series 
  of 
  obser- 
  

   vations 
  have 
  been 
  arranged 
  in 
  tables. 
  If 
  a 
  longitudinal 
  series 
  of 
  

   cells 
  is 
  considered 
  an 
  individual 
  plant, 
  only 
  a 
  portion 
  of 
  a 
  plant 
  

   was 
  measured 
  in 
  each 
  case. 
  It 
  would, 
  in 
  fact, 
  be 
  impossible 
  to 
  be 
  

   sure 
  in 
  collecting 
  material 
  that 
  an 
  entire 
  thread, 
  resulting 
  from 
  

   the 
  germination 
  of 
  a 
  zygospore, 
  had 
  been 
  obtained. 
  In 
  this 
  work, 
  

  

  tially 
  the 
  same. 
  

  

  Spirogyra 
  

  

  Series 
  A 
  (Fig. 
  i) 
  represents 
  a 
  pair 
  of 
  threads 
  chosen 
  for 
  study 
  

   by 
  reason 
  of 
  their 
  great 
  convexity 
  and 
  torsion. 
  In 
  this 
  series 
  none 
  

   of 
  the 
  opposing 
  cells 
  had 
  apparently 
  mingled 
  their 
  contents, 
  and 
  

   the 
  nuclei 
  are 
  to 
  be 
  seen 
  in 
  their 
  central 
  positions 
  with 
  the 
  chro- 
  

   matophores 
  unrelaxed 
  and 
  contiguous 
  to 
  the 
  cell 
  wall, 
  

   ordinary 
  vegetative 
  cells. 
  In 
  mounting 
  these 
  threads 
  'in" 
  the 
  

  

  as 
  in 
  

  

  curvatures 
  between 
  A 
  and 
  B 
  and 
  between 
  

  

  and 
  D 
  in 
  the 
  figure 
  projected 
  much 
  above 
  the 
  surface. 
  Though 
  a 
  

   cover-glass 
  was 
  carefully 
  lowered 
  upon 
  them 
  the 
  torsion 
  was 
  such 
  

   that 
  the 
  flattening 
  of 
  the 
  surface 
  caused 
  a 
  breaking 
  of 
  the 
  d^ 
  

   thread 
  of 
  the 
  pair 
  at 
  D, 
  one 
  of 
  the 
  most 
  curved 
  points. 
  Camera 
  

   drawings 
  were 
  made 
  of 
  the 
  threads 
  as 
  they 
  were 
  thus 
  mounted, 
  

  

  