﻿296 
  BOTANICAL 
  GAZETTE. 
  [ 
  November, 
  

  

  end 
  of 
  the 
  block 
  is 
  wet 
  in 
  solution 
  no. 
  i, 
  a 
  piece 
  of 
  paper 
  

  

  with 
  the 
  desired 
  data 
  is 
  stuck 
  on 
  and 
  washed 
  over 
  with 
  solu- 
  

   tion 
  no. 
  3. 
  

  

  In 
  conclusion 
  I 
  may 
  say 
  that 
  I 
  have 
  tried 
  nearly 
  all 
  the 
  

   methods 
  employed 
  in 
  celloidin 
  manipulation 
  and 
  have 
  suc- 
  

   ceeded 
  best 
  with 
  the 
  above, 
  which 
  is 
  largely 
  a 
  combination 
  

   or 
  modification 
  of 
  methods 
  already 
  known. 
  

  

  Botanical 
  Laboratory, 
  University 
  of 
  Michigan. 
  

  

  The 
  Collodion 
  method 
  in 
  botany. 
  

  

  M. 
  B. 
  THOMAS. 
  

  

  In 
  any 
  original 
  investigation 
  in 
  the 
  field 
  of 
  histological 
  

   botany 
  the 
  worker 
  is 
  at 
  the 
  outset 
  confronted 
  with 
  the 
  all 
  

   important 
  question 
  of 
  how 
  to 
  prepare 
  the 
  material 
  so 
  that 
  it 
  

   may 
  be 
  available 
  in 
  the 
  best 
  possible 
  condition 
  for 
  thorough 
  

   systematic 
  observation 
  and 
  studv. 
  The 
  old 
  method 
  of 
  mak- 
  

   ing 
  freehand 
  sections 
  in 
  careful 
  investigations 
  is 
  now 
  gone 
  

   by 
  and 
  the 
  best 
  histologlsts 
  look 
  for 
  some 
  substance 
  with 
  

   which 
  to 
  infiltrate 
  the 
  tissue 
  and 
  bring 
  it 
  into 
  a 
  condition 
  

   where 
  uniform 
  serial 
  sections 
  can 
  be 
  made. 
  Many 
  sub- 
  

   stances 
  have 
  from 
  time 
  to 
  time 
  been 
  offered 
  and 
  met 
  with 
  

   varying 
  success. 
  Some 
  of 
  the 
  more 
  important 
  ones 
  that 
  have 
  

   been 
  tried 
  are 
  gelatin, 
  gelatin 
  soap, 
  gum, 
  paper, 
  shellac, 
  wax, 
  

   gum 
  arable 
  soap, 
  paraffine 
  and 
  collodion 
  The 
  last 
  twj 
  

   substances 
  have 
  seemingly 
  supplanted 
  the 
  others 
  and 
  indeed 
  

  

  nn^ 
  f 
  fi!" 
  ^^ 
  ""^^^ 
  ^^1 
  the 
  advantages 
  that 
  can 
  be 
  secured 
  b} 
  

   any 
  of 
  the 
  othpr« 
  ^ 
  

  

  pub- 
  

  

  ihSr 
  ^^ 
  1 
  • 
  ^°" 
  ^" 
  the 
  Botanical 
  Gazette 
  of 
  January 
  

   ^^l^^.t 
  f^' 
  "^'^"^^ 
  modifications 
  of 
  it 
  have 
  been 
  given 
  ana 
  

   exte^.f 
  ^"^ 
  ""^"^ 
  improved. 
  The 
  method 
  has 
  been 
  qu' 
  

   man?n 
  '1^^ 
  ""^J^^ 
  ^^^ 
  '^ 
  ^^O' 
  ^ong 
  and 
  quite 
  disagreeable 
  

   ?^an 
  ipulate, 
  often 
  requiring^o 
  0^12 
  days 
  to 
  bring 
  the 
  tissu 
  

   whh 
  naff^ 
  ^°«^^tion 
  for 
  sectioning. 
  For 
  proper 
  infiltra 
  'f 
  

   rnd 
  for 
  '^^' 
  V^'^P^^'^ture 
  of 
  from 
  45° 
  to 
  50° 
  C. 
  is 
  req^r^^^; 
  

   hasDrovTr" 
  "f 
  ^^^ 
  ^^^^ 
  ^l^l^cate 
  tissues'this 
  in 
  ^v 
  han 
  

   nas 
  proved 
  fatal. 
  The 
  method 
  is 
  admirably 
  adapted, 
  hm, 
  

  

  tionb^ 
  L""'"^^ 
  ^^'^^^ 
  that 
  can 
  be 
  held 
  in 
  position 
  fd^^^ 
  

  

  woodf 
  Bern's 
  ^'th 
  "^^Vi 
  ^^ 
  ^^ 
  ^^^^ 
  ^^^^ 
  ^^^^^ 
  "^^""jr. 
  "t^ 
  

   gene,4li 
  «?f" 
  ^^ 
  collodion 
  method 
  is 
  now 
  coni'"f^u,e 
  

   general 
  use 
  for 
  nearly 
  all 
  kinds 
  of 
  plant 
  tissue. 
  For 
  the 
  u- 
  

  

  