﻿112 
  Thirtieth 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  we 
  have 
  had 
  opportunity 
  to 
  make 
  the 
  following 
  important 
  

   observations 
  on 
  their 
  structure 
  : 
  

  

  In 
  order 
  to 
  make 
  the 
  study 
  of 
  the 
  sponge- 
  structure 
  more 
  

   complete, 
  it 
  has 
  been 
  necessary 
  to 
  prepare 
  a 
  number 
  of 
  cuts 
  

   both 
  vertical 
  and 
  transverse. 
  The 
  machinery 
  and 
  appliances 
  

   already 
  established 
  in 
  the 
  State 
  Museum 
  enabled 
  us 
  to 
  accom- 
  

   plish 
  this 
  object 
  in 
  a 
  very 
  satisfactory 
  manner. 
  

  

  Besides 
  the 
  polished 
  sections 
  which 
  in 
  themselves 
  were 
  inter- 
  

   esting 
  as 
  already 
  indicating 
  organic 
  structure, 
  we 
  have 
  made 
  

   many 
  transparent 
  preparations 
  for 
  microscopic 
  investigation. 
  

  

  The 
  mineralogical 
  condition 
  of 
  the 
  material 
  infiltrating 
  the 
  

   sponge 
  was 
  such 
  as 
  enabled 
  us 
  to 
  make 
  the 
  thinnest 
  possible 
  

   objects 
  for 
  the 
  microscope, 
  and 
  thus 
  subject 
  them 
  to 
  the 
  

   highest 
  power 
  ; 
  though 
  more 
  satisfactory 
  results 
  have 
  been 
  

   obtained 
  by 
  the 
  use 
  of 
  the 
  lower 
  magnifying 
  powers. 
  

  

  These 
  sections 
  by 
  the 
  assistance 
  of 
  the 
  microscope, 
  and 
  by 
  

   the 
  aid 
  of 
  photography 
  furnish 
  the 
  material 
  for 
  minute 
  descrip- 
  

   tion 
  and 
  the 
  means 
  of 
  exact 
  pictorial 
  representation. 
  

  

  The 
  photographic 
  print 
  being 
  nothing 
  more 
  nor 
  less 
  than 
  a 
  

   microscopic 
  enlargement 
  transferred 
  by 
  mechanical 
  means 
  from 
  

   the 
  transparent 
  section 
  itself, 
  to 
  the 
  paper, 
  admits 
  of 
  no 
  such 
  

   deviations 
  from 
  the 
  original 
  as 
  must 
  of 
  necessity 
  occur 
  where 
  

   the 
  illustration 
  of 
  a 
  specimen 
  has 
  to 
  undergo 
  the 
  manipulation 
  

   of 
  the 
  draughtsman 
  and 
  lithographer. 
  

  

  There 
  is 
  much 
  difference 
  in 
  the 
  chemical 
  composition 
  of 
  the 
  

   various 
  parts 
  of 
  the 
  living 
  sponge, 
  therefore, 
  during 
  the 
  process 
  

   of 
  petrifaction 
  these 
  different 
  tissues 
  would 
  react 
  and 
  be 
  acted 
  

   upon 
  in 
  different 
  ways, 
  which 
  in 
  regard 
  to 
  their 
  crystalline 
  

   molecular 
  arrangement 
  is 
  clearly 
  shown 
  by 
  the 
  use 
  of 
  the 
  

   polariscope. 
  

  

  There 
  are 
  also 
  chemical 
  differences, 
  which 
  being 
  made 
  use 
  of 
  

   by 
  the 
  careful 
  application 
  of 
  dilute 
  hydrochloric 
  acid, 
  and 
  in 
  

   some 
  cases 
  where 
  a 
  more 
  delicate 
  operation 
  is 
  requisite, 
  by 
  the 
  

   use 
  of 
  acetic 
  acid, 
  show 
  also 
  the 
  peculiarities 
  of 
  the 
  sponge 
  

   structure. 
  

  

  We 
  have 
  sometimes 
  taken 
  the 
  whole 
  sponge 
  upon 
  which 
  to 
  

   operate 
  after 
  this 
  manner. 
  Some 
  of 
  the 
  mineral 
  matter 
  having 
  

   been 
  dissolved, 
  the 
  result 
  was 
  a 
  most 
  exquisitely 
  delicate 
  

   representation 
  of 
  the 
  form 
  of 
  the 
  sponge 
  during 
  life. 
  

  

  