﻿116 
  Thirtieth 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  In 
  fig. 
  3, 
  of 
  Plate 
  3, 
  we 
  have 
  given 
  an 
  illustration 
  of 
  a 
  vertical 
  

   section 
  of 
  one 
  of 
  these 
  sponges. 
  The 
  principal 
  feature 
  observable, 
  

   is 
  the 
  systematical 
  arrangement 
  of 
  the 
  colons 
  or 
  tubes 
  formed 
  of 
  

   a 
  number 
  of 
  balloon- 
  shaped 
  cells 
  ; 
  these 
  commencing 
  on 
  the 
  

   concave 
  surface, 
  gradually 
  diverge 
  as 
  they 
  approach 
  the 
  outer 
  

   or 
  convex 
  side. 
  Taking 
  for 
  example 
  two 
  neighboring 
  tubes, 
  it 
  

   will 
  be 
  seen 
  that 
  the 
  cells 
  appear 
  to 
  alternate, 
  or 
  the 
  cell 
  of 
  one 
  

   tube 
  partially 
  fills 
  the 
  space 
  occurring 
  between 
  two 
  of 
  the 
  cells 
  

   of 
  the 
  next 
  and 
  so 
  on 
  ; 
  though 
  exceptions 
  to 
  this 
  mode 
  of 
  

   growth 
  are 
  observable. 
  

  

  In 
  some 
  of 
  the 
  vertical 
  sections, 
  there 
  appears 
  to 
  be 
  a 
  division 
  

   marked 
  by 
  a 
  transverse 
  line 
  of 
  cells 
  from 
  which 
  the 
  vertical 
  

   growth 
  seems 
  to 
  have 
  taken 
  place 
  in 
  both 
  directions 
  at 
  the 
  

   same 
  time, 
  though 
  the 
  lines 
  of 
  cells 
  diverging 
  to 
  the 
  convex^ 
  

   are 
  more 
  m 
  .rked 
  and 
  larger 
  than 
  those 
  passing 
  toward 
  the 
  

   concave 
  surface. 
  

  

  Although 
  stars 
  do 
  occur 
  in 
  making 
  the 
  vertical 
  sections, 
  they 
  

   appear 
  to 
  be 
  rather 
  the 
  exception 
  than 
  the 
  rule, 
  and 
  can 
  be 
  

   explained 
  by 
  the 
  fact 
  of 
  the 
  germinating 
  power 
  inherent 
  in 
  the 
  

   cells 
  forming 
  the 
  branches 
  or 
  side 
  growths. 
  

  

  The 
  miner 
  alogical 
  components 
  are 
  first 
  calc 
  spar 
  which 
  is 
  

   indicated 
  by 
  the 
  fracture, 
  also 
  alumina 
  which 
  has 
  already 
  been 
  

   mentioned 
  as 
  composing 
  the 
  greater 
  portion 
  of 
  the 
  tegument, 
  

   and 
  which 
  can 
  readily 
  be 
  detected 
  by 
  the 
  taste 
  and 
  odor. 
  

   Blue 
  and 
  red 
  chalcedony 
  are 
  present 
  in 
  variable 
  proportions 
  — 
  

   in 
  some, 
  hardly 
  observable, 
  and 
  in 
  others 
  forming 
  the 
  greater 
  

   portion 
  of 
  the 
  body 
  of 
  the 
  sponge. 
  We 
  have 
  also 
  noticed 
  in 
  

   the 
  specimens 
  under 
  examination 
  that, 
  as 
  a 
  rule, 
  the 
  flat 
  sponges 
  

   were 
  nearly 
  destitute 
  of 
  this 
  mineral, 
  while 
  the 
  deeper 
  or 
  cup 
  

   shaped 
  sponges 
  were 
  largely 
  composed 
  of 
  chalcedony. 
  

  

  Note. 
  — 
  It 
  is 
  scarcely 
  necessary 
  to 
  remark 
  upon 
  the 
  rapid 
  progress 
  made 
  in 
  the 
  

   use 
  of 
  the 
  microscope 
  as 
  applied 
  to 
  science 
  during 
  the 
  past 
  few 
  years. 
  Mineralogy 
  

   and 
  Petrography 
  have 
  already 
  materially 
  advanced 
  through 
  its 
  assistance, 
  and 
  

   Palaeontology 
  has 
  but 
  just 
  entered 
  upon 
  this 
  comparatively 
  new 
  branch 
  of 
  

   investigation. 
  

  

  The 
  use 
  of 
  these 
  fine 
  microscopic 
  sections 
  in 
  the 
  study 
  of 
  Corals 
  as 
  well 
  as 
  

   Sponges, 
  and 
  in 
  almost 
  all 
  fossils, 
  will 
  eventually 
  become 
  a 
  necessity 
  and 
  will 
  form 
  

   a 
  marked 
  era 
  in 
  the 
  progress 
  of 
  the 
  science 
  to 
  which 
  they 
  are 
  applied. 
  

  

  