﻿8 
  A 
  MONOGRAPH 
  OF 
  THE 
  VICTORIAN 
  SPONGES. 
  

  

  polygonal 
  in 
  outline, 
  and 
  each 
  with 
  a 
  swelling 
  in 
  the 
  centre 
  where 
  the 
  nucleus 
  is 
  

   situate. 
  The 
  cell 
  itself 
  averages 
  about 
  0-0136 
  mm. 
  in 
  diameter, 
  and 
  the 
  nucleus, 
  

   which 
  is 
  very 
  distinctly 
  outlined 
  and 
  more 
  or 
  less 
  spherical 
  (or 
  perhaps 
  somewhat 
  

   flattened 
  in 
  the 
  same 
  manner 
  as 
  the 
  cell), 
  has 
  a 
  diameter 
  of 
  about 
  O-OOS-l 
  mm. 
  

   Within 
  the 
  nucleus 
  appear 
  a 
  few 
  small, 
  deeply 
  staining 
  granules. 
  Around 
  the 
  nucleus 
  

   the 
  protoplasm 
  is 
  highly 
  granular, 
  exactly 
  as 
  described 
  by 
  Schulze, 
  while 
  towards 
  the 
  

   periphery 
  of 
  the 
  cell 
  it 
  becomes 
  gradually 
  hyaline. 
  Adjacent 
  cells 
  are 
  in 
  contact 
  at 
  

   the 
  edges, 
  and 
  all 
  together 
  form 
  a 
  single-layered, 
  continuous 
  epithelium 
  over 
  the 
  out- 
  

   side 
  of 
  the 
  Ascon-tube. 
  As 
  a 
  rule, 
  in 
  ordinary 
  preparations, 
  although 
  the 
  nuclei 
  and 
  

   granules 
  of 
  the 
  ectoderm 
  cells 
  may 
  be 
  clearly 
  enough 
  visible, 
  it 
  is 
  very 
  difficult 
  to 
  

   distinguish 
  the 
  outlines. 
  

  

  Von 
  Lendenfeld* 
  observes 
  : 
  " 
  The 
  whole 
  outer 
  free 
  surface 
  of 
  the 
  Sponge 
  is 
  

   covered 
  Avitli 
  a 
  low 
  Epithelium, 
  consisting 
  of 
  flat 
  covering 
  cells, 
  each 
  of 
  which 
  may 
  

   possess 
  one 
  swinging 
  cilia." 
  This 
  author 
  habitually 
  figures 
  cilia 
  on 
  the 
  ectodermal 
  

   cells 
  both 
  of 
  calcareous 
  and 
  non-calcareous 
  sponges, 
  and 
  it 
  would 
  be 
  interesting 
  to 
  

   know 
  if 
  he 
  has 
  actually 
  seen 
  them 
  or 
  merely 
  assumed 
  their 
  presence, 
  perhaps 
  from 
  

   observing 
  currents 
  in 
  the 
  surrounding 
  water. 
  It 
  does 
  not 
  seem 
  to 
  me 
  probable 
  

   that 
  the 
  ectodermal 
  cells 
  of 
  the 
  Calcarea 
  Homocoela 
  are 
  ciliated. 
  

  

  The 
  Endoderm. 
  

  

  According 
  to 
  Hseckelf 
  the 
  cells 
  (termed 
  by 
  Sollas 
  "choanocytes" 
  and 
  by 
  Carter 
  

   "spongozoa," 
  but 
  generally 
  known 
  as 
  "collared 
  cells") 
  of 
  which 
  the 
  endoderm 
  in 
  the 
  

   Calcarea 
  Homoccela 
  is 
  entirely 
  composed 
  are 
  so 
  uniform 
  in 
  structure, 
  not 
  only 
  

   amongst 
  the 
  Calcareous 
  sponges 
  but 
  also 
  in 
  other 
  groups, 
  that 
  the 
  description 
  of 
  

   one 
  species 
  will 
  serve 
  for 
  all. 
  Until 
  recently 
  this 
  has 
  been 
  the 
  general 
  view 
  and 
  it 
  

   has 
  become 
  customary 
  with 
  some 
  spongologists 
  to 
  figure 
  the 
  collared 
  cells 
  in 
  their 
  

   drawings 
  like 
  so 
  many 
  bricks 
  in 
  the 
  plan 
  of 
  a 
  building, 
  apparently 
  without 
  taking 
  the 
  

   least 
  trouble 
  to 
  investigate 
  for 
  themselves 
  the 
  true 
  state 
  of 
  the 
  case. 
  No 
  one 
  can 
  suppose, 
  

   for 
  instance, 
  that 
  Polejaeff 
  ever 
  saw 
  the 
  collared 
  cells 
  in 
  the 
  not 
  too 
  well 
  preserved 
  

   material 
  at 
  his 
  disposal 
  anything 
  like 
  so 
  plainly 
  or 
  so 
  regularly 
  arranged 
  as 
  he 
  figures 
  

   them 
  in 
  his 
  Keports 
  on 
  the 
  Calcarea 
  and 
  Keratosa 
  of 
  the 
  "Challenger" 
  Expedition. 
  The 
  

   structure 
  of 
  the 
  collared 
  cells 
  having 
  been 
  made 
  out 
  by 
  James-Clark, 
  J 
  Carter, 
  § 
  Hseckel]] 
  

   and 
  Schulzell 
  in 
  a 
  few 
  cases, 
  it 
  was 
  assumed 
  that 
  all 
  collared 
  cehs 
  were 
  the 
  same, 
  and 
  

  

  * 
  Proceedings 
  of 
  the 
  Linnean 
  Society 
  of 
  New 
  South 
  Wales, 
  Vol. 
  IX., 
  Part 
  2, 
  p. 
  318. 
  

  

  I 
  " 
  Die 
  Kalkschwamme." 
  Vol. 
  I. 
  p. 
  137. 
  

  

  \ 
  " 
  Spongife 
  ciliatse, 
  as 
  Infusoria 
  flagellata." 
  Memoirs 
  of 
  the 
  Boston 
  Society 
  of 
  Natural 
  History, 
  Vol. 
  i. 
  Part 
  3, 
  1867. 
  

  

  § 
  " 
  Notes 
  Introductory 
  to 
  the 
  Study 
  and 
  Classification 
  of 
  the 
  Spongida." 
  Annals 
  and 
  Magazine 
  of 
  Natural 
  

   History. 
  Ser. 
  4, 
  Vol. 
  xvi., 
  1875. 
  

  

  II 
  " 
  Die 
  Kalkschwamme," 
  loc. 
  cit. 
  

   M 
  Loc. 
  cit. 
  

  

  