﻿6 
  A 
  MONOGRAPH 
  OF 
  THE 
  VICTORIAN 
  SPONGES. 
  

  

  Throughout 
  the 
  life 
  of 
  the 
  sponge 
  a 
  stream 
  of 
  water 
  may 
  be 
  observed 
  issuing 
  

   through 
  the 
  oscuhim 
  from 
  the 
  gastral 
  cavity, 
  the 
  water 
  which 
  thus 
  flows 
  out 
  being 
  

   constantly 
  replaced 
  by 
  smaller 
  streams 
  which 
  flow 
  in 
  through 
  the 
  prosopyles. 
  This 
  

   stream 
  of 
  water 
  is 
  maintained 
  by 
  the 
  activity 
  of 
  the 
  flagella 
  of 
  the 
  collared 
  cells 
  com- 
  

   posing 
  the 
  endoderm. 
  

  

  Such 
  then, 
  in 
  brief, 
  is 
  the 
  structure 
  of 
  the 
  Olynthiis, 
  which 
  is 
  to 
  be 
  regarded 
  as 
  

   a 
  single 
  individual 
  or 
  Ascou-person.* 
  No 
  examples 
  of 
  the 
  Olynthus 
  type 
  occur 
  in 
  the 
  

   collection 
  of 
  Victorian 
  sponges, 
  but 
  for 
  an 
  illustration 
  I 
  would 
  refer 
  students 
  to 
  

   Hgeckel's 
  Ascetta 
  (Lencosolenia) 
  primordialis, 
  admirably 
  illustrated 
  in 
  his 
  Atlas 
  of 
  the 
  

   Calcareous 
  Sponges. 
  f 
  It 
  is 
  probable 
  that 
  all 
  Calcareous 
  sponges 
  pass 
  through 
  an 
  

   Olynthus 
  stage 
  at 
  an 
  early 
  period 
  of 
  their 
  life 
  history. 
  

  

  B. 
  — 
  The 
  Histology 
  of 
  the 
  Calcaeea 
  Homocgela. 
  

  

  The 
  Ectoderm. 
  

  

  The 
  true 
  nature 
  of 
  the 
  ectoderm 
  of 
  Calcareous 
  sponges 
  was 
  first 
  elucidated 
  by 
  

   Schulze 
  in 
  his 
  well-known 
  memoir 
  on 
  the 
  structure 
  and 
  development 
  of 
  Sycandra 
  

   raphanus.'l 
  Hffickel, 
  in 
  his 
  Monograph 
  on 
  the 
  Calcareous 
  Sponges, 
  had 
  altogether 
  

   failed 
  to 
  comprehend 
  the 
  true 
  condition 
  of 
  things, 
  and 
  had 
  confused 
  the 
  two 
  layers, 
  

   ectoderm 
  and 
  mesoderm, 
  under 
  the 
  one 
  name 
  Exoderni 
  (used 
  as 
  a 
  synonym 
  for 
  

   Edoderin). 
  H^eckel 
  states§ 
  that 
  the 
  " 
  exoderm 
  " 
  consists 
  firstly 
  of 
  a" 
  syncytium," 
  

   and 
  secondly 
  of 
  the 
  spicules. 
  " 
  Syncytium 
  nenne 
  ich 
  bei 
  den 
  Kalkschwammen 
  die 
  

   ganze 
  Gewebsmasse, 
  welche 
  durchdie 
  Verschmelzung 
  der 
  Geisselzellen 
  desExoderms 
  

   der 
  Flimmerlarve 
  entstanden 
  ist, 
  mit 
  Ausschluss 
  der 
  darin 
  gebildeten 
  Kalknadehi. 
  

   Dieses 
  Syncytium 
  ist 
  aus 
  folgenden 
  Bestandtheilen 
  zusammengesetzt 
  : 
  (1) 
  der 
  

   Sarcodine, 
  einer 
  hyalinen, 
  structurlosen, 
  contractilen 
  Grundsubstanz, 
  dem 
  modificirten 
  

   Protoplasma 
  der 
  verschmolzenen 
  Zellen 
  ; 
  (2) 
  den 
  bleibenden 
  und 
  sich 
  vermehreuden 
  

   Kernen 
  dieser 
  Zellen, 
  und 
  (^) 
  den 
  Spicnla-Scheiden, 
  welche 
  durch 
  Verdichtung 
  der 
  

   Grundsubstanz 
  rings 
  um 
  die 
  Oberflache 
  der 
  Spicula 
  entstanden 
  sind." 
  Hasckel 
  

   himself, 
  in 
  his 
  latest 
  work 
  on 
  sponges, 
  recognises 
  his 
  error, 
  and 
  acknowledges 
  the 
  

   correctness 
  of 
  Schulze's 
  view 
  ; 
  to 
  quote 
  his 
  own 
  words 
  : 
  " 
  Three 
  years 
  later 
  (in 
  1875) 
  

   this 
  conception 
  was 
  corrected 
  by 
  the 
  accurate 
  observations 
  of 
  Franz 
  Eilhard 
  Schulze, 
  

   the 
  excellent 
  spongiologist, 
  who 
  has 
  advanced 
  in 
  so 
  many 
  important 
  directions 
  the 
  

  

  * 
  We 
  may 
  conveniently 
  retain 
  this 
  term 
  although 
  Hseckel's 
  group 
  name 
  " 
  Ascones" 
  has 
  been 
  abandoned. 
  

  

  t 
  " 
  Die 
  Kalkschwiimme," 
  Vol. 
  3, 
  Plate 
  1. 
  

  

  \ 
  "Ueber 
  den 
  Bau 
  und 
  dieEntwicklung 
  von 
  Sycandra 
  ravhanus 
  E.xckeL" 
  Zeitschrift 
  f. 
  wissensch. 
  Zoolosie. 
  Vol. 
  

   XXV. 
  Suppl., 
  p. 
  247. 
  

  

  § 
  " 
  Die 
  Kalkschwamme," 
  Vol. 
  I., 
  p. 
  160. 
  

  

  