﻿536 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [48] 
  

  

  fully 
  and 
  rhythmically 
  through 
  the 
  contents 
  of 
  the 
  water 
  space 
  sur- 
  

   rounded 
  by 
  the 
  zona. 
  

  

  The 
  water 
  space 
  from 
  the 
  first 
  was 
  filled 
  with 
  an 
  immense 
  number 
  of 
  

   free 
  refringent 
  but 
  very 
  minute 
  corpuscles, 
  which 
  made 
  it 
  difficult 
  to 
  

   make 
  out 
  the 
  form 
  of 
  the 
  embryo 
  during 
  the 
  early 
  stages, 
  unless 
  the 
  

   zona 
  was 
  first 
  removed. 
  These 
  corpuscles 
  were 
  not 
  of 
  the 
  nature 
  of 
  

   blood 
  cells, 
  and 
  seemed 
  to 
  become 
  less 
  abundant 
  toward 
  the 
  close 
  of 
  

   the 
  period 
  of 
  development 
  within 
  the 
  egg. 
  So 
  abundant 
  were 
  these 
  

   corpuscles 
  at 
  first, 
  coupled 
  with 
  the 
  opacity 
  of 
  the 
  vitellus 
  and 
  the 
  

   peculiar 
  whiteness 
  of 
  the 
  germinal 
  matter, 
  that 
  even 
  an 
  experienced 
  

   observer 
  would 
  be 
  led 
  to 
  suppose 
  at 
  first 
  that 
  all 
  of 
  the 
  eggs 
  were 
  

   bad, 
  having 
  the 
  "rice-grain" 
  appearance 
  of 
  blasted 
  shad 
  ova. 
  The 
  

   corpuscles 
  mentioned 
  are 
  visible 
  in 
  sections 
  of 
  the 
  entire 
  egg 
  of 
  lc- 
  

   talurus, 
  and 
  are 
  very 
  abundant 
  in 
  the 
  water 
  space 
  forming 
  adherent 
  

   masses. 
  In 
  life 
  the 
  movements 
  of 
  the 
  tail 
  of 
  the 
  embryo 
  cat-fish 
  whirl 
  

   these 
  corpuscles 
  about 
  in 
  the 
  water 
  space 
  in 
  clouds, 
  so 
  that 
  it 
  seems 
  as 
  

   if 
  a 
  whitish 
  sediment 
  was 
  being 
  constantly 
  stirred 
  up 
  within 
  the 
  egg- 
  

   membrane. 
  The 
  presence 
  of 
  vast 
  numbers 
  of 
  such 
  bodies 
  of 
  plasmic 
  

   origin 
  within 
  the 
  egg-membranes 
  of 
  Teleosts 
  it 
  seems 
  had 
  not 
  been 
  ob- 
  

   served 
  in 
  any 
  other 
  form 
  up 
  to 
  the 
  time 
  that 
  the 
  writer 
  had 
  published 
  

   his 
  observations 
  on 
  the 
  development 
  of 
  the 
  cat-fish. 
  Recently, 
  however, 
  

   it 
  has 
  been 
  found 
  by 
  Solger 
  51 
  that 
  they 
  are 
  present 
  in 
  the 
  water 
  space 
  

   of 
  the 
  ova 
  of 
  other 
  species, 
  especially 
  of 
  Leuciscus 
  rutilus. 
  These 
  

   corpuscles 
  becoming 
  less 
  abundant 
  toward 
  the 
  close 
  of 
  the 
  hatching 
  

   period 
  is 
  very 
  probably 
  to 
  be 
  accounted 
  for 
  on 
  the 
  supposition 
  that 
  

   they 
  are 
  taken 
  up 
  and 
  appropriated 
  by 
  the 
  epiblastic 
  tissues 
  of 
  the 
  em- 
  

   bryo 
  by 
  a 
  process 
  of 
  intracellular 
  digestion. 
  

  

  On 
  the 
  third 
  day 
  the 
  vascular 
  system 
  begins 
  to 
  be 
  evident, 
  and 
  the 
  

   heart 
  h, 
  figs. 
  156 
  and 
  157, 
  is 
  extended 
  forward 
  beneath 
  and 
  in 
  advance 
  

   of 
  the 
  head 
  over 
  the 
  anterior 
  end 
  of 
  the 
  yelk. 
  A 
  pair 
  of 
  vascular 
  arches 
  

   (Cuvierian 
  ducts) 
  are 
  soon 
  formed 
  just 
  in 
  advance 
  of 
  the 
  rudiments 
  of 
  

   the 
  pectorals. 
  These 
  vessels 
  grow 
  outward 
  and 
  split 
  up 
  into 
  vitelline 
  

   capillaries 
  and 
  eventually 
  join 
  a 
  median 
  ventral 
  vitelline 
  vessel 
  which 
  

   empties 
  into 
  the 
  venous 
  end 
  of 
  the 
  heart, 
  as 
  shown 
  in 
  figs. 
  163 
  and 
  164. 
  

  

  The 
  mouth 
  is 
  not 
  yet 
  open 
  on 
  the 
  second 
  day, 
  fig. 
  155, 
  but 
  at 
  this 
  

   stage 
  if 
  the 
  embryo 
  be 
  removed 
  from 
  its 
  envelope 
  and 
  viewed 
  as 
  an* 
  

   opaque 
  object, 
  the 
  rudimentary 
  branchial 
  arches 
  and 
  clefts, 
  fig. 
  154, 
  

   &, 
  are 
  visible. 
  The 
  first 
  traces 
  of 
  the 
  pectoral 
  thickenings 
  or 
  outgrowths 
  

   2>, 
  in 
  advance 
  of 
  the 
  lateral 
  extensions 
  of 
  the 
  muscular 
  somites 
  of 
  the 
  

   body, 
  are 
  evident 
  at 
  this 
  stage. 
  The 
  eyes 
  e, 
  fig. 
  154, 
  are 
  unusually 
  

   small 
  for 
  young 
  fishes 
  at 
  this 
  stage, 
  and 
  remind 
  one 
  of 
  the 
  compara- 
  

   tively 
  small 
  eyes 
  of 
  embryo 
  sturgeons, 
  bony 
  gars, 
  and 
  amphibians. 
  The 
  

   choroid 
  fissure 
  is 
  prolonged 
  obliquely 
  downward 
  and 
  forward 
  on 
  the 
  

   second 
  day, 
  as 
  shown 
  in 
  fig. 
  155. 
  

  

  51 
  B. 
  Solger. 
  Dottertropfen 
  in 
  der 
  intracapsuliircn 
  Fliissigkeit 
  von 
  Fischoieru. 
  

   Arch. 
  f. 
  ruik. 
  Auat. 
  xxvi, 
  1885 
  pp. 
  321-334. 
  

  

  