﻿516 
  REPORT 
  OF 
  COMMISSIONER 
  OP 
  FISH 
  AND 
  FISHERIES. 
  [28] 
  

  

  no 
  suggestion 
  to 
  make, 
  but 
  there 
  are 
  certain 
  glandular 
  structures 
  lying 
  

   close 
  by, 
  tlie 
  significance 
  of 
  which 
  I 
  am 
  at 
  a 
  loss 
  to 
  understand." 
  

  

  Since 
  the 
  above 
  was 
  written 
  the 
  inspection 
  of 
  additional 
  material 
  en- 
  

   ables 
  me 
  to 
  state 
  that 
  the 
  secretion 
  is 
  present 
  only 
  during 
  the 
  breeding 
  

   season. 
  

  

  Mobius 
  has 
  investigated 
  the 
  subject 
  much 
  more 
  thoroughly 
  in 
  the 
  

   larger 
  European 
  stickleback, 
  Spinachia 
  vulgaris, 
  and 
  he 
  finds 
  that 
  the 
  

   sac, 
  found 
  by 
  me 
  in 
  Apeltes 
  to 
  be 
  filled 
  with 
  a 
  viscid 
  secretion, 
  is 
  really 
  

   the 
  urinary 
  bladder. 
  And, 
  further, 
  that 
  the 
  sources 
  of 
  the 
  viscid 
  secre- 
  

   tion 
  are 
  the 
  kidneys, 
  the 
  secretion 
  being 
  poured 
  out 
  from 
  the 
  epithelial 
  

   cells 
  of 
  the 
  uriniferous 
  tubules. 
  The 
  bladder 
  acts 
  simply 
  as 
  a 
  reservoir 
  

   in 
  which 
  it 
  accumulates. 
  In 
  Spinachia 
  the 
  threads 
  measure 
  0.12 
  to 
  

   0.13 
  mra 
  in 
  diameter, 
  the 
  male 
  winding 
  them 
  around 
  weeds 
  to 
  form 
  a 
  nest, 
  

   in 
  the 
  same 
  manner 
  as 
  the 
  male 
  of 
  Apeltes. 
  The 
  secretion 
  or 
  viscid 
  

   spinning 
  material 
  belongs, 
  according 
  to 
  Mobius, 
  to 
  the 
  mucines. 
  Boil- 
  

   ing 
  hydrochloric 
  acid 
  stains 
  it 
  a 
  violet 
  color 
  and 
  then 
  dissolves 
  it. 
  

   Nitric 
  acid 
  stains 
  it 
  yellow 
  but 
  does 
  not 
  dissolve 
  it. 
  It 
  is 
  insoluble 
  in 
  

   acetic 
  acid 
  ; 
  soluble 
  in 
  caustic 
  potash 
  solution, 
  and 
  when 
  in 
  solution 
  in 
  

   the 
  latter, 
  if 
  acetic 
  acid 
  is 
  added 
  drop 
  by 
  drop, 
  a 
  white 
  precipitate 
  is 
  

   formed, 
  which 
  is 
  again 
  dissolved 
  if 
  acetic 
  acid 
  is 
  added 
  in 
  excess. 
  Boil- 
  

   ing 
  baryta-water 
  dissolves 
  it, 
  but 
  boiling 
  lime-water 
  does 
  not. 
  

  

  Mobius 
  traced 
  the 
  secretion 
  to 
  the 
  epithelial 
  cells 
  lining 
  the 
  urinary 
  

   tubules 
  of 
  the 
  kidneys 
  or 
  wolffian 
  bodies. 
  After 
  the 
  breeding 
  season 
  

   the 
  volume 
  of 
  the 
  kidneys 
  and 
  urinary 
  bladder 
  diminishes, 
  and 
  they 
  

   then 
  contain 
  urine 
  only, 
  while 
  during 
  the 
  breeding 
  season 
  they 
  are 
  

   principally 
  filled 
  with 
  the 
  slimy 
  secretion, 
  the 
  thread 
  being 
  spun 
  from 
  

   the 
  genito-urinary 
  opening 
  just 
  behind 
  the 
  vent. 
  

  

  X. 
  — 
  Esox 
  reticulatus 
  Le 
  Sueur. 
  (Common 
  Eastern 
  Pickerel; 
  Green 
  

  

  Pike.) 
  

  

  From 
  material 
  supplied 
  by 
  Mr. 
  W. 
  P. 
  Seal, 
  I 
  am 
  enabled 
  to 
  give 
  fig- 
  

   ures 
  of 
  two 
  stages 
  of 
  this 
  type 
  ; 
  the 
  youngest 
  9 
  mm 
  long 
  and 
  the 
  most 
  

   advanced 
  11.5 
  ,nm 
  in 
  length. 
  These 
  are 
  represented 
  by 
  figs. 
  28 
  and 
  20. 
  

  

  The 
  young 
  of 
  this 
  species 
  become 
  pigmented 
  rather 
  soon. 
  The 
  gill 
  

   arches 
  remain 
  exposed 
  for 
  a 
  considerable 
  time, 
  as 
  is 
  shown 
  in 
  fig. 
  20, 
  

   in 
  which 
  the 
  depressed, 
  produced 
  snout 
  characteristic 
  of 
  the 
  pike 
  

   family 
  is 
  also 
  already 
  evident. 
  Caudal 
  metamorphosis 
  is 
  also 
  begin- 
  

   ning 
  to 
  manifest 
  itself 
  in 
  this 
  older 
  stage, 
  the 
  tail 
  having 
  become 
  lancet- 
  

   shaped, 
  and 
  proportionately 
  narrower 
  than 
  in 
  the 
  younger 
  stage 
  pre- 
  

   ceding. 
  There 
  is 
  a 
  well-developed 
  vitelline 
  circulation 
  which 
  has 
  been 
  

   figured 
  by 
  Truman 
  43 
  in 
  the 
  embryo 
  of 
  Esox 
  lucius. 
  The 
  same 
  species 
  

   has 
  also 
  been 
  investigated 
  by 
  'Swirski, 
  44 
  who 
  has 
  worked 
  out 
  the 
  devel- 
  

  

  ^E. 
  B. 
  Truman. 
  Observations 
  on 
  the 
  development 
  of 
  the 
  ovum 
  of 
  the 
  pike, 
  

   Monthly 
  Mic. 
  Jouru., 
  Oct., 
  1869, 
  pp. 
  185-203, 
  pis. 
  27-29 
  and 
  part 
  of 
  30. 
  

  

  44 
  Georg 
  'Swirski. 
  Untersnchungen 
  iiber 
  die 
  Entwickelung 
  des 
  Schultergiirtels 
  und 
  

   des 
  Skelets 
  der 
  Brustflosse 
  des 
  Hechis. 
  Inaug. 
  Diss., 
  Dorpat, 
  1880, 
  pp. 
  CO, 
  pis. 
  2. 
  

  

  