﻿62 
  

  

  contents 
  to 
  escape 
  upon 
  a 
  glass 
  slide. 
  The 
  escaped 
  vltellus 
  

   was 
  then 
  examined 
  with 
  Zeiss 
  ocular 
  4, 
  objectives 
  D 
  and 
  F, 
  

   and 
  I 
  was 
  able 
  to 
  discover 
  a 
  few 
  spermatozoa 
  among 
  the 
  oil- 
  

   globules. 
  

  

  This 
  may 
  be 
  considered 
  as 
  not 
  entirely 
  conclusive, 
  but 
  it 
  

   is 
  questionable 
  if 
  any 
  more 
  conclusive 
  method 
  can 
  be 
  adopted, 
  

   since 
  it 
  is 
  utterly 
  impossible 
  to 
  see 
  the 
  spermatozoa 
  penetrate 
  

   the 
  ovum 
  through 
  the 
  vitelline 
  membrane^ 
  either 
  at 
  the 
  mi- 
  

   cropyle 
  or 
  elsewhere, 
  on 
  account 
  of 
  the 
  relative 
  sizes 
  of 
  ova 
  

   and 
  of 
  spermatozoa. 
  

  

  Impregnated 
  Ovuji. 
  

  

  For 
  quite 
  a 
  time 
  after 
  the 
  ovum 
  has 
  been 
  impregnated, 
  

   there 
  is 
  no 
  perceptible 
  difference 
  in 
  the 
  changes 
  which 
  take 
  

   place 
  from 
  those 
  in 
  the 
  unimpregnated 
  egg. 
  One 
  side 
  

   becomes 
  clearer, 
  Fig. 
  4, 
  PI. 
  I, 
  with 
  fine 
  granulations, 
  a 
  

   portion 
  protrudes, 
  and 
  then 
  take 
  place 
  those 
  segmental 
  

   phases, 
  some 
  of 
  which 
  are 
  represented 
  in 
  Figs 
  1), 
  10 
  and 
  11, 
  PI. 
  I 
  

  

  These 
  changes 
  were 
  very 
  slow 
  in 
  taking 
  place 
  in 
  the 
  eggs 
  

   of 
  the 
  Smelt, 
  probably 
  on 
  account 
  of 
  the 
  sudden 
  lowering 
  of 
  

   temperature 
  which 
  took 
  place 
  about 
  the 
  time 
  that 
  most 
  of 
  

   the 
  eggs 
  were 
  taken 
  and 
  continued 
  for 
  a 
  week 
  or 
  more. 
  

   Hence 
  many 
  of 
  these 
  changes 
  were 
  overlooked 
  in 
  the 
  confu- 
  

   sion 
  of 
  observing 
  ova 
  in 
  the 
  earlier 
  phases, 
  and 
  all 
  stages 
  of 
  

   living 
  and 
  dying, 
  and 
  accordingly 
  I 
  lack 
  a 
  complete 
  series 
  

   of 
  the 
  segmentation 
  stages. 
  These 
  stages 
  are 
  undoubtedly 
  

   similar, 
  however, 
  to 
  those 
  in 
  the 
  egg 
  of 
  the 
  shad, 
  a 
  descrip- 
  

   tion 
  of 
  which 
  changes 
  will 
  be 
  given 
  in 
  another 
  place. 
  The 
  

   fine 
  granular 
  portion 
  wliich 
  results 
  from 
  this 
  segm«;ntal 
  

   difierentiation, 
  gradually 
  extends 
  for 
  quite 
  a 
  distance 
  around 
  

   the 
  periphery 
  of 
  the 
  egg, 
  Fig. 
  7, 
  PI. 
  1, 
  and 
  represents 
  the 
  

   blastodermic 
  tissue, 
  or 
  simply 
  blastoderm, 
  from 
  which 
  the 
  

   young 
  fish 
  is 
  to 
  be 
  built 
  up. 
  Previous 
  to, 
  or 
  during 
  the 
  

   formation 
  of 
  the 
  clear 
  granular 
  portion, 
  there 
  were 
  no 
  indi- 
  

   cations 
  of 
  any 
  polar 
  globules* 
  at 
  this 
  or 
  any 
  other 
  portion 
  of 
  

  

  * 
  Richtunffsblattjchen 
  or 
  direction 
  cells 
  of 
  authors. 
  

  

  