﻿98 
  

  

  2, 
  PI. 
  VI; 
  and 
  in 
  about 
  ten 
  per 
  cent,* 
  or 
  less, 
  of 
  un- 
  

   imprcgnated 
  ova, 
  the 
  absorption 
  of 
  water 
  is 
  complete, 
  and 
  

   the 
  vitelline 
  membrane 
  becomes 
  completely 
  distended. 
  The 
  

   increase 
  in 
  diameter 
  of 
  the 
  ova 
  b}'' 
  this 
  absorption 
  of 
  water, 
  

   and 
  distention 
  of 
  the 
  membrane, 
  is 
  about 
  one-half 
  of 
  the 
  

   fully 
  distended 
  ova, 
  in 
  some 
  cases 
  not 
  quite 
  as 
  much 
  as 
  this. 
  

   Shortly 
  after 
  the 
  distention 
  of 
  the 
  vitelline 
  membrane, 
  and 
  

   sometimes^ 
  even 
  when 
  the 
  ovum 
  is 
  as 
  represented 
  in 
  Fig, 
  2, 
  

   PI. 
  VI, 
  the 
  vitellus, 
  which 
  is 
  floating 
  free 
  in 
  the 
  centre 
  of 
  

   the 
  ovum, 
  becomes 
  changed 
  somewhat 
  upon 
  one 
  side. 
  A 
  

   gathering 
  together 
  of 
  the 
  oil-globules 
  upon 
  this 
  side, 
  and 
  a 
  

   change 
  of 
  their 
  form 
  takes 
  place. 
  The 
  globules 
  are 
  drawn 
  

   out 
  into 
  somewhat 
  pear-shaped 
  bodies, 
  with 
  the 
  smaller 
  ends 
  

   directed 
  towards 
  a 
  common 
  centre. 
  Fig. 
  3, 
  PI. 
  VI, 
  and 
  

   over 
  this 
  common 
  centre 
  a 
  prominence,, 
  or 
  limb, 
  arises, 
  

   which 
  protrudes 
  for 
  quite 
  a 
  little 
  distance 
  from 
  the 
  vitellus, 
  

   Fig. 
  5, 
  PI. 
  VI. 
  

  

  This 
  limb 
  is 
  composed 
  almost 
  entirely 
  uf 
  granular 
  sub- 
  

   stance, 
  with 
  a 
  few 
  small 
  oil-globules 
  in 
  the 
  base, 
  and 
  is 
  a 
  

   shade 
  or 
  two 
  less 
  translucent 
  than 
  the 
  rest 
  of 
  the 
  vitellus, 
  

   having 
  acquired 
  apparently 
  a 
  tint 
  of 
  brownish 
  yellow. 
  In 
  

   those 
  ova 
  which 
  remain 
  only 
  partially 
  distended, 
  no 
  limb 
  is 
  

   formed. 
  The 
  contour 
  line 
  of 
  the 
  vitellus 
  is 
  unbroken 
  during 
  

   this 
  entire 
  period, 
  or 
  at 
  any 
  other 
  period 
  during 
  the 
  life 
  of 
  

   the 
  ovum, 
  by 
  any 
  glomeration 
  from 
  the 
  surface 
  or 
  the 
  product- 
  

   ion 
  of 
  any 
  direction 
  cells 
  from 
  the 
  blastoderm. 
  The 
  ovum 
  

   will 
  often 
  remain 
  in 
  this 
  stage 
  of 
  difierentiation 
  for 
  a 
  day 
  or 
  

  

  *Mr. 
  C. 
  G. 
  Atkins, 
  who 
  was 
  in 
  attendance 
  at 
  the 
  Hatching 
  Camp 
  of 
  the 
  

   United 
  States 
  Fieh 
  Commission, 
  at 
  S»uth 
  Haclley 
  Falls, 
  Massachusetts, 
  during 
  

   the 
  past 
  summer, 
  sends 
  me 
  the 
  folloTving 
  schedule 
  of 
  observations 
  made 
  by 
  

   him 
  upon 
  this 
  point 
  : 
  

  

  Date. 
  No. 
  of 
  Eggs. 
  Ko. 
  BWoUen. 
  Percentage. 
  

  

  July 
  11 
  306 
  6 
  03 
  

  

  19 
  300 
  35 
  11 
  

  

  31 
  103 
  9 
  09 
  

  

  August 
  10 
  small 
  number 
  , 
  GO 
  

  

  