﻿EGGS. 
  83 
  

  

  Pelodytes 
  punctatus 
  . 
  . 
  . 
  1,000 
  — 
  1,630 
  

  

  Bana 
  agilis 
  669 
  — 
  1,200 
  

  

  Hyla 
  arhorea 
  800—1,000 
  

  

  These 
  results, 
  however, 
  do 
  not 
  always 
  agree 
  with, 
  

   my 
  own, 
  as 
  will 
  be 
  seen 
  further 
  on 
  under 
  the 
  various 
  

   specific 
  headings. 
  

  

  In 
  the 
  Discoglossidds, 
  which 
  spawn 
  two 
  or 
  three 
  

   times 
  a 
  year, 
  each 
  brood 
  consists 
  of 
  300 
  to 
  1000 
  

   eggs 
  in 
  Discoglossus 
  pictus, 
  80 
  to 
  100 
  in 
  Bomhinator 
  

   pachypus, 
  and 
  20 
  to 
  90 
  in 
  Alytes 
  ohstetvicans. 
  This 
  

   makes 
  a 
  probable 
  maximum 
  total 
  of 
  3000 
  for 
  the 
  first 
  

   species, 
  300 
  for 
  the 
  second, 
  and 
  270 
  for 
  the 
  third. 
  

   These 
  numbers 
  are, 
  however, 
  only 
  approximative, 
  for 
  

   no 
  observer 
  has 
  yet 
  been 
  able 
  to 
  follow 
  the 
  spawning 
  

   of 
  a 
  given 
  specimen 
  throughout 
  the 
  year, 
  and 
  to 
  record 
  

   the 
  total 
  number 
  of 
  eggs 
  produced. 
  

  

  Manipulating 
  frogs' 
  eggs 
  is 
  not 
  easy, 
  on 
  account 
  

   of 
  the 
  sticky 
  mucilage 
  which 
  adheres 
  to 
  the 
  fingers 
  or 
  

   instruments, 
  and 
  the 
  counting 
  is 
  a 
  very 
  trying 
  opera- 
  

   tion. 
  Approximate 
  computations 
  are 
  more 
  easily 
  

   arrived 
  at 
  with 
  the 
  egg-strings 
  of 
  toads, 
  which 
  can 
  be 
  

   divided 
  into 
  small 
  portions, 
  in 
  which 
  the 
  eggs 
  are 
  

   counted 
  and 
  the 
  result 
  multiplied 
  by 
  measuring 
  the 
  

   leng"th 
  of 
  the 
  whole 
  strino^s. 
  

  

  Fig. 
  31. 
  

  

  Cleavage 
  of 
  egg 
  of 
  Bana 
  temporaria 
  (after 
  Ecker). 
  

  

  After 
  fecundation 
  the 
  vitelline 
  sphere 
  undergoes 
  a 
  

   process 
  of 
  division, 
  or 
  segmentation, 
  which 
  can 
  be 
  

   readily 
  observed 
  under 
  the 
  microscope 
  or 
  an 
  ordinary 
  

   hand 
  lens, 
  and 
  of 
  which 
  the 
  above 
  diagrammatic 
  

  

  