﻿DEVELOPMENT 
  AND 
  METAMOKPHOkSIS. 
  97 
  

  

  whilst 
  the 
  latter 
  takes 
  only 
  living 
  prey. 
  Nevertheless 
  

   the 
  intestine 
  in 
  all 
  tadpoles 
  is 
  exceedingly 
  elongate, 
  

   being 
  several 
  times 
  longer 
  and 
  of 
  a 
  greater 
  calibre 
  

   than 
  after 
  the 
  metamorphosis. 
  Bataillon 
  has 
  ascer- 
  

   tained 
  by 
  direct 
  experiment 
  that 
  the 
  abbreviation 
  of 
  

   the 
  gnt 
  is 
  not 
  localised 
  to 
  any 
  special 
  region. 
  Tad- 
  

   poles 
  of 
  Alijtes 
  obstetricans 
  having 
  been 
  anaesthetised 
  

   a 
  few 
  days 
  before 
  the 
  egress 
  of 
  the 
  fore 
  limbs, 
  the 
  

   abdominal 
  cavity 
  was 
  cut 
  open, 
  and 
  the 
  intestine, 
  after 
  

   having 
  been 
  slightly 
  uncoiled, 
  marked 
  at 
  regular 
  dis- 
  

   tances 
  by 
  silk 
  threads 
  tied 
  round 
  it. 
  The 
  abdomen 
  

   was 
  then 
  sewn 
  up, 
  and 
  the 
  tadpoles, 
  having 
  recovered, 
  

   continued 
  their 
  evolution. 
  At 
  the 
  close 
  of 
  the 
  meta- 
  

   morphosis 
  the 
  gut 
  was 
  again 
  examined, 
  and 
  it 
  was 
  

   found 
  that 
  the 
  threads, 
  which 
  were 
  tied 
  at 
  intervals 
  

   of 
  twenty 
  millimetres, 
  were 
  then 
  only 
  seven 
  or 
  eight 
  

   millimetres 
  apart. 
  

  

  I 
  have 
  measured 
  the 
  uncoiled 
  digestive 
  canal 
  in 
  

   fully 
  developed 
  tadpoles 
  and 
  in 
  recently 
  transformed 
  

   young 
  of 
  the 
  three 
  following 
  species. 
  It 
  will 
  be 
  seen 
  

   from 
  the 
  measurements, 
  in 
  millimetres, 
  how 
  consider- 
  

   able 
  the 
  range 
  of 
  variation 
  between 
  different 
  forms 
  

   may 
  be, 
  both 
  in 
  the 
  larval 
  and 
  perfect 
  conditions. 
  

   Thus 
  in 
  Bana 
  esculenta 
  the 
  length 
  of 
  the 
  intestine 
  of 
  

   the 
  tadpole 
  is 
  nearly 
  ten 
  times 
  that 
  of 
  the 
  perfect 
  

   form, 
  whilst 
  in 
  Alytes 
  obstetricans 
  its 
  length 
  is 
  only 
  

   as 
  4 
  : 
  1 
  ; 
  Pelodytes 
  punctatus, 
  with 
  6:1, 
  is 
  inter- 
  

   mediate. 
  This 
  diff'erence 
  is 
  correlated 
  with 
  the 
  

   diet, 
  Bana 
  esculenta 
  being 
  the 
  most 
  herbivorous, 
  

   and 
  Alytes 
  obstetricans, 
  as 
  noticed 
  above, 
  almost 
  ex- 
  

   clusively 
  carnivorous 
  in 
  the 
  tadpole 
  condition. 
  

  

  Length 
  of 
  intestine 
  in 
  tadpole 
  (i) 
  and 
  young 
  (ii) 
  of 
  — 
  

  

  I. 
  II. 
  

  

  Alytes 
  obstetricans 
  (25 
  mm. 
  body-length) 
  235 
  60 
  

   Pelodytes 
  punctatus 
  {20 
  ,, 
  ., 
  ) 
  194 
  32 
  

  

  Bana 
  esculenta 
  (23 
  ,, 
  ,, 
  ) 
  472 
  45 
  

  

  Before 
  closing 
  this 
  chapter 
  on 
  Development, 
  the 
  

   highly 
  interesting 
  fact 
  remains 
  to 
  be 
  alhided 
  to 
  that 
  

  

  G 
  

  

  