﻿98 
  

  

  INTEODUCTION. 
  

  

  whereas 
  the 
  transformed 
  tailless 
  Batrachians, 
  unlike 
  

   their 
  tailed 
  precursors, 
  occupy 
  too 
  high 
  a 
  position 
  in 
  

   the 
  zoological 
  scale 
  to 
  be 
  able 
  to 
  regenerate 
  ampu- 
  

   tated 
  extremities, 
  the 
  hind 
  limbs 
  reproduce 
  without 
  

   difficulty 
  during 
  the 
  larval 
  existence, 
  a 
  fact 
  first 
  

   observed 
  by 
  Spallanzani 
  in 
  the 
  last 
  century, 
  and 
  

   since 
  verified 
  by 
  Griinther 
  and 
  Barfurth. 
  In 
  order 
  

   to 
  be 
  regenerated 
  it 
  is, 
  however, 
  necessary 
  that 
  the 
  

   limb 
  be 
  not 
  completely 
  removed. 
  A 
  basal 
  fragment 
  

   of 
  the 
  femur 
  must 
  remain 
  to 
  give 
  off 
  the 
  cartilage- 
  

   cells 
  which, 
  most 
  curiously, 
  will 
  become 
  differentiated 
  

   into 
  the 
  various 
  segments, 
  proceeding 
  from 
  the 
  distal 
  

   to 
  the 
  proximal 
  ; 
  and 
  the 
  mutilation 
  must 
  have 
  taken 
  

   place 
  some 
  time 
  before 
  the 
  close 
  of 
  the 
  third 
  larval 
  

   period 
  or 
  true 
  tadpole 
  stage. 
  It 
  has 
  been 
  stated, 
  that 
  

   reproduction 
  of 
  the 
  limbs 
  can 
  only 
  be 
  obtained 
  in 
  

   young 
  larvse, 
  long 
  before 
  they 
  have 
  reached 
  their 
  full 
  

   size. 
  This 
  is, 
  however, 
  contrary 
  to 
  my 
  own 
  experience 
  

   on 
  large, 
  full-grown 
  tadpoles 
  of 
  Alytes 
  obstetricans^ 
  in 
  

   which 
  the 
  well-developed 
  hind 
  limb, 
  after 
  having 
  been 
  

   amputated 
  below 
  the 
  knee-joint, 
  was 
  regenerated 
  with 
  

   the 
  greatest 
  facility. 
  

  

  Fig. 
  41. 
  

  

  -\ 
  

  

  Series 
  of 
  embryos 
  of 
  Bombinator 
  pachypus. 
  (Aiter 
  Goette.) 
  

   Sliowing 
  the 
  formation 
  of 
  the 
  larval 
  mouth, 
  together 
  -with 
  the 
  . 
  

   atrophy 
  of 
  the 
  adhesive 
  disks; 
  the 
  gradual 
  disappearance 
  of 
  

   the 
  external 
  gills, 
  and 
  the 
  formation 
  of 
  the 
  median 
  spiraculum 
  

   by 
  approximation 
  of 
  the 
  two 
  opercular 
  slits 
  ; 
  and 
  the 
  develop- 
  

   ment 
  of 
  the 
  gut 
  (the 
  abdominal 
  membranes 
  being 
  removed). 
  

  

  