﻿INTEGUMENT. 
  2 
  

  

  r> 
  

  

  skin 
  possesses 
  of 
  effecting 
  those 
  changes 
  in 
  the 
  blood 
  

   which 
  are 
  usually 
  performed 
  by 
  the 
  lungs 
  or 
  gills, 
  

   and 
  by 
  which 
  frogs 
  may 
  remain 
  active 
  for 
  long 
  

   periods 
  under 
  water. 
  Results 
  of 
  various 
  experiments 
  

   have 
  proved 
  that 
  pulmonary 
  respiration 
  alone 
  is 
  not 
  

   sufficient 
  to 
  support 
  life 
  without 
  the 
  aid 
  of 
  that 
  of 
  the 
  

   cutaneous 
  surface; 
  whilst 
  some 
  of 
  the 
  tailed 
  Batra- 
  

   chians 
  have 
  lately 
  been 
  shown 
  to 
  be 
  deprived 
  of 
  both 
  

   lungs 
  and 
  gills, 
  so 
  that 
  the 
  contrary 
  does 
  not 
  hold 
  

   good 
  for 
  them. 
  But 
  in 
  order 
  to 
  carry 
  out 
  this 
  im- 
  

   portant 
  function 
  it 
  is 
  of 
  course 
  necessary 
  that 
  the 
  

   surface 
  be 
  kept 
  in 
  a 
  moist 
  state, 
  and 
  this 
  is 
  effected 
  

   by 
  a 
  secretion 
  of 
  fluid 
  from 
  the 
  skin 
  itself. 
  

  

  An 
  immense 
  number 
  of 
  close-set 
  glandular 
  caeca 
  

   open 
  upon 
  the 
  surface 
  of 
  the 
  skin, 
  the 
  slime-cells, 
  in 
  

   addition 
  to 
  which 
  a 
  greater 
  or 
  lesser 
  number 
  of 
  larger 
  

   poison-secreting 
  glands 
  are 
  scattered 
  or 
  disposed 
  in 
  

   very 
  conspicuous 
  prominent 
  aggregations, 
  such 
  as 
  the 
  

   dorso-lateral 
  fold 
  of 
  Bana, 
  the 
  large 
  dorsal 
  warts 
  of 
  

   Bufo 
  and 
  Bombinator, 
  and 
  especially 
  the 
  so-called 
  

   parotoids, 
  situated 
  above 
  the 
  ear 
  in 
  Bufo 
  and 
  Alytes, 
  

   and 
  a 
  similar 
  gland 
  on 
  the 
  calf 
  of 
  Bufo 
  calamita 
  

   (Fig. 
  9, 
  p, 
  24). 
  These 
  glands 
  are 
  pierced 
  with 
  large 
  

   pores, 
  visible 
  to 
  the 
  naked 
  eye 
  or 
  with 
  the 
  aid 
  of 
  a 
  

   low 
  magnifier. 
  A 
  round 
  gland, 
  the 
  frontal 
  or 
  pineal 
  

   gland, 
  the 
  homologue 
  of 
  the 
  so-called 
  parietal 
  eye 
  of 
  

   reptiles, 
  is 
  more 
  or 
  less 
  discernible 
  under 
  the 
  skin 
  

   of 
  the 
  forehead 
  in 
  front 
  of 
  and 
  between 
  the 
  eyes 
  ; 
  this 
  

   gland, 
  in 
  the 
  early 
  stages, 
  was 
  connected 
  with 
  the 
  

   brain. 
  The 
  presence 
  of 
  lime 
  concretions 
  in 
  the 
  skin 
  

   of 
  old 
  specimens 
  of 
  Bufo 
  vulgaris 
  has 
  been 
  first 
  

   pointed 
  out 
  by 
  Leydig. 
  The 
  same 
  have 
  been 
  found 
  

   in 
  B. 
  calamita 
  by 
  O. 
  Seeck. 
  

  

  A 
  character 
  which 
  does 
  not 
  appear 
  to 
  have 
  been 
  

   noticed 
  before 
  is 
  the 
  presence 
  of 
  a 
  filiform 
  line 
  or 
  

   raphe, 
  on 
  which 
  the 
  skin 
  is 
  much 
  thinner, 
  extending 
  

   along 
  the 
  middle 
  line 
  of 
  the 
  back 
  from 
  the 
  snout 
  to 
  

   the 
  extremity 
  of 
  the 
  coccygeal 
  region 
  in 
  all 
  specimens 
  

   of 
  Bufo. 
  This 
  raphe, 
  which 
  may 
  best 
  be 
  observed 
  on 
  

  

  