﻿2-! 
  

  

  H. 
  S. 
  Pratt, 
  

  

  ished 
  principally 
  by 
  the 
  posterior 
  pair 
  of 
  glands. 
  This 
  nutrirnent 
  

   consists 
  of 
  a 
  fluid 
  containing 
  a 
  mass 
  of 
  round 
  or 
  oval 
  disc-shaped 
  

   bodies 
  which 
  are 
  presurnably 
  fat-bodies; 
  they 
  are 
  fairly 
  constant 
  in 
  

   size 
  having 
  an 
  average 
  diameter 
  of 
  0,01 
  mm. 
  The 
  secretion 
  of 
  these 
  

   glands 
  is 
  thus 
  extremely 
  similar 
  to 
  milk. 
  It 
  is 
  poured 
  through 
  the 
  

   opening 
  already 
  mentioned 
  into 
  the 
  anterior 
  end 
  of 
  the 
  uterus 
  where 
  

   the 
  larva 
  sucks 
  it 
  into 
  its 
  mouth. 
  Düring 
  the 
  entire 
  uterine 
  life 
  of 
  

   the 
  larva 
  its 
  anterior 
  end 
  is 
  constantly 
  at 
  the 
  anterior 
  end 
  of 
  the 
  

   uterus, 
  the 
  increase 
  in 
  length 
  which 
  the 
  larva 
  undergoes 
  resulting 
  in 
  

   its 
  extension 
  towards 
  the 
  posterior 
  end 
  of 
  the 
  uterus 
  until 
  that 
  organ 
  

   is 
  completely 
  fllled. 
  The 
  mouth 
  of 
  the 
  larva, 
  however, 
  does 
  not 
  

   change 
  its 
  position 
  in 
  the 
  uterus, 
  and 
  would 
  be 
  thus 
  constantly 
  bathed 
  

   in 
  the 
  milk-like 
  secretion 
  (PI. 
  II, 
  Fig. 
  4 
  lar.M), 
  which 
  is 
  sucked 
  

   in 
  by 
  a 
  complicated 
  sucking 
  apparatus 
  I 
  have 
  already 
  described 
  in 
  

   another 
  place 
  (Peatt, 
  1 
  6). 
  For 
  the 
  sake 
  of 
  completeness, 
  I 
  will 
  briefly 
  

   describe 
  this 
  organ 
  again. 
  Directly 
  back 
  of 
  the 
  larva' 
  s 
  mouth, 
  in 
  its 
  

   pharyngeal 
  cavity, 
  is 
  a 
  muscular 
  tongue-like 
  organ 
  (PL 
  II, 
  Fig. 
  4 
  

   ynus.ton), 
  ventrad 
  of 
  which 
  the 
  Oesophagus 
  passes 
  to 
  the 
  sac-like 
  

   stomach. 
  Dorsad 
  of 
  the 
  muscular 
  tongue 
  is 
  a 
  sac 
  whose 
  dorsal 
  wall 
  

   is 
  connected 
  by 
  a 
  median, 
  iongitudinal 
  muscle 
  with 
  the 
  dorsal 
  body- 
  

   wall. 
  The 
  muscular 
  tongue 
  contracts 
  and 
  dilates 
  regularly 
  like 
  the 
  

   beating 
  of 
  a 
  heart, 
  about 
  forty 
  times 
  a 
  minute: 
  the 
  dorsal 
  Iongi- 
  

   tudinal 
  muscle 
  must 
  also 
  contract, 
  although 
  I 
  have 
  never 
  been 
  able 
  

   to 
  observe 
  it 
  in 
  the 
  live 
  animal. 
  As 
  a 
  result 
  of 
  these 
  movements 
  

   the 
  milk 
  is 
  drawn 
  into 
  the 
  mouth 
  of 
  the 
  larva 
  and 
  forced 
  through 
  

   the 
  Oesophagus 
  into 
  the 
  stomach, 
  which 
  is 
  at 
  all 
  times 
  completely 
  

   filled. 
  The 
  beating 
  of 
  the 
  tongue 
  probably 
  goes 
  on 
  without 
  interrupt- 
  

   ion 
  during 
  the 
  entire 
  uterine 
  life 
  of 
  the 
  larva. 
  As 
  soon 
  as 
  it 
  is 
  born, 
  

   however, 
  and 
  thus 
  removed 
  from 
  its 
  food 
  supply, 
  the 
  beating 
  ceases, 
  

   and 
  during 
  the 
  day 
  or 
  two 
  which 
  intervenes 
  while 
  the 
  larva 
  is 
  

   preparing 
  to 
  enter 
  upon 
  the 
  pupal 
  stage 
  and 
  the 
  first 
  part 
  of 
  the 
  

   metamorphosis, 
  the 
  young 
  animal 
  is 
  nourished 
  by 
  the 
  milk 
  which 
  

   was 
  already 
  in 
  the 
  stomach 
  at 
  the 
  time 
  of 
  birth. 
  The 
  milk 
  rapidly 
  

   decreases 
  in 
  volume 
  during 
  this 
  period 
  and 
  by 
  the 
  middle 
  of 
  the 
  

   metamorphosis 
  is 
  entirely 
  exhausted. 
  

  

  The 
  flner 
  structure 
  of 
  the 
  milk-glands 
  presents 
  the 
  following 
  

   features. 
  The 
  extreme 
  proximal, 
  median 
  ends 
  of 
  the 
  two 
  gland- 
  

   pairs 
  are 
  bound 
  together 
  just 
  before 
  the 
  opening 
  into 
  the 
  uterus 
  by 
  a 
  

   common 
  muscle-sheath 
  (PL 
  III, 
  Fig. 
  9), 
  composed 
  of 
  irregularly 
  ar- 
  

   ranged, 
  striped 
  fibres. 
  

  

  