﻿412 
  ANNUAL 
  EEPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1929 
  

  

  first 
  axillary. 
  As 
  the 
  posterior 
  edge 
  of 
  the 
  wing 
  comes 
  against 
  the 
  

   side 
  of 
  the 
  body, 
  the 
  jugal 
  lobe 
  {Jv) 
  is 
  deflected 
  and 
  turned 
  beneath 
  

   the 
  vannus 
  along 
  the 
  line 
  of 
  the 
  jugal 
  plica 
  {jj). 
  If 
  a 
  vannal 
  plica 
  

   (?/) 
  is 
  present, 
  the 
  reniigial 
  region 
  is 
  usually 
  turned 
  downward 
  during 
  

   the 
  flexion 
  of 
  the 
  wing; 
  but 
  man}^ 
  insects, 
  such 
  as 
  the 
  flies 
  and 
  bees, 
  

   keep 
  both 
  the 
  remigium 
  and 
  the 
  vannus 
  in 
  a 
  horizontal 
  plane. 
  

  

  The 
  final 
  pull 
  of 
  the 
  flexor 
  muscle 
  is 
  apparently 
  expended 
  on 
  the 
  

   general 
  wing 
  base, 
  for, 
  in 
  manj^ 
  insects, 
  when 
  the 
  wing 
  is 
  fully 
  flexed, 
  

   the 
  second 
  axillary 
  is 
  turned 
  into 
  a 
  nearly 
  longitudinal 
  position 
  and 
  is 
  

   brought 
  close 
  to 
  the 
  side 
  of 
  the 
  back 
  by 
  a 
  vertical 
  revolution 
  of 
  the 
  

   first 
  axillary 
  on 
  its 
  hinge 
  with 
  the 
  tergum. 
  Thus, 
  in 
  the 
  typical, 
  

   fully 
  flexed 
  condition 
  of 
  the 
  wing, 
  the 
  first 
  axillary 
  (fig. 
  12, 
  lAx) 
  

   stands 
  in 
  a 
  vertical 
  plane 
  on 
  the 
  edge 
  of 
  the 
  tergum; 
  the 
  second 
  axillary 
  

   {2 
  Ax), 
  supported 
  by 
  the 
  first, 
  lies 
  horizontally 
  close 
  to 
  the 
  body; 
  

   the 
  first 
  median 
  plate 
  (m) 
  either 
  stands 
  vertically 
  from 
  the 
  outer 
  edge 
  

   of 
  the 
  second 
  axillary, 
  or 
  it 
  is 
  inclined 
  mesally 
  and 
  overlaps 
  the 
  latter; 
  

   the 
  second 
  median 
  plate 
  (w'), 
  or 
  the 
  base 
  of 
  the 
  medio-cubital 
  wing 
  

   area, 
  lies 
  horizontally 
  but 
  makes 
  ^ 
  sharp 
  fold 
  along 
  the 
  hinge 
  line 
  

   (6/) 
  with 
  the 
  first 
  median 
  plate, 
  the 
  fold 
  crossing 
  the 
  wing 
  base 
  obliquely 
  

   from 
  the 
  base 
  of 
  the 
  radial 
  vein 
  posteriorly 
  and 
  medially; 
  the 
  third 
  

   axillary 
  is 
  completely 
  inverted 
  with 
  its 
  apex 
  (c) 
  directed 
  mesally 
  and 
  

   forward.' 
  Flexion 
  of 
  the 
  wing 
  does 
  not 
  alter 
  the 
  position 
  of 
  the 
  first 
  

   and 
  second 
  axillaries 
  in 
  some 
  insects; 
  but 
  the 
  revolution 
  of 
  the 
  third 
  

   axillary 
  is 
  invariable, 
  showing 
  that 
  it 
  is 
  the 
  motion 
  produced 
  in 
  this 
  

   sclerite 
  by 
  its 
  muscle, 
  and 
  the 
  consequent 
  folding 
  in 
  the 
  parts 
  immedi- 
  

   ately 
  affected 
  by 
  its 
  movements, 
  that 
  bring 
  about 
  the 
  rotation 
  of 
  the 
  

   distal 
  parts 
  of 
  the 
  wing 
  on 
  the 
  basal 
  elements, 
  which 
  constitutes 
  

   flexion. 
  

  

  The 
  automatic 
  nature 
  of 
  the 
  complicated 
  movements 
  of 
  the 
  wing 
  

   folding, 
  resulting 
  from 
  the 
  pidl 
  of 
  a 
  single 
  muscle, 
  ma}^ 
  be 
  roughly 
  

   demonstrated 
  with 
  a 
  piece 
  of 
  stiflf 
  paper 
  cut 
  and 
  creased 
  along 
  the 
  

   lines 
  of 
  Figure 
  22 
  A, 
  but 
  leaving 
  an 
  extension 
  to 
  the 
  left 
  for 
  support. 
  

   Lifting 
  the 
  apex 
  (c) 
  of 
  the 
  axillary 
  triangle, 
  and 
  revolving 
  it 
  on 
  the 
  

   base 
  (a- 
  — 
  h) 
  to 
  the 
  left 
  (B), 
  will 
  turn 
  the 
  vannal 
  region 
  of 
  the 
  model 
  

   {V) 
  posteriorly 
  and 
  deflex 
  the 
  remigial 
  part 
  (Rm). 
  If 
  the 
  apex 
  (c) 
  

   is 
  finally 
  turned 
  mesad 
  of 
  the 
  base 
  line 
  (C), 
  the 
  distal 
  parts 
  of 
  the 
  paper 
  

   model 
  will 
  take 
  positions 
  quite 
  comparable 
  with 
  those 
  of 
  the 
  parts 
  in 
  

   a 
  wing 
  of 
  similar 
  form 
  flexed 
  and 
  folded 
  by 
  the 
  revolution 
  of 
  the 
  third 
  

   axillary 
  sclerite. 
  The 
  details 
  of 
  interaction 
  between 
  the 
  sclerites 
  of 
  

   the 
  axillary 
  region, 
  and 
  the 
  folding 
  of 
  the 
  latter 
  upon 
  itself, 
  can 
  not, 
  

   of 
  course, 
  be 
  duplicated 
  unless 
  the 
  entire 
  mechanism 
  is 
  reproduced. 
  

   A 
  well-constructed 
  model 
  of 
  the 
  base 
  of 
  an 
  insect's 
  wing, 
  made 
  on 
  a 
  

   large 
  scale, 
  would 
  enable 
  us 
  to 
  understand 
  more 
  accurately 
  the 
  working 
  

   of 
  the 
  flexor 
  mechanism, 
  and, 
  incidentally, 
  it 
  should 
  be 
  an 
  excellent 
  

   object 
  for 
  museum 
  display. 
  

  

  