﻿PACKARD] 
  THE 
  LOCUSTS 
  OF 
  THE 
  OLD 
  WORLD. 
  655 
  

  

  even 
  in 
  countries 
  very 
  northern 
  ; 
  Ibns, 
  it 
  was 
  observed 
  in 
  England 
  (1693 
  and 
  1748), 
  

   and 
  even 
  at 
  the 
  latter 
  date, 
  near 
  Edinburgh 
  ; 
  in 
  Sweden 
  (as 
  far 
  as 
  Ostrogoth), 
  

   at 
  latitude 
  57° 
  to 
  58'^ 
  north, 
  in 
  1748 
  and 
  1844, 
  aud 
  finally 
  on 
  the 
  Duna, 
  nearDunabourg 
  

   and 
  at 
  Polozk, 
  in 
  1545. 
  But 
  these 
  troops 
  of 
  voyagers 
  did 
  not 
  hatch 
  out 
  in 
  the 
  same 
  

   placed 
  where 
  they 
  were 
  observed, 
  nor 
  did 
  they 
  leave 
  any 
  progeny 
  in 
  subsequent 
  years. 
  

   The 
  only 
  known 
  example 
  of 
  an 
  exception 
  to 
  this 
  rule 
  is 
  the 
  discovery 
  made 
  once 
  by 
  

   Boheman, 
  in 
  September, 
  in 
  the 
  middle 
  of 
  Sweden, 
  of 
  a 
  Pachytylus 
  migratorius 
  in 
  the 
  

   proper 
  state. 
  Evidently 
  this 
  is 
  an 
  exception 
  wholly 
  accidental, 
  which 
  does 
  not 
  prove 
  

   anything 
  against 
  the 
  rule. 
  The 
  more 
  we 
  advance 
  toward 
  the 
  north, 
  the 
  less 
  are 
  large 
  

   swarms 
  of 
  locusts 
  observed, 
  and 
  we 
  end 
  by 
  meeting 
  only 
  isolated 
  individuals, 
  as 
  have 
  

   been 
  seen 
  several 
  times 
  at 
  St. 
  Petersburg, 
  and 
  even 
  near 
  Wasa 
  in 
  Finland 
  (latitude 
  

   6?P 
  north). 
  

  

  The 
  want 
  of 
  facts 
  prevents 
  onr 
  extending 
  these 
  studies 
  to 
  the 
  southern 
  boundary 
  of 
  

   the 
  area 
  of 
  distribution 
  of 
  Pachytylus 
  migratorius. 
  However, 
  we 
  can 
  remark 
  that 
  in 
  

   New 
  Zealand, 
  the 
  extreme 
  southern 
  point 
  of 
  this 
  distribution, 
  the 
  mean 
  temperature 
  

   of 
  the 
  warmer 
  months 
  is, 
  according 
  to 
  Schmid 
  (Lehrbuch 
  der 
  Meteorologie, 
  p. 
  363), 
  at 
  

   15°.5 
  R. 
  (about 
  66° 
  Fahrenheit), 
  which 
  does 
  not 
  ditfer 
  much 
  from 
  the 
  corresponding 
  

   temperature 
  of 
  the 
  northern 
  limit 
  of 
  the 
  area 
  in 
  Europe. 
  

  

  The 
  localities 
  out 
  of 
  Eurojie 
  where 
  the 
  Pachytylus 
  migratorius 
  has 
  been 
  observed 
  are 
  

   as 
  follows: 
  Madeira, 
  Algeria, 
  Tunis, 
  Egypt, 
  Chartoum, 
  Asia 
  Minor, 
  Syria, 
  Arabia, 
  Per- 
  

   sia, 
  India, 
  Siam, 
  China, 
  Japan, 
  Java, 
  LuQon, 
  Fidschi, 
  New 
  Caledonia, 
  New 
  Zealand, 
  

   Northern 
  Australia, 
  and 
  finally 
  Mauritius 
  island; 
  but 
  this 
  last 
  locality 
  indicated 
  by 
  

   Serville 
  needs 
  confirmation. 
  In 
  Central 
  Asia 
  the 
  species 
  has 
  been 
  observed 
  near 
  Lake 
  

   Aral, 
  on 
  the 
  borders 
  of 
  Syr-Darja, 
  on 
  the 
  upper 
  side 
  of 
  Ischim 
  and 
  of 
  Irtisch, 
  and 
  

   finally 
  toward 
  the 
  lakes 
  Kurgaldschin, 
  Nor-Saisan, 
  and 
  Balchaasch. 
  

  

  According 
  to 
  M. 
  Koppen, 
  the 
  great 
  chains 
  of 
  mountains 
  are 
  a 
  powerful 
  obstacle 
  to 
  

   the 
  diffusion 
  of 
  Pachytylus 
  migratorius. 
  The 
  Alps 
  especially 
  play 
  a 
  large 
  part 
  in 
  its 
  dis- 
  

   tributiou 
  in 
  Europe, 
  and 
  it 
  is 
  without 
  doubt 
  to 
  them 
  that 
  we 
  should 
  attribute 
  its 
  rela- 
  

   tive 
  rarity 
  in 
  the 
  countries 
  of 
  the 
  southwest 
  of 
  Europe 
  and 
  northwest 
  of 
  Africa, 
  where 
  

   it 
  is 
  almost 
  completely 
  replaced 
  by 
  other 
  species 
  of 
  the 
  same 
  gronp, 
  i. 
  e., 
  the 
  Caloptenus 
  

   itaJica 
  in 
  Spain, 
  Italy, 
  aud 
  in 
  the 
  middle 
  of 
  France 
  ; 
  the 
  Acrydium 
  iieregrimim 
  in 
  Algeria. 
  

  

  It 
  should 
  be 
  observed 
  that 
  this 
  species, 
  and 
  in 
  general 
  all 
  the 
  Acrydiidm, 
  shun 
  mount- 
  

   ainous 
  and 
  wooded 
  countries. 
  They 
  are 
  most 
  fond 
  of 
  the 
  plains, 
  of 
  regions 
  quite 
  diy, 
  

   and 
  it 
  is 
  also 
  a 
  circumstance 
  which 
  influences 
  necessarily 
  their 
  geographical 
  distribu- 
  

   tion. 
  

  

  " 
  The 
  development 
  of 
  the 
  organs 
  of 
  flight 
  of 
  the 
  migratory 
  locust," 
  continues 
  M. 
  Kop- 
  

   pen, 
  " 
  determines 
  the 
  facility 
  and 
  the 
  amplitude 
  of 
  its 
  flight, 
  and 
  consequently 
  favors 
  

   its 
  migrations. 
  Thty 
  are 
  evidently 
  the 
  cause 
  of 
  this 
  colossal 
  geographical 
  distiibution 
  

   of 
  the 
  species. 
  They 
  remind 
  us 
  of 
  the 
  remark 
  of 
  Darwin, 
  that 
  species 
  rich 
  in 
  individ- 
  

   uals 
  and 
  with 
  a 
  wide 
  habitat, 
  which, 
  owing 
  to 
  their 
  organization, 
  have 
  had 
  in 
  their 
  

   country 
  the 
  pre-eminence 
  over 
  many 
  surrounding 
  species, 
  are 
  those 
  which, 
  in 
  the 
  case 
  

   of 
  emigrations 
  cut 
  of 
  their 
  area, 
  should 
  have 
  the 
  greater 
  chances 
  of 
  overrunning 
  new 
  

   territories." 
  

  

  Koppen 
  examines 
  successively 
  the 
  causes 
  which 
  may 
  determine 
  the 
  migrations 
  of 
  

   this 
  orthopter 
  in 
  armies 
  more 
  or 
  less 
  numerous, 
  and 
  then 
  the 
  observed 
  direction 
  of 
  these 
  

   movements. 
  It 
  is 
  said 
  that 
  they 
  fly 
  more 
  often 
  from 
  east 
  to 
  west, 
  but 
  M. 
  Koppen 
  

   thinks 
  that 
  it 
  is 
  not 
  necessary 
  to 
  attribute 
  this 
  circumstance, 
  as 
  has 
  been 
  done, 
  to 
  the 
  

   predominance 
  of 
  the 
  east 
  winds 
  at 
  times 
  when 
  the 
  sterility 
  of 
  the 
  country 
  that 
  they 
  

   inhabit, 
  increased 
  still 
  by 
  the 
  prevalence 
  of 
  these 
  same 
  winds, 
  forces 
  them 
  to 
  seek 
  

   places 
  which 
  can 
  furnish 
  them 
  a 
  more 
  abundant 
  pasturage. 
  Numerous 
  facts 
  appear, 
  

   he 
  says, 
  to 
  contradict 
  this 
  explanation. 
  In 
  reality, 
  the 
  movements 
  of 
  these 
  hordes 
  is 
  

   rather 
  centrifugal, 
  as 
  M. 
  Koppen 
  establishes 
  from 
  observations 
  made 
  especially 
  in 
  the 
  

   plains 
  of 
  Eastern 
  Europe; 
  that 
  is 
  to 
  say, 
  that 
  all 
  the 
  migrations 
  appear 
  to 
  radiate 
  

   from 
  countries 
  where 
  the 
  species 
  breeds 
  most. 
  In 
  Europe 
  they 
  would 
  consequently 
  be 
  

   diiected 
  to 
  the 
  west, 
  while 
  in 
  China 
  they 
  should 
  have 
  a 
  direction 
  ordinarilj' 
  toward 
  

   the 
  southeast, 
  

  

  M. 
  Koppen 
  thinks 
  that 
  the 
  same 
  centrifugal 
  radiation 
  has 
  presided 
  over 
  the 
  scatter- 
  

   ing 
  of 
  this 
  species 
  beyond 
  its 
  original 
  limits, 
  and 
  that 
  this 
  radiation, 
  propagating 
  in 
  

   waves, 
  such 
  as 
  we 
  still 
  see 
  produced 
  at 
  the 
  limits 
  of 
  its 
  geographical 
  area, 
  has 
  carried 
  

   the 
  species 
  from 
  its 
  center 
  of 
  creation 
  or 
  its 
  original 
  country 
  to 
  points 
  where 
  it 
  is 
  

   powerless 
  to 
  overcome 
  the 
  climatic 
  conditions 
  or 
  that 
  concurrence 
  of 
  vital 
  forces 
  which 
  

   are 
  opposed 
  to 
  it. 
  The 
  center 
  of 
  creation 
  or 
  the 
  point 
  of 
  departure 
  of 
  the 
  species 
  will 
  

   be 
  found, 
  then, 
  in 
  Central 
  Asia. 
  The 
  complete 
  absence 
  of 
  this 
  species 
  on 
  the 
  American 
  

   continent 
  shows 
  that 
  it 
  only 
  began 
  to 
  exist 
  as 
  a 
  species 
  after 
  the 
  epoch 
  of 
  the 
  separa- 
  

   tion 
  of 
  America 
  from 
  the 
  Old 
  World. 
  

  

  M. 
  Prudhomme 
  de 
  Borre 
  adds, 
  "In 
  this 
  study, 
  so 
  interesting, 
  there 
  is 
  one 
  point 
  on 
  

   which 
  we 
  should 
  insist. 
  It 
  is 
  this, 
  that 
  the 
  observations 
  of 
  M. 
  Koppen 
  tend 
  to 
  confirm 
  

   the 
  principle 
  of 
  zoological 
  geography, 
  that 
  the 
  area 
  of 
  a 
  species 
  cannot 
  be 
  limited 
  on 
  

   the 
  map 
  by 
  a 
  simple 
  curve, 
  but 
  between 
  places 
  where 
  the 
  species 
  exist 
  in 
  a 
  constant 
  or 
  

   normal 
  manner 
  and 
  those 
  where 
  its 
  absence 
  is 
  constant 
  there 
  is 
  always 
  a 
  zone, 
  often 
  

  

  