﻿APPEND 
  IX 
  VIII. 
  

  

  YERSIN'S 
  RESEARCHES 
  ON 
  THE 
  FUNCTIONS 
  OF 
  TnE 
  NERV- 
  

   OUS 
  SYSTEM 
  OF 
  THE 
  ARTICULATE 
  ANIMALS. 
  

  

  [Compare 
  with 
  chapter 
  XI 
  on 
  the 
  Brain 
  of 
  the 
  Locust.] 
  

  

  In 
  our 
  chapter 
  on 
  the 
  Brain 
  of 
  the 
  Locust 
  we 
  omitted 
  to 
  record 
  Yersin's* 
  opinions 
  as 
  

   to 
  the 
  functions 
  of 
  the 
  nervous 
  system 
  of 
  crickets. 
  We 
  translate 
  from 
  H. 
  de 
  Saussure's 
  

   "Notice 
  sur 
  la 
  Vie 
  et 
  les 
  Ecrits 
  de 
  Alexandre 
  Yersin," 
  1866, 
  the 
  following 
  abstract 
  of 
  

   his 
  researches 
  on 
  this 
  subject. 
  

  

  The 
  author 
  followed 
  two 
  different 
  methods 
  in 
  his 
  researches; 
  first, 
  by 
  making 
  sec- 
  

   tions 
  of 
  the 
  nervous 
  chain; 
  second, 
  by 
  endeavoring 
  to 
  isolate 
  the 
  ganglia. 
  

  

  The 
  results 
  attained 
  by 
  means 
  of 
  sections 
  were 
  quite 
  varied. 
  Iu 
  performing 
  on 
  some 
  

   crickets 
  the 
  section 
  of 
  the 
  two 
  nervous 
  cords 
  in 
  the 
  head, 
  between 
  the 
  supra-cesoph- 
  

   ageal 
  and 
  infra-cesophageal 
  ganglia, 
  there 
  resulted 
  as 
  a 
  consequence 
  of 
  this 
  operation 
  

   a 
  series 
  of 
  physiological 
  phenomena. 
  After 
  a 
  moment 
  of 
  stupor, 
  the 
  insect 
  rose 
  on 
  the 
  

   extremities 
  of 
  its 
  feet 
  while 
  carrying 
  its 
  head 
  directed 
  forwards. 
  Then 
  the 
  cricket 
  

   turned 
  in 
  a 
  circle 
  to 
  the 
  rigkt, 
  while 
  rubbing 
  its 
  head 
  with 
  the 
  left 
  foot, 
  or 
  vice 
  versa. 
  

  

  When 
  the 
  section 
  of 
  the 
  two 
  commissural 
  cords 
  is 
  performed 
  between 
  the 
  head 
  and 
  

   the 
  thorax, 
  as, 
  for 
  example, 
  when 
  we 
  decapitate 
  a 
  Blatta, 
  the 
  insect 
  can 
  still 
  live 
  ten 
  

   or 
  twelve 
  days 
  ; 
  the 
  body 
  continues 
  to 
  bend 
  itself 
  in 
  such 
  a 
  way 
  as 
  to 
  carry 
  the 
  poste- 
  

   rior 
  feet 
  towards 
  the 
  head, 
  which 
  is 
  wanting, 
  as 
  if 
  to 
  clean 
  them 
  with 
  the 
  mandibles. 
  

   When 
  the 
  insect 
  thus 
  mutilated 
  is 
  excited 
  it 
  endeavors 
  rather 
  to 
  defend 
  itself 
  than 
  to 
  

   escape, 
  as 
  an 
  uninjured 
  individual 
  would. 
  If 
  the 
  section 
  is 
  performed 
  on 
  crickets 
  be- 
  

   tween 
  the 
  second 
  cephalic 
  ganglion 
  and 
  the 
  first 
  thoracic, 
  without 
  decapitation, 
  it 
  

   will 
  be 
  found 
  that 
  we 
  have 
  isolated 
  the 
  community 
  of 
  action 
  in 
  the 
  head 
  and 
  body, 
  

   which 
  move 
  independently 
  of 
  each 
  other 
  ; 
  the 
  animal 
  constantly 
  tries 
  to 
  extend 
  its 
  feet 
  

   as 
  if 
  to 
  clean 
  them 
  with 
  the 
  mandibles, 
  but 
  the 
  inaxillaB 
  do 
  not 
  recognize 
  them. 
  These 
  

   are 
  almost 
  the 
  only 
  movements 
  which 
  the 
  insect 
  makes. 
  Exposure 
  to 
  the 
  sun 
  reani- 
  

   mates 
  it, 
  and 
  it 
  leaps 
  about 
  a 
  little 
  ; 
  forty 
  days 
  after 
  the 
  operation 
  it 
  sometimes 
  becomes 
  

   suddenly 
  aroused 
  from 
  its 
  torpor. 
  The 
  act 
  of 
  coupling 
  can 
  be 
  performed, 
  even 
  with 
  

   a 
  female 
  operated 
  upon, 
  but 
  the 
  latter 
  is 
  incapable 
  of 
  laying 
  eggs. 
  The 
  insect 
  still 
  

   eats 
  a 
  little, 
  but 
  while 
  only 
  the 
  head 
  eats, 
  the 
  trunk 
  does 
  not 
  perceive 
  it, 
  and 
  continues 
  

   to 
  extend 
  the 
  feet 
  towards 
  the 
  mouth 
  as 
  if 
  to 
  rub 
  them 
  ; 
  so 
  that 
  the 
  head 
  eats, 
  without 
  

   perceiving 
  the 
  fact, 
  its 
  own 
  feet 
  as 
  well 
  as 
  the 
  food; 
  the 
  mutilation 
  of 
  the 
  feet 
  causes 
  

   the 
  insect 
  to 
  tumble 
  about, 
  which 
  seems 
  to 
  prove 
  the 
  presence 
  of 
  pain. 
  The 
  reflex 
  

   movements 
  are 
  very 
  easy 
  to 
  provoke 
  in 
  this 
  particular 
  case, 
  and 
  the 
  voluntary 
  move- 
  

   ments 
  either 
  of 
  the 
  trunk 
  or 
  of 
  the 
  head 
  are 
  exercised 
  with 
  a 
  remarkable 
  facility, 
  

   although 
  in 
  an 
  independent 
  way. 
  Thus 
  the 
  insect 
  is 
  capable 
  of 
  leaping 
  ; 
  if 
  it 
  is 
  stim- 
  

   ulated 
  too 
  long 
  it 
  gives 
  some 
  symptoms 
  of 
  anger; 
  if 
  it 
  is 
  placed 
  on 
  its 
  back 
  it 
  promptly 
  

   turns 
  over. 
  The 
  crickets 
  operated 
  upon 
  live 
  as 
  long 
  as 
  those 
  which 
  are 
  uninjured. 
  

  

  In 
  making 
  two 
  sections 
  of 
  the 
  cords 
  of 
  the 
  ganglionic 
  chain, 
  so 
  as 
  to 
  completely 
  

   isolate 
  one 
  of 
  the 
  ganglia, 
  we 
  likewise 
  isolate 
  the 
  iunctions 
  of 
  the 
  nerves 
  which 
  are 
  

   distributed 
  from 
  this 
  ganglion, 
  but 
  without 
  interrupting 
  them. 
  The 
  reflex 
  actions 
  

   become 
  in 
  this 
  case 
  very 
  pronounced. 
  They 
  are 
  always 
  of 
  long 
  duration 
  ; 
  for 
  exam- 
  

   ple, 
  when 
  we 
  excite 
  the 
  valves 
  of 
  the 
  ovipositor, 
  they 
  continue 
  to 
  open 
  and 
  shut 
  per- 
  

   sistently 
  ; 
  in 
  exciting 
  a 
  foot 
  belonging 
  to 
  the 
  third 
  pair 
  we 
  obtain 
  an 
  immediate 
  reflex 
  

   action 
  on 
  the 
  one 
  corresponding 
  to 
  it. 
  The 
  feet 
  of 
  the 
  second 
  pair 
  seem, 
  however, 
  to 
  

   be 
  an 
  exception 
  to 
  the 
  rule, 
  and 
  only 
  react 
  with 
  great 
  difficulty 
  on 
  each 
  other. 
  If 
  we 
  

   isolate 
  several 
  ganglia 
  collectively 
  from 
  the 
  rest 
  of 
  the 
  chain, 
  we 
  obtain 
  analogous 
  and 
  

   naturally 
  more 
  varied 
  reflex 
  actions. 
  

  

  Yersin 
  followed 
  up 
  his 
  experiments 
  by 
  afterwards 
  producing 
  some 
  lesions 
  in 
  the 
  

  

  * 
  Alexander 
  Yersin 
  was 
  a 
  Swiss 
  naturalist, 
  who 
  wrote 
  several 
  important 
  and 
  fruitful 
  essays 
  on 
  the 
  

   habits 
  and 
  physiology 
  of 
  the 
  locusts 
  and 
  crickets. 
  His 
  essay 
  on 
  the 
  nervous 
  system 
  of 
  insects 
  was 
  the 
  

   following 
  : 
  Itechcrches 
  sur 
  les 
  fonctions 
  du 
  systeme 
  nerveux 
  dans 
  les 
  animaux 
  articulcs. 
  Societe 
  Vau- 
  

   dois 
  des 
  Sciences 
  Natorelles, 
  et 
  Acadeniie 
  des 
  Sciences 
  de 
  Paris, 
  185G-'57. 
  

  

  [73] 
  

  

  