﻿MIND 
  OF 
  AN 
  INSECT 
  SNODGRASS 
  405 
  

  

  organs 
  presents 
  any 
  perceptible 
  liquid 
  exudation, 
  we 
  can 
  only 
  judge 
  

   that 
  those 
  having 
  the 
  thinnest 
  cuticular 
  covering 
  are 
  the 
  ones 
  most 
  

   likely 
  to 
  be 
  the 
  organs 
  of 
  smell. 
  Such 
  organs 
  would 
  include 
  minute 
  

   peglike, 
  innervated 
  hairs 
  either 
  standing 
  on 
  the 
  surface 
  or 
  sunken 
  

   into 
  deep 
  pits, 
  thin 
  membranous 
  grooves 
  surrounding 
  elliptical 
  or 
  

   oval 
  plates 
  with 
  a 
  nerve-ending 
  at 
  one 
  side, 
  and 
  minute 
  disks 
  of 
  ex- 
  

   tremely 
  thin 
  cuticula 
  over 
  the 
  ends 
  of 
  sensory 
  cells. 
  Organs 
  of 
  the 
  

   first 
  two 
  kinds 
  occur 
  principally 
  on 
  the 
  antennse; 
  the 
  others 
  are 
  found 
  

   on 
  the 
  head, 
  the 
  body, 
  and 
  the 
  appendages, 
  but 
  occur 
  particularly 
  on 
  

   the 
  bases 
  of 
  the 
  legs 
  and 
  the 
  wings. 
  

  

  For 
  practical 
  experimental 
  work 
  on 
  odor 
  reactions 
  with 
  insects 
  

   it 
  is 
  not 
  necessary 
  that 
  the 
  organs 
  of 
  smell 
  should 
  be 
  identified. 
  If 
  

   insects 
  can 
  be 
  shown 
  to 
  be 
  definitely 
  attracted 
  or 
  repelled 
  by 
  certain 
  

   odorous 
  substances, 
  the 
  facts 
  of 
  their 
  olfactory 
  powers 
  can 
  be 
  ascer- 
  

   tained. 
  At 
  present 
  much 
  experimenting 
  is 
  being 
  done 
  on 
  the 
  reac- 
  

   tion 
  of 
  insects 
  to 
  odors 
  in 
  view 
  of 
  the 
  possibility 
  of 
  making 
  use 
  of 
  

   the 
  information 
  acquired 
  in 
  the 
  control 
  of 
  injurious 
  species. 
  Cer- 
  

   tain 
  species, 
  it 
  is 
  found, 
  can 
  be 
  attracted 
  from 
  long 
  distances 
  to 
  

   specific 
  odorous 
  substances 
  exposed 
  in 
  their 
  neighborhood. 
  In 
  some 
  

   instances 
  the 
  effective 
  substances 
  are 
  component 
  elements 
  of 
  favorite 
  

   food 
  plants, 
  and 
  in 
  other 
  cases 
  they 
  appear 
  to 
  have 
  no 
  relation 
  what- 
  

   ever 
  to 
  anything 
  in 
  the 
  insect's 
  natural 
  environment. 
  The 
  second 
  

   fact 
  seems 
  surprising 
  at 
  first, 
  since 
  we 
  have 
  become 
  accustomed 
  to 
  

   thinking 
  of 
  every 
  character 
  or 
  trait 
  of 
  an 
  animal 
  as 
  being 
  in 
  some 
  

   way 
  related 
  to 
  its 
  mode 
  of 
  life. 
  Unquestionably, 
  a 
  sensitivity 
  to 
  

   odors 
  has 
  been 
  acquired 
  as 
  an 
  " 
  adaptive 
  " 
  faculty 
  — 
  i. 
  e., 
  one 
  enabling 
  

   the 
  insect 
  to 
  make 
  specifically 
  useful 
  reactions 
  — 
  but 
  nature 
  apparently 
  

   can 
  give 
  no 
  guarantee 
  that 
  only 
  certain 
  odors 
  may 
  be 
  perceived 
  or 
  

   may 
  act 
  as 
  stimuli 
  to 
  definite 
  responses. 
  The 
  mechanism 
  of 
  reaction 
  

   to 
  odor, 
  once 
  acquired, 
  may 
  react 
  powerfully 
  to 
  a 
  new 
  stimulus 
  in 
  

   a 
  manner 
  having 
  no 
  relation 
  to 
  the 
  creature's 
  hereditary 
  instincts. 
  

   The 
  experimenter 
  on 
  insect 
  olfactory 
  reflexes, 
  therefore, 
  sometimes 
  

   unexpectedly 
  obtains 
  his 
  most 
  promising 
  results 
  by 
  purely 
  random 
  

   tests 
  with 
  chemicals 
  from 
  his 
  laboratory 
  shelves. 
  

  

  Concerning 
  the 
  sense 
  of 
  taste 
  in 
  insects, 
  less 
  is 
  known 
  than 
  of 
  

   the 
  sense 
  of 
  smell. 
  It 
  has 
  been 
  shown 
  by 
  Will, 
  Forel, 
  Mclndoo, 
  

   Minnich, 
  and 
  von 
  Frisch 
  that 
  insects 
  perceive 
  differences 
  in 
  solutions 
  

   of 
  various 
  things 
  that 
  give 
  us 
  different 
  sensations 
  of 
  taste. 
  In 
  gen- 
  

   eral, 
  the 
  taste 
  organs 
  are 
  situated 
  in 
  the 
  mouth 
  or 
  on 
  the 
  feeding 
  

   organs 
  of 
  the 
  head, 
  but 
  Minnich 
  has 
  made 
  some 
  interesting 
  experi- 
  

   ments 
  on 
  butterflies 
  showing 
  that 
  taste 
  receptive 
  organs 
  in 
  these 
  

   insects 
  are 
  located 
  on 
  the 
  feet. 
  Von 
  Frisch 
  has 
  recently 
  published 
  

   the 
  results 
  of 
  experiments 
  on 
  honeybees 
  that 
  indicate 
  the 
  range 
  of 
  

   the 
  bee's 
  taste 
  sensitivity 
  for 
  varying 
  strengths 
  of 
  solutions 
  of 
  

   different 
  things. 
  

  

  74906—28 
  ^27 
  

  

  