﻿boycott: 
  on- 
  acanthinula 
  aculeata. 
  21b 
  

  

  molliiscau 
  free-martin 
  ; 
  it 
  is 
  difficult 
  on 
  this 
  liypotliesis 
  to 
  explain 
  

   the 
  normal 
  structure 
  of 
  such 
  organs 
  as 
  are 
  present 
  or 
  the 
  frequency 
  

   of 
  the 
  condition. 
  

  

  The 
  only 
  anatomical 
  point 
  which 
  I 
  have 
  observed 
  which 
  might 
  

   lielp 
  to 
  a 
  decision 
  between 
  these 
  various 
  possibilities 
  is 
  that 
  the 
  

   glandular 
  organ 
  with 
  granular 
  cells 
  in 
  connection 
  with 
  the 
  spermovi- 
  

   duct, 
  which 
  is 
  known 
  as 
  the 
  prostate, 
  was 
  not 
  found 
  where 
  the 
  penis 
  

   was 
  absent. 
  This 
  suggests, 
  though 
  quite 
  indefinitely, 
  that 
  these 
  

   individuals 
  were 
  not 
  functional 
  males. 
  ^ 
  

  

  Hermaphroditism 
  is 
  often 
  associated 
  with 
  an 
  indifferent 
  capacity 
  

   for 
  locomotion, 
  and 
  it 
  is 
  a 
  clear 
  advantage 
  to 
  snails 
  that, 
  when 
  two 
  do 
  

   happen 
  to 
  meet, 
  botli 
  should 
  be 
  able 
  to 
  produce 
  spermatozoa 
  as 
  well 
  

   as 
  eggs. 
  Hence 
  arises 
  another 
  consideration 
  which 
  may 
  have 
  to 
  do 
  

   with 
  the 
  absence 
  of 
  male 
  organs. 
  Large 
  snails 
  walk 
  faster 
  than 
  

   small 
  snails, 
  and 
  with 
  very 
  small 
  species 
  the 
  rate 
  of 
  progression 
  may 
  

   become 
  so 
  slow 
  that 
  the 
  chance 
  of 
  two 
  individuals 
  meeting 
  becomes 
  

   so 
  trivial 
  that 
  it 
  is 
  not 
  worth 
  while 
  to 
  maintain 
  an 
  effective 
  male 
  

   copulatory 
  apparatus. 
  Locomotion 
  becomes 
  so 
  slow 
  that 
  the 
  habit 
  

   of 
  self-fertilization 
  is 
  added 
  to 
  the 
  hermaphrodite 
  structure. 
  That 
  

   dispersion 
  of 
  the 
  members 
  of 
  a 
  family 
  from 
  their 
  birtliplace 
  is 
  limited 
  

   in 
  the 
  same 
  way 
  is 
  no 
  substantial 
  objection 
  to 
  this 
  view 
  when 
  we 
  

   consider 
  that 
  the 
  time 
  devoted 
  to 
  sexual 
  confluence 
  is 
  very 
  small 
  

   compared 
  to 
  that 
  spent 
  in 
  wandering 
  in 
  search 
  of 
  food. 
  It 
  is 
  perhaps 
  

   also 
  noteworthy 
  that 
  aculeata 
  is 
  not 
  a 
  gregarious 
  species 
  ; 
  the 
  area 
  

   in 
  which 
  it 
  occurs 
  may 
  be 
  circumscribed 
  rather 
  closely 
  by 
  environ- 
  

   mental 
  conditions, 
  but 
  the 
  individuals 
  generally 
  occur 
  in 
  groups 
  of 
  

   one 
  each, 
  and 
  the 
  density 
  of 
  the 
  population 
  is 
  low 
  ; 
  it 
  is 
  not 
  an 
  

   " 
  abundant 
  " 
  species 
  as 
  is 
  often, 
  e.g. 
  Carychhim 
  minimum, 
  in 
  the 
  

   same 
  habitats.' 
  As 
  far 
  as 
  I 
  know, 
  lamellata 
  has 
  much 
  the 
  same 
  

   habits, 
  though 
  it 
  is 
  perhaps 
  more 
  abundant 
  where 
  it 
  occurs. 
  In 
  

   some 
  other 
  small 
  snails 
  gregarious 
  habits 
  render 
  congress 
  more 
  

   likely, 
  e.g. 
  Fyramidula 
  rupestris, 
  Pupa 
  umhilicata, 
  Vertigo 
  spp., 
  and 
  

   in 
  these 
  a 
  penis 
  is 
  found, 
  though 
  whether 
  in 
  all 
  specimens 
  I 
  do 
  not 
  

   know; 
  male 
  organs 
  are 
  also 
  described 
  in 
  Carychium. 
  

  

  On 
  the 
  whole 
  I 
  incline 
  to 
  the 
  speculative 
  explanation 
  that 
  the 
  

   aphallic 
  state 
  is 
  due 
  to 
  the 
  simplification 
  of 
  structure 
  which 
  is 
  

   necessarily 
  associated 
  with 
  diminution 
  in 
  absolute 
  size, 
  that 
  an 
  

   animal 
  cares 
  more 
  for 
  what 
  it 
  docs 
  than 
  for 
  the 
  apparatus 
  by 
  Avhich 
  

   it 
  does 
  it, 
  and 
  that 
  both 
  phallic 
  and 
  aphallic 
  forms 
  are 
  alike 
  

   hermaphrodite 
  and 
  reproductive. 
  The 
  view 
  that 
  the 
  possibilities 
  of 
  

   organic 
  action 
  are 
  limited 
  by 
  narrow 
  morphological 
  boundaries 
  has 
  

   been 
  productive 
  enough 
  along 
  the 
  line 
  of 
  phyletic 
  speculation, 
  but 
  

  

  ^ 
  An 
  organ 
  of 
  similar 
  histological 
  constitution 
  is 
  present 
  in 
  lamellata, 
  but 
  in 
  

   connection 
  with 
  the 
  lower 
  part 
  of 
  the 
  glandular 
  oviduct, 
  and 
  hence 
  

   possibly 
  different 
  in 
  character 
  ; 
  aculeata 
  has 
  nothing 
  like 
  it 
  in 
  the 
  

   lamellata 
  position. 
  

  

  ^ 
  I 
  am 
  referring 
  especially 
  to 
  dead 
  leaves, 
  particularly 
  beech 
  leaves, 
  in 
  woods. 
  

   In 
  the 
  few 
  specimens 
  of 
  Punctum 
  pygmceum 
  from 
  the 
  same 
  habitat 
  which 
  

   have 
  been 
  examined, 
  no 
  penis 
  has 
  been 
  found. 
  

  

  