﻿PROPAGATION 
  OF 
  FEESH-WATEE 
  MUSSELS. 
  

  

  31 
  

  

  Table 
  2. 
  — 
  Natural 
  Host 
  op 
  Fresh-Water 
  Mussel 
  Quadrula 
  heros. 
  

  

  The 
  results 
  of 
  the 
  artificial 
  infection 
  experiments 
  and 
  the 
  observa- 
  

   tions 
  upon 
  natural 
  infections 
  would 
  indicate 
  that 
  this 
  mussel 
  may 
  carry 
  

   out 
  its 
  development 
  upon 
  both 
  the 
  gills 
  and 
  fins 
  of 
  a 
  number 
  of 
  

   species 
  of 
  fish. 
  In 
  the 
  natural 
  infections 
  it 
  will 
  be 
  noted 
  that 
  the 
  

   infection 
  of 
  the 
  fins 
  was 
  more 
  common. 
  

  

  This 
  is 
  an 
  interesting 
  case 
  of 
  a 
  bookless 
  glochidium 
  adopting 
  par- 
  

   tially 
  the 
  fin-infection 
  habit 
  which 
  is 
  found 
  in 
  the 
  Anodontas. 
  It 
  has 
  

   other 
  characters 
  in 
  common 
  with 
  this 
  group 
  in 
  the 
  large 
  size 
  of 
  the 
  

   glochidium, 
  in 
  the 
  presence 
  of 
  the 
  large 
  thread 
  gland, 
  and 
  in 
  the 
  

   winter 
  (though 
  probably 
  not 
  long 
  period 
  or 
  bradytictic) 
  breeding 
  

   habit. 
  The 
  opinion 
  of 
  Simpson 
  (1900, 
  p. 
  766, 
  footnotes) 
  that 
  this 
  

   species 
  breeds 
  only 
  at 
  long 
  intervals 
  was 
  based 
  upon 
  the 
  absence 
  of 
  

   observations 
  of 
  gravid 
  specimens. 
  I 
  think 
  this 
  scarcity 
  of 
  records 
  

   may 
  be 
  ascribed 
  partly 
  to 
  the 
  following 
  causes: 
  The 
  breeding 
  season 
  

   is 
  at 
  the 
  time 
  of 
  year 
  when 
  less 
  collecting 
  is 
  being 
  carried 
  on, 
  as 
  well 
  

   as 
  at 
  a 
  different 
  season 
  from 
  that 
  of 
  related 
  forms. 
  Again, 
  gravid 
  

   mussels 
  abort 
  the 
  glochidia 
  so 
  that 
  the 
  evidence 
  is 
  liable 
  to 
  be 
  lost 
  

   unless 
  observed 
  when 
  the 
  mussels 
  are 
  first 
  removed 
  from 
  the 
  water. 
  

   I 
  think 
  the 
  assumption 
  that 
  they 
  breed 
  annually 
  is 
  safe 
  until 
  more 
  

   definite 
  evidence 
  to 
  the 
  contrary 
  is 
  found. 
  

  

  Artijlcial 
  infection. 
  — 
  Mature 
  glochidia 
  suitable 
  for 
  infection 
  were 
  

   first 
  obtained 
  September 
  24, 
  and 
  subsequently 
  other 
  gravid 
  mussels 
  

   were 
  obtained, 
  apparently 
  being 
  not 
  difficult 
  to 
  find. 
  It 
  was 
  noticed 
  

   that 
  the 
  glochidia 
  had 
  unusual 
  vitality, 
  it 
  being 
  possible 
  to 
  use 
  the 
  

   same 
  lot 
  day 
  after 
  day 
  for 
  more 
  than 
  a 
  week. 
  This 
  is 
  in 
  marked 
  

   contrast 
  to 
  the 
  conditions 
  I 
  have 
  encountered 
  among 
  other 
  Quadrulas. 
  

   It 
  is 
  possible 
  that 
  it 
  may 
  be 
  associated 
  with 
  the 
  lower 
  temperatures 
  

   at 
  this 
  season. 
  Another 
  feature 
  of 
  importance 
  is 
  the 
  immense 
  number 
  

   of 
  glochidia, 
  which 
  increases 
  greatly 
  the 
  ease 
  of 
  manipulations. 
  

  

  Some 
  10 
  species 
  of 
  fish 
  were 
  subjected 
  to 
  infection 
  in 
  six 
  different 
  

   lots, 
  according 
  to 
  the 
  usual 
  method. 
  The 
  results 
  of 
  these 
  experiments 
  

   are 
  summarized 
  in 
  table 
  3. 
  

  

  