﻿PROPAGATION 
  OF 
  FRESH-WATER 
  MUSSELS. 
  27 
  

  

  longer 
  and 
  the 
  thread 
  gland 
  curves 
  in 
  from 
  the 
  ventral 
  edge 
  of 
  the 
  

   right 
  valve 
  in 
  TJ. 
  gibhosus. 
  In 
  Q. 
  pJicata 
  the 
  ventral 
  loops 
  follow 
  a 
  

   peripheral 
  course 
  (see 
  fig. 
  32). 
  Unfortunately, 
  this 
  cnaracter 
  is 
  

   difficult 
  to 
  distinguish 
  in 
  glochidia 
  which 
  are 
  imbedded 
  in 
  the 
  tissues 
  

   of 
  a 
  fish. 
  Again, 
  since 
  tlie 
  gland 
  is 
  an 
  embryonic 
  organ, 
  it 
  does 
  not 
  

   persist 
  long 
  after 
  metamorphosis 
  commences 
  in 
  tissues 
  ol 
  the 
  host. 
  

   In 
  natural 
  infections 
  it 
  is 
  not 
  always 
  possible 
  to 
  obtain 
  an 
  orientation 
  

   ol 
  the 
  specimens 
  so 
  as 
  to 
  obtain 
  the 
  most 
  accurate 
  measurements; 
  

   especially 
  is 
  this 
  the 
  case 
  when 
  a 
  fish 
  carries 
  only 
  one 
  or 
  a 
  few 
  glo- 
  

   chidia, 
  when 
  distinction 
  between 
  glochidia 
  is 
  made 
  more 
  difficult. 
  

  

  The 
  number 
  of 
  infections 
  determined 
  as 
  U. 
  gibhosus 
  were 
  as 
  follows 
  : 
  

   Black 
  and 
  white 
  crappies, 
  5; 
  yellow 
  cat 
  (Leptops 
  olivaris), 
  1; 
  Sauger 
  

   (Stizostedion 
  canadense), 
  1. 
  In 
  addition 
  to 
  these, 
  I 
  have 
  records 
  of 
  

   three 
  infections 
  on 
  the 
  black 
  bass 
  (Micropterus 
  salmoides) 
  which 
  

   belong 
  to 
  one 
  of 
  these 
  species 
  but 
  which 
  I 
  am 
  at 
  present 
  obliged 
  to 
  

   consider 
  as 
  doubtful. 
  

  

  Summarizing 
  the 
  results, 
  the 
  chief 
  hosts 
  for 
  Q. 
  plicata 
  are 
  nidicated 
  

   as 
  the 
  crappie, 
  Pomoxis 
  annularis 
  and 
  Pomoxis 
  sparoides, 
  with 
  the 
  

   sauger 
  and 
  black 
  bass 
  as 
  occasional 
  possible 
  hosts. 
  The 
  reported 
  

   (Lete^'Te 
  and 
  Curtis, 
  1912) 
  successful 
  art'ficial 
  infection 
  of 
  Micropterus 
  

   salmoides 
  with 
  Q. 
  plicata 
  would 
  warrant 
  the 
  expectation 
  of 
  finding 
  

   this 
  fish 
  infected 
  in 
  nature. 
  

  

  The 
  presence 
  of 
  an 
  embryonic 
  thread 
  suggests 
  the 
  possibility 
  of 
  

   fin 
  infection 
  from 
  analogy 
  with 
  forms 
  that 
  possess 
  that 
  organ. 
  The 
  

   smaU 
  size 
  of 
  the 
  glochidium 
  and 
  lack 
  of 
  color 
  would 
  make 
  them 
  more 
  

   difficult 
  to 
  detect 
  than 
  the 
  fin-infecting 
  glochidia 
  of 
  the 
  Anodontas. 
  

  

  Artificial 
  infection. 
  — 
  The 
  artificial 
  infection 
  with 
  this 
  species 
  which 
  

   I 
  have 
  just 
  mentioned 
  as 
  having 
  been 
  made 
  by 
  Lefevre 
  and 
  Curtis 
  

   (1912) 
  was 
  the 
  first 
  reported 
  and 
  the 
  only 
  successful 
  infection 
  with 
  

   Quadrula 
  mussels 
  so 
  far 
  as 
  known 
  to 
  mc. 
  The 
  fish, 
  black 
  bass, 
  

   Micropterus 
  salmoides, 
  were 
  infected 
  August 
  5, 
  1908, 
  exposed 
  30 
  

   minutes 
  to 
  infection, 
  and 
  young 
  mussels 
  hberated 
  on 
  August 
  17, 
  

   giving 
  a 
  parasitic 
  period 
  of 
  12 
  days 
  in 
  water 
  of 
  24.4° 
  C. 
  average 
  

   temperature. 
  

  

  I 
  have 
  experimentally 
  infected 
  the 
  following 
  fish 
  with 
  this 
  species: 
  

   White 
  crappie, 
  Pomoxis 
  annularis; 
  black 
  crappie, 
  P. 
  sparoides; 
  

   yellow 
  perch, 
  Perca 
  flavescens; 
  sunfish, 
  Lepomis 
  pallidus; 
  bulUiead, 
  

   Ameiurus; 
  flathead 
  catfish, 
  Leptops 
  olivaris; 
  channel 
  cat, 
  Ictalurus 
  p 
  unc- 
  

   tatus; 
  quillback, 
  Carpiodes 
  velifer. 
  The 
  first 
  four 
  named 
  proved 
  suitable 
  

   as 
  carriers 
  of 
  this 
  species; 
  the 
  young 
  mussels 
  were 
  carried 
  through 
  

   the 
  metamorphosis 
  in 
  large 
  numbers, 
  and 
  I 
  was 
  able 
  to 
  secure 
  

   specimens 
  of 
  the 
  young 
  juveniles 
  aUve 
  on 
  the 
  bottom 
  of 
  the 
  aquaria 
  

   in 
  which 
  the 
  fish 
  were 
  retained. 
  In 
  tne 
  sunfish 
  a 
  large 
  number 
  were 
  

   apparently 
  shed 
  prematurely, 
  while 
  a 
  few 
  were 
  carried 
  through 
  to 
  

   maturity. 
  The 
  buUheads 
  can-ied 
  a 
  few 
  for 
  the 
  fuU 
  time, 
  but 
  on 
  the 
  

  

  