﻿PROPAGATION 
  OP 
  FRESH-WATER 
  MUSSELS. 
  7 
  

  

  in 
  10 
  per 
  cent 
  formalin 
  or 
  a 
  one- 
  third 
  saturated 
  solution 
  of 
  bichloride 
  

   of 
  mercury. 
  The 
  usual 
  histological 
  procedm-e 
  for 
  whole 
  mounts 
  was 
  

   followed 
  after 
  fixation. 
  Acid 
  fixing 
  fluids 
  and 
  acid 
  stains 
  have 
  been 
  

   avoided 
  on 
  account 
  of 
  the 
  dehcate 
  calcareous 
  shells 
  of 
  the 
  glochidia. 
  

   For 
  the 
  sake 
  of 
  accurate 
  comparison 
  in 
  identifications 
  it 
  has 
  seemed 
  

   desirable 
  to 
  apply 
  the 
  same 
  method 
  of 
  preparation 
  for 
  the 
  natural 
  

   infections 
  that 
  is 
  used 
  for 
  the 
  glochidia. 
  

  

  When 
  evidence 
  of 
  the 
  natural 
  host 
  was 
  obtained 
  by 
  the 
  above 
  

   method, 
  the 
  kind 
  or 
  kinds 
  of 
  fish 
  thus 
  designated 
  were 
  tested 
  by 
  

   artificial 
  infection 
  to 
  verify 
  the 
  results 
  already 
  secured 
  and 
  to 
  deter- 
  

   mine 
  the 
  possibihties 
  of 
  artificial 
  propagation. 
  

  

  The 
  method 
  of 
  making 
  artificial 
  infections 
  is 
  as 
  follows: 
  Young 
  

   mussels 
  or 
  glochidia, 
  which 
  are 
  produced 
  to 
  the 
  number 
  of 
  many 
  

   thousands 
  by 
  each 
  female 
  mussel, 
  are 
  taken 
  from 
  the 
  gill 
  of 
  the 
  latter 
  

   and 
  placed 
  in 
  a 
  receptacle 
  with 
  the 
  fish 
  to 
  be 
  infected. 
  The 
  myriads 
  

   of 
  glochidia 
  thus 
  distributed 
  through 
  the 
  water, 
  passing 
  constantly 
  

   thi'ough 
  the 
  gill 
  openings 
  of 
  the 
  fish, 
  become 
  attached 
  to 
  the 
  filaments 
  

   of 
  the 
  gills 
  or 
  in 
  some 
  cases 
  fasten 
  externally 
  upon 
  the 
  fins. 
  As 
  soon 
  

   as 
  they 
  become 
  attached 
  there 
  is 
  a 
  reaction 
  of 
  the 
  tissue 
  in 
  the 
  nature 
  

   of 
  an 
  hypertrophy 
  of 
  the 
  external 
  epithelium 
  which 
  produces 
  a 
  cyst 
  

   enveloping 
  the 
  glochidium. 
  

  

  For 
  a 
  fuller 
  discussion 
  of 
  infection 
  methods 
  I 
  would 
  refer 
  to 
  the 
  

   paper 
  by 
  Lefevre 
  and 
  Curtis 
  (1912). 
  Some 
  special 
  difficulties 
  encoun- 
  

   tered 
  in 
  dealing 
  with 
  the 
  short-period 
  breeding 
  Quadrulas 
  will 
  be 
  

   discussed 
  in 
  connection 
  with 
  the 
  propagation 
  of 
  Quadrula 
  pustulosa 
  

   and 
  artificial 
  infection 
  of 
  Quadrula 
  ehena. 
  

  

  Glochidia 
  were 
  obtained 
  from 
  gravid 
  mussels 
  collected 
  with 
  the 
  

   "crowfoot" 
  and 
  mussel 
  rake, 
  the 
  usual 
  methods 
  in 
  vogue 
  among 
  

   clammers. 
  The 
  preparation 
  of 
  these 
  was 
  for 
  the 
  most 
  part 
  by 
  the 
  

   method 
  described 
  by 
  Surber 
  (1912). 
  For 
  differentiating 
  the 
  thread 
  

   gland, 
  Grenacher's 
  borax 
  carmine 
  was 
  employed 
  as 
  a 
  stain. 
  Exami- 
  

   nations 
  in 
  alcohol 
  covered 
  to 
  prevent 
  evaporation 
  gave 
  better 
  differ- 
  

   entiation 
  for 
  some 
  features 
  than 
  the 
  stained 
  and 
  cleared 
  material. 
  

  

  The 
  collection 
  of 
  juveniles 
  has 
  been 
  carried 
  on 
  chiefly 
  by 
  two 
  

   methods 
  — 
  dredging 
  and 
  hand 
  or 
  shore 
  collecting. 
  The 
  dredge 
  em- 
  

   ployed 
  was 
  of 
  the 
  Chester 
  rake 
  pattern 
  and 
  of 
  suitable 
  dimensions 
  

   for 
  use 
  with 
  a 
  gasoline 
  launch. 
  This 
  method 
  is 
  adapted 
  for 
  deep 
  water 
  

   or 
  for 
  shallow 
  water 
  that 
  is 
  so 
  muddy 
  as 
  to 
  make 
  it 
  impossible 
  to 
  see 
  

   the 
  bottom. 
  As 
  the 
  Mississippi 
  has 
  been 
  almost 
  constantly 
  muddy 
  

   during 
  the 
  warmer 
  months 
  this 
  method 
  has 
  proved 
  to 
  be 
  the 
  chief 
  

   reliance. 
  The 
  small 
  shells 
  are 
  separated 
  from 
  sand 
  and 
  mud 
  by 
  

   means 
  of 
  a 
  sieve 
  or 
  by 
  washing 
  in 
  a 
  fine-meshed 
  bag. 
  Hand 
  collect- 
  

   ing 
  was 
  about 
  the 
  only 
  method 
  apphcable 
  to 
  very 
  shallow 
  water 
  and 
  

   stony 
  bottom, 
  and 
  was 
  employed 
  during 
  winter 
  or 
  on 
  very 
  rare 
  occa- 
  

   sions 
  in 
  summer 
  when 
  the 
  water 
  was 
  sufficiently 
  clear. 
  

  

  