﻿CONTENTS. 
  

  

  ■Page. 
  

  

  Introduction 
  & 
  

  

  Methods 
  and 
  techniqiip 
  of 
  expcrur 
  ents 
  6 
  

  

  Details 
  of 
  observation? 
  8 
  

  

  Warty-back 
  & 
  

  

  Pimple-back 
  15 
  

  

  Purple 
  warty-back 
  16 
  

  

  Maple-leaf 
  16 
  

  

  Monkey-face 
  1"/ 
  

  

  Niggerhead 
  17 
  

  

  Quadrula 
  solida 
  23 
  

  

  Pig-toe 
  23 
  

  

  Blue-point 
  25 
  

  

  Washboard 
  28 
  

  

  General 
  discussion 
  35 
  

  

  Reproduction 
  and 
  embryonic 
  stages 
  35 
  

  

  Parasitism 
  36 
  

  

  Restricted 
  infection 
  36 
  

  

  Susceptibility 
  and 
  immunity 
  36 
  

  

  Induced 
  susceptibility 
  38 
  

  

  Frequency 
  of 
  infections 
  39 
  

  

  Extent 
  of 
  individual 
  infections 
  39 
  

  

  Conditions 
  of 
  infection 
  in 
  nature 
  39 
  

  

  Type 
  of 
  infection 
  40 
  

  

  Type 
  of 
  cysts 
  41 
  

  

  Seasons 
  of 
  infection 
  41 
  

  

  Metamorphosis 
  during 
  the 
  iiarasitic 
  stA^e 
  42 
  

  

  Duration 
  of 
  the 
  parasitic 
  period 
  43 
  

  

  Larval 
  thread 
  43 
  

  

  Absence 
  of 
  parasitism 
  44 
  

  

  Juvenile 
  stage 
  45 
  

  

  Bibliography 
  48 
  

  

  Description 
  of 
  figures 
  51 
  

  

  3 
  

  

  