xii CONTENTS 



CHAPTER VII 



PAGE 

 POLYTOMA ... . 122 



CHAPTER VIII 

 MONOCYSTIS .... 125 



CHAPTER IX 

 Paramecium and Vorticella. Protozoa . . . 129 



CHAPTER X 

 The Protozoa as Parasites of Man . 144 



CHAPTER XI 

 Hydra and Obelia. Polyps and Medus.*. Individuality 161 



CHAPTER XII 

 Reproduction and Sex ... .189 



CHAPTER XIII 

 Platyhelminthes .... . 201 



CHAPTER XIV 

 The Earthworm, Nereis, and the Leech. Annelida 214 



