PREFACE vii 



expression of my thanks to my wife were out of place 

 here, I beg leave to give myself the pleasure of 

 acknowledging how great has been her share in 

 this work. 



The original memoirs, giving detailed accounts of 

 the life histories of the plant-animals, have appeared 

 in the Quarterly Journal of Microscopic Science. A 

 list of these memoirs and of other researches to which 

 reference is made in the text is included in the short 

 bibliography appended to this volume. The dates, 

 enclosed within brackets in sundry places in the text, 

 refer each, to the year of publication of the research 

 which is cited and indicate that the title of the re- 

 search in question may be found in the bibliography 

 under that date. 



The black and white illustrations have been pre- 

 pared specially for this volume by Mrs Seward from 

 the original drawings made by Miss Dorothea 

 Richardson in the laboratory at Tregastel. I am 

 deeply indebted to Mrs Seward and Miss Richardson 

 for their kind assistance, and to the skill and patience 

 which they have bestowed on the drawings I offer 

 a sincere and admiring tribute. 



Should the reader find that the main arguments 

 exposed in the course of the volume are intelligible, 

 he may, perhaps, be inclined to forgive the use, 

 which I hope is as occasional as inadvertent, of un- 



