CONTENTS. 



PREFACE . , 

 LIST OF WOODCUTS 



CHAPTER I. 

 The Natural History of the Common Crayfish ... 1 



CHAPTER II. 



The Physiolog y of the Common Crayfish. The Mechanism 

 by whicn~the parts of the living engine are supplied 

 with hie materials necessary for their maintenance 

 and growth 46 



CHAPTER III. 



The Physiology of the Common Crayfish. The Mechanism 

 by which the Living Organism adjusts itself to sur- 

 rounding CONDITIONS AND REPRODUCES ITSELF ... 87 



CHAPTER IV. 



The Morphology of the Common Crayfish. The structure 



and the development of the individual . . . . 137 



