Reproduction in the protozoa 

 Fission in the metazoa 

 The regeneration of lost parts 

 Reproduction by budding 

 Sexual reproduction 

 Illustration of development . 

 Parental sacrifice 

 The law of increase . . 



CONTENTS. 



CHAPTER I. 



THE NATURE OP ANIMAL LIFE, 



PAGE 



The characteristics of animals . . . . . . . . . . 2 



The relation of animals to food-stuffs . . . . . . . . 15 



„ „ „ the atmosphere . . . . . . . . 15 



„ energy .. .. ., .. 16 



CHAPTER II. 



THE PROCESS OF LIFE. 



Illustration from respiration . . . . . . . . . . 21 



., „ nutrition . . . , . . . . . . 25 



The utilization of the materials incorporated . . . . . , 27 



The analogy of a gas-engine. Explosive metabolism . . . . 30 



CHAPTER III. 



REPRODUCTION AND DEVELOPMENT, 



37 

 41 

 41 



42 

 42 

 51 

 56 

 58 



CHAPTER IV. 



VARIATION AND NATURAL SELECTION. 



The law of persistence . . . . . . , . , . . . 61 



The occurrence of variations . . ». ,. ,. ., 63 



Application of the law of increase . . . . , . . . 76 



Natural selection . . . . . , , , . . . , 77 



