X Contents part hi 



PART III 



The Forms of Animal Life 



CHAPTER XI 



THE ELEMENTS OF STRUCTURE 



I. The resemblances and contrasts between plants and animals — 2. 

 The relation of the simplest animals to those which are m.ore com- 

 plex — 3. The parts of the animal tody . . Pages 167-183 



CHAPTER XII 



THE LIFE-HISTORY OF ANIMALS 



I. Modes of reproduction — 2. Divergent modes — 3. Historical — 4. The 

 egg-cell or ovum — g. The male-cell or spermatozoon — 6. Matura- 

 tion of the ovum — 7. Fertilisation — 8. Segmentation and the first 

 stages in development — 9. Some generalisations : the ovum 

 theory, the Gastrcea theory, fact of recapitulation, organic con- 

 tinuity ...... 184-203 



CHAPTER XIII 



THE PAST HISTORY OF ANIMALS 



I. The two records — 2. Imperfection of the geological record — 3. 

 PalcBontological series — 4. Extinction of types — 5. Various diffi- 

 culties — 6. Relative antiquity of animals . , 204-209 



CHAPTER XIV 



THE SIMPLEST ANIMALS 



1. The simplest forms of life — 2. Survey of Protozoa — 3. The common 

 Amieta — 4. Structure of the Protozoa — 5. Life of Protozoa — 6. 

 Psychical life of the Protozoa — 7. History of the Protozoa — 8. Rela- 

 tion to the earth — 9. Relation to other forms of life — 10. Relation 

 to Tnan ...... 210-221 



