X Contents part m 



PART III 



The Forms of Animal Life 



CHAPTER XI 



THE ELEMENTS OF STRUCTURE 



E. 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 body , . Pages 167-183 



CHAPTER XII 



THE LIFE-HISTORY OF ANIMALS 



t. Modes cf reproduction — -2. Divergent modes — 3. Historical — 4. The 

 egg-cell or ovum — 5. The male-cell or spermatozoon — 6. Matura- 

 tion of the ovum — 7. Fertilisation—^. 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 



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

 Palceontological series — 4. Extinction of types — S- Various diffi- 

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



CHAPTER XIV 



THE SIMPLEST ANIMALS 



I. The simplest forms of life — 2. Survey of Prototsoa — 3. The common 

 Amceba — 4. Structure of the Protozoa — S- ^if^ 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 man ...... 210-221 



