194 



Ferns, 171 



Fishes, history of, no 



Fossils, value of, 3 



Gastraea, 70 ; formation of, 76 ; 



modification of, 78 ; significance 



of, 72 



Gastrula, typical, 72 

 Geological ages, 88 

 C Granules, 54 

 Growth, 23 

 Gymnosperms, 171 



Haeckel, 72 



Hard parts, development of, 142 



Hydra, figure of, 74 



Influence of man on animals, 186 

 Insects, 147 ; history of, 108 

 Instinct, 146 

 Intelligence, 147 

 Intermediate types, 122 



Jurassic age, 91 



Law of continuity, 14, 47 

 Life, essential characters of, 17 

 Limitation of differentiation, 82 

 Limit of organic development, 180 

 Love, among animals, 152 ; among 



men, 153 



Low forms of life, 13 

 Lycopods, 171 



Mammals, expension of, 134 ; his- 

 tory of, 112 



Man, 147 ; capability of develop- 

 ment, 187 ; classification of, 150 



Mechanical, origin of life, 40 ; 

 theory of life, 30 



Mental factor, 145 



Mesozoic, 91, 114 

 Metamorphosis, 5 

 Modern fauna, paucity of, 162 ; 



flora, 172 



Mollusca, history of, 104 

 Molluscoidea, history of, 103 

 Multicellular animals, origin of, 



67 



New fields for expansion, 132 ; 



lines of specialization, 183 

 Nucleus, 61, 64 



Ocean as starting-point of life, 55 

 i Organism as a machine, 26 

 \ Origin of life, 33 



I Paleozoic, 90, 114 

 Permian age, 91 

 Persistent species, 118 

 Physical basis of life, 51 

 Physiological chemistry, 12 

 Plants and animals, 45 ; history 



compared, 184 

 Plants, as fossils, 170 ; history of, 



ID?, 173 



Properties of compounds, 31 

 Protophyta, 62 

 Protoplasm, 43, 51 ; chemistry of, 



52, 64 ; structure of, 52 

 Protozoa, 62 ; history of, 99 



Quaternary age, 92 



Rapidity of early development, 81, 



178 



Redi, 35 



Reproduction, 24 

 Reptiles, history of, no 

 Rhizocarps, 171 



