Females, 100 



Fertilization, 101 (see also Repro- 

 duction) 



Finches, 337 



Fins, 281 



Fishes, 19, 20, 281 



Fission, 187 



Fissures (of brain), 363, 364 



Flat-worms, 187, 188 



Flies, 244, 245 



Fly-catcher, 337 



Flying fox, 353 



Flying-lizard, 311 



Flying reptile, 307 



Foods, 77, 396 (see also Diges- 

 tion) 



Frog, 277, 303 



Functions, animal, 73 (see vari- 

 ous Special Functions) 



Fungi, 52 



Hexapoda (see Insects) 

 Homologous, 64 

 Hoofed mammals, 354 

 Human qualities, 360 

 Hydra, 172, 174 



Imago, 262 

 Ingestion, 77 

 Insectivora, 353 

 Insects, 242-252 

 Instincts, 365 



Intercellular substance, 115 

 Invertebrates, 20 

 Irritability, 40, 90 

 Isolation, 392 



