CONTENTS 



SKX DP;THRMI NATION 208 

 SUMMAR\' 212 



7 THE CLASSIFICATION OF ANIMALS 214 



CLASSIFICATION 2 1 5 



Historical 215 



The Modern System 217 



The Principal Types of Animals 220 



Evolutionary Interpretation of Classification 225 



8 UNICELLULAR ANIMALS: THE PROTOZOA 228 



THE SARCODINA 230 



ITie Amoeba 230 



THE FLAGELLATA 239 



The Euglena 239 

 Other Flagellates 243 



THE SPOROZOA 244 



Malaria and the Malaria Parasite 246 

 THE CILIATA 248 



The Paramecium 248 



Other Ciliates 257 



THE SUCTORIA 258 

 BIOGENESIS 259 



Historical 259 



Final Establishment of Biogenesis 260 

 THE PROTOZOAN CELL 263 



MULTICELLULARITY, AND THE SIMPLEST METAZOAN ANIMALS: 



MESOZOA AND PORIFERA 264 



COLONIAL PROTOZOA 265 

 THE PHYLUM MESOZOA 270 



Structure and Life Cycle 270 



The Body Plan and Life Cycle 272 

 THE PHYLUM PORIFERA 273 



General Structure 274 



The Sponge Body Plan 282 

 EVOLUTIONARY SIGNIFICANCE OF MESOZOA AND PORIFERA 282 



10 RADIAL ANIMALS: THE PHYLA COELENTERATA AND CTENOPHORA 284 



THE PHYLUM COELENTERATA 284 

 THE CLASS HYDROZOA 286 



The Hydra 286 



The Hvdroids and H\dromedusac 301 



