CONTEXTS 



XI 



CHAPTER 



XII. 



XIII. 



XIV. 



XV. 



XVI. 



XVII. 



XVIII. 



PAGE 



RESPIRATION 161 



A. Lungs . 162 



R. Respiratory Mechanism 164 



C. Respiratory Interchange 166 



CIRCULATION 168 



A. Circulation in the Lower Vertebrates 171 



R. Circulation in the Higher Vertebrates .... 174 



EXCRETION 180 



A. Gills and Lungs 181 



R. Skin 181 



C. Liver 182 



D. Kidneys 182 



1. Urine 182 



2. Evolution of Kidneys 183 



REPRODUCTION .. . • 188 



A. Invertebrates 188 



R. Vertebrates 189 



1. Uterine Development 191 



2. Hormones 192 



3. Urogenital System 193 



COORDINATION 196 



A. Chemical Coordination 196 



R. Coordination by the Nervous System 198 



1. Rrain and Spinal Cord 200 



2. Cranial and Spinal Nerves 205 



3. Autonomic System 208 



C. Sense Organs 209 



1. Cutaneous Senses 210 



2. Sense of Taste 211 



3. Sense of Smell 211 



4. Ear 212 



5. Eye 213 



ORIGIN OF LIFE 218 



A. Riogenesis and Abiogenesis 218 



R. Origin of Life on the Earth 221 



1. Cosmozoa Theory 223 



2. Pfliiger's Theory 224 



3. Moore's Theory 225 



4. Allen's Theory 225 



5. Troland's Theory 226 



6. Osborn's Theory 226 



7. Huxley's Statement 227 



CONTINUITY OF LIFE 229 



A. Reproduction 229 



R. Origin of the Germ Cells 238 



1. Mitosis 239 



2. Chromosomes of the Germ Cells 243 



