CONTENTS xv 







CHAPTER PAOE 



Nature of Organic Response 246 



Electric Response 247 



Individual Response to Unsymmetrical Stimuli . 248 



Adaptive Response 253 



Immunity 255 



Morphogenetic Response 256 



Non-adaptive Morphogenetic Response . . 257 



Influence of Food 258 



General Adaptation 259 



Some Types of Adaptation 260 



Aquatic Organisms 260 



Aerial Adaptations 262 



Subterranean Adaptations . . . .263 



Protective Adaptations 266 



Protective Coloration . . . .267 



Specific Resemblance .... 268 



Aggressive Resemblance .... 269 



Mimicry 269 



The Care of the Young .... 272 



Environmental Adaptations of Plants . . . 274 



Adaptations for Seed Dispersal . . .278 



Associations of Animals ....... 279 



Commensalism ........ 280 



Parasitism in Protozoa 283 



Parasitism in Worms 285 



Parasitism in Insects 287 



Sacculina 289 



Associations among Plants 290 



Lichens . .291 



Parasitism in Plants 292 



Associations of Plants and Animals .... 293 



Grafts . 294 



IX. SPECIES AND THEIR ORIGIN 296 



Meaning of Species 296 



Polymorphism 301 



Elementary Species and Linnsean Species . . 305 



