CHAPTER VII.

THE SENSES OF ANIMALS.

The primary object of sensation 243 Organic sensations and the muscular sense 244 Touch 245 The temperature-sense 249 Taste 250 Smell 257 Hearing 261 Sense of rotation or acceleration 269 Sight 273 Restatement of theory of colour-vision 278 Variation in the limits of colour-vision 281 The four types of "visual" organs 293 Problematical senses 294 Permanent possibilities of sensation 298