CHAPTER VIII. Auxiliary Senses

AUXILIARY SENSES

The color-changing sense and "homing instinct" so-called--These faculties not instincts but true senses--The chromatic function --Tinctumutation--Chromatophores and their function--Various theories--Experiments of Paul Bert with axolotls--Semper's contention--The difference between plant coloring and animal coloring--Effects of light--Experiments with newts--Lister's observations--Pouchet's experiments--Sympathetic nerves--Author's experiments with frogs--The sense-centre of tinctumutation--Effects of atropia--Experiments with fish--With katydid--The "homing instinct" a true sense--Evidences of the sense in a water-louse--Author's experiments with snails--Location of sense-centre in snails--Evidences of the homing sense in the limpet--In beetles--In fleas--In ants--In snakes--In birds--In fish. 181