CHAPTER XI.

INSTINCTS, HABITS, AND ADAPTATIONS.

The Habits of Fishes.--Irritability of Animals.--Nerve-cells and Fibers.--The Brain or Sensorium.--Reflex Action.--Instinct.--Classification of Instincts.--Variability of Instincts.--Adaptations to Environment.--Flight of Fishes.--Quiescent Fishes.--Migratory Fishes.--Anadromous Fishes.--Pugnacity of Fishes.--Fear and Anger in Fishes.--Calling the Fishes.--Sounds of Fishes.--Lurking Fishes.--The Unsymmetrical Eyes of the Flounder.--Carrying Eggs in the Mouth. 152