CHROMATOPHORES

Abstract

Summary.Chromatophores, the parts concerned with the colour changes in animals, are best developed in the cephalopods, the crustaceans, and the three lower classes of vertebrates, the fishes, amphibians, and reptiles. In the cephalopods chromato‐ phores are really diminutive organs in that each one consists of a central coloured cell which is expanded against its own elasticity by radial muscle fibres. In the crustaceans a cellular complex often with several colours makes up each chromato‐ phore. This expands and contracts slowly and thus changes the tint of the animal. In the vertebrates a coloured background in the skin is exposed to view or covered up by motile black pigment cells whose melanin granules are made to migrate within the containing cell. Most animals show relatively uniform changes of colour, but in a few, as, for instance, flat‐fishes, a pattern may be imitated showing that the central control of the chromatophore system must be somewhat differentiated in the direction in which the musculature is.