Chameleon turquoise, and purple. Chameleon skin has a superficial layer which contains pigments, and under the layer are cells with guanine crystals. Chameleons change colour by changing the space between the guanine crystals, which changes the wavelength of light reflected off the crystals which changes the colour of the skin. Colour change in chameleons has functions in camouflage, but most commonly in social signaling and in reactions to temperature and other conditions. The relative importance of these functions varies with the circumstances, as well as the species. Colour change signals a chameleon's physiological condition and intentions to other chameleons. Chameleons tend
Military camouflage mimetico in Italy and the angular Splittermuster 31 in Germany. During the War, both patterns were used for paratrooper uniforms for their respective countries. The British soon followed suit with a brush-stroke type pattern for their paratrooper's Denison smock, and the Soviets introduced an "amoeba" pattern overgarment for their snipers. Hugh Cott's 1940 book "Adaptive Coloration in Animals" systematically covered the different forms of camouflage and mimicry by which animals protect themselves, and explicitly drew comparisons throughout with military camouflage: Both British and Soviet aircraft were given wave-type camouflage paintwork for their upper surfaces throughout the war, while American ones