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
Aircraft camouflage were also painted in the same colour. At the same time, disruptive schemes using several colours were also tried out. By mid-1916 a silver-grey aluminium dope became the norm for Nieuports until the French introduced a standardized disruptive camouflage scheme for combat aircraft in 1917. This was used widely on such aircraft as the Breguet XIV and SPAD XIII that consisted of dark and light green, dark and light brown, black (sometimes omitted) and an underside of grey or beige. In mid-1916, the Germans experimented with a transparent cellon covering on several aircraft, including a Fokker E.III, that rendered the