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 of weapons such as the musket, meant that recognition and cohesion were more important than camouflage in combat clothing well into the baroque period. The introduction of infantry weapons with longer range, especially the Baker rifle, opened up new roles which needed camouflaged clothing. In the colonial Seven Years' War (1756–1763), the rifle-armed Rogers' Rangers wore gray or green uniforms. John Graves Simcoe, one of the unit's later commanders, noted in 1784: Green is without comparison the best colour for light troops with dark accouterments; and if put on in the spring, by autumn it nearly fades with the leaves,