Spider are apparently absent. In some species, the exocuticle of the legs and prosoma is modified by a tanning process, resulting in brown coloration. Bilins are found, for example, in "Micrommata virescens", resulting in its green color. Guanine is responsible for the white markings of the European garden spider "Araneus diadematus". It is in many species accumulated in specialized cells called guanocytes. In genera such as "Tetragnatha", "Leucauge", "Argyrodes" or "Theridiosoma", guanine creates their silvery appearance. While guanine is originally an end-product of protein metabolism, its excretion can be blocked in spiders, leading to an increase in its storage. Structural colors
Timothy Garden, Baron Garden defence capabilities, Defence Diplomacy, interoperability for NATO forces and counter-terrorism. He appeared as the military advisor on the BBC television series "Crisis Command". Garden wrote widely on security topics, and his publications include two books: "Can Deterrence Last?" and "The Technology Trap", both written while he was a serving RAF officer. He wrote for a number of security-related projects, including developments in NATO, European defence, missile defence proposals and global security issues. He served as a member of the panel of experts for the UK government's 1998 Strategic Defence Review, and gave evidence to the Defence Committee on the new