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
Roger Turner (garden designer) Roger Turner (garden designer) Roger Turner is a British garden designer and writer of gardening-related non-fiction books. He trained as an architect, and now practises as a garden designer in Gloucestershire. He lectures widely on garden subjects, and is the author of several gardening books. Turner has given talks in the UK, Ireland and the US on a wide range of gardening subjects, specialising in perennials of all kinds, garden design and garden history. He trained as an architect and now works as a landscape designer. He is a knowledgeable plantsman, active in the Hardy Plant Society, and a founding