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
Botanical garden (Royal Botanic Garden Edinburgh, 1670); and in France ("Jardin des plantes de Montpellier", 1593; Faculty of Medicine Garden, Paris, 1597; "Jardin des Plantes", Paris, 1635), Denmark (University of Copenhagen Botanical Garden, 1600); Sweden (Uppsala University, 1655). During the 16th and 17th centuries, the first plants were being imported to these major Western European gardens from Eastern Europe and nearby Asia (which provided many bulbs), and these found a place in the new gardens, where they could be conveniently studied by the plant experts of the day. For example, Asian introductions were described by Carolus Clusius (1526–1609), who was director, in