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
Ljubljana Botanical Garden Ljubljana Botanical Garden The Ljubljana Botanical Garden (), officially the University of Ljubljana Botanical Garden (), is the central Slovenian botanical garden, the oldest botanical garden in Southeastern Europe, and one of the oldest cultural, scientific, and educational organisations in Slovenia. Its headquarters are located in the Rudnik District of Ljubljana, the Slovenian capital, at Ig Street () along the Gruber Canal to the southeast of Castle Hill. The garden started operating under the leadership of Franc Hladnik in 1810, when Ljubljana was the capital of the Illyrian Provinces. It is thus an averagely old European botanical garden. The institution