A Porphyrin Pigment in the Integument of Arion a Ter (l.)

MacMunn (1886) extracted a porphyrin from the integument of the starfish Asterias rubens-then known as Uraster rubens-and he considered that this and similar pigments which he had obtained from the slug Arion empiricorum and the coelenterates Flabellum variabile and Fungia symmetrica were identical with the haematoporphyrin of Hoppe-Seyler (1871), which was then the only porphyrin known. Dhere & Baumeler (1928a) confirmed the presence of a porphyrin in Arion empiricorum, but did not specify which porphyrin they had found. Kennedy & Vevers (1953), working at the Plymouth Laboratory of the Marine Biological Association, found that the pigment of the integument of Asterias rubens L. was protoporphyrin, and in a further survey of the porphyrins of marine invertebrates (Kennedy & Vevers, 1954), they examined the integuments of two molluscs, Aplysia punctata Cuvier and Duvaucelia plebeia (Johnston), and showed that each contained uroporphyrin I. This pigment was also found by Kennedy & Vevers (1956) to be present in the integument of the tectibranch mollusc Akera bullata (0. F. Muller). The present paper describes the isolation and identification of the po··phyrin from the integument of the black garden slug Arion ater (L.). Arion empiricorum was a synonym introduced by Ferussac, Ferussac & Deshayes (1819-51) to cover the numerous colour and pattern varieties of the slug more generally known as Arion ater. The work appears here since it is a continuation of investigations of mollusc pigments initiated in the Plymouth Laboratory, the results of which have already been published in this Journal.