Malachite green metabolized into LMG. Only the cation MG is deeply colored, whereas the leuco and alcohol derivatives are not. This difference arises because only the cationic form has extended pi-delocalization, which allows the molecule to absorb visible light. The leuco form of malachite green was first prepared by Hermann Fischer in 1877 by condensing benzaldehyde and dimethylaniline in the molecular ratio 1:2 in the presence of sulfuric acid. Malachite green is traditionally used as a dye. Kilotonnes of MG and related triarylmethane dyes are produced annually for this purpose. MG is active against the oomycete "Saprolegnia", which infects fish eggs in
Italian submarine Malachite Spezia. In 1937 she undertook a training campaign near the Greek coast, in the Dodecanese and around Tobruk. During the Spanish Civil War, the submarine conducted a special mission between 24 August and 4 September 1937, and on August 29 she was subject to a anti-submarine search and attack. Between 1938 and 1940 "Malachite" was training and exercising for long periods around Tobruk. Upon her return to Italy, she was assigned to 47th Squadron (IV Submarine Group) based at Taranto. At the time of Italy's entrance into World War II, "Malachite" was reassigned to the X Submarine Group based at