Bombyx mori 300 to about 900 m (1,000 to 3,000 ft) long. The fibers are very fine and lustrous, about 10 μm (0.0004 in) in diameter. About 2,000 to 3,000 cocoons are required to make a pound of silk (0.4 kg). At least 70 million pounds of raw silk are produced each year, requiring nearly 10 billion cocoons. Due to its small size and ease of culture, the silkworm has become a model organism in the study of lepidopteran and arthropod biology. Fundamental findings on pheromones, hormones, brain structures, and physiology have been made with the silkworm. One example of this was
Mori Ōgai case. Mori Ōgai discovered the cause of the beriberi disease and managed to create a foundation to build a remedy, but the problem was only resolved after his death. He was appointed director of the Imperial Museum when he retired in 1916. Mori Ōgai then died of renal failure and pulmonary tuberculosis six years later, aged 60. Although Mori did little writing from 1892 to 1902, he continued to edit a literary journal ("Mezamashi gusa", 1892–1909). He also produced translations of the works of Goethe, Schiller, Ibsen, Hans Christian Andersen, and Hauptmann. It was during the Russo-Japanese War (1904–05) that