From 1914 to 1919, when Hirohito was in middle school, Professor Hattori Hirotarô became his teacher of natural history and physics. Hattori remained his servant in scientific pursuits for more than thirty years, cultivating Hirohito’s childhood fondness for insects and helping him to develop a keen, lifelong interest in marine biology and taxonomy. Under Hattori’s guidance, Hirohito read Darwin’s theory of evolution as interpreted by the popular writer Oka Asajirô, whose book Shinkaron kôwa (Lessons on evolution) was published in 1904. He may also have read a Japanese translation of Darwin’s Origin of Species. Around 1927 he was given a small bust of Darwin, which thereafter adorned his study alongside busts of Abraham Lincoln and Napoleon Bonaparte.
In September 1925, during the fourth year of his regency, Hirohito had a small, well-equipped biological laboratory established within the Akasaka Palace. Three years later, during the second year of his reign, he built … the Imperial Biological Research Institute, consisting of a greenhouse and two large laboratories, each with specimen rooms and libraries. Hattori became associated with this laboratory …. Years later Hattori edited Sagamiwan sango erarui zufu (Pictorial specimens of marine life in Sagami Bay), while Sanada Hiroo and Katô Shirô did the colored drawings, Baba Kikutarô wrote the accompanying explanations. Because the re-formed Imperial Household Agency held the copyright, the book was ascribed to Hirohito. Nowhere in the book, however, did the emperor’s name appear, which raised the question, How much of its research had actually been done by him?
Hirohito himself was always very modest about his interest in biology. When Sagamiwan sango appeared, Hattori offered an assessment of his former pupil’s scientific bent in a discussion that appeared in the Sande Mainichi on October 2, 1949. Asked whether the emperor’s studies should be viewed as genuine scientific research rather than the work of an amateur, Hattori replied:
Recently Professor Satô Tadao [of Nagoya University] wrote in the Nagoya newspaper that it belonged to the category of an amateur’s research. Indeed, depending on how one looks at the matter, I think that is true. He never published anything under his own name and ended up furnishing raw data to various specialists. Therefore, from one point of view he is, in the final analysis, probably a mere collector. But I don’t think so. He did not just hand them material he had collected. Rather, he first thoroughly investigated that material himself, and on that point he is no amateur.
Hattori’s assessment makes sense … Taught by Hattori, the emperor became a naturalist and a patron of marine biology, pursuing as a hobby the collection of sea plants and animals, such as slugs, starfish, hydrozoa, and jellyfish.