Udagawa Yoan

1798–1846

Rangaku (Western studies) scholar of the late Edo period (approx. 1750–1850). Born in Edo. His father Ezawa Yoju was a physician and Rangaku scholar in the service of the Ogaki Domain. His childhood name was Shigejiro. In 1811, he became the adoptive heir of Udagawa Genshin, a physician practicing Western medicine in the service of the Tsuyama Domain, and took the name Yoan upon coming of age the following year. Along with traditional Chinese medicine, he familiarized himself with honzogaku (herbalism, or the study of plants, minerals, and animals for use in Chinese medicine) and bussan-gaku (the study of material goods), at which he excelled, and he studied the Dutch language under Baba Sajuro and Yoshio Shunzo. Entering into the service of the Tsuyama Domain as a physician in 1817, he changed his name to a different form of Yoan, using the characters 榕菴 rather than 養菴. Around this time, he read Kosei Shinpen (“New Volumes for the Public Welfare”), a translation of Noël Chomel's encyclopedia into Japanese. Coming to learn that in Western scholarship there was a field of study called botany (shokubutsugaku in Japanese, referred to as “shokugaku” by Yoan with a term he coined himself), which involved studying plants themselves in a way distinct from the approach of Chinese honzogaku herbalism, his interest in fields including pharmacology, medical science, botany, zoology, and chemistry deepened further.

In 1822, he authored the first Japanese botanical work, Botanika Kyo (“Sutra of Botany”), introducing Western botanical science to Japan. He also collaborated in the publication of pharmacological works by his adoptive father Udagawa Genshin, Ensei Iho Meibutsu Ko (“A Reference on the Specialty Products of Far Western Medicine,” 1822–1825) and Oranda Yakukyo (“Mirror of Dutch Medicine,” 1828–1830).

In 1826, he became an official translator of Western books into Japanese for the bakufu shogunate, participating in the translation of Noël Chomel's encyclopedia, a project that would last until the end of his life. Also, the same year, he interacted with Philipp Franz von Siebold who was visiting Edo, calling on him at his place of lodging. He presented Siebold with botanical specimens, hand-drawn illustrations of flora, Japanese books, and more, and some of the botanical illustrations were used as the original drawings for Siebold’s Flora Japonica, translated as Nihon Shokubutsu-shi.

Subsequently, he continued to devote himself to the study of fields including pharmacology, botany, and chemistry, conducting his own experiments in addition to translating Western science texts. His published works include Shokugaku Keigen (“Introduction to Botany”; 1834), Ensei Iho Meibutsu Ko Hoi (“A Reference on the Specialty Products of Far Western Medicine Addendum,” 1834), and Seimi Kaiso (“Introduction to Chemistry,” 1837–1847). His Shokugaku Keigen is highly appraised as an authentic text of Western botany, and Seimi Kaiso as the first Japanese text covering chemistry in a systematic manner.

Also well versed in fields including mathematics, land surveying, and military science, he left a considerable mark on the history of Japanese science as the person responsible for introducing a number of fields of study, including chemistry, to Japan. Having no biological children, he accepted Kosai, the son of Iinuma Yokusai, a honzogaku herbalism scholar as well as physician for the Ogaki Domain, as his heir. On August 13, 1846, he died at the age of 49. While he was buried at Choan-in at Seigan-ji Temple in Asakusa, he was later reburied at the Tama Cemetery.