During his visits in town, Thunberg began to recruit students, mainly the Nagasaki interpreters and local physicians. he taught them new medical treatments, such as using mercury to treat syphilis, and the production of new medicines. During this process, he also instructed his pupils in the Dutch language and European manners, furthering the growing interest into Dutch and European culture by the Japanese, known as "rangaku". Thunberg had brought some seeds of European vegetables with him and showed the Japanese some botanical practices, expanding Japanese horticultural practices.