Schmidt was born at Jaegerspris in Denmark and became director of the Carlsberg Physiological Laboratory, Copenhagen. He is chiefly known for his discovery of the breeding ground and life history of the European eel in 1904. Schmidt attained this end by a careful compilation of statistics of the length of eel larvae (leptocephali) found at different points and at different times in the Atlantic. From these he was able to link together leptocephali of similar size, radiating from a central area, the smaller and younger nearer the center. The center of radiation, and the breeding ground of all European eels, proved to be the Sargasso Sea, near Bermuda. Schmidt also carried out research and produced publications on bacteria and the flora of the island of Ko Chang, Thailand.