The central nervous system of a medicinal leech

• Biologische Untersuchungen. Neue Folge. Vols. I-XIX. -
• Author: RETZIUS, Gustaf (1842–1919)
• Many of Retzius’ sumptous monographs are illustrated with excellent plates made by himself. Most of his papers were published in his own journal, Biologische Untersuchungen, in which Retzius alone was responsible for the cost, was the sole contributor, and usually the craftsman as well. The truly monumental volumes contain thousands of illustrations on more than 500 plates.