The paper describes the discovery and early studies of the lancelet, "Amphioxus", (Brachiostoma lanceolatus). It became very popular as a scientific object in the 19th century as it was supposed to be a link between vertebrates and invertebrates. Most of the early investigators belonged to the medical profession. In Sweden still a freshmen in a medical school is called "Amphioxus" because once the medical studies started with comparative anatomy and dissection of lancelets. Recent studies of the molecular genetics of the lancelet has renewed the interest in "the little fish" as it seems to be furnished with only one HOX gene and thus may be the sole surviving representative of extinct primitive vertebrates.