Alexander Kovalevsky

Alexander Onufrievich Kovalevsky (Polish: Aleksander Kowalewski, 7 November 1840 in Vārkava, Vitebsk Governorate (present-day Vārkava Municipality, Latvia) – 1901), also written Alexander Kowalevsky, was a Russian embryologist of Polish descent, who studied medicine at the University of Heidelberg and became professor at St Petersburg.^[1][2][3][4]

Discoveries

A. Lancelet (a chordate), B. Larval tunicate, C. Adult tunicate. Kovalevsky saw that the notochord (1) and gill slit (5) are features shared by tunicates and vertebrates.

Kowalewski showed that all animals go through a period of gastrulation.^[1][2][3][4]

Kovalevsky discovered that tunicates were not molluscs, but that their larval stage had a notochord and pharyngeal slits, like vertebrates. Further, these structures developed from the same germ layers in the embryo as the equivalent structures in vertebrates, so he argued that the tunicates should be grouped with the vertebrates as chordates. 19th century zoology thus converted embryology into an evolutionary science, connecting phylogeny with homologies between the germ layers of embryos, foreshadowing evolutionary developmental biology.^[5]

Antoine Fortuné Marion and Alexander Kovalevsky, founder and collaborator of the Annals of Natural History Museum of Marseille

Bibliography

• Kowalevsky A. (1901). "Les Hedylidés, étude anatomique". Zapiski Imperatorskoi Akademii Nauk 12: 1–32.

References