Alexander Kovalevsky

Alexander Kovalevsky
Alexander Kovalevsky
Born	7 November 1840 Vārkava, Vitebsk Governorate
Died	1901
Citizenship	Russian
Nationality	Polish
Fields	Embryology
Alma mater	University of Heidelberg
Known for	Gastrulation

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.

Kowalevsky showed that all animals go through a period of gastrulation.

Kovalevsky discovered that tunicates were not molluscs, but that their larval stage had a 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.