Kovalevskii, Aleksandr Onufrievich

Born Nov. 7 (19), 1840, in Varkavaskaia Volost, now in Preiji Raion, Latvian SSR; died Nov. 9 (22), 1901, in St. Petersburg. Russian biologist; one of the founders of evolutionary embryology and physiology. Academician of the St. Petersburg Academy of Sciences (1890). Brother of V. O. Kovalevskii.

In 1863, A. O. Kovalevskii graduated from the University of St. Petersburg, where he defended his master’s and doctoral dissertations in 1865 and 1867, respectively. He was a professor at the University of Kazan (from 1868), the University of Kiev (from 1869), Novorossiia University in Odessa (from 1874), and the University of St. Petersburg (from 1891 to 1894). From 1892 to 1901 he was director of the Sevastopol’ Biological Station. By his studies on the embryonal development of lower vertebrates (lancelets) and invertebrates (ascidians, holothurians, worms, arthropods) Kovalevskii not only showed the common patterns of development characterizing vertebrates and invertebrates, extending the theory of germ layers to invertebrates, but also demonstrated the mutual evolutionary relationship existing between these groups of animals. He made a comparative study of the structure and functions of the secretory system and a comparative study of the phagocytic organs that he discovered in invertebrates and their role in the metamorphosis of insects. The studies of Kovalevskii, I. I. Mechnikov, and E. Haeckel laid the foundation for the phylogenetic trend in embryology that arose at the end of the 19th century.