NAVASHIN, SERGEY GAVRILOVICH

(b. Tsarevshin, Saratov guberniya, Russia, 14 December 1857; d. Detskoye Selo [now Pushkin], U.S.S.R., 10 December 1930)

biology, plant cytology, plant embryology.

The son of a physician, Navashin graduated from the Saratov Gymnasium in 1874 and entered the St. Petersburg Academy of Medicine and Surgery although medicine did not especially interest him. His courses in chemistry with Borodin led to a strong interest in the subject. After four years Navashin transferred to the University of Moscow and entered second-year courses in the natural sciences section of the department of physics and mathematics. He was especially enthusiastic about his courses in chemistry with Markovnikov and in botany with Timiryazev. After his graduation from the university, Markovnikov offered Navashin an assistantship, first at Moscow University (1881) and then at the Petrov Academy (1884). After he passed his master’s examination in 1887 Navashin began to teach courses: “Introduction to the Taxonomy of Fungi” at the university and plant pathology at the Petrov Academy. After the dissolution of the Petrov Academy in 1888, he became Borodin’s assistant at the University of St. Petersburg. His interest in mycology drew Navashin to the mycologist Voronin, who suggested a study of the fungus Sclerotiniabetulae (Woroninaceae), a parasite of the birch tree, for the subject of his master’s thesis, which he defended in 1894 at St. Petersburg. After receiving the master’s degree in botany, Navashin became professor of botany at the University of Kiev, where he accomplished his most fruitful scientific research and teaching. In 1915 serious illness obliged him to leave Kiev for the warmer climate of Tbilisi, where he devoted much energy to the university. Invited to Moscow in 1923 to organize the K. A. Timiryazev Institute of Plant Physiology, he was its director until 1929, the year before his death.

Navashin’s basic research was devoted to the morphology and taxonomy of mosses and parasitic fungi. The study of the development of Sclerotinia in the ovaries of birches (1894) led him in 1895 to the discovery of chalazogamy in birches and, in 1899, in alders, elms, and other trees. Chalazogamy is a process of fertilization in which the pollen tubes penetrate to the embryo sac not through the micropyle but through its base, the chalaza. The phenomenon had previously been observed in the beefwood (Casuarina), only by Melchior Treub (1891), who considered it a distinguishing feature of these flowering plants. Navashin’s observations introduced a correction into Treub’s division of angiosperms into chalaziferous and porogamic.

Navashin’s embryological research led him to the important discovery in 1898 of double fertilization in angiosperms. Observing fertilization in the Turk’s- cap lily (Lilium martagon) and Fritillaria tenella, he was the first to note that this process involves not one but two sperm, which form in the pollen tube. One of them merges with the ovicell; the other, with the nucleus of the embryo sac, so that both the embryo and the endosperm develop as a result of the sexual process. On 24 August 1898 Navashin communicated this discovery to the Tenth Congress of Natural Scientists and Physicians, held in Kiev; later that year a description of the phenomenon appeared in print. The important discovery of double fertilization immediately attracted international attention; several scientists had already observed this phenomenon but had not given it proper attention. The presence of double fertilization made possible discovery of the fact that the endosperms of angiosperms and gymnosperms are not homologous formations but are completely distinct in nature and origin, despite the external similarity caused by their identical functions.

The last period of Navashin’s life was dedicated to research in karyology. His work contributed to the comparative karyological trend in cytology, which was especially intensively developed in the Soviet Union. The success of Navashin’s research was determined in substantial measure by his outstanding abilities as a microscope technician and observer.

For his research in embryology and plant cytology Navashin was made a corresponding member (1901) and an academician (1918) of the Russian Academy of Sciences, and an active member of the Ukrainian S.S.R. Academy of Sciences (1924). In 1929 he was awarded the title of Honored Scientist of the R.S.F.S.R.

BIBLIOGRAPHY

I. Original Works. Navashin’s collected works were published as Izbrannye trudy (Moscow-Leningrad, 1951). His writings include “Sklerotinia berezy (Sclerotinia betulae Woroninaceae)” (“Sclerotinia of Birches”), in Trudy Sankt-Peterburskago obshchestva estestvoispytatelei, Otd. botanichesky, 23 (1893), 56–64; “Ein neues Beispiel der Chalazogamie,” in Botanisches Zentralblatt, 63 , no. 12 (1895), 353–357; “Resultate einer Revision der Befruchtungsvorgänge bei Lilium martagon und Fritillaria tenella,” in Mélanges biohgiques tirés du Bulletin de l’Académie des sciences de Pétersbourg, 9 , no. 9 (Nov. 1898), 377–382; “Neue Beobachtungen über Befruchtung bei Fritillaria tenella und Lilium martagon,” in Botanisches Zentralblatt, 77 (1899), 62; and “Getero- i idiokhromozomy rastitelnogo yadra kak prichina dimorfizma nekotorykh vidov rastenii” (“Hetero- and Idiochromosomes in the Plant Nucleus as the Reason for Dimorphism in Certain Plant Species”), in Izvestiya Akademii nauk, no. 17 (1915), 1812–1834.

II. Secondary Literature. On Navashin and his work, see his autobiography, in Izbrannye trudy, 13–20, with illustrations and portrait; V. V. Finn, “K 50-letiyu otkrytia S. G. Navashinym dvoynogo oplodotvorenia y pokrytosemennykh rastenii” (“On the Fiftieth Anniversary of Navashin’s Discovery of Double Fertilization in Angiosperms”), in Priroda, no. 9 (1948), 80–81; and D. A. Granovsky, Sergey Gavrilovich Navashin (Moscow, 1947), with illustrations, portrait, and bibliography of nineteen works on Navashin.

E. M. Senchenkova