(December 1857 – December 1930)

Sergey Gavrilovich Navashin was born in Tsarevshchina village (Saratov province, Russia) in December 1857 in the family of physician. In 1874, after finishing gymnasium in Saratov, S.G. Navashin entered Medico-Surgical Academy in St Petersburg. However in the Academy he was interested mainly in organic chemistry, which was read by Professor I.P. Borodin. At the 4th year of study S.G. Navashin realized that medicine is not the sphere of knowledge and activity which he wanted to devote himself to. In this connexion he entered the second course of Natural Sciences Faculty of Moscow University, where he continued to specialize in chemistry. Profound knowledge of S.G. Navashin in this field was noticed by K.A. Timiriazev, which read lectures on plant physiology at the University. When S.G. Navashin graduated from the University, K.A. Timiriazev invited him to work as junior teaching staff at the University, and consequently at Petrovskaya (now Timiriazevskaya) Academy. Lecturing on plant physiology, besides of knowledge of chemistry, required the profound grounding in botany. So, S.G. Navashin began to educate himself in this field in the course of numerous excursions, collecting and defining higher plants of Moscow outskirts. As a result, the final master examination, which S.G. Navashin passed successfully at St Petersburg University, was on botany. It allowed S.G. Navashin to read courses as senior lecturer. The both courses of lectures, which he read, were bound with mycology and phytopathology: at the University he gave the introduction to fungi systematics, and in Petrovskaya Academy - plant pathology (1887-1888 academic year). He considered necessary to give the concept overview about fungi systematics not only to students of the University, but also to future agronomists. In introductory lecture to the course of plant pathology "The notion on plant diseases and their causes" S.G. Navashin wrote: "The only possible way of material statement lies in describing of parasitic fungi in the same order, which is given for fungi systematics. Fortunately, almost all groups of fungi contain important parasites. Thus, the course on plant diseases will not represent the fragmentary descriptions of forms, but give the complete systematics of the whole class" (1951, P. 55). At the same time S.G. Navashin began his first mycological investigations. At first they were as if "by-product" of studying of mosses. Investigating heterospory in sphagnous moss S.G. Navashin proved that filiform structures in so-called 'female flower" of Sphagnum species are hyphae of the new fungus species Helotium shimperi (Discomycetes). In that way he disproved the false point of view of German bryologist V.F. Shimper, which regarded that filiforms as characteristic structures of Sphagnum species. The new discomycetes species S.G. Navashin named after this scientist, who for the first time observed filiform structures in Sphagnum species. Continuing investigation of heterospory in sphagnums S.G. Navashin demonstrated, that microspores of these mosses in fact are spores of smut fungus Tilletia sphagni, described also as new for science species. At the same time S.G. Navashin collected intensively mycological material at different regions of Russia. He revealed some interesting fungi species, including Gymnosporangium tremelloides and Puccinia wolgensis, described from feather grass as new species of rust fungi.

In 1889 S.G. Navashin moved to St Petersburg University as an assistant of Professor I.P. Borodin. Here he continued to read the course "Introduction to fungi systematics". Removing to St Petersburg became very important for S.G. Navashin because he made the acquaintance with outstanding Russian mycologist M.S. Voronin. Due to Voronin' advice S.G. Navashin drew his attention to two mycological objects: fungi of genus Sclerotinia on plants of the genus Vaccinium and the slime mould Plasmodiophora brassicae - agent of club root of cabbage. Since 1893 S.G. Navashin began to investigate Sclerotinia on alder-tree, rhododendron and, especially thoroughly, on birch. He described all stages of the development of Sclerotinia betulae on catkins of birch, from peculiarities of structure of mature pyrenocarp to germination of sclerothecium by apothecia early spring with description in details of morphology and anatomy of disk and stalk of apothecium. S.G. Navashin conducted experiments on artificial contamination of healthy seed-bud of the birch by ascospores of S. betulae. Since these experiments had not produced positive effect, S.G. Navashin concluded that S. betulae has saprotroph phase, after which contamination of healthy seed-bud of the birch take place. On the basis of materials, collected at the beginning of summer, S.G. Navashin proved the fact of initialization of pistil tissues by fungi hyphas with subsequent penetration into ovary. On numerous sections S.G. Navashin demonstrated that S. betulae, as a genuine parasite, does not kill the ovary before their complete forming. In 1894 S.G. Navashin conferred the degree of Master of Botany for his investigations of developmental history of S. betulae.

In 1894 S.G. Navashin headed the Chair of Morphology and Systematics of Plants of St Vladimir University in Kiev. There he began to study thoroughly Plasmodiophora brassicae and described vegetative stage of this intracellular parasite and its sporogenesis. S.G. Navashin for the first time concentrated his attention on cytology of sporogenesis, in particular determined the phenomenon of simultaneous nuclei division in plasmodium of P. brassicae. Studying the relationships between parasite and host-plant S.G. Navashin demonstrated for the first time, that protoplasm of cabbage cells, affected by amoebas of slime mould, remains viable (about this kinetic division of nucleus indicates). Amoebae of parasite concentrate around nucleus of the cell of host-plant and together with his neogenic nuclei pass to new health cells. This observation of S.G. Navashin disproved assertion on settling of P. brassicae amoebae by dint of crawling over.

After discovery of double fertilization in angiosperms, which did credit to S.G. Navashin (1898), he dedicated himself to embryological and karyological investigation of higher plants. But mycology always remains in a sphere of his scientific interests. So, 21 from 105 works of S.G. Navashin are devoted to different questions of fungi biology, morphology and cytology. In 1913 because of the state of his health S.G. Navashin moved from Kiev to Tiflis. In 1923 he was invited to Moscow to the post of director of Timiriazev Institute.

S.G. Navashin died in December 1930. Scientific achievements of S.G. Navashin, including such in the field of mycology, were highly appreciated by colleagues all over Russia and abroad. In 1901 he was elected the corresponding member of Russian Academy of Sciences and German Botanical Society, honorary member of Vienna Zoological and Botanical Society. In 1904 Russian Academy of Sciences rewarded him the first Ber Premium. In 1907 S.G. Navashin was elected honorary member of German Botanical Society, in 1908 - corresponding member of Bavarian Academy of Sciences, in 1911 - foreign member of London Linnaean Society (UK), in 1917 - full member of Russian Academy of Sciences and ordinary member of Uppsala Academy of Sciences (Sweden) and in 1925 - corresponding member of American Botanical Society.

Lists. Taxa. Kirk & Ansell form of name: Navashin.

Sergei Gavrilovich Navashin

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