Dmitrii Iosifovich Ivanovskii

Born Oct. 28 (Nov. 9), 1864, in the village of Nizy, in present-day Leningrad Oblast; died Apr. 20, 1920, in Rostov-on-Don. Russian plant physiologist and microbiologist; founder of virology. Student of A.S. Famintsyn.

Ivanovskii graduated from the University of St. Petersburg in 1888. He was subsequently an assistant at the Botanical Laboratory of the St. Petersburg Academy of Sciences (from 1890), a lecturer at the University of St. Petersburg (1895–1901), and a professor at the University of Warsaw (1901–15) and Don University (from 1915). He began to study tobacco diseases in southern Russia in 1887, distinguishing between wildfire and mosaic diseases. He showed (1892) that the causal agent of mosaic disease, unlike bacteria, was invisible even when magnified as greatly as possible by the microscope, that it permeated porcelain filters, and that it did not grow on ordinary nutrient media. He discovered crystalline inclusions (Ivanovskii’s crystals) in the cells of diseased plants, thus revealing nonbacterial and nonprotozoan disease agents, which were subsequently called viruses. Ivanovskii considered them to be the smallest living organisms. He also published works on the characteristics of the physiological processes in diseased plants, on the effect of oxygen on alcohol fermentation in yeasts, on chlorophyll in plants and its resistance to light, on the significance of carotene and xanthophyll, and on soil microbiology.