F.F. Fortunatov’s Concept about the Parts of Speech in the Russian Language

The article explores  the role of F.F. Fortunatov’s  concept about parts of speech  in the development of the 20th-century grammatical theory.  The author analyses  principles of classifying Parts of Speech  proposed by Fortunatov. A particular attention is paid to the form of the word as a basis for the classification of Parts of Speech in Indo-European languages. The article considers  the viewpoints  of both opponents and supporters of Fortunatov’s  classification as applied to the Russian language.