sentences:  While in Leningrad, Filipchenko contracted streptococcal meningitis and later died at midnight between May 19 and May 20, 1930.His head was donated to Bekhterev’s Brain Institute for research, while the rest of his remains were buried in Smolensky Cemetery.In his 1927 German text "Variabilität und Variation", Filipchenko introduced the idea of two separate forms of evolution