President from 1941 to 1955, he was heading Department of Zoology for 20 years. An energetic member of the Society, commonly known protistologist, zoologist, expert in comparative anatomy of invertebrates. The founder of classical parasitology, the head of two large scientific schools (of protistology and parasitology). The author of a number of fundamental textbooks for high school. In the midst of "Lysenkoism" he held a plenary meeting of the Society to criticize the ideas of Lysenko. Head of the Department of Invertebrate Zoology at the University of Leningrad.