Within the project “Creators” supported by Richard Lounsbery Foundation T-invariant together with RASA (Russian-American Science Association) continues to publish a series of biographical essays about people from Russian Empire, who made a significant contribution to world science and technology. Alexander Petrunkevitch was born in the Chernigov Governorate, but most of his life he worked at Yale University. He became especially famous for his research on arachnids.