 In the summer of 1871, the circle of Natanson merged with a female self-education circle of Alexandra Kornilova and Sophia Perovskaya.Soon, they were joined by Peter Kropotkin, Sergei Stepnyak-Kravchinsky, Dmitry Klements, Sergei Sinegub, Nikolai Charushin, Leonid Shishko, and others.The central Petersburg circle comprised around 60 people.